Apparatus and method for coating and drying paper sheets

Apparatus and method for coating lower surfaces of paper sheets with lacquer and drying the sheets include fans for simultaneously drying the sheets and for forcing the sheets upwardly against the lower surface of spaced-apart moving conveyer belts. The streams of air produced by the fans are directed upwardly against the paper sheets and against and through the conveyer belts, and the paper sheets are moved from a first location to a second location within the apparatus. Features provide for washing and cleaning the apparatus and for circulating the lacquer to keep the lacquer in a uniform mixed state.

BACKGROUND OF THE INVENTION 
This invention relates to sheet coating and drying apparatus and more 
particularly to paper sheet coating and drying apparatus which uses a 
simple and efficient configuration for coating the lower surfaces of paper 
sheets with lacquer or other coating liquid and which then efficiently 
uses air streams created by fans to simultaneously dry the lower surfaces 
of the coated paper sheets while holding or supporting the paper sheets 
upwardly against a conveyer as the paper sheets pass through the 
apparatus. 
When one side of paper sheets, such as photographic paper sheets, are to be 
coated with a liquid, such as lacquer, it is most efficient to provide the 
coating liquid to the paper sheets from below the paper sheets so that the 
lower sides of the sheets are the sides that are coated. This is true 
because it is more difficult and less efficient to handle and move a 
coating liquid in a manner relative to the sheets so that the top surfaces 
of the sheets are coated. Applying a coating liquid to the tops of the 
sheets requires more complicated mechanisms than are required for coating 
the lower surfaces of the sheets. 
When the lower sides of sheets are coated, however, drying of the lower 
sides of the sheets becomes difficult with known coating and drying 
machines. This is because the lower, wet sides of the sheets cannot be 
permitted to contact a conveyer or any other structure used to transport 
the sheets through the machine or to eject the coated sheets from the 
machine until the sheets are dried. 
Various types of coating machines are known for use in coating and drying 
paper sheets. However, none of the known machines use gas or air streams 
for simultaneously drying lower surfaces of the paper sheets and for 
supporting the paper sheets as the sheets pass through the machine. Also, 
known machines have not proved entirely satisfactory under all conditions 
of service because it is often difficult to maintain uniformity in the 
lacquer mixture used to coat the paper during the coating process and it 
is often difficult and time-consuming to clean lacquer from the internal 
working mechanisms of the machines. 
It is, therefore, an object of the present invention to provide an 
apparatus and method for coating and drying paper sheets. 
Another object is to provide such an apparatus and method which efficiently 
uses the force of air generated by fans to simultaneously dry the paper 
sheets and to support the paper sheets against a conveyer as the sheets 
are transported through the apparatus. 
A further object of the invention is the provision of such an apparatus and 
method which recirculates lacquer or coating liquid to maintain uniformity 
of the lacquer or coating liquid during operation of the apparatus. 
Still another object is to provide such an apparatus and method which 
includes a simple and expedient configuration for quickly and easily 
washing and cleaning internal parts of the apparatus which become covered 
with lacquer or other coating liquid. 
Another object is to provide such an apparatus and method which coats lower 
sides of paper sheets, such as photographic paper sheets, and which 
simultaneously dries the paper sheets and supports the paper sheets by use 
of air streams as the sheets move through the apparatus. 
Additional objects and advantages of the invention will be set forth in 
part in the description which follows, and in part will be obvious from 
the description, or may be learned by practice of the invention. The 
objects and advantages are realized and attained by means of the 
instrumentalities and combinations particularly pointed out in the 
appended claims. 
SUMMARY OF THE INVENTION 
To achieve these and other objects the present invention provides sheet 
coating and drying apparatus, comprising: first means for receiving and 
coating the sheet with a coating liquid and for moving the sheet to a 
first location; gas stream permeable sheet conveyer means positioned for 
receiving the sheet from the coating and moving means at the first 
location and for conveying the sheet in a first direction to a second 
location; second means in operative relationship with the conveyer means 
for supplying and directing gas streams between the first and second 
locations and from beneath and against the sheet and from beneath and 
through the conveyer means for pressing and holding the sheet upwardly 
against the conveyer means and for drying the sheet; and third means at 
the second location in operative relationship with the conveyer means and 
with the second means for receiving the sheet from the conveyer means and 
for ejecting the sheet from the apparatus. 
The invention also provides means for washing and cleaning internal parts 
of the apparatus, and means are also provided for automatically 
circulating the lacquer or coating liquid during operation of the 
apparatus to maintain the lacquer or other coating liquid in a uniform 
state. 
It is to be understood that both the foregoing general description and the 
following detailed description are exemplary and explanatory but are not 
restrictive of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference now to the drawings, wherein like reference characters 
designate like or corresponding parts throughout the several views, there 
is shown sheet coating and drying apparatus 10. Apparatus 10 includes 
first means, generally shown at 12, for receiving and coating a lower 
surface 15 of a sheet or sheets 14 with a coating liquid 16 and for moving 
sheet 14 to a first location 18. 
Gas stream permeable sheet conveyer means 20 are positioned for receiving 
sheet 14 from coating and moving means 12 at first location 18 and for 
conveying sheet 14 in a first direction 21 to a second location 22. 
Fans or second means 24 are provided in operative relationship with 
conveyer means 20 for supplying and directing air or gas streams between 
first and second locations 18, 22 and from beneath and against lower 
surface 15 of sheet 14 and from beneath and through conveyer means 20 for 
pressing and holding sheet 14 upwardly against conveyer means 20 and for 
simultaneously drying lower surface 15 of sheet 14. 
Third means 26 are provided at second location 22 for receiving sheet 14 
from conveyer means 20 as the sheet is supported by air streams from fans 
24 and for ejecting the sheet from apparatus 10. Third means 26 preferably 
includes opposed rollers 28, 28' through which sheet 14 passes, and 
rollers 28, 28' move sheet 14 in substantially first direction 21 to eject 
sheet 14 from apparatus 10. 
Conveyer means 20 preferably includes a plurality of spaced-apart conveyer 
belts 30, and conveyer belts 30 are positioned for receiving sheet 14 
against and beneath the conveyer belts. 
Fans or second means 24 supply and direct air streams upwardly and 
substantially continuously along conveyer belts 30 between first and 
second locations 18, 22 to hold sheet 14 upwardly against and beneath 
conveyer belts 30 between locations 18 and 22. 
In accordance with the invention, first means 12 include an open-topped 
container 32 for holding coating liquid 16. First means 12 further include 
a first roller 34 defining a first axis 34', and roller 34 is positioned 
with respect to container 32 for depositing coating liquid 16 onto roller 
34 as roller 34 rotates about its axis 34'. 
First means 12 further include a second roller 36 defining a second axis 
36', and roller 36 is positioned to receive liquid 16 from first roller 34 
as rollers 34 and 36 rotate about their respective axes. A third roller 38 
defining a third axis 38' is positioned in cooperation with second roller 
36 for receiving sheet 14 between rollers 36 and 38. Means 40 (FIG. 2) are 
provided which are connected with rollers 34, 36 and 38 for turning the 
rollers about their respective axes. 
A scraper or squeegee 41 positioned against roller 38 scrapes the lacquer 
or coating liquid on roller 38 and a supporting roller 43 can be provided 
for assisting the feeding of sheets 14 into apparatus 10. 
Conveyer means 20 preferably include a first, driving wheel 42 defining a 
fourth axis 42'. Conveyer means 20 further include means 40 connected to 
driving wheel 42 for turning the driving wheel about its axis. Conveyer 
means 20 further include a second, idler wheel 44, and conveyer belts 30 
are connected between driving wheel 42 and idler wheel 44. Of course, 
wheel 44 could be a driving wheel and wheel 42 could be an idler wheel. 
In accordance with the invention, apparatus 10 also includes means 
generally indicated at 46 for selectively washing and cleaning rollers 34, 
36, 38 and container 32. Washing and cleaning means 46 include means 48 
positioned adjacent to rollers 34, 36, 38 for spraying a cleaning liquid, 
such as water, over and around the rollers. Cleaning means 46 also include 
a cleaning liquid supply conduit 50 and a first conduit 52 connected 
between supply conduit 50 and spraying means 48 for passing the cleaning 
liquid to spraying means 48 from supply conduit 50. Cleaning means 46 
further include a first valve 54 and a second valve 56 connected to supply 
conduit 50 and to container 32 for controlling flow of the cleaning liquid 
through supply conduit 50 to container 32. 
In accordance with the invention, washing and cleaning means 46 further 
include a first drain conduit 58 connected to valve 54, a third valve 60 
connected to first conduit 52 for controlling flow of the cleaning liquid 
through conduit 52 to spraying means 48, and a second drain conduit 62 
connected to container 32 for draining the cleaning liquid from container 
32 when the cleaning liquid level within container 32 reaches a first 
predetermined level. 
Apparatus 10 preferably also includes fourth means generally shown at 64 
connected with container 32 for automatically removing coating liquid 16 
from container 32 and for returning the coating liquid to container 32 to 
maintain the coating liquid in a state of recirculation through container 
32. 
In accordance with the invention, fourth means 64 include a reservoir 66 
for holding coating liquid 16. A third drain conduit 68 is connected 
between container 32 and reservoir 66 for draining coating liquid 16 from 
container 32 to reservoir 66 when the coating liquid reaches a 
predetermined level within container 32. A fourth valve 70 is connected to 
drain conduit 68 for controlling the flow of coating liquid through drain 
conduit 68. A fourth conduit or pipe 72 is connected between reservoir 66 
and valve 56, and a liquid pump 74 is connected to fourth conduit 72 for 
pumping coating liquid 16 from reservoir 66, through conduit 72, through 
valve 56 and into container 32 so that coating liquid 16 can be 
recirculated into, through and out of container 32 to maintain the coating 
liquid in a uniformly mixed condition. 
Drain conduit 62 is positioned in container 32 to act as an overflow drain 
so that cleaning liquid can approach the upper margins of container 32 
before being drained from the container. In this manner, container 32 can 
be thoroughly cleaned. 
A cleaning liquid or water supply valve 76 is provided within supply 
conduit 59 for controlling the supply of water or cleaning liquid to 
apparatus 10. Also, a safety valve 78 is preferably connected to conduit 
72 and between pump 74 and valve 56 for controlling the flow of coating 
liquid 16. 
Valves 54, 56 are each conventional two-way valves which direct liquid flow 
in ode of two directions through the valves depending upon the positions 
of the valves. Valves 60, 70, 76 and 78 are each conventional on/off 
valves. 
In accordance with the invention, apparatus 10 also includes control means 
40 (FIG. 2) connected to rollers 34, 36, 38, to conveyer means 20, to fans 
or second means 24, to valves 54, 56, 60, 70, 76 and 78 and to pump 74 for 
controlling the operation of apparatus 10. Controlling means 40 may be a 
microprocessor, for example, and a flow diagram showing operation of 
apparatus 10 and the microprocessor is illustrated in FIG. 3. 
Coating liquid 16 is preferably a water-based lacquer, and the cleaning 
liquid used is preferably water. However, it should be understood that 
this invention contemplates the use of different coating liquids and 
different cleaning liquids. 
In operation and use of apparatus 10, paper sheets 14, such as photographic 
paper sheets, are fed over supporting roller 43 and between rollers 36, 
38. Lacquer or other coating liquid 16 is transferred from roller 34 as it 
rotates about its axis 34' to roller 36 as it rotates about its axis 36'. 
The lacquer or other coating liquid is applied from roller 36 to lower 
surfaces 15 of sheets 14 as the sheets pass separately through and between 
rollers 36, 38. 
As sheet 14 emerges from between rollers 36, 38, the force of air streams 
directed upwardly by fans 24 against lower surface 15 of sheet 14 acts to 
force sheet 14 upwardly and against conveyer belts 30. The upwardly 
directed air streams are provided continuously along the path of travel of 
sheet 14 between locations 18 and 22 so that sheet 14 is constantly forced 
upwardly against conveyer belts 30 as the belts move in direction 21. 
The upward force of air from fans 24 also continues to support sheet 14 for 
the short distance between conveyer belts 30 as they pass around wheel 44 
and second location 22. As a result, each sheet 14 is directed between 
driven rollers 28, 28' which engage sheet 14 and continue to transport the 
sheet substantially in direction 21 to eject the sheet from apparatus 10. 
A collector or other support, not shown, can be used to receive and 
collect the ejected sheets. 
As sheets 14 move along beneath conveyer belts 30, the air streams 
generated by fans 24 simultaneously support sheets 14 and dry lower 
surfaces 15 of the sheets as the sheets pass from first location 18 to 
second location 22. 
This invention specifically contemplates the use of water soluble lacquer 
16 to coat photographic paper sheets 14. Because of the nature of the 
lacquer and because additional small amounts of water may be added to the 
lacquer as a result of the washing and cleaning process, which will be 
explained hereinafter, it is advantageous to circulate lacquer 16 during 
operation of apparatus 10 to maintain the lacquer in a uniformly mixed 
condition. This mixing is accomplished by use of reservoir 66 in 
cooperation with liquid pump 74. During operation of apparatus 10, 
controlling means 40 is programmed or otherwise configured to open valves 
70, 78 and to position two-way valve 56 so that lacquer 16 is drained from 
container 32 through drain conduit 68 and through valve 70 into reservoir 
66. Pump 74 then pumps the lacquer from reservoir 66 through conduit or 
pipe 72, through valve 78 and through valve 56 into container 32. This 
circulation of lacquer can continue during operation of apparatus 10, or 
controlling means 40 can be programmed to circulate the lacquer in the 
manner described for predetermined periods of time. 
During usage of apparatus 10, lacquer can build up and collect on rollers 
34, 36 and 38 and within container 32. In order to maintain the rollers 
and container 32 in optimum operating condition, it is desirable to wash 
and clean the rollers and the container to prevent the undesirable 
build-up of lacquer. This invention provides a simple and efficient 
configuration for washing and cleaning the rollers and the container 
without requiring the cumbersome and time-consuming removal of the rollers 
or the container from the apparatus. 
The washing and cleaning process is preferably controlled by control means 
40 (FIG. 2) which includes motor 47. Pump 74, motor 47 and fans 24 are 
turned off and valve 70 is closed to permit lacquer or other coating 
liquid 16 located within container 32 to drain through valve 56, through 
valve 78, through pump 74 and into reservoir 66. Container 32 is 
configured so that the lowest portion 33 (FIG. 2) of the container permits 
substantially all of the lacquer to drain from container 32 and into 
reservoir 66. 
After a predetermined period of time sufficient to allow container 32 to be 
completely drained of lacquer, controlling means 40 then acts to close 
valve 78 and to open valves 60 and 76 so that water or other cleaning 
liquid passes through valve 76, through conduit 52, through valve 60 and 
out through spraying nozzles 48 for a predetermined period of time. Motor 
47 will also be turned on high speed. Nozzles 48 are positioned to direct 
steams of water or other cleaning liquid over, against and around rollers 
34, 36 and 38 as the rollers are turned at high speed by motor 47. 
Controlling means 40 also act to position two-way valves 54 and 56 so that 
water or other cleaning liquid will flow from supply conduit 50, through 
valves 54, 56 and into container 32. The water or other cleaning liquid 
will rise upwardly within container 32 to clean lacquer from the interior 
of the container, and the water or other cleaning liquid will drain from 
container 32 through overflow drain line 62 when the water or other 
cleaning liquid reaches a predetermined level within container 32. 
This washing step will continue for a predetermined time and then 
controlling means 40 will act to close valves 60 and 76 and valve 54 will 
be repositioned to permit container 32 to drain through drain pipe 58. 
Valve 54 will then be repositioned by controlling means 40 and valves 60, 
76 will be opened to allow another washing to take place. This washing and 
draining cycle can be repeated as determined by controlling means 40. 
Any overflow of water or cleaning liquid from container 32 and any run off 
from spray nozzles 48 not collected by container 32 will be collected 
within overflow container 80, which will be drained through drain pipe 82. 
Controlling means 40 will then close valves 60 and 76 and will turn off 
motor 47 for a predetermined time period. Valve 76 can then be reopened 
and motor 47 can be turned on for a period of time to further clean 
container 32 and rollers 34, 36 and 38. Valve 76 will then be closed and 
motor 47 will be turned off. 
When it is desired to apply lacquer to sheets 14, controlling means 40 will 
position two-way valve 54 so that water or other cleaning liquid will 
drain from container 32, through valve 56, through valve 54 and through 
drain conduit 58. This draining process will continue for a predetermined 
time, as determined by controller 40. 
When apparatus 10 is again ready to be used to coat sheets 14, controller 
40 activates motor 47 and positions two-way valve 56, opens valves 70, 78 
and activates pump 74 so that lacquer or other coating liquid 16 is again 
circulated from reservoir 66 and through container 32, as previously 
described. The speed of motor 47 can also be manually controlled in a 
conventional manner to control the speed of sheets 14 as they move through 
apparatus 10. 
A preferred example of a flow diagram or operating sequence for apparatus 
10 and for controller 40 is shown in FIG. 3, and it is preferred that 
controller 40 include a microprocessor 45 and motor 47. Microprocessor 45 
will be connected in a conventional manner to control action of motor 47, 
and microprocessor 45 will also be electrically connected in a 
conventional manner to control the operation of pump 74 and valves 54, 56, 
60, 70, 76 and 78. Electrical control of valves and pumps is well known 
and is not described in detail herein. Alternatively, the operation of 
apparatus 10 and the control of pump 74 and valves 54, 56, 60, 70, 76 and 
78 could be manually controlled. Motor 47 is connected through 
conventional gearing, not shown, to control movement of rollers 28, 28', 
34, 36, 38, 43 and to control movement of wheels 42, 44 of conveyer belts 
30. 
For the purpose of interpreting the flow diagram of FIG. 3, the following 
table identifies the elements of apparatus 10 shown in FIGS. 1 and 2 and 
correlates those elements with the terms used in FIG. 3. 
______________________________________ 
Controlled Elements 
______________________________________ 
V Lacquer return = valve 70 
V H.sub.2 O = valve 76 
V Wash/drain = valve 54 
P Lacquer = pump 74 
V Lacquer = valve 78 
V Wash/lacquer = valve 56 
V Spray = valve 60 
Fans on/off = fans 24 
Motor high/low = motor 47 
Motor on/off = motor 47 
______________________________________ 
This invention provides for an efficient apparatus and method for 
simultaneously coating lower surfaces of paper sheets, such as 
photographic paper sheets, with lacquer and drying the sheets with fans 
wherein the fans simultaneously dry the paper sheets and cooperate with 
conveyer belts to support the sheets and transport the sheets through the 
apparatus. The invention also provides a configuration for circulating the 
lacquer or cleaning liquid to keep the lacquer in a uniform mixed state, 
and structure is provided for quickly and easily washing the apparatus 
without requiring any disassembly. 
The invention in its broader aspects is not limited to the specific details 
shown and described, and departures may be made from such details without 
departing from the principles of the invention and without sacrificing its 
chief advantages.