Plate cleaning apparatus and cleaning roller therefor

A plate cleaning apparatus comprising a pair of cleaning members disposed above and beneath a passageway of the plate, a first pair of nozzles and a second pair of nozzles for emitting high speed clean air streams, a clean zone for supplying low speed clean air, and feed rollers for advancing the plate. A cleaning roller comprising a plurality of thin discs of nonwoven fabric bonded side by side with adhesive, and a longitudinal shaft extending through central holes in the thin discs is particularly suited for the cleaning members.

BACKGROUND OF THE INVENTION 
This invention relates to a plate cleaning apparatus and a cleaning roller 
therefor both arranged in a production line of miscellaneous plates such 
as resin plate, glass plate and printed circuit plate. 
A conventional plate cleaning apparatus for removing dust from a surface of 
a plate is provided with a cleaning roller and air stream supplying 
nozzles. In Japanese patent public disclosure No. 230390/86 issued on Oct. 
14, 1986, there is disclosed a dust eliminating apparatus for printed 
circuit plates employing a roller brush, air supplying nozzles and a dust 
eliminating ion generator. 
The plate cleaning apparatus presently in use, however, is confronted with 
a problem that a swirl is produced nearby the surface of the plate thereby 
entraining a dust and directing it to the surface again. As a result, the 
dust is not effectively removed from the plate. Another problem is the 
fact that high speed air stream entraining a dust is exhausted from the 
apparatus, so that external air becomes contaminated by the dust. This is 
particularly a serious problem because this type of apparatus is often 
utilized in a clean room for processing electronic components. 
Another aspect of the present invention is directed to a cleaning roller 
utilized in above-described plate cleaning apparatus. A conventional 
cleaning roller comprises a longitudinal shaft, a rubber core wound around 
the shaft and a nonwoven fabric cylindrical cover for contacting with a 
plate. Such conventional roller has a drawback that a particle of dust 
tends to fall off the surface of the roller and sticks to the plate again. 
Another drawback is that the elasticity of the rubber core is so high that 
the nonwoven fabric is easily worn out and the life of the roller is 
considerably short. As the roller is worn out its surface becomes uneven, 
so that the plate is not evenly cleaned. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a plate cleaning 
apparatus which can diminish the swirl produced nearby the plate so as to 
prevent a dust from sticking to the plate again. 
It is another object of the present invention to provide a plate cleaning 
apparatus which can prevent a dust from leaving the apparatus so as to 
maintain the clean level of the external atmosphere. 
The foregoing and other objects of the invention are accomplished by 
providing a plate cleaning apparatus comprising a pair of cleaning means 
disposed above and beneath a passageway of the plate, a first pair of 
nozzles disposed above and beneath the passageway at the upstream side 
adjacent said cleaning means, said first pair of nozzles directing high 
speed clean air angularly forward along the moving direction of the plate, 
a second pair of nozzles disposed above and beneath the passageway at the 
downstream side adjacent said cleaning means, said second pair of nozzles 
directing high speed clean air angularly backward against the moving 
direction of the plate, a clean zone disposed immediately after the second 
pair of nozzles for supplying low speed or gentle breeze clean air, and 
feed rollers for advancing the plate disposed outside an area between said 
first pair of nozzles and said second pair of nozzles. All of the high 
speed clean air and low speed or breeze clean air are circulated by a 
blower and passed through a high efficiency particulate filter (referred 
as "HEPA filter" hereinunder). Each cleaning means is accommodated within 
a suction chamber leading to the HEPA filter. 
Accordingly, the high speed air streams are directed to the plate and 
cleaning means, and then introduced into the suction chambers leading to 
the HEPA filter, whereby the dust leaving the plate does not return to the 
plate. Since the plate goes out the apparatus through the clean zone, the 
majority of the dust is not emitted from the apparatus. 
It is a further object of the present invention to provide a cleaning 
roller adapted for use in a plate cleaning apparatus in such a way that a 
roller can eliminate the drawbacks of prior art. 
The above object of the invention is accomplished by providing a cleaning 
roller comprising a plurality of thin discs of nonwoven fabric bonded side 
by side with adhesive therebetween, said adhesive having substantially the 
same softness before it is applied to the nonwoven fabric, and a 
longitudinal shaft extending through central holes provided in said thin 
discs. The shaft and the nonwoven fabric are bonded together by the 
adhesive. Thus, the cleaning roller of the invention maintains its 
softness and continuously provides even cleaning surface while in use. 
Other objects, features and advantages of the invention will become 
apparent from a reading of the specification, when taken in conjunction 
with the drawings, in which like reference numerals refer to like elements 
in the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 to 5, there is shown a plate cleaning apparatus which 
embodies one form of the invention. The apparatus includes a housing 30, a 
pair of cleaning rollers 11 disposed above and beneath a passageway of a 
plate 10, a first pair of nozzles 12 disposed above and beneath the 
passageway at the upstream side adjacent the cleaning rollers 11, a second 
pair of nozzles 13 disposed above and beneath the passageway at the 
downstream side adjacent the cleaning rollers 11, a clean zone 14 disposed 
immediately after the second pair of nozzles 13, and a plurality of feed 
rollers 15 for advancing the plate 10. The first pair of nozzles 12 emits 
high speed clean air stream G angularly forward along the moving direction 
R of the plate 10, and the second pair of nozzles 13 emits high speed 
clean air stream H angularly backward against the moving direction of the 
plate 10. The clean zone 14 is filled with low speed or gentle breeze 
clean air and a portion of the air flows out from the outlet 18. All the 
feed rollers 15 are disposed outside an area between the first pair of 
nozzles 12 and the second pair of nozzles 13. The high speed clean air and 
the gentle breeze clean air are circulated by a turbo blower 20 and are 
passed through a HEPA filter 22. The cleaning rollers 11 are accommodated 
within suction chambers 24 and 25 which are connected to the HEPA filter 
22 through hose ducts 72 and 73 (FIG. 5). 
In FIG. 1, there are shown several attachments such as castors 43 for 
carrying the apparatus, level adjustors 44 for controlling the horizontal 
level of the apparatus, and an operating panel with switchboard 45. An 
adjusting mechanism 76 for controlling the distance and clearance between 
the cleaning rollers 11 is connected to each shaft 19 of the rollers 11. 
If an operator rotates a handle 79, a screw rod 78 moves up and down by 
means of a worm gear mechanism thereby adjusting the distance between the 
rollers 11. The cleaning rollers 11 are driven by a variable speed motor 
61, and feed rollers 15 are driven by a variable speed motor 62. The hose 
ducts 72 and 73 communicate with a junction chamber 74 which leads to the 
turbo blower 20. A hose duct 63 is connected between the turbo blower 20 
and a plenum chamber 64 which is assembled to the HEPA filter 22 by way of 
a prefilter 65 (FIG. 3). At the downstream side of the HEPA filter 22 a 
distribution chamber 67 is assembled for supplying new clean air to hose 
ducts 68 and 69. 
In FIG. 2, there is shown a beam switch 52 which detects an entering of the 
plate 10 into the apparatus. In this embodiment six pairs of feed rollers 
15 are disposed along the passageway of the plate 10. Between the first 
pair of feed rollers and the second pair of feed rollers a static 
electricity eliminating brush 52 is disposed so as to prevent an 
electrostatic charge from being loaded on the plate 10. The brush 52 
contacts with lateral edges of the plate 10 and removes particles of dust. 
Between the fifth pair of feed rollers and the sixth pair of feed rollers 
15, a pair of corona discharge electrodes 59 are disposed so as to prevent 
an electrostatic charge from being loaded on the plate 10. 
In FIG. 3, the distribution chamber 67 is provided with an exhausting hole 
75 and a heater 77 for preheating the emitting air so as to prevent a 
temperature of the plate from going down. 
In FIG. 4, outside the suction chambers 24 and 25 air supply chambers 53 
and 55 are arranged so as to provide air toward the first and second pairs 
of nozzles 12 and 13. The clean zone 14 is divided into a central clean 
chamber 71 and expansion chambers 57 which are provided with expansion 
holes 70 at the wall thereof. 
FIG. 5 shows air flow directions in the first embodiment of the invention. 
All elements contained in FIG. 5 are illustrated in FIGS. 1 to 4. 
The operation of the apparatus of the first embodiment is described 
following particularly with reference to FIG. 4. 
A plate 10 to be cleaned is admitted into the housing 30 of the apparatus 
along the direction R. When the plate passes through the inlet portion of 
the housing 30 the beam switch 42 detects the entering of the plate and 
the variable speed motors 61 and 62 start in motion whereby the rollers 11 
and 15 are driven to the direction u. 
First, the lateral edges of the plate 10 are rubbed by the brush 52 and 
particles of dust sticking to the edges are removed. 
The high speed air emitting nozzles 12 are inclined at 45 degrees angle 
relative to the plate 10, and from the nozzles high speed air streams G at 
a velocity of about 80 meters per second are directed to the surfaces of 
the plate thereby blowing away the dust off the plate. At the same time, 
additional air g having a volume of 20 percent of the air stream G is 
induced from the upstream side of the plate 10. 
Then, the plate 10 reaches the cleaning rollers 11 which are rotating at a 
circumferential tangential speed faster than that of the feed rollers 15, 
so that a relative speed is effected between the surface of the cleaning 
rollers 11 and that of the plate 10. Thus, the surfaces of the plate 10 
are rubbed by the cleaning rollers 11 and particles of dust sticking to 
the surfaces are removed. It is preferable to select and determine the 
rotating speed of the rollers 11 and 15 so as to obtain most effective 
results corresponding to the kind of the plate. If a thickness of the 
plate varies, the contact pressure between the cleaning roller and the 
plate changes thereby causing a fluctuation of cleaning results. In 
response to the case, an operator can control the distance and clearance 
between the cleaning rollers 15 through a manual handling of the adjusting 
mechanism 76 (FIG. 1). 
While the plate 10 passes through the cleaning rollers 11, high speed air 
streams H at a velocity of about 80 meters per second are directed to the 
surfaces of the plate from the nozzles 13 which are inclined at 45 degrees 
angle relative to the plate 10, thereby blowing away the dust off the 
plate. At the same time, additional air h having a volume of about 20 
percent of the air streams H is induced from the downstream side of the 
plate 10. These high speed air streams G and H together with the induced 
air g and h are introduced into the suction chambers 24 and 25, and then 
supplied to the junction chamber 74 by way of the hose ducts 72 and 73 
(FIG. 5). The junction chamber 74 is connected to the blower 20 which 
advances the air stream through the plenum chamber 64, prefilter 65, HEPA 
filter 22 and distribution chamber 67. After the distribution chamber 67, 
air stream is divided into two streams toward passages 68 and 69, and then 
two air streams are supplied into the air supply chambers 53 and 55 which 
include the high speed air nozzles 12 and 13. 
A portion of the air admitted into the suction chambers 24 and 25 enters 
into the expansion chambers 57 through the expansion holes 70 at a 
velocity of substantially the same as the air stream emitted from the 
nozzles 12 and 13, and then becomes a gentle breeze at a velocity of about 
0.5 meter per second on account of expansion and divergence. The gentle 
breeze advances from the expansion chambers 57 to the clean chamber 71, 
but a portion of the gentle breeze is exhausted from the outlet 18 of the 
housing 30. If the apparatus is accommodated within a clean room, it is 
not inconvenient for external air to be admitted into the housing 30 from 
the outlet 18. The air introduced into the clean chamber 71 becomes the 
air stream h, which is induced by the high speed air stream H and directed 
toward the cleaning rollers 11. On the other hand, a portion of an 
entering air stream I becomes the air stream g which is induced by the 
high speed air stream G and directed toward the cleaning roller 11. 
It would be easily understood from FIG. 5 that an exhaust air stream EX1 
going out of the distribution chamber 67 through the hole 75 and an 
exhaust air stream EX2 going out of the housing 30 through the outlet 18 
permit external air to admit into the housing 30 based upon the balance of 
air volume. If the exhaust air EX1 is not prepared, there is a possibility 
that the induced air streams g and h cause a countercurrent flow due to a 
lack of escaping air volumes. Accordingly, it is relatively important to 
locate the exhausting hole 75 at the wall of the distribution chamber 67. 
Because the entering air stream I is accelerated by the induced air stream 
g, an intermediate speed duct is formed immediately before the nozzle 12, 
so that an air escaping problem in prior art that a portion of the high 
speed air stream after blowing away the dust off the plate escapes from 
the housing and contaminates external atmosphere can be effectively 
prevented. A countercurrent flow of the dust is not produced and the dust 
is introduced into the suction chambers 24 and 25 with the aid of moving 
energy of the air stream for the nozzle 12. At the downstream side of the 
plate 10, the induced air stream h is flowing from the clean chamber 71 to 
the nozzles 13, so that a countercurrent flow of the dust toward the clean 
chamber and exterior can be effectively prevented. 
With the above arrangement utilizing the expansion holes, expansion 
chambers and induced air streams, there is no need for another fan or 
blower to produce a gentle breeze air flow. 
Since the cleaning rollers 11 and the high speed air nozzles 12 and 13 are 
disposed adjacent each other without feed rollers between them and a 
countercurrent flow is prevented by the induced air stream h, the dust 
circulation problem in prior art that a particle of dust removed by the 
cleaning roller circulates and sticks to the plate again can be 
effectively eliminated. 
Some kinds of plate tend to become charged with static electricity in the 
cleaning process. For the purpose of eliminating a sticking of a dust to 
the plate due to the static electricity, the corona discharge electrodes 
59 are disposed. Since a corona discharge electrode has a tendency of 
collecting a dust like an electrical dust collector, in the embodiment of 
FIG. 4, the corona discharge electrodes 59 are positioned within the clean 
chamber 71 which is filled with clean air passed through the HEPA filter. 
Thus, a sticking of a dust to the electrodes 59 is considerably 
diminished. Furthermore, the induced air flow h from the clean chamber 71 
contains an ionic flow after passing through the electrodes 59, so that 
the static electricities loaded on the cleaning rollers 11 and the plate 
10 are eliminated by the ionic flow, thereby the dust removing action 
being promoted. 
By reason of a productive process, some plates are admitted into the 
housing keeping at a heated condition. The plate cleaning apparatus, 
however, has a problem that a high speed air stream cools down the surface 
of the plate. In response to the problem, the heater 77 (FIG. 3) is 
disposed inside the distribution chamber 67 in such a way that the heater 
77 can raise the temperature of the air supplied to the high speed air 
nozzles 12 and 13. 
Several modifications of the apparatus are possible. The cleaning roller 11 
is preferably detachably mounted by the driving shaft 19 in such a way 
that an exchanging handling of a new roller or other cleaning parts can be 
easily completed. 
It is also preferable to make the feed roller 15 of a rubber material 
having electrical conductivity so as to provide an earth circuit for 
removing static electricity on the plate. 
FIG. 6 shows an air flow diagram of an alternative embodiment of the 
invention. In this arrangement, a pair of fixed cleaning brushes 80 having 
electrical conductivities are substituted for the cleaning rollers 11. 
Other elements in FIG. 6 are the same as in the first embodiment in FIGS. 
1 to 5. 
Another aspect of the present invention is directed to a new construction 
of the cleaning roller. In FIG. 7, the cleaning roller 90 of the invention 
comprises a plurality of thin discs of nonwoven fabric 91 bonded side by 
side with adhesive 93 therebetween, and a longitudinal shaft 92 extending 
through central holes provided in the thin discs. The adhesive 93 has 
substantially the same softness before it is applied to the nonwoven 
fabric 91. An example of such adhesive is a TYPE ML-20 made by Japan 
Vilene Co., Ltd. in Japan. The shaft 92 and the nonwoven fabric 91 are 
bonded together by the adhesive 93. 
FIG. 8 illustrates a sectional construction of the cleaning roller 90 
before it is used. It should be noted that there is no rubber core between 
the nonwoven fabric 91 and the shaft 92. Since there is no rubber core the 
whole surface of the roller 90 preserves the softness of the nonwoven 
fabric itself. As a result, when the roller contacts with a plate the 
friction therebetween is considerably diminished as compared with prior 
art. With the exception of the shaft 92, the roller 90 is composed of 
nonwoven fabric from its surface to the core, so that a thickness of the 
nonwoven fabric contributes to an extension of the life. Since the 
external surface is formed by a plurality of thin discs, there is an 
advantage that the dust sticking to the surface scarcely falls off. 
FIG. 9 illustrates a sectional construction of the cleaning roller 90 after 
it is used. As shown in this figure, the external surface is compressed 
and deformed, but the even cylindrical configuration is still maintained 
because only outer discs 94 are subjected to a buckling and inner discs 95 
can escape from the buckling. Therefore, even if another plate having a 
different width to be cleaned is supplied to the cleaning roller 90, a 
flat cleaning action is continuously maintained. 
While there have been shown and described preferred embodiments, it is to 
be understood that various other adaptations and modifications may be made 
within the skill of the art for use with particular applications, without 
departing from the spirit and scope of the invention.