Electricity: electrical systems and devices – Electric charge generating or conducting means – Modification of environmental electric charge
Reexamination Certificate
2001-05-21
2003-11-25
Berhane, Adolf D. (Department: 2838)
Electricity: electrical systems and devices
Electric charge generating or conducting means
Modification of environmental electric charge
C361S232000
Reexamination Certificate
active
06654225
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a static eliminator.
A conventional static eliminator has only a short flying distance of ions. In particular, an alternate current type of static eliminator has a very short flying distance of ions since plus ions and minus ions recombine to each other immediately after their generation. Therefore, the ions must be flied away by a blower. On the other hand, a direct current type of static eliminator can achieve a more flying distance to some extent. However, it merely reaches 70 cm at most. As a result, in actual use, sufficient effects of static elimination cannot be achieved because of lack of flying distance of ions.
As shown in
FIGS. 1 through 3
, the voltage in alternate current input is boosted to be discharged from discharge electrodes or needles
14
,
14
in a static eliminator
10
and the ions thus generated are directed by a fan
70
toward a body
74
to be statically eliminated. In this case, since the distance between the needles
14
,
14
are relatively short, the electric field on the electrodes is strengthened. As a result, corona discharge is more likely generated from the discharge needles.
As for one example,
FIG. 4
shows a situation in that the area where static electricity cannot be removed exists since the flying distance from the discharge electrode
14
is short and the ions do not reach the center area between the discharge electrodes
14
,
14
which are provided on power supply lines
12
,
12
.
As for another example,
FIG. 5
shows another situation in that static electricity is eliminated in a clean room for semiconductor production. Since the ions
20
issued from the static eliminator
10
provided on the ceiling
22
reach 1 meter at most from the ceiling
22
, static electricity cannot be eliminated from a person
24
, work
26
and the like.
As for a still another example,
FIG. 6
shows a still another situation in that the area where static electricity cannot be eliminated exists in the central portion between the static eliminators
10
,
10
provided in the gate
28
since the ions
20
do not reach. Therefore, the gate should be made narrow which results in inconvenience in actual use.
Thus, with conventional static eliminators, sufficient effects of static elimination cannot be achieved in a large area because of lack of flying distance of ions.
FIG. 16
shows a still another example of static eliminator. In
FIG. 16
, the static eliminator is of an alternate current type, and alternately issues plus ions
15
in a positive half cycle and minus ions
17
in a next negative half cycle from a discharge electrode
14
. Thus, the plus ions
15
and minus ions
17
issued from the discharge electrode
14
are, respectively, drawn back by the minus ions
17
and the plus ions
15
of opposite polarities and recombine them to disappear. Therefore, the static eliminator of this type cannot fly the issued ions away sufficiently.
Then, as shown in
FIG. 17
, a strong stream of air should be led around the discharge electrode
14
to prevent plus ions
15
and minus ions
17
from recombining to each other. Actually, unless the compressed air is used, or a blower or a fan is used to blow the discharge electrode
14
, the generated ions cannot be taken out.
However, this static eliminator has an advantage in that if stream of air is supplied, plus ions
15
and minus ions
17
always come out in the mixed state. Then, the mixing of ions is in a good condition and the distribution balance of ions is also in a good condition.
On the other hand, as shown in
FIG. 18
, in a direct current type of static eliminator, two discharge electrodes or needles
14
a
,
14
b
are separately provided for issuing plus ions
15
and minus ions
17
, respectively. Each of discharge needles issues ions of opposite polarity. In other words, the positive needle
14
a
issues plus ions and the negative needle
14
b
issues minus ions. Since each of discharge electrodes and the ions issued therefrom are of the same polarity, the ions are flied or pushed away by Coulomb's force. In other words, the ions
15
,
17
automatically flies away to diffuse through a long distance without use of the compressed air, blower or fan. Therefore, its obtained long flying distance is characteristic of the static eliminator of this type.
However, since the distribution of plus ions and minus ions differs in position, the distribution balance of ions is not good. In order to overcome this disadvantage, the polarity of each of the discharge electrodes is caused to reverse sequentially so that the ions are easily mixed as much as possible. However, in this case, since the ions coming later have opposite polarity, the ions first come out are drawn back by the later coming ions, which results in the short flying distance.
Moreover, since the ions of opposite polarities are issued from the two electrodes in the physically separate positions, the mixing of the ions is not attained more than that of one electrode. In other words, plus-tendency ion balance is generated near the plus electrode and minus-tendency ion balance is generated near the minus electrode. When the polarity is reversed and the period for cycle of reversal of polarity is long, the variation in balance of ions appears along time axis. In order to mix the ions completely, the period for cycle of reversal of polarity should be shortened. However, if do so, this static eliminator approaches the alternate current type of static eliminator. In such a case, the ions do not fly away.
Thus, conventional systems have its merits and demerits. There has been no perfect static eliminator which has long flying distance and good balance of ions unless the stream of air by blowers, etc is utilized.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a static eliminator which can extend flying distance of ions and can attain effects of static elimination through wide area sufficiently.
To accomplish the above-mentioned object, there is provided a direct current type of static eliminator which comprises one pair of discharge electrodes, one of said discharge electrode issuing ions while the other discharge electrode issues ions of opposite polarity.
In addition to the foregoing, the polarity of ions issued from each of the opposed discharge electrodes is caused to switch over to the opposite polarity. At that time, it is preferred that the switchover for each of discharge electrodes is made in timed relationship.
It is another object of the present invention to provide a static eliminator which can extend flying distance of ions without blowing of the discharge electrode by use of compressed air, blower or fan, suppress the variation in balance of ions in position, and suppress the variation in balance of ions along time axis.
To accomplish the above-mentioned object, there is provided a static eliminator which has a rotary ionizer or rotary ion issuing discharge electrodes.
It is a still another object of the present invention to provide an array type of static eliminator which can attain a more wide static eliminating space.
To accomplish the above-mentioned object, there is provided an array type of static eliminator in which more than three discharge electrodes are disposed and ions issued from adjacent discharge electrodes are of an opposite polarity.
REFERENCES:
patent: 5245503 (1993-09-01), Rodrigo
Berhane Adolf D.
Chong Leighton K.
Ostrager Chong & Flaherty (Hawaii)
Takayanagi Research Inc.
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