Abstrict A cover for a desiccant dispenser is mounted over an opening of
a bucket-shaped container containing a plurality of desiccant bags.
The cover includes a hard main plate having a taking-out bore for
insertion of a hand to take out the desiccant bags, and one elastic
plate mounted on the main plate to cover the taking-out bore and
having a plurality of cuts arranged radiately to permit the insertion
and withdrawal of the hand. This can greatly extend the duration
of the activity of desiccant bags placed in a bucket-shaped container
of a dispenser, particularly desiccant bags located in an uppermost
layer.
Claims 1. A cover for a desiccant dispenser, which is adapted to be mounted
over an opening of a bucket-shaped container containing a plurality
of desiccant bags, the cover comprising a hard main plate having
a taking-out bore for insertion of a hand to take out said desiccant
bags, and at least one elastic plate mounted on said main plate
to cover said taking-out bore and having a plurality of cuts arranged
radiately to permit the insertion and withdrawal of the hand.
2. A cover for a desiccant dispenser according to claim 1 wherein
said main plate is made of a transparent synthetic resin.
3. A cover for a desiccant dispenser according to claim 1 or 2
wherein there are provided two elastic plates which are mounted
on opposite faces of said main plate.
4. A cover for a desiccant dispenser according to claim 3 wherein
a plurality of cuts in the elastic plate on the outer face and a
plurality of cuts in the elastic plate on the inner face are offset
in a staggered manner.
5. A cover for a desiccant dispenser according to claim 1 2 3
or 4 wherein said main plate has, on its outer peripheral surface,
a seal member in close contact with an inner peripheral surface
of the opening of said bucket-shaped container and, on an outer
periphery of its outer face, a plurality of stoppers in engagement
with an end face of the opening of said bucket-shaped container.
Description BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cover for desiccant dispenser,
and particularly to a cover adapted to be mounted over an opening
of a bucket-shaped container containing a plurality of desiccant
bags. As used herein, the term "desiccant bag" means an
air-permeable bag containing a powdered or granular desiccant packed
therein.
[0003] 2. Relevant Art
[0004] Such a desiccant dispenser has been used to store desiccant
bags which are placed in a moisture-proof package containing chips,
for example, on a packing line in a semiconductor-producing factory.
The reason why the desiccant bag is placed in the moisture-proof
package is to prevent the following disadvantage: If moisture is
contained in the chip, there is a possibility that the moisture
is expanded in heating and bonding process, to thereby damage the
chip.
[0005] In this case, a large number of desiccant bags are placed
in the bucket-shaped container, and the opening of the container
is left to be opened in order that that an operator may take out
the desiccant bags easily.
[0006] In the above-described dispenser, however, a plurality of
desiccant bags located in an uppermost layer are exposed to the
environmental humidity, and for this reason, in such a case where
the operation is discontinued, the activity of these desiccant bags
is liable to decline significantly due to the absorption of moisture.
Even if such desiccant bags are placed in the moisture-proof package,
the purpose of this placement cannot be achieved, and there is a
possibility that a large amount of damage may be provided.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide a cover
of the above-described type which can greatly extend the duration
of the activity of desiccant bags placed in a bucket-shaped container
of a dispenser, particularly desiccant bags located in an uppermost
layer.
[0008] To achieve the above object, according to the present invention,
there is provided a cover for a desiccant dispenser, which is adapted
to be mounted over an opening of a bucket-shaped container containing
a plurality of desiccant bags, and which comprises a hard main plate
having a taking-out bore for insertion of a hand to take out the
desiccant bags, and at least one elastic plate mounted on the main
plate to cover the taking-out bore and having a plurality of cuts
arranged radiately to permit the insertion and withdrawal of the
hand.
[0009] With the above arrangement, in a state in which the plurality
of desiccant bags are placed in the bucket-shaped container and
the cover is mounted over the opening of the container, elastic
pieces of the elastic plate between the adjacent cuts are in extended
states to minimize the degree of communication between the inside
and outside of the container through the cuts. Thus, the exposure
of the plurality of desiccant bags located in the uppermost layer
to the environmental humidity is inhibited and hence, the duration
of the activity of the desiccant bags can be greatly extended.
[0010] The motion of an operator inserting his hand into the taking-out
bore to take out the desiccant bags is permitted by the flexing
of the elastic pieces of the elastic plate toward the inside of
the container. At this time, the degree of communication between
the inside and outside of the container is maintained small, because
the elastic pieces are brought into the hand. On the other hand,
the motion of the operator grasping the plurality of desiccant bags
to withdraw his hand out of the taking-out bore is permitted by
the flexing of the elastic pieces of the elastic plate toward the
outside of the container. At this time, the degree of communication
between the inside and outside of the container is maintained smaller,
because the elastic pieces are brought into the hand. When the operator's
hand is parted from the elastic pieces, the elastic pieces extends
as described above, whereby the degree of communication between
the inside and outside of the container through the cuts is minimized.
[0011] The above and other objects, features and advantages of
the present invention will be apparent from the following detailed
description of preferred embodiments made in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a side view of a first embodiment of a desiccant
dispenser,
[0013] FIG. 2 is a view taken in the direction of arrow 2 in FIG.
1
[0014] FIG. 3 is a vertical sectional view of an essential portion
of the first embodiment of the desiccant dispenser, taken along
a line 3-3 in FIG. 2
[0015] FIG. 4 is a plan view of a main plate of a cover,
[0016] FIG. 5 is a perspective view of the desiccant dispenser
in a state in use,
[0017] FIG. 6 is a graph showing a first instance of the relationship
between the lapsed time and the average amount of moisture absorbed,
[0018] FIG. 7 is a graph showing a second instance of the relationship
between the lapsed time and the average amount of moisture absorbed,
[0019] FIG. 8 is a graph showing a third instance of the relationship
between the lapsed time and the average amount of moisture absorbed,
[0020] FIG. 9 is a graph showing a fourth instance of the relationship
between the lapsed time and the average amount of moisture absorbed,
[0021] FIG. 10 is a vertical sectional view similar to FIG. 3
but showing an essential portion of a second embodiment of a desiccant
dispenser,
[0022] FIG. 11 is a plan view similar to FIG. 2 but showing a
third embodiment of a desiccant dispenser.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0023] FIGS. 1 to 5 show a first embodiment of the present invention.
A desiccant dispenser 1 comprises a bucket-shaped container 2 and
a disk-shaped cover detachably mounted over a circular opening 3
of the container 2. The container 3 is made of, for example, a metal
and contains a plurality of desiccant bags 5. Examples of desiccants
which may be used are clay, silica gel, a molecular sieve and the
like.
[0024] The cover 4 includes a main hard plate 8 having at its central
portion a circular taking-out bore 7 for insertion of a hand 6 to
take out the desiccant bags 5 and at least one (one in the first
embodiment) elastic plate 10 which is mounted to the main plate
8 to cover the taking-out bore 7 and has a plurality of cuts 9 arranged
radiately to permit the insertion and withdrawal of the hand 6.
The main plate 8 is formed of a transparent synthetic resin, e.g.,
an acrylic plastic. The elastic plate 10 is cut from a plate material
made of a destaticized synthetic rubber, e.g., a chloroprene rubber,
into a regular octagonal shape, and is mounted on an outer face
of the main plate 8 around the taking-out bore 7 in such a manner
that its portions corresponding to the bisected points of the sides
are secured to the outer face by means of washers 11 and tapping
screws 12. The center of the elastic plate 10 is aligned with the
center of the taking-out bore 7 and eight cuts 9 are arranged radiately
to extend from the center of the elastic plate 10 to the vicinity
of an inner peripheral edge of the taking-out bore 7 so that the
cuts 8 form eight equilateral triangular elastic pieces 13 having
the same vertical angles .alpha..
[0025] The main plate 8 has an annular seal member 14 provided
on its outer peripheral surface so as to come into close contact
with an inner peripheral surface of the opening 3 of the container
2 and a plurality of stoppers 15 provided on an outer periphery
of its surface and engaged with an end face of the opening 3 of
the container 2. The annular seal member 14 is made of a synthetic
rubber, e.g., a chloroprene rubber. Each of the stoppers 15 is formed
a transparent acrylic plastic similar to the material forming the
main plate 8 and attached at its one end to the main plate 8 by
a tapping screw 16 with the other end protruding outside the seal
member 14 so that the stoppers 15 functions as an engage portion
for engagement with the end face of the opening 3 of the container
2.
[0026] As shown in FIGS. 2 and 3 in a state in which the plurality
of desiccant bags 5 are placed in the containers 2 and the cover
4 is mounted over the opening 3 of the container 2 each of the
elastic pieces 13 between the adjacent cuts in the elastic plate
10 is in an extended state, so that the degree of communication
between the inside of the container 2 and the outside through the
cuts 9 is the smallest. Thus, the exposure of the plurality of desiccant
bags 5 located in the uppermost layer to the environmental moisture
is inhibited and hence, the activity of the desiccant bags 5 can
be greatly extended.
[0027] As shown in FIG. 5 the motion of an operator inserting
his hand 6 into the taking-out bore 7 to take out the desiccant
bags 5 is permitted by the flexing of the elastic pieces 13 of the
elastic plate 10 toward the inside of the container 2. At this time,
the degree of communication between the inside of the container
2 and the outside is maintained small, because the elastic pieces
13 are brought into contact with the hand 6. On the other hand,
the motion of the operator grasping the plurality of desiccant bags
5 to withdraw his hand out of the taking-out bore 7 is permitted
by the flexing of the elastic pieces 13 of the elastic plate 10
toward the outside. At this time, the degree of communication between
the inside of the container 2 and the outside is maintained small
through cuts 9 because the elastic pieces 13 are brought into contact
with the hand. When the hand 6 is parted from the elastic pieces
13 the elastic pieces 13 extends as described above and as a result,
the degree of communication between the inside and outside of the
container 2 is minimized.
[0028] In addition, the annular seal member 14 of the main plate
8 is in close contact with the inner peripheral surface of the opening
3 of the container 2 and hence, the sealability for the opening
3 is good. Also, even when the container 2 is laid down, the cover
4 cannot be detached from the container 2 and hence, scattering
of the desiccant bags 5 through the opening 3 of the container is
prevented. In this case, the spillage of the desiccant bags 5 through
the taking-out bore 7 is inhibited by the elastic plate 10.
[0029] Further, the detachment of the cover 4 from the opening
3 of the container 2 is easily conducted by grasping an edge of
the taking-out bore 7. Yet further, the main plate 8 is transparent
and hence, it is possible for the operator to know the amount of
the desiccant bags 5 remaining in the container 2 without removal
of the cover 4 that is, without exposure of the desiccant bags
5 to the environmental humidity.
[0030] A moisture absorption test will be described below.
[0031] 33 g of powdered clay was packed in each of bags made of
an air-permeable synthetic paper (made under a trade name of Tyvek
by Du Pont de Nemours), to thereby prepare a plurality of desiccant
bags 5. These desiccant bags 5 were made in the S-CPP Belen plant
of S-CPP Co., Ltd. in United State of America.
[0032] First, three desiccant bags 5 were placed on a bottom of
a container 2 of about 19 L and then, a cover 4 was mounted over
an opening 3 of the container 2. This is hereinafter referred to
as Example 1. Three similar desiccant bags 5 were placed on a bottom
of another container 2. In this case, the container 3 was left open
without a cover 4 mounted over an opening 3 of the container 3.
This is hereinafter referred to as Example 2.
[0033] Both the containers 2 were placed under an environment having
a temperature of 30.degree. C. and a relative humidity of 60% according
to a rule under JEDEC standard floor conditions, and the relationship
between lapsed time and the amount of moisture absorbed in the desiccant
bags 5 were examined. JEDEC is initials of JOINT ELECTRON DEVICE
ENGINEERING COUNCIL. The amount A of humidity absorbed was obtained
from an equation; A={(W2-W1)/W1}.times.100 (% by weight) wherein
W1 represents the weight of the desiccant bag at the start of the
humidity absorption test, and W2 represents the weight of the desiccant
bag after lapse of a predetermined time. In each of Examples 1 and
2 an average value of the amounts A of humidity absorbed in the
three desiccant bags 5 was calculated.
[0034] FIG. 6 shows variations in average amounts of moisture absorbed
in Examples 1 and 2 when three hours lapsed. FIG. 7 shows a variation
in average amount of moisture absorbed in Example 1 when twenty
hours lapsed, and a variation in average amount of moisture absorbed
in Example 2 when four hours lapsed. FIG. 8 shows variations in
average amounts of moisture absorbed in Examples 1 and 2 when 120
hours lapsed.
[0035] As apparent from FIGS. 6 to 8 it can be seen that the average
amount of moisture absorbed in the desiccant bag 5 in Example 1
using the cover 4 is smaller than that in Example 2 not using the
cover 4. A difference between the moisture-proof abilities is manifest
from the start of the test as seen from FIGS. 6 and 7. Such difference
is only increased from the start of the test to a time when 28 hours
lapsed, as shown in FIG. 8. Thereafter, Example 2 proceed to a saturated
state at a very slow moisture absorption rate, and Example 1 proceed
to a saturated state at a moisture absorption rate larger than that
of Example 2.
[0036] To ensure that the desiccant bag 5 performs its function
within a moisture-proof package containing chips, the exposure time
for reaching such amount of moisture absorbed in the above-described
high-temperature and high-humidity environment was 75 minutes from
the start of the test in the case of Example 1 and 15 minutes from
the start of the test in the case of Example 2 provided that the
amount of moisture absorbed by the desiccant bag before being placed
in the moisture-proof package was 0.5% by weight. From this, a moisture-proof
effect provided by the cover 4 is obvious.
[0037] FIG. 9 is similar to FIG. 6 but shows moisture-proof properties
in a cover-free state for a desiccant bag using a molecular sieve
as a desiccant and for a desiccant bag using silica gel as a desiccant.
Even for such desiccant bags, it is possible to enhance the moisture-proof
property by applying the cover 4. In this case, the exposure time
was 4 minutes in both the silica gel and molecular sieve desiccant
bags, but if the cover 4 is used, the exposure time can be extended
to about 20 minutes.
[0038] FIG. 10 shows a second embodiment in which a cover 4 comprises
two elastic plates 10 attached to opposite faces of a main plate
8. In this case, pluralities of cuts 9 in the two elastic plates
10 are opposed to each other. If a taking-out bore 7 is covered
from opposite directions as described above, the moisture-proof
property in a container 2 can be further improved.
[0039] FIG. 11 shows a third embodiment. In a cover 4 a plurality
of cuts 9 in an elastic plate 10 on the outer face and a plurality
of cuts 9 in an elastic plate 10 on the inner face are offset in
a staggered manner. With this structure, the inside and outside
of a container 2 cannot be put into direct communication with each
other through cuts 9 in the elastic plate 10 on the outer face,
leading to an improved moisture-proof property in the container
2.
[0040] The container 3 may be of a moisture-absorbing property,
and a plastic may be used as a material for the container 3. A polycarbonate
may be used as a material for forming the main plate 8. A synthetic
rubber other than a chloroprene rubber may be used, or a thermoplastic
material such as a polyvinyl chloride or an ethylene-vinyl acetate
copolymer may be used as a material for forming the elastic plate
10 and the annular seal member 14.
[0041] According to the present invention, by the above-described
arrangement, it is possible to provide a cover which can greatly
extend the duration of the activity of the desiccant bags placed
in the bucket-shaped container of the dispenser, particularly, the
desiccant bags located in the uppermost layer. |