EP0876964A1

EP0876964A1 - Air-tightly sealable container with bell jar covering

Info

Publication number: EP0876964A1
Application number: EP98108319A
Authority: EP
Inventors: Masato Hosoi
Original assignee: Shin Etsu Polymer Co Ltd; Shin Etsu Chemical Co Ltd; Shin Etsu Handotai Co Ltd
Current assignee: Shin Etsu Polymer Co Ltd; Shin Etsu Chemical Co Ltd; Shin Etsu Handotai Co Ltd
Priority date: 1997-05-09
Filing date: 1998-05-07
Publication date: 1998-11-11
Also published as: KR19980086879A; JPH10310158A; TW371290B

Abstract

Provided by the invention is an air-tightly sealable bell jar container comprising a base plate (1) and a bell jar covering (2) mountable on the base plate. An air-tight sealing mechanism is obtained by forming a laterally and downwardly opening annular groove (3) in the base plate to support an O-ring gasket (4) of rubber and providing, below the base plate, a presser plate (5) which presses up the O-ring gasket against the base plate by a means of cams or screw means (7) in such a fashion that the O-ring gasket is elastically deformed and laterally bulged out to be brought into air-tight contacting with the inner wall of the bell jar covering surrounding the base plate.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an air-tightly sealable container with a bell jar covering provided with a sealing mechanism between the bell jar covering and the base plate on which the bell jar covering is mounted to be used for storage and transportation of various precision products to be kept absolutely free from contamination with atmospheric dust particles such as semiconductor silicon wafers.

The routine delivery system of semiconductor silicon wafers is that the silicon wafers as produced in the plant of a wafer producer are packaged in a specially designed container for transportation and transported therein to the plant of a manufacturer of semiconductor devices such as integrated circuits. Similar containers are used also within the plant of the device manufacturers in-house for the purpose of transfer of intermediate products from a line to a subsequent line for the next step of working.

Needless to say, a semiconductor silicon wafer is a product of extremely high purity and must be kept away from any trace contamination on the base of which ultrafine and extremely delicate electronic circuits are to be built so that the container therefor must be provided with a very reliable sealing mechanism by means of which intrusion of any trace amount of particulate foreign matters such as dust particles can be completely prevented.

One of the most traditional way to obtain an air-tight sealing condition of the opening in such a container is that a pressure-sensitive adhesive tape is attached along the seam line of the container body and the covering all around or an elastic gasket member is interposed between the open periphery of the container body and the periphery of the covering under an appropriate compression so as to eliminate any smallest interstice or gap, otherwise through which intrusion of dust particles may take place, to ensure a hermetic sealing condition.

These conventional methods for sealing are each not free from difficult problems. For example, adhesion of the pressure-sensitive adhesive tape to the surface of the container is sometimes not perfect by the occurrence of creases or twisting of the tape depending on the outer configuration of the container and the worker's skill so that the hermetic sealing condition by this means is not always very reliable unless an unduly long time is taken for the taping works if not to mention possible contamination of the outer surface of the container with the adhesive. In addition, such a taping work is hardly susceptible to automatization.

The sealing method by using a rubber gasket also requires a clamping mechanism by which the container body and the covering are engaged and fastened each to the other and an appropriate compressive force is applied to the elastic gasket member.

In the current trend toward full automation of various production lines, it is eagerly desired to develop an air-tight sealing mechanism of a container with a bell jar covering which can be operated by an automatic machine for closing and opening the container.

SUMMARY OF THE INVENTION

The present invention accordingly has an object to provide a novel air-tightly sealable container with a sealing mechanism of a simple structure between a cylindrical bell jar covering and the base plate, on which the bell jar covering is mounted, by means of which mechanism a very reliable hermetic sealing condition can be ensured and which mechanism can be operated by an automatic machine for closing and opening of the container.

Thus, the air-tightly sealable container with a sealing mechanism according to the invention comprises:

(A) a cylindrical bell jar covering;

(B) a base plate having a laterally and downwardly opening groove therearound along the outer side periphery, the dimensions of the base plate being smaller than the inner dimensions of the bell jar covering;

(C) an elastic sealing member, such as an O-ring gasket of rubber, to fit the groove of the base plate;

(D) a presser plate positioned below the base plate and for moving up and down to press the elastic sealing member against the base plate in such a fashion that the elastic sealoing member is elastically deformed and bulged out laterally to be brought into contact with the inner wall of the bell jar covering surrounding the base plate; and

(E) a mechanical means for pushing the presser plate against the base plate such as a mechanism of cams and screws.

Needless to say, the above mentioned cylindrical bell jar covering as the part (A) need not have a circular cross section but the horizontal cross section thereof can be generally a square or rectangular form provided that each corner is rounded having a sufficiently large radius of curvature so that the elastic sealing member as the part (C) can fit the groove around the base plate as the part (B).

BRIEF DESCRIPTION OF THE DRAWING

Figures 1A and 1B each illustrate the bell jar container of the invention by an axial cross sectional view in an open state and sealed state, respectively.

Figures 2A and 2B each illustrate the bell jar container of the invention in another embodiment by an axial cross sectional view with the bell jar covering lifted above the base plate and mounted on the base plate to establish a sealed state, respectively.

Figures 3A and 3B each illustrate the bell jar container (bell jar covering not shown) of the invention in a further different embodiment showing an assembly of the base plate and the pressing plate corresponding to an open and sealed states, respectively, of the container by an axial cross sectional view.

Figure 4 is an axial cross sectional view of a still different embodiment of the inventive container.

Figure 5 is an axial cross sectional view of the same container as shown in Figure 4 on use in an upside-down disposition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As is described above, the air-tightly sealable bell jar container according to the invention comprises, as the principal parts thereof, (A) a bell jar covering having, for example, a circular cross section and mountable on a base plate, (B) a circular base plate having a diameter smaller than the inner diameter of the bell jar covering and provided with an annular groove open downwardly and laterally, (C) an elastic sealing member such as an O-ring gasket of a rubbery material to fit the annular groove in the base plate and (D) a presser plate which presses the elastic sealing member against the base plate by (E) a mechanism such as cams or screw bolts and nuts to such an extent that the elastic sealing member is compressed and laterally bulged out to be brought into contact with the inner wall of the bell jar covering mounted on the base plate to give an air-tight sealing condition between the base plate and the inner wall of the bell jar covering.

It is assumed in the above given description that the materials to be contained in the container are placed on the base plate and then the bell jar covering is mounted thereon although it is optional that the materials are placed on the bottom of the bell jar covering standing in an upside-down disposition and the assembly consisting of the base plate and the presser plate is mounted on the upward opening of the bell jar covering.

In the following, the air-tightly sealable bell jar container of the invention is illustrated by making reference to the accompanying drawing. Although the following description is given by assuming that the bell jar covering has a circular cross section, about the same description is applicable even when the bell jar covering has a noncircular cross section such as a generally rectangular cross section.

Figures 1A and 1B are each an axial cross sectional view of the inventive bell jar container in an open and sealed state, respectively. The container comprises a circular base plate 1, on which the materials to be contained are mounted, and a bell jar covering 2, of which the inner diameter is slightly larger than the diameter of the base plate 1, mountable on the base plate 1 in such a fashion that the base plate 1 is entirely enveloped inside of the bell jar covering 2 mounted thereon leaving a small clearance therebetween and a presser plate 5 below the base plate 1. The base plate 1 is provided with an annular groove 3 along the outer periphery thereof in such a fashion that the groove 3 is open laterally and downwardly. An O-ring gasket 4 of a rubber fits the annular groove 3 with elastic resilience. It is not always necessary in the open state of the container (Figure 1A) that the O-ring gasket 4 is in contact with the inner wall of the bell jar covering 2. A presser plate 5 is provided below the base plate 1 in such a fashion that the presser plate 5 is movable up and down by sliding on the

rods

6,6 downwardly extending from the lower surface of the base plate 1 by operating the

cams

7,7 pivotally supported on the

rods

6,6 by means of the

cam handles

8,8.

When the presser plate 5 is at the lowermost position as is illustrated in Figure 1A, the container is in an open state and the bell jar covering 2 can be freely removed from the base plate 1. When the presser plate 5 is pushed up against the base plate 1 by turning the

cams

7,7 in the direction indicated by the openwork arrows in Figure 1A, as is illustrated in Figure 1B, the O-ring gasket 4 in the annular groove 3 of the base plate 1 is upwardly compressed by the presser plate 5 against the upper wall of the annular groove 3 and is elastically deformed and bulged out laterally to have an elliptic cross section and to be brought into contact with the inner wall of the bell jar covering 2 so that an air-tight sealing condition is established between the base plate 1 and the inner wall of the bell jar covering 2.

In Figure 1B, the base plate 1 and the presser plate 5 are fastened together by the mechanism of

cams

7,7. When the fastening force is released by turning the

cams

7,7, the base plate 1 is pushed up by the elastic resilience of the O-ring gasket which regains the circular cross section as in Figure 1A.

Figures 2A and 2B are for the illustration of the inventive container in an embodiment similar to that illustrated in Figures 1A and 1B. While the bell jar covering 2 illustrated in Figures 1A and 1B has a smooth inner surface, the inner surface of the bell jar covering 2' in Figures 2A and 2B is not smoothly cylindrical but has an annular groove 9 around the lower portion of the covering 2'. When the bell jar covering 2' is mounted on the base plate 1 with an O-ring gasket 4 in the annular groove 3 of the base plate, the groove 9 on the inner wall of the bell jar covering 2' comes to the same height as the O-ring gasket 4 so that, when the presser plate 5 is pushed up against the base plate 1, the O-ring gasket 4 is upwardly compressed and laterally bulged out into the annular groove 9, as is illustrated in Figure 2B, so that engagement between the base plate 1 and bell jar covering 2' can be improved as compared with the embodiment illustrated in Figures 1A and 1B.

Although Figures 1A and 1B and Figures 2A and 2B show an O-ring gasket 4 which is solid, i.e. not hollow, it is optional to use a hollow O-ring gasket 4' as is illustrated in Figures 3A and 3B provided that a reliable air-tight sealing condition can be obtained by the contact between the elastically deformed O-ring gasket 4' and the inner wall of the bell jar covering (not shown in Figures 3A and 3B).

Figures 3A and 3B further illustrate an alternative mechanical means for fastening the base plate 1 and the presser plate 5, in place of the mechanism of cams illustrated in Figures 1A and 1B and Figures 2A and 2B, consisting of

screw bolts

10,10 implanted in and extending downwardly from the base plate 1 and

screw nuts

11,11 movable on the

screw bolts

10,10. When the

nuts

11,11 are at the lower positions, the O-ring gasket 4' is in an uncompressed state, as is illustrated in Figure 3A, allowing free mounting and removal of the ball jar covering on and from the base plate 1 while, when the nuts are turned to push up the presser plate 5 against the base plate 1, as is illustrated in Figure 3B, the O-ring gasket 4' is upwardly compressed and bulged out laterally to be brought into contact with the inner wall of the bell jar covering.

In the above described embodiments of the inventive container, the presser plate 5 is assumed to have a diameter approximately equal to the diameter of the base plate 1 which is slightly smaller than the inner diameter of the bell jar covering 2. It is, however, optional that the presser plate 5 has a diameter smaller or larger than the diameter of the base plate 1. In particular, as is illustrated in Figure 4, the diameter of the presser plate 5' can be larger than the inner diameter of the bell jar covering 2 so that the bell jar covering 2 can rest at the lower periphery thereof on the presser plate 5'.

The embodiment of the inventive container illustrated in Figure 4, in which the presser plate 5' has a diameter larger than the inner diameter of the bell jar covering 2, can be used as being turned upsidedown so that, while, in the other embodiments described earlier, the materials to be contained in the container are placed on the base plate 1 and then the bell jar covering 2 is mounted thereon, the materials are first placed on the bottom of the bell jar covering in an upsidedown disposition and then the assembly of the base plate 1 and the presser plate 5 is mounted on the upper periphery of the covering 2 without a trouble of falling down into the bell jar covering 2.

As is illustrated in Figure 5, the bell jar container of the invention shown, for example, in Figure 4 can be used in an upside-down disposition. In this case, the bell jar covering 2 in Figure 4 is now the container bottom 2 in Figure 5 standing on the flat bottom and the presser plate 5 now serves as the covering. The material contained in the container naturally rests on the bottom of the container body 2.

Claims

An air-tightly sealable bell jar container which comprises:

(A) a bell jar covering;

(B) a base plate having a laterally and downwardly opening groove along the outer side periphery, the dimensions of the base plate being smaller than the inner dimensions of the bell jar covering;

(C) an elastic sealing member to fit the groove of the base plate;

(D) a presser plate positioned below the base plate and for moving up and down to press the elastic sealing member against the base plate in such a fashion that the elastic sealing member is elastically deformed and bulged out laterally to be brought into contact with the inner wall of the bell jar covering surrounding the base plate; and

(E) a mechanism for pushing the presser plate against the base plate.
The air-tightly sealable bell jar container as claimed in claim 1 in which the mechanism (E) for pushing the presser plate against the base plate is a means of cams each pivotally supported on a rod downwardly extending from the lower surface of the base plate.
The air-tightly sealable bell jar container as claimed in claim 1 in which the mechanism (E) for pushing the presser plate against the base plate is a means of screw bolts each extending downwardly from the lower surface of the base plate and screw nuts thereon.
The air-tightly sealable bell jar container as claimed in claim 1 in which the bell jar covering is provided with a groove on the inner wall at such a height that, when the bell jar covering is mounted on the base plate, the elastic sealing member in the groove of the base plate is brought into contact with the groove on the inner wall of the bell jar covering.
The air-tightly sealable bell jar container as claimed in claim 1 in which the presser plate has dimensions larger than the inner dimensions of the bell jar covering.
The air-tightly sealable bell jar container as claimed in claim 1 in which the bell jar covering has a circular cross section.
The air-tightly sealable bell jar container as claimed in claim 1 in which the bell jar covering has a generally rectangular cross section having rounded corners.
The air-tightly sealable bell jar container as claimed in claim 1 in which the elastic sealing member is an O-ring gasket made from a rubber.