Board storage container and check valve

A substrate container has a container main body to contain a substrate and a check valve which has a cylindrical housing and a valve disc installed in the housing and controls gas flowing from and to the interior and the exterior of the container main body, and is formed by inserting the housing into a through-hole of the container main body. When an end of the valve located inside the container main body is defined as a front end, a check valve has a fixing ring that is mounted on the rear end side in the manner of being rotatable relative to the housing and fixes the housing to the container main body from rearward, and the housing has a first housing installed on the front end side and a second housing inserted into the first housing at the front end and attached to the first housing.

TECHNICAL FIELD

The present invention relates to: a substrate container used for storing, transporting, conveying, and retaining a precision substrate such as a semiconductor wafer, a mask glass, or the like; and a check valve attached to the substrate container.

BACKGROUND ART

In recent years, the miniaturization and the trends towards a finer pitch of wiring in a semiconductor component have been advancing. For that reason, a substrate container to store a semiconductor wafer (a precision substrate) is required to have a high hermeticity and the automization of handling in order to prevent the precision substrates from being contaminated. As such a substrate container, a substrate container equipped with a check valve used on the occasion of gas purge (for example, refer to Patent Documents 1 to 3) is known.

FIG. 16is an exploded perspective view showing a check valve in a conventional substrate container. As shown inFIG. 16, in a conventional substrate container, a through-hole51ais formed on a wall51of the container main body in which substrates are contained and a check valve52used on the occasion of gas purge is mounted in the through-hole51a. The check valve52is provided with a valve disc53having an annular sealing face and a cylindrical housing54to contain the valve disc53. The housing54has a retaining cylinder55installed on the inner face side of the container main body and a fixing cylinder56installed on the outer face side of the container main body and threads55aand56aare formed on the outer face side of the retaining cylinder55and on the inner face side of the fixing cylinder56, respectively. Then the retaining cylinder55and the fixing cylinder56are placed in the manner of interposing the wall51in between and, by screwing them together, the housing54is formed and fixed to the wall.Patent Document 1: Japanese Patent Application Laid-open No. 2004-146676Patent Document 2: Japanese Patent Application Laid-open No. 2004-179449Patent Document 3: Japanese Patent Application Laid-open No. 2002-521189

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

By the conventional technology described in Patent Documents 1 and 2 however, the retaining cylinder55and the fixing cylinder56are screwed together when the check valve is assembled, hence the assembly work is complicated, and the simplification of the assembly work is desired. Further, since the check valve is attached to the container main body by screw joint, the tightening torque has to be controlled and resulting problem has been that the control of the tightening torque requires great care.

The present invention has been established in order to solve such problems and an object of the present invention is to provide: a check valve that do not require the control of tightening torque and can simplify assembly work; and a substrate container equipped with the check valve.

Means for Solving the Problem

A substrate container according to the present invention is, in a substrate container: equipped with a container main body to contain a substrate and a check valve which has a cylindrical housing and a valve disc installed in the housing and controls gas flowing from and to the interior and the exterior of the container main body; and formed by inserting the housing into a through-hole of the container main body, characterized in that, when an end of the valve located inside the container main body is defined as a front end: the check valve has a fixing ring that is mounted on the rear end side in the manner of being rotatable relative to the housing and fixes the housing to the container main body from rearward; the housing has a first housing installed on the front end side and a second housing inserted into the first housing at the front end and attached to the first housing; the first housing has a fixing piece protruding rearward from the rear end and a fixing claw being formed at the rear end of the fixing piece and fixing the fixing ring; the fixing ring has a cylindrical sidewall mounted outside the first housing and a flange protruding outward from the sidewall; and on the inner circumferential face of the sidewall, a guide recess extending in the axial direction and guiding the fixing claw, a detent protruding inward and abutting on the fixing piece, and a hook bent from the detent in the circumferential direction and locked to the fixing piece are installed.

Such a substrate container has a check valve being placed so that the front end side of the check valve may be located inside the container main body and controlling gas flowing from and to the interior and the exterior of the container main body, and the housing of the check valve has a first housing installed on the front end side and a second housing installed on the rear end side. Further, the substrate container has a fixing ring in the housing that is mounted from the rear side of the housing in the manner of being rotatable relative to the housing and fixes the check valve to the container main body. Consequently, the check valve can be fixed to the container main body with the fixing ring and hence it is unnecessary to fix the check valve with screws and control tightening torque unlike the conventional case. Further, the first housing has a fixing piece and a fixing claw to fix the fixing ring to the first housing and hence it is possible to firmly fix the check valve to the container main body by plunging the fixing ring. Further, the fixing ring has a flange protruding outward and hence it is possible to stably fix the check valve by abutting the flange on the container main body. Furthermore, the fixing ring has a guide recess to guide the fixing claw in the axial direction on the cylindrical sidewall mounted on the outside of the first housing and hence it is possible to smoothly mount the fixing ring on the first housing and improve the efficiency of assembly work. Yet further, a detent protruding inward and abutting on the fixing piece, and a hook bent from the detent in the circumferential direction and locked to the fixing piece are installed on the inner circumferential face of the sidewall of the fixing ring and hence it is possible to lock the hook of the fixing ring to the fixing piece of the housing by mounting the fixing ring on the fixing piece and rotating the fixing ring relative to the housing.

Here it is desirable that the check valve further has a positioning mechanism to position the second housing to the first housing and a locking mechanism to lock the second housing to the first housing. Consequently, it is possible to position the second housing to the first housing with the positioning mechanism and lock the second housing to the first housing with the locking mechanism. As a result, screw joint is not required when the first housing and the second housing are assembled unlike the conventional case and assembly work can be simplified.

Further, it is desirable that: the second housing has a folded flange being folded back from the front end side and abutting on the inner circumferential face of the first housing all around the circumference; and the locking mechanism has a locking recess formed on the inner circumferential face of the first housing and a locking protrusion being formed at the folded flange of the second housing and engaging with the locking recess. Consequently, it is possible to engage the locking recess formed on the inner circumferential face of the first housing with the locking protrusion formed at the folded flange of the second housing by plunging the second housing to the first housing. As a result, it is possible to simplify assembly work.

Furthermore, it is desirable that the positioning mechanism has a positioning recess formed at the rear end of the first housing and a positioning protrusion being formed at the folded flange of the second housing and engaging with the positioning recess. Consequently, it is possible to position the second housing to the first housing with the positioning recess formed at the rear end of the first housing and the positioning protrusion formed at the folded flange of the second housing.

Yet further, it is desirable that: the valve disc has a columnar shape; the valve disc has an end at which an annular sealing face is formed, an annular flange at which an annular biasing face biased by a biasing means is formed, and other end at which a degassing recess allowing gas to pass through is formed in a radial direction; the annular sealing face is nearly concentric with the annular biasing face; and the outer diameter of the annular biasing face is not smaller than the outer diameter of the annular sealing face. Consequently, the outer diameter of the annular biasing face biased by a biasing means is not smaller than the outer diameter of the annular sealing face in the valve disc and hence it is possible to prevent the valve disc from tilting and seal off gas without fail. Further, a degassing recess allowing gas to pass through is formed in a radial direction at the other end opposite to the end at which the sealing face is formed and hence it is possible to pass through gas in the degassing recess even when the other end touches the flat face. As a result, unnecessary sealing face is not formed on the side opposite to the sealing face. Here, when the portion where the biasing means touches the annular flange is linear, the linear touching portion is used as the biasing face and the diameter of the linear touching portion is regarded as “the outer diameter of the biasing face.”

Still further, a check valve according to the present invention is, in a check valve being inserted into a through-hole of the container main body of a substrate container containing a substrate and controlling gas flowing from and to the interior and the exterior of the substrate container, characterized in that, when an end of the check valve located inside the container main body is defined as a front end: the check valve has a cylindrical housing mounted on the through-hole, a valve disc contained in the housing, and a fixing ring that is mounted on the rear end side of the housing in the manner of being rotatable relative to the housing and fixes the housing to the container main body from rearward; the housing has a first housing installed on the front end side and a second housing inserted into the first housing at the front end and attached to the first housing; the first housing has a fixing piece protruding rearward from the rear end and a fixing claw being formed at the rear end of the fixing piece and fixing the fixing ring; the fixing ring has a cylindrical sidewall mounted outside the first housing and a flange protruding outward from the sidewall; and on the inner circumferential face of the sidewall, a guide recess extending in the axial direction and guiding the fixing claw, a detent protruding inward and abutting on the fixing piece, and a hook bent from the detent in the circumferential direction and locked to the fixing piece are installed.

In the case of such a check valve, when an end of the check valve located inside the container main body is defined as a front end, the cylindrical housing has a first housing installed on the front end side and a second housing installed on the rear end side. Further, the check valve has a fixing ring that is mounted from rear side of the housing in the manner of being rotatable relative to the housing and fixes the housing to the container main body. Consequently, it is possible to fix the check valve to the container main body with the fixing ring and hence it is unnecessary to fix the check valve with screws and control tightening torque unlike the conventional case. Further, the first housing has a fixing piece and a fixing claw to fix the fixing ring to the first housing and hence it is possible to fix the check valve to the container main body without fail. Furthermore, the fixing ring has a flange protruding outward and hence it is possible to fix the check valve stably by abutting the flange on the container main body. Yet further, the fixing ring has a guide recess to guide the fixing claw in the axial direction on the cylindrical sidewall mounted on the outside of the first housing and hence it is possible to mount the fixing ring to the first housing smoothly and improve the efficiency of assembly work. Still further, on the inner circumferential face of the sidewall of the fixing ring, a detent protruding inward and abutting on the fixing piece and a hook bent from the detent in the circumferential direction and locked to the fixing piece are installed. Hence it is possible to lock the hook of the fixing ring to the fixing piece of the housing by mounting the fixing ring on the fixing piece and rotating the fixing ring relative to the housing.

Here, it is desirable that the check valve further has a positioning mechanism to position the second housing to the first housing and a locking mechanism to lock the second housing to the first housing. Consequently, it is possible to position the second housing to the first housing with the positioning mechanism and lock the second housing to the first housing with the locking mechanism. As a result, it is unnecessary to use screw joint unlike the conventional case when the first housing and the second housing are assembled and it is possible to simplify the assembly work.

Effect of the Invention

The present invention makes it possible to provide: a check valve that does not require the control of tightening torque and can simplify assembly work; and a substrate container equipped with the check valve.

DESCRIPTION OF REFERENCE SYMBOLS

BEST MODES FOR CARRYING OUT THE INVENTION

A preferable embodiment of a substrate container and check valves according to the present invention is hereunder explained in reference to drawings. The substrate container according to the present embodiment has a suction valve and an exhaust valve as the check valves. Here, in the explanations of drawings, identical or equivalent components are denoted by the same reference symbols and duplication of the explanations is avoided.FIG. 1is an exploded perspective view showing a substrate container having a suction valve and an exhaust valve according to an embodiment of the present invention andFIG. 2is a bottom view of the substrate container shown inFIG. 1.

The substrate container1shown inFIG. 1is a substrate container that contains plural semiconductor wafers (substrates; not shown in the figure) (25 or 26 sheets for example) 300 mm (about 12 inches) in diameter for example and is used for transporting, conveying, and retaining the semiconductor wafers. The substrate container1is of a so-called front open box type and has a container main body2to store the substrates and a lid4with which an opening formed on the container main body2is covered. Further, in the present description, the face on which the opening is formed (the face on which the lid4is installed) is defined as “the front face of the container main body2” and the words “front,” “rear,” “left,” and “right” are used for expressing the directions.

The container main body2has a shape of a box and has an opening to take substrates in and out on the face on the left side in the figure. Supports to support plural substrates aligned parallel in the vertical direction are installed on the inner faces of a pair of opposing sidewalls2aof the container main body2. Further, plural (two in the present embodiment) through-holes2dpiercing through from the interior to the exterior are formed on a bottom wall2cof the container main body2(refer toFIG. 3). A cylindrical rib10is formed at the rim of each of the through-holes2din the manner of protruding downward. Further, a robotic handle2bfor roof transportation is installed on the top plate of the container main body2.

The opening is closed with the lid4with a sealing gasket interposed between the container main body2and the lid4. The lid4incorporates a latch mechanism with which the lid4is locked to the opening of the container main body2. On the front face side of the lid4(on the outer face side of the substrate container), operation holes4ainto which operation keys to operate the latch mechanism are inserted are formed. It is possible to extract and retract locking claws of the latch mechanism from the lid4to the side of the container main body2by inserting the operation keys into the operation holes4aand rotating the operation keys by 90 degrees from side to side. It is possible to make the lid4detachable from the container main body2by inserting and rotating the operation keys by 90 degrees counterclockwise and retracting the locking claws of the latch mechanism from the positions where the locking claws protrude to the side of the container main body2to the side of the lid4. On the other hand, when the lid4is attached to the container main body2, it is possible to lock the lid4to the container main body2by attaching the lid4in the state where the locking claws are retracted inside to the container main body2, rotating the operation keys by 90 degrees clockwise, and protruding the locking claws of the latch mechanism. Further, on the rear face side of the lid4(on the outer face side of the substrate container), a retainer to support plural substrates aligned parallel in the vertical direction is installed.

As shown inFIG. 2, a bottom plate7is fixed on the outer face side of the bottom wall2c(the bottom) of the container main body2. The bottom wall2cis covered with the bottom plate7and the bottom plate7has positioning members7aused for positioning the substrate container1to a processing apparatus or the like to which the substrate container1is applied. Further, the bottom plate7has openings7bto expose a suction valve8and an exhaust valve9to the exterior. The openings7bare formed at positions corresponding to the through-holes2dof the container main body2.

Further, the substrate container1has the suction valve8and the exhaust valve9to control gas flowing from and to the interior and the exterior of the container main body2as stated above. The suction valve8and the exhaust valve9are used when gas in the substrate container1is replaced. The suction valve8functions as a supply-side open/close valve used when gas is supplied to the interior and the exhaust valve9functions as an exhaust-side open/close valve used when gas is exhausted to the exterior.

The suction valve8and the exhaust valve9(hereunder referred to as check valves8and9when both the suction valve8and the exhaust valve9are denoted) are hereunder explained.FIG. 3is an exploded perspective view showing the suction valve shown inFIG. 1.FIG. 4is a sectional view showing the suction valve in the closed state.FIG. 5is a sectional view showing the suction valve in the open state.FIG. 6is a side view of the housing shown inFIG. 3.FIG. 7is a plan view of the housing shown inFIG. 6.FIG. 8is a bottom view of the housing shown inFIG. 6.FIG. 9is a bottom view showing the housing in the state where a fixing ring is locked.FIG. 10is a bottom view showing the housing in the state where a fixing ring is not locked.FIG. 11is a side view showing the valve disc shown inFIG. 3.FIG. 12is an exploded perspective view showing the exhaust valve shown inFIG. 1.FIG. 13is a sectional view showing the exhaust valve in the closed state.FIG. 14is a sectional view showing the exhaust valve in the open state.FIG. 15is a side view showing the valve disc shown inFIG. 12. Here, in the explanations of the suction valve8and the exhaust valve9, an end of each of the valves located inside the container main body2is defined as a front end.

Each of the check valves8and9has a cylindrical housing11as shown inFIGS. 3 to 6and12to14. Each of the housings11has a fixing cylinder (a first housing)12installed at the front end side and fixed to a bottom wall2cand a valve disc containing cylinder (a second housing)14being installed on the rear end side and containing a valve disc13or23. The valve disc containing cylinder14contains the valve disc13in the case of the suction valve8and the valve disc23in the case of the exhaust valve9. Each of the housings11contains, besides the valve disc13or23, a round filter15, a filter retainer16to retain the filter15, a compression coil spring (a biasing means)17to bias the valve disc13or23, and O-rings18and21. Further, each of the check valves8and9has a fixing ring19to fix the relevant housing11to the container main body2. Here, the differences between the suction valve8and the exhaust valve9are that the valve discs13and23are installed respectively and that the O-rings18, the valve discs13and23, and the compression coil springs17are located reversely between the valves.

Each of the fixing cylinders12has a cylindrical shape and plural windows surrounded by a grid-like window frame12aare formed at an end (the front end) of the fixing cylinder12as shown inFIG. 7. The end at which the grid-like window frame12ais formed is located inside the container main body2. Gas flows into the container main body2through the windows in the case of the suction valve8and gas flows outside the container main body2through the windows in the case of the exhaust valve9. Further, a flange12bprotruding outward is formed all around the circumference at the end of each of the fixing cylinders12.

Further, plural locking recesses12dare formed on the inner circumferential face of a cylindrical sidewall12cof each of the fixing cylinders12as shown inFIGS. 3,6,8, and12. Then the locking recesses12dengage with after-mentioned locking protrusions (a locking mechanism)14bof each of the valve disc containing cylinders14respectively. Further, a groove12fon which an O-ring20is mounted is formed on the outer face of each of the sidewalls12calong the root of the relevant flange12b.

Further, plural positioning recesses (notches)12eare formed at the other end (the rear end) of the sidewall12cof each of the fixing cylinders12. The positioning recesses12eare formed so as to be recessed from the rear end to the front side of the relevant sidewall12c.

Furthermore, plural (four in the present embodiment) fixing pieces12gprotruding rearward are formed at the other end of the sidewall12cof each of the fixing cylinders12. The fixing pieces12gare formed at identical intervals in the circumferential direction. Moreover, fixing claws12iprotruding outward in the radial direction are formed at the rear ends of the fixing pieces12g, respectively. The fixing pieces12gare flexible and the fixing claws12ilock the relevant fixing ring19from inside.

The filter15is installed on the side of an end of each of the fixing cylinders12and prevents contaminations from intruding into the container main body2. As the filter15, for example: a molecular filter comprising tetrafluoroethylene, a polyester fiber, a porous Teflon film (registered trademark, bland name, a porous fluororesin film), a glass fiber, or the like; or a chemical filter produced by supporting a filtering medium such as an activated carbon fiber with a chemical absorbent is used. Here, the filter15may comprise either single sheet or plural sheets. Further, the filter15may be a combination of plural kinds of filters. For example, by combining a molecular filter with a chemical filter, it is possible to prevent substrates from being contaminated by particles in the container main body2and moreover prevent substrates from being contaminated by organic gas.

Each of the filter retainers16has a disc6aand a cylinder16bextending outward (rearward) from the disc16a. The disc16ahas a size nearly identical to the filter15and plunges the filter15against the window frame12aof each of the fixing cylinders12from inside. Further, the disc16aand the cylinder16bare installed coaxially with each other and plural through-holes16cpiercing through the disc16ain the plate thickness direction are formed at the joint with the cylinder16bon the disc16a. Then gas passing through the interior of each of the housings11passes through the relevant through-holes16c. Here, the interior of the cylinder16bis closed and is structured so that gas may not pass through.

Each of the valve discs13and23has a columnar shape and an annular groove is formed on each of end faces13aand23aand an O-ring18is mounted in each of the grooves as shown inFIGS. 11 and 15. Each of the O-rings18protrudes outward from each of the end faces13aand23aof the valve discs13and23in the state where the O-ring is mounted on each of the valve discs13and23. An annular sealing face18ais formed by each of the O-rings18. At the other ends13band23bof the valve discs13and23, degassing recesses13cand23callowing gas to pass through are formed in the radial direction respectively.

Further, annular flanges13eand23eprotruding outward are formed on the circumferential faces of the valve discs13and23respectively. The faces of the annular flanges13eand23eon the side of the other ends13band23bform annular biasing faces13fand23fbiased with the compression coil springs17respectively. Then the valve discs13and23, the compression coil springs17, and the O-rings18are installed nearly on an identical axis L respectively and the outer diameter D1of each of the annular biasing faces13fand23fis set so as to be larger than the outer diameter D2of each of the annular sealing faces21a.

Further, plural guide ribs13gand plural guide ribs23gprotruding toward the annular flanges13eand23eare formed on the circumferential faces of the valve discs13and23respectively in the manner of being equally spaced in the circumferential direction respectively. The guide ribs13gand23gare formed so as to intersect with the circumferential faces and the annular flanges13eof the valve discs13and23respectively and installed so as to form triangles in a side view and expand in the radial direction from the sides of the other ends13band23btoward the annular flanges13eand23erespectively. The compression coil springs17can be guided by the guide ribs13gand23grespectively and hence the compression coil springs17can easily be installed coaxially with the valve discs13respectively.

Further, a round opening13dis formed on the valve disc13in the manner of extending from the other end13bin the axial direction. The cylinder16bof the relevant filter retainer16is inserted into the opening13d. Meanwhile, a round opening23dis formed on the valve disc23in the manner of extending from an end23ain the axial direction. The cylinder16bof the relevant filter retainer16is inserted into the opening23d. Each of the valve discs13and23is mounted on the cylinder16bof the relevant filter retainer16and is structured so as to be slidable in the axial direction L.

Each of the valve disc containing cylinders14has a cylindrical shape and has a size enough to contain one of the valve discs13and23. A step on which an O-ring21is mounted is formed at the outer rim at an end as shown inFIGS. 4 to 6,14, and15. Further, each of the valve disc containing cylinders14has a folded flange14athat is folded back from an end (the front end) and abuts on the inner circumferential face of the relevant fixing cylinder12all around the circumference. That is, each of the folded flanges14ais inserted into the relevant fixing cylinder12and the outer circumferential face of the folded flange14aabuts on the inner circumferential face of the sidewall12cof the relevant fixing cylinder12.

Further, locking protrusions14bare formed at the positions corresponding to the locking recesses12dof each of the fixing cylinders12on the outer circumferential face of the relevant folded flange14aas shown inFIG. 6(refer toFIG. 6). The locking protrusions14bprotrude outward from each of the folded flanges14aand are constructed so as to be able to engage with the locking recesses12drespectively. The locking recesses12dof each of the fixing cylinders12and the locking protrusions14bof the relevant valve disc containing cylinder14constitute locking mechanism for locking the relevant valve disc containing cylinder14to the fixing cylinder12according to the present invention.

Further, positioning protrusions14cto engage with the positioning recesses12eof each of the fixing cylinders12respectively are formed at the rear end of the relevant folded flange14aas shown inFIG. 8. Each of the positioning protrusions14chas an L-shape in a side view and protrudes rearward from the rear end of the relevant folded flange14aand also outward from the rear end. The positioning recesses12eof each of the fixing cylinders12and the positioning protrusions14cof the relevant valve disc containing cylinder14constitute positioning mechanism for positioning the relevant valve disc containing cylinder14to the fixing cylinder12according to the present invention.

A flange14dprotruding inward is formed at the other end of each of the valve disc containing cylinders14. The inner face of each of the flanges14dis a flat surface. At the other end of each of the valve disc containing cylinders14, an opening surrounded by the relevant flange14dacts as a ventilation port14ethrough which gas passes. The suction valve8allows gas to pass through the relevant ventilation port14eand flow inside the relevant housing11and the exhaust valve9allows gas to pass through the relevant ventilation port14eand flow outside the relevant housing11.

Each of the fixing rings19has a cylindrical sidewall19aand a flange19bprotruding outward from the rear end of the sidewall19aas shown inFIGS. 3 to 5. The inner diameter of each of the sidewalls19ais a little bit larger than the outer diameter of the sidewall12cof the relevant fixing cylinder12and each of the sidewalls19ais constructed so as to be able to be mounted outside the sidewall12cof the relevant fixing cylinder12. Each of the fixing rings19is mounted on the relevant fixing cylinder12from rearward.

Guide recesses19cto guide fixing claws12irespectively when each of the fixing rings19is mounted on the relevant fixing cylinder12are formed on the inner face of the relevant sidewall19aas shown inFIGS. 9 and 10. The guide recesses19cextend in the axial direction at the positions corresponding to the fixing claws12irespectively. Further, each of the guide recesses19chas a tilted face in the vicinity of the rear end of the relevant fixing ring19. The tilted face tilts increasingly inward from the front to the rear. When each of the fixing rings19is mounted on the relevant fixing cylinder12, the fixing claws12iare guided by the guide recesses19cand touch the tilted faces respectively and thereby the fixing pieces12gbend inward. When the fixing claws12ipass through the tilted faces, the fixing claws12icome to protrude from the rear end of the relevant fixing ring19and the fixing pieces12gare restored. On this occasion, each of the fixing rings19comes to be locked from inside with the fixing claws12iand the rearward movement of the fixing ring19is constraint. Here, inFIG. 10, the guide recesses19care formed at positions where the guide recesses19coverlap with the fixing claws12irespectively.

Each of the flanges19bis formed all around the circumference in the manner of facing the flange12bof the relevant fixing cylinder12as shown inFIGS. 4 and 5. The flange12bof each of the fixing rings19and the flange12bof the relevant fixing cylinder12interpose the bottom wall2cand the rib10of the container main body2and thereby it is possible to fix the relevant housing11to the container main body2.

Further, each of the fixing rings19has detents19dprotruding inward and being able to abut on the fixing pieces12grespectively as shown inFIGS. 9 and 10. The detents19dhave a tabular shape and are formed plurally so as to correspond to the fixing pieces12gof the relevant fixing cylinder12. When each of the fixing rings19is mounted on the relevant fixing cylinder12and is rotated in the circumferential direction (in the right direction in the present embodiment), the fixing pieces12gabut on the detents19drespectively and the movement of the fixing ring19in the circumferential direction can be constraint.

Further, each of the fixing rings19has hooks19ethat are bent from the detents19din the circumferential direction (in the left direction in the present embodiment) and locked to the fixing pieces12grespectively. Each of the hooks19ehas a tabular shape, is bent from an end of the relevant detent19d, and extends in the circumferential direction. The size of each of the hooks19ein the circumferential direction corresponds to the width of each of the fixing pieces12gand each of the hooks19ehas a protrusion to which the relevant fixing piece12can be locked from inside. In the state where each of the fixing rings19is locked to the relevant fixing cylinder12, each of the fixing pieces12gis interposed between the relevant sidewall19aand the relevant hook19ein the radial direction and also interposed between the relevant detent19dand the relevant hook19ein the circumferential direction.

Here, as the material for the check valves8and9, for example a resin such as polycarbonate, polystyrene, polyethylene, a cycloolefin polymer, polyacetal, polyether-imide, or the like is used and it is desirable to produce the check valves8and9by properly selecting a material from among the above resins. Further, it is desirable that the fixing cylinder12and the valve disc containing cylinder14constituting each of the housings11are made of a transparent resin so as to be able to confirm the internal situation. Further, as the material for the O-rings18,20, and21, for example one of various kinds of thermoplastic elastomers such as: rubber including melamine rubber, isoprene rubber, butyl rubber, silicone rubber, and fluororubber; a polyester thermoplastic elastomer; and a polyolefin elastomer is used. Further, as the material for the compression coil springs17, a metal such as stainless steel, a resin, or the like is used. When compression coil springs17made of a metal are adopted, it is desirable to apply a coating formed by using a resin component such as PEEK, a coating formed by using an elastomer component, a diamond-like coating, or the like on the surface of the metal in order to prevent the interior of the container main body2from being contaminated by metal components.

The assembly of the suction valve8and the exhaust valve9of a substrate container1configured as stated above is hereunder explained. Firstly, a filter15and a filter retainer16are inserted into each of the fixing cylinders12while the other end (the end on the side of the fixing claws12i) of the fixing cylinder12is turned upward.

Successively, in the case of the suction valve8, the valve disc13on which the compression coil spring17and the O-ring18are mounted is installed on the filter retainer16. More specifically, the compression coil spring17is installed between the filter retainer16and the valve disc13and the cylinder16bof the filter retainer16is inserted into the opening13dof the valve disc13.

Meanwhile, in the case of the exhaust valve9, the valve disc23on which the O-ring18is mounted and the compression coil spring17are installed on the filter retainer16. More specifically, the cylinder16bof the filter retainer16is inserted into the opening23dof the valve disc23and the compression coil spring17is mounted from the side of the other end23bof the valve disc23.

Successively, each of the valve disc containing cylinders14on which an O-ring21is mounted is prepared and is mounted on the relevant fixing cylinder12. More specifically, as shown inFIG. 6, the positioning protrusions14cof each of the valve disc containing cylinders14are adjusted to the positioning recesses12eof the relevant fixing cylinder12respectively, each of the valve disc containing cylinders14is plunged into the relevant fixing cylinder12, and the locking protrusions14bof each of the valve disc containing cylinders14are fitted to the locking recesses12dof the relevant fixing cylinder12respectively. The state where the outer circumferential face of the folded flange14aof each of the valve disc containing cylinders14abuts on the inner circumferential face of the sidewall12cof the relevant fixing cylinder12is obtained. Further, each of the filters15and the disc16aof the relevant filter retainer16are plunged and fixed onto the window frame12aof the relevant fixing cylinder12by the other end of the relevant valve disc containing cylinder14.

In the case of the suction valve8, as shown inFIG. 4, an end of the compression coil spring17abuts on the disc16aof the filter retainer16and the other end of the compression coil spring17abuts on the annular flame13bof the valve disc13. Then the valve disc13is biased by the compression coil spring17and the O-ring18mounted on the valve disc13is plunged on the inner face of the flange14dof the valve disc containing cylinder14. The face sealed with the O-ring18is formed so that the size thereof may be larger than the outer diameter of the ventilation port14ein the manner of surrounding the ventilation port14eof the valve disc containing cylinder14. Consequently, it is possible to keep the container main body2sealed.

Meanwhile, in the case of the exhaust valve9, as shown inFIG. 13, an end of the compression coil spring17abuts on the annular flange23bof the valve disc23and the other end of the compression coil spring17abuts on the inner face of the flange14dof the valve disc containing cylinder14. Then the valve disc23is biased by the compression coil spring17and the O-ring18mounted on the valve disc23is plunged to the disc16bof the filter retainer16. The face sealed with the O-ring18is formed so that the size thereof may be larger than the outside of the plural through-holes16cin the manner of surrounding the outside of the plural through-holes16cof the filter retainer16. Consequently, it is possible to keep the container main body2sealed.

Here, the ventilation port14eof the exhaust valve9may be formed so as to be larger than the ventilation port14eof the suction valve8. By so doing, it comes to be easy to distinguish the suction valve8and the exhaust valve9from each other. Further, in the case of the exhaust valve9where the ventilation port14eis not closed by the sealing face, a cleaning liquid intrudes into the valve disc containing cylinder14during cleaning and hence it is possible to improve the efficiency of draining and drying after cleaning by keeping the ventilation port14elarge.

The fixation of each of the housings11to the container main body2is hereunder explained. Firstly, an O-ring20is mounted on the groove12fof each of the fixing cylinders12as shown inFIGS. 4,5,13, and14. Successively, each of the fixing cylinders12is mounted on the relevant through-hole2don the bottom wall2cof the container main body2. More specifically, the other end of each of the fixing cylinders12is inserted into the relevant through-hole2dfrom the inner face side of the container main body2. Then the flange12of each of the fixing cylinders12abuts on the rim of the relevant through-hole2d. On this occasion, the fixing claws12iof each of the fixing cylinders12protrude outward from the relevant rib10.

Successively, each of the fixing rings19is mounted on the fixing claws12iof the relevant fixing cylinder12from the outer face side of the container main body2. More specifically, as shown inFIG. 10, the guide recesses19cof each of the fixing rings19are placed at positions corresponding to the fixing claws12iof the relevant fixing cylinder12respectively and each of the fixing rings19is plunged to the relevant fixing cylinder12. The fixing claws12iare guided by the guide recesses19crespectively and engage with the rim inside the flange19bof each of the fixing rings19. Successively, each of the fixing rings19is rotated relative to the relevant fixing cylinder12and the fixing pieces12gof the relevant fixing cylinder12abut on the detents19dof each of the fixing rings19respectively. In the state, the hooks19eof each of the fixing rings19are locked to the relevant fixing pieces12grespectively and the movement of each of the fixing rings19is constraint. Then the flange19bof each of the fixing rings19abuts on the end of the relevant rib10. That is, each of the housings11is firmly fixed to the container main body2in the manner of interposing the bottom wall2cand the rib10of the container main body2between the flange12bof the relevant fixing cylinder12and the flange19bof the relevant fixing ring19. Since each of the housings11is fixed to the container main body2with the relevant fixing ring19as stated above, it is unnecessary to fix each of the housings11with screws and control tightening torque unlike the conventional case.

The operations of the suction valve8are explained hereunder. In the suction valve8of the normal state, the valve disc13is plunged to the flange14dof the valve disc containing cylinder14and the suction valve8is in the closed state as shown inFIG. 4. Then, when gas is supplied into the container main body2, the valve disc13moves against the compression coil spring17by the pressure of the gas and the suction valve8takes the open state as shown inFIG. 5. The gas supplied into the container main body2flows into the housing11through the ventilation port14eand passes through the through-holes16cof the filter retainer16and the filter15. The gas from which impurities are removed with the filter15passes through the windows of the fixing cylinder12and is supplied into the container main body2. When the pressure of the supplied gas lowers, the valve disc13moves by being biased with the compression coil spring17and the suction valve8takes the closed state.

The operations of the exhaust valve9are explained hereunder. In the exhaust valve9of the normal state, the valve disc23is plunged to the disc16aof the filter retainer16and the exhaust valve9is in the closed state as shown inFIG. 13. Then, when gas is exhausted outside the container main body2, the valve disc23moves against the compression coil spring17by the pressure of the gas and the exhaust valve9takes the open state as shown inFIG. 14. The gas exhausted outside the container main body2passes through the windows of the fixing cylinder12, the filter15, and then the through-holes16cof the filter retainer16. The gas having passed through the through-holes16cflows into the valve disc containing cylinder14and is exhausted trough the ventilation port14e. When the pressure of the gas in the container main body2lowers, the valve disc23moves by being biased with the compression coil spring17and the exhaust valve9takes the closed state.

Such a substrate container1as stated above has a suction valve8and an exhaust valve9and hence it is possible to apply gas purge appropriately. Further, the housing11of each of the suction valve8and the exhaust valve9has a fixing cylinder12and a valve disc containing cylinder14and the fixing cylinder12and the valve disc containing cylinder14have positioning recesses12eand positioning protrusions14crespectively. Consequently, it is possible to position the valve disc containing cylinder14to the fixing cylinder12easily and assemble the suction valve8and the exhaust valve9efficiently. Further, since the fixing cylinder12and the valve disc containing cylinder14have locking recesses12dand locking protrusions14brespectively, it is possible to lock the valve disc containing cylinder14to the fixing cylinder12. Consequently, it is unnecessary to join the housing11with screws unlike the conventional case. Furthermore, in each of the suction valve8and the exhaust valve9of the substrate container1, the housing11can be fixed to the container main body2with the fixing ring19and hence it is unnecessary to fix the housing11with screws unlike the conventional case. Consequently, since screw joint is not required unlike the conventional case, it is unnecessary to control tightening torque. As a result, assembly work can be simplified.

Further, since each of the fixing cylinders12has fixing pieces12gand fixing claws12ito fix the relevant fixing ring19, it is possible to fix the relevant fixing ring19to the fixing cylinder12without fail. Furthermore, since each of the fixing rings19has a flange19bprotruding outward, the relevant housing11is stably fixed to the container main body2by abutting the flange19bon the rim of the relevant through-hole2dof the container main body2. Yet further, since guide recesses19cto guide the movement of the fixing claws12iare formed on the inner circumferential face of the sidewall19aof each of the fixing rings19, it is possible to smoothly mount the fixing ring19on the relevant fixing cylinder12. Consequently, it is possible to further improve the efficiency of assembly work. In addition, since detents19eprotruding inward and being able to abut on the fixing pieces12grespectively and hooks19ebending from the detents19etoward the circumferential direction and being locked to the fixing pieces12grespectively are formed on the inner circumferential face of the sidewall19aof each of the fixing rings19, it is possible to lock the hooks19eof the fixing ring19to the fixing pieces12gof the relevant fixing cylinder12respectively by mounting the fixing ring19on the fixing pieces12gand rotating the fixing ring19relative to the relevant fixing cylinder12.

Further, since the outer diameter D1of each of the annular biasing faces13fand23fbiased with the relevant compression coil spring17is larger than the outer diameter D2of the annular sealing face18aof each of the valve discs13and23, it is possible to prevent the valve discs13and23from tilting and seal off gas without fail. Furthermore, since degassing recesses13cand23callowing gas to pass through are formed in the radial direction at the other ends13band23bon the other side of the ends13aand23aat which the sealing faces18aare formed respectively, it is possible to let the gas pass through the degassing recesses13cand23ceven when the other end13btouches the disc16aof the relevant filter retainer16or the other end23btouches the flange14bof the relevant valve disc containing cylinder14. Consequently, it is possible to prevent an unnecessary sealing face from forming on the side opposite to the sealing face18a.

Although the present invention has heretofore been explained concretely on the basis of the embodiment, the present invention is not limited to the above embodiment. Although substrates are specified as the objects contained in a substrate container according to the present invention in the above embodiment, the contained substrates are not limited to semiconductor wafers and other substrates such as mask glasses may also be contained.

Further, although a bottom plate7is installed in the above embodiment, the bottom plate7may not be installed.

Furthermore, although a compression coil spring17is used as the biasing means in the above embodiment, a flat spring or a rubber including a thermoplastic elastomer may be used for example. Here, as the material for a flat spring, stainless steel or resin is used.

Further, although the outer diameter D1of each of the annular biasing faces is larger than the outer diameter D2of the relevant annular sealing face18ain the above embodiment, the outer diameter D1of each of the biasing faces may be smaller than the outer diameter D2of the relevant sealing face. It is desirable however that the outer diameter D1of each of the biasing faces is not smaller than the outer diameter D2of the relevant sealing face.

INDUSTRIAL APPLICABILITY

The present invention provides: check valves that do not require the control of tightening torque and can simplify assembly work; and a substrate container equipped with the check valves.