JPH0749988B2 - Balance with windshield - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a windshield balance,
Particularly, the present invention relates to a balance with a draft shield suitable for use in a clean room.

[0002]

2. Description of the Related Art In a high-precision balance, a windshield that surrounds a sample dish is usually provided in order to prevent a change in the weight value caused by the wind hitting the sample dish. In particular, in a clean room, an air flow from the upper part to the lower part of the room, so-called downflow, is flowing, and if there is no windshield, the weighing display value will fluctuate and it will not be possible to use a balance more precise than a certain level. .

The conventional windshield generally has a structure in which a weighing chamber is formed by a side wall and a ceiling provided around the sample dish, and a door is provided on a part of the side wall. And
The door is slidably guided by the components of the weighing chamber on the upper and lower sides of the plate-like body.

[0004]

In the conventional weighing chamber as described above, when the door is opened and closed, a small amount of dust is generated due to the rubbing of the guide portion, and the dust is applied to the object to be weighed. In particular, it is unsuitable for use in the case where an item that requires treatment in a clean room is weighed in the clean room.

In view of the above situation, the present inventor has already moved the windshield door to the left or right or up and down, and the windshield with which dust generated by rubbing with the guide portion does not splash on the object to be weighed. We have proposed balances (Japanese Patent Application No. 3-39330, Japanese Patent Application No. 4-3135), but these are aimed at incorporation in large-scale equipment for automatic measurement, etc. There is a problem that the installation space becomes large when applied to a balance.

It is an object of the present invention to provide a compact and relatively simple structure that does not affect the measured value due to downflow even when used in a clean room, and the dust that accompanies the opening and closing of the door is the object to be measured. It is to provide a balance with a windshield that does not have the risk of being hit by the wind.

[0007]

A structure for achieving the above-mentioned object will be described with reference to FIGS. 1 and 2 which are drawings of an embodiment.
Is fixed to the upper surface of the balance housing 2 accommodating the above, has an opening 31a in the side wall, and is provided inside the cylindrical outer windshield 3 provided with the ceiling plate 32 without contacting the outer windshield 3. An opening 41a is formed in the side wall, and the bottom plate 42
A cylindrical inner windshield 4 is provided, and the inner windshield 4 is rotatably supported by at least three tops 5 ... Therefore, the sample dish 6 is arranged inside the inner windshield 4 and engages with the load sensor 1 through the through holes 2a, 42a of the balance housing 2 and the bottom plate 42 of the inner windshield 4. Characterized.

[0008]

When the inner windshield 4 is rotated in a non-contact state with respect to the outer windshield 3 and the openings 31a and 41a of the two windshields coincide with each other, the windshield is substantially opened, and when they do not coincide, the windshield is closed. Become. Here, since the inner windshield 4 rotates while being supported by the tops 5 on the bottom surface of the bottom plate 42, the dust generated here penetrates the bottom plate 42 of the inner windshield 4 and is arranged inside thereof. There is no possibility of splashing on the object to be weighed on the prepared sample dish 6.

[0009]

1 is a partial sectional front view of a basic embodiment of the present invention, and FIG. 2 is a schematic exploded perspective view thereof.

An outer windshield 3 having a cylindrical side wall 31 and a ceiling plate 32 is fixed to the upper surface of the balance housing 2 accommodating the load sensor 1. The side wall 31 of the outer windshield 3 has an opening 31a facing the front side of the balance.

The inner windshield 4 has a cylindrical side wall 41 and a bottom plate 42. The side wall 41 has an opening 41a and a knob 4.
1b is formed and inside the outer windshield 3,
It is arranged so as to be rotatable about its axis φ in a non-contact state.

That is, three tops 5 ... 5 are rotatably mounted on the upper surface of the balance housing 2 via supporting members 51 ... 51, respectively. The inner windshield 4 is supported on the lower surface of its bottom plate 42. With this configuration, the inner windshield 4 is rotated in that direction by manually moving the knob 41b to the left or right through the opening 31a of the outer windshield 3, and the inner windshield 4 is rotated to the rotation position. Accordingly, the opening portion 41a of the inner windshield 4 overlaps with the opening portion 31a of the outer windshield 3 in FIG.
And the opening portion 31a of the outer windshield 3 has the inner windshield 4
The side wall 41 is configured to be closed. When the material of the tops 5 is made of resin, the inner windshield 4 and the support members 51 are connected to each other in order to suppress a measurement error due to a Coulomb force caused by static electricity generated when sliding on the inner windshield 4. It is desirable to provide a ground cable 9 between the two.

The sample dish 6 is arranged inside the inner windshield 4,
The inside of the inner windshield 4 forms a weighing chamber 7. Therefore, the weighing chamber 7 is opened and closed by the rotation of the inner windshield 4 described above.

The sample dish 6 is connected to the load sensor 1 in the balance housing 2 by the following structure. That is, concentric through holes 2a and 42a are formed in the upper surface of the balance housing 2 and the bottom plate 42 of the inner windshield 4, and the sample dish 6 is provided with the through holes 2a and 42a in the balance housing 2. It is placed on the sensing section of the load sensor 1. A windshield ring 8 is fixed to the upper surface of the balance housing 2 by enclosing the through hole 2a and extending upward, penetrating through the through hole 42a of the bottom plate 42 of the inner windshield 4 and reaching the weighing chamber 7. This prevents the wind from acting on the sample pan 6 or the load sensor 1 with the weighing chamber 7 closed.

In the above-described embodiment, the object to be weighed on and off the sample pan 6 is placed and opened with the openings 31a and 41a overlapped with each other, and the weighing chamber 7 is opened to the outside. Similarly, the weighing chamber 7 is closed to the outside. In this measurement state, the sample dish 6 and the object to be weighed thereon are surrounded by the upper surface of the balance housing 2, the side walls 31 and 41 of the outer windshield 3 and the inner windshield 4, and the ceiling plate 32 of the outer windshield 3. Therefore, the downflow in the clean room does not affect the measured value. Further, when the weighing chamber 7 is opened / closed, that is, when the inner windshield 4 is rotated, the bottom plate 4 of the inner windshield 4 is
The dust generated by the contact / sliding between 2 and the tops 5 ... 5 or the rotation of the tops 5 ... 5 itself has a sliding position lower than the opening 41a of the inner windshield 4, In the presence of downflow, the airflow that has passed through the tops 5 ... 5 through the opening 31a in the presence of downflow does not fall on the outside downwards due to its own weight. Since the dust flows, the above-mentioned dust does not enter the weighing chamber 7 even by the downflow, and the object to be weighed is always placed in a clean environment.

FIG. 3 is a sectional view showing the structure of the main part of another embodiment of the present invention. In this example, the airflow due to downflow is used more effectively. A louver 31b that opens upward is formed on the upper side wall 31 of the outer windshield 3, and a window 31c is appropriately formed on the lower part. . According to this configuration, an air flow as indicated by Q in the figure is formed by the downflow, and the dust generated near the tops 5 ... 5 is more effectively discharged to the outside of the external windshield 3.

For the same purpose, as shown in FIG. 4 which is a sectional view of the main structure, a part of each top 5, ...
It is also possible to project the dust through the window 31c formed in No. 1 to generate an air flow as indicated by R to flow the dust to the outside.

Further, for example, when used in an environment where there is a side wind other than downflow, it is necessary to rotate the inner windshield 4 and close the weighing chamber 7 to enhance the airtightness inside the weighing chamber 7. 5A, 5B and 5C, the outer windshield is shown in FIG. 5A, FIG. 5B and FIG. 5C with the weighing chamber 7 closed. The thin plate 33 extending in the vertical direction is attached to the inner surface of the side wall 31 of the inner side windshield 4 when the weighing chamber 7 is opened.
The vertical edge E of the opening 41a is configured to contact the thin plate 33. As a result, the airtightness inside the weighing chamber 7 is improved, and at the same time, by using the thin plate 33 as a metal plate, the weighing chamber 7 is fully closed even when the tops 5 are made of resin. Each time, the inner windshield 4 is automatically grounded to the balance housing 2 via the outer windshield 3, and the grounding cable 9 shown in FIG.
The influence of static electricity can be suppressed. In addition, by setting the contact amount between the edge E and the thin plate 33 to be very small, it is possible to suppress the amount of dust generated due to the rubbing between the inner windshield 4 and the thin plate 33 to such an extent that there is no practical problem. it can. Moreover, you may use a square bar instead of the thin plate 33.

By the way, in the example shown in FIG. 1, the ceiling plate 32 of the outer windshield 3 is integrally formed with the side wall 31, but in this configuration, for example, in order to prevent contamination of the object to be weighed, its material is stainless steel or the like. If it is necessary, the object to be weighed in the weighing chamber 7 cannot be seen from the outside.

Therefore, it is necessary to make the ceiling plate 32 of the outer windshield 3 a transparent glass plate or a resin plate. in this case,
As shown in FIG. 6 (A) or (B) as a cross-sectional view of the main part configuration, the ceiling plate is a laminate of a transparent plate 320 and a conductive material 321 such as a conductive film or a wire mesh, and When the body is configured to be attracted to the side wall 31 side by the screws 325 and 326 by utilizing the elastic force of the spring plate 323 or 324, there is no gap between the side wall 31 and the ceiling plate, and especially when used in a clean room. It is convenient that the cleaning work inside the weighing chamber 7 which is peculiar and important when doing so can be performed only by removing the screws 325 or 326 and removing the ceiling plate. The reason why the conductive material 321 is laminated on the ceiling plate in this configuration is to prevent the Coulomb force due to the static electricity charged on the transparent plate 320 from acting on the object to be weighed and including an error in the weighing result.

In the present invention, the shape of the tops 5 and 5 and the relationship with the inner windshield 4 are not limited to those illustrated in FIG. 1 and FIG. 4, but may be modified in several ways. 7 or something like FIG. In the example shown in FIGS. 7A and 7B, a top 50 (A) having an hourglass shape or a top 50 ′ having a concave outer peripheral surface is used.
(B) is provided, and a guide rail 43 (A) having a circular outer peripheral surface or a guide rail 43 '(B) having a chevron cross section is provided on the inner windshield 4 side. Further, in the example shown in FIG. 8, the tops 51 and 52 respectively having horizontal and vertical rotation axes are combined, and the top 51 shares the vertical support and the top 5 supports the radial support.

Further, in the present invention, the top in each of the above examples is constituted to be rotationally driven by a motor or the like, and the inner windshield 4 is rotated based on an opening / closing signal by a switch operation or the like to automatically weigh. It can also be configured to open and close the chamber 7.

Further, the supporting position of the inner windshield 4 by the top is not limited to the lower surface of the bottom plate 42, but may be any position as long as it is a position below the opening 41a.

[0024]

As described above, according to the present invention,
Inside the outer windshield, which has a ceiling plate and a cylindrical outer windshield with an opening in the side wall, has a bottom plate and also has a cylindrical inner windshield with an opening in the side wall. Is a weighing chamber with a sample pan, and the inner windshield is rotatably supported by at least three pieces below the opening. The inner and outer windshields are opened by rotating the inner windshield. The weighing chamber is configured to open with the parts aligned with each other.Therefore, dust that accompanies opening and closing of the weighing chamber will not be generated against the lightweight objects measured in a clean room where there is downflow. There is no risk of swaying, and there is no need for space to open and close the weighing chamber as in the conventional method of opening the door vertically or horizontally, so it has a compact structure. It can be, it can be easy to use especially as a stand-alone balance in a clean room.

[Brief description of drawings]

FIG. 1 is a partial sectional front view of a basic embodiment of the present invention.

FIG. 2 is a schematic exploded perspective view thereof.

FIG. 3 is a sectional view showing the configuration of the main part of another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of the main part of still another embodiment of the present invention.

FIG. 5 is a front sectional view (A) of a main part, a left side view (B) and a plan sectional view of the main part showing a configuration of still another embodiment of the present invention, which is suitable for use in an environment with cross wind. (C)

FIG. 6 is a sectional view of an essential part showing another example of the structure of the ceiling plate 32 of the outer windshield 3 of the present invention.

FIG. 7 is an explanatory view of another example of the relationship between the inner windshield 4 and the top of the present invention.

FIG. 8 is an explanatory view of still another example of the relationship between the inner windshield 4 and the top of the present invention.

[Explanation of symbols]

 1 load sensor 2 balance housing 2a through hole 3 outer windshield 31 side wall 31a opening 32 ceiling plate 4 inner windshield 41 side wall 41a opening 41b knob 42 bottom plate 42a through hole 5 · 5 pieces 6 sample dish 7 weighing chamber 8 windshield ring

Claims (1)

[Claims] 1. A cylindrical outer windshield fixed to the top surface of a balance housing accommodating a load sensor, having an opening in a side wall, and provided with a ceiling plate, without contacting the outer windshield. , An opening is formed in the side wall, and a cylindrical inner windshield having a bottom plate is disposed, and the inner windshield is rotated by at least three pieces below the lower edge of the opening of the inner windshield. The sample pan, which is freely supported and carries the load to be measured, is engaged with the load sensor through the through holes in the balance housing and the bottom plate of the inner windshield while being placed inside the inner windshield. Balance with windshield.