JPH0628657Y2 - Electronic balance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronic balance having a built-in calibration weight.

<Prior art> Generally, electronic balances are calibrated by loading a weight detection mechanism with a known weight in the vicinity of the weighing capacity and updating the span coefficient so that the measured display value in that state matches the weight mass. Done by

By the way, particularly in a high-precision electronic balance, the change in the displayed value due to the span change caused by the temperature change is remarkable, and it is necessary to frequently perform span calibration in order to maintain a constant accuracy.

Therefore, conventionally, for the purpose of facilitating this calibration operation, there is an electronic balance in which a calibration weight and its addition / removal mechanism are built in a balance housing, and calibration is possible without separately preparing a reference weight.

The built-in weight addition / removal mechanism generally moves the weight up and down to load or unload the load detection mechanism. Normally, the built-in weight is moved up and down by supporting it at least at two points. The composition is adopted.

<Problems to be solved by the invention> In order to incorporate the calibration weight and its addition / removal mechanism, a space is required in the balance housing, but in the balance with a relatively large capacity, the volume of the weight becomes large. Up,
There is a problem that the balance itself is getting larger. In addition, since the conventional adding and removing mechanism is complicated, it not only causes the cost of the balance to rise, but also has the problem that it is easy to break down. Furthermore, the method of fixing the calibration weight when there is no load Also, in order to withstand shock during transportation, it was necessary to take measures such as using a special fixture separately.

The present invention has been made in view of such a point, and enables the incorporation of a calibration weight and its addition / removal mechanism without increasing the size of a balance with a large weighing capacity. The purpose of the present invention is to provide an electronic balance capable of securely fixing a built-in weight at any time.

<Means for Solving the Problems> In order to achieve the above object, in the present invention, as shown in FIG. 1 corresponding to the embodiment, a gap between the upper surface of the housing 1 and the sample dish 2, or An annular calibration weight 4 surrounding the sensitive member 3 is disposed in a space formed above the inside of the housing 1 by projecting the upper surface of the housing 1 toward the lower surface of the sample dish 2. is doing. Further, below the calibration weight 4, there is provided a vertically displaceable rod 5 and a vertical drive mechanism 6 thereof at a position separated from the center of the calibration weight 4 by a predetermined distance. Above the calibration weight 4, at least a position A separated from the center of the calibration weight 4 on the side where the vertical moving rod 5 is disposed, and
At a position B near the outer peripheral portion of the calibration weight on the opposite side thereof, a weight contact member 7 capable of contacting the calibration weight 4 is provided. Further, the sensing member 3 is provided with a weight receiver 8 below the calibration weight 4 that can support the calibration weight 4. Either one of the state in which the calibration weight 4 is sandwiched between the one rod 5 and the weight contact member 7 by the vertical movement of the one vertical moving rod 5 or the calibration weight 4 is placed on the weight receiver 8. It is configured so that the state of can be selected.

<Operation> The calibration weight 4 is provided by utilizing the space between the lower surface of the sample dish 2 and the upper surface of the housing 1, which are normally empty spaces.

One vertical moving rod 5 is provided at a position deviated from the center of the ring-shaped calibration weight 4, and the calibration weight 4 initially tilts and rises when the rod 4 is raised, but the calibration weight 4
Due to the presence of the weight contact member 7 that abuts on the calibration weight 4 at the position A above, the calibration weight 4 has a point A as a fulcrum from a certain point during the ascent of the rod 5, as shown in FIG. ,
The rod 5 moves with the contact point of the rod 5 as the point of action so that the above-mentioned inclination is eliminated. As shown in FIG. 1, the calibration weight 4 is fixed while contacting the weight contact member 7 at a point A on the upper surface and a point B on the opposite side, and a bar 5 on the lower surface.

When the rod 5 is lowered from that state, the calibration weight 4 is lowered by a movement opposite to the above, and eventually it is placed on the weight receiver 8 as shown in FIG.

<Embodiment> FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, showing a state in which the calibration weight 4 is not loaded on the weight receiver 8 of the load detection mechanism.

A known load detection mechanism including a load sensor such as an electromagnetic force balance mechanism is provided in the housing 1 of the balance, and this load detection mechanism can detect the load acting on the sensing member 3.

The sensing member 3 is a member that stands upright along a vertical line, and its upper end portion is exposed to the outside through a hole 1a formed in the upper surface of the housing 1. Then, the sample dish 2 is supported on the tip of the sensing member 3. A cup-shaped weight receiver 8 is formed in the vicinity of the upper end portion of the sensing member 3, for example, immediately below the support portion of the sample dish 2.

The sample dish 2 is a disc-shaped integral dish as a whole, and its peripheral edge is bent downward and a hole for inserting the tip of the sensing member 3 is formed in the center of the lower surface.
An annular calibration weight 4 centered on the axis of the sensitive member 3 is arranged in the space between the lower surface of the sample dish 2 and the upper surface of the housing 1.

Inside the housing 1, a vertically movable rod 5 which is vertically displaceable is arranged at a predetermined distance from the sensing member 3, and thus at a position displaced from the center of the calibration weight 4 by a predetermined distance. There is. The vertical moving rod 5 supports the vertical moving rod 5 at its lower end and is slidable in the horizontal direction along the bottom surface of the housing 1 and, for example, a manual lever for sliding the slide cam 6a. Alternatively, a vertical drive mechanism 6 including an actuator (not shown) such as a solenoid provides vertical displacement.

At the position corresponding to the lower surface of the calibration weight 4 and directly above the vertical moving rod 5, a V groove 4a is formed to the extent that the tip of the vertical moving rod 5 is inserted.

An annular weight contact member 7 is fixed above the housing 1 so as to cover the upper surface of the calibration weight 4. The weight contact member 7 has a taper surface that opens downward at the peripheral edge thereof, and a taper surface equivalent to this taper surface is formed on the upper outer edge portion of the calibration weight 4.

In the figure, 9a and 9b are housing fixed columns.

In the above structure, as shown in FIG. 1, when the slide cam 6a is moved to the left and the vertical moving rod 5 is raised to the upper limit, the calibration weight 4 moves to the vertical moving rod 5 by V.
It is pushed upward through the groove 4a and its upper surface is pressed against the entire lower surface of the member 7 against the weight. In this state, the calibration weight 4 does not come into contact with any of the sample pan 2, the sensing member 3 and the weight receiver 8, and the calibration weight 4 is fitted into the tapered surface of the weight contact member 7. ,And,
In addition to fitting the vertical moving rod 5 into the V groove formed on the lower surface, the vertical moving rod 5 is securely fixed without being displaced even when a slight impact is applied from the outside. The state of FIG. 1 is a state in which the calibration weight 4 is not loaded on the load detection mechanism, and this state is selected in a normal measurement state or the like.

FIG. 2 is a diagram showing a state in which the slide cam 6a is moved to the right from the state of FIG. 1 and the vertical moving rod 5 is lowered to the lower limit.

When the vertical moving rod 5 is lowered, the calibration weight 4 is lowered accordingly, but when the vertical moving rod 5 is lowered to its lower limit, the contact with the calibration weight 4 is released. That is, the height of the tip of the vertical moving rod 5 is lower than the upper surface of the weight receiver 8 at the descending end thereof, and therefore the calibration weight 4 is placed on the upper surface of the weight receiver 8 in this state. In this state, the calibration weight 4 is also released from contact with the member 7 for contacting the weight, and the entire mass thereof is transmitted to the load detection mechanism via the weight receiver 8 and the sensing member 3. The state of FIG. 2 is
The calibration weight 4 is loaded on the load detection mechanism, and this state is selected during span calibration.

In the state of FIG. 2, that is, when the calibration weight 4 is changed from the loaded state to the unloaded state, the slide cam 6a is slid to the left. As a result, the vertical moving rod 5 rises and its tip fits into the V groove of the calibration weight 4 and starts to push it up, but the vertical moving rod 5 moves from the center of the calibration weight 4, in other words, from the center of gravity. Since the calibration weight 4 is pushed up at a position shifted by a predetermined distance, the calibration weight 4 is only inclined at the beginning. However, when the vertical moving rod 5 rises to some extent, as shown in FIG. 3, the vertical moving rod 5 of the calibration weight 4 is moved.
Above the edge of the side, that is, the highest position is the member 7 per weight.
Touch point A. Therefore, when the vertical moving rod 5 further rises from the state shown in FIG. 3, the calibration weight 4 uses the point A as a fulcrum, and the tip end of the vertical moving rod 5 acts as a point of action to perform a lever movement to move to a position opposite to the point A. The portion also rises, and eventually that portion also comes into contact with the point B of the weight contact member 7, and finally contacts and is fixed to the entire lower surface of the weight contact member 7 as shown in FIG.

Here, in the state shown in FIG. 1, when the pushing amount of the vertical moving rod 5 is small, the calibration weight 4 is affected by an external impact.
However, there is a fear that it will shift from the correct storage position. Therefore, it is preferable to consider a mechanism for adjusting the amount by which the vertical moving rod 5 is pushed up.

As this adjustment mechanism, for example, one of the housing fixed columns 9a is used, and an expansion / contraction mechanism or the like is provided to position the upper surface of the housing 1 (hereinafter referred to as the case) with respect to the bottom surface (hereinafter referred to as the base). It is possible to raise and lower.

That is, as shown in FIG. 1, the housing fixing column 9a
The upper end of the is fixed to the case with screws or the like, and the lower end is inserted into the guide hole 11 provided in the base, and is fixed to the base using the loosening prevention screw 10 which can be rotated from the outside of the base. At this time, the outer periphery of the housing fixing column 9a and the guide hole 11 are square or hexagonal so as not to rotate together with the rotation of the screw 10. With such a mechanism, the loosening prevention screw 10 is turned from the outside to adjust the vertical position of the housing fixing column 9a with respect to the behase, whereby the position of the case (the upper surface of the housing 1) is moved up and down, and accordingly, the weight contact member 7 is moved. The position of the vertical moving rod 5 with respect to the tip moves up and down, and the strength of fixing the calibration weight 4 in the unloaded state can be adjusted.

The loosening prevention screw 10 may be any screw as long as it has a rotation-preventing action even during screwing, and for example, a well-known screw commercially available under the trade name of power lock screw or the like can be used.

Further, as another adjusting mechanism, the up-and-down moving rod 5 itself may be provided with a stretching function. That is, FIG. 4 (a) is a view in which the vertical moving rod 5 is divided into two and screwed together, and the spacer S ₁ is inserted between them to change the thickness thereof. ) The vertical moving rod 5 is provided with an adjusting screw S ₂ at one end thereof.

Here, the position of the calibration weight 4 in the present invention is substantially the same space as the above-described embodiment except the space between the upper surface of the housing 1 and the lower surface of the sample dish 2, but the upper surface of the housing 1 May be a space formed in the housing 1 by projecting toward the lower surface of the sample dish 2.

FIG. 5 shows an example thereof, in which the upper surface of the housing 1 is
The calibration weight 4 is housed in the space of the upper end inside the housing 1 formed by this projection so as to project toward the lower surface side of the sample dish 2 around the hole 1a. In this case, the upper surface of the housing 1 can also serve as the weight 7 '.

Further, in each of the above embodiments, the V groove in which the vertical moving rod 5 is fitted is formed on the lower surface of the calibration weight 4, but a circular (dish-shaped) recess may be provided instead of the V groove. .

Further, the calibration weight 4 in the present invention has a ring shape,
Needless to say, it may be a rectangular ring, and may be, for example, a C-shape having a notch in a part of the ring.

Further, it suffices that the member contacting the weight comes into contact with the calibration weight at least at points A and B shown in FIG. However,
In order to ensure the fixing of the calibration weight in the unloaded state, it is preferable to make contact with almost the entire upper edge of the calibration weight.

<Effects of the Invention> As described above, according to the present invention, the space between the sample pan and the balance housing, which is normally a wasted space, is used to dispose the calibration weight here, and Since the calibration weight can be added to and removed from the sensing member with a single rod, it is possible to incorporate a calibration weight into a balance with a relatively large capacity without increasing the size of the balance.
The addition / removal mechanism is simple, so it is not prone to failure, and is low cost, and because the calibration weight is securely fixed in the unloaded state, it is strong against shock during transportation, especially fixed separately. It is possible to obtain a balance that can withstand transportation without preparing tools or the like.

[Brief description of drawings]

1 to 3 are longitudinal sectional views of an embodiment of the present invention, FIG. 1 is a diagram showing a non-loaded state of the calibration weight 4, FIG. 2 is a diagram showing a loaded state of the calibration weight 4, and FIG. FIG. 3 is a diagram showing an intermediate state. FIG. 4 is an explanatory view of a push-up amount adjusting mechanism by a vertically moving rod according to another embodiment of the present invention, and FIG. 5 is a longitudinal sectional view of a main portion of still another embodiment of the present invention. 1 ... Housing 2 ... Sample dish 3 ... Sensing member 4 ... Calibration weight 4a ... V groove 5 ... Vertical moving rod 6 ... Vertical drive mechanism 6a ... Slide cam 7 ... Weight contact member 8 ...... Weight receiver

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Laid-Open No. 2-10228 (JP, A) Japanese Patent Laid-Open No. 62-27626 (JP, A) Actual Japanese Laid-Open No. 63-137827 (JP, U) Japanese Patent Publication No. 49- 10273 (JP, B1)

Claims (1)

[Scope of utility model registration request] 1. A sensing member of a load detecting mechanism disposed in a housing is exposed to the outside through a hole formed in the upper surface of the housing, and the sensing member is disposed outside the housing. In a balance in which a sample dish is engaged, the balance is formed above the inside of the housing by projecting the upper surface of the housing toward a gap between the upper surface of the housing and the sample dish or the lower surface of the sample dish. A ring-shaped calibration weight that surrounds the sensing member as a center is disposed in the space that is provided, and a predetermined distance is provided below the center of the calibration weight below the calibration weight. One rod that can be displaced in the vertical direction and its vertical drive mechanism are provided at the position, and above the calibration weight,
At least a position that is a predetermined distance from the center of the calibration weight to the side where the rod is disposed, and a weight that can abut the calibration weight at a position in the vicinity of the outer periphery of the calibration weight on the opposite side. Further, a member is provided, and further, the sensing member is provided with a weight receiver capable of supporting the calibration weight below the calibration weight, and the calibration weight is moved by the vertical movement of the one rod. An electronic balance characterized by being configured so that it can be selected from a state of being sandwiched between a bar of a book and the weight contact member or a state of being placed on the weight receiver.