JPH0563735B2 - - Google Patents

Description

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

<Prior art> Generally, when calibrating an electronic balance, a weight with a known mass in the vicinity of the weighing capacity is loaded onto a load detection mechanism including a load sensor, and the calibration is performed so that the displayed value in that state matches the mass of the weight. This is done by updating the coefficients, etc.

Incidentally, such calibration should be performed frequently by the user, not only when installing the electronic balance, but also as needed or periodically to eliminate span changes due to aging of the components of the electronic balance. is desirable.

Therefore, in order to make this calibration operation easier, there are electronic balances that have a dedicated calibration weight built into the balance housing, making it possible to calibrate without separately preparing a precise reference weight. .

<Problem to be solved by the invention> By the way, in order to incorporate a calibration weight,
A space is required within the housing to accommodate the built-in weight and its adjustment mechanism, but this has been difficult to achieve in large-capacity electronic balances because the volume of the weight is large.

As a countermeasure to this problem, there is a conventional method of calibrating a large weight with a small weight using a lever. However, with this method, it is difficult to avoid changes in the lever ratio during transportation of the balance, changes in the lever ratio due to ambient temperature, etc., and there is a problem in terms of accuracy.

The present invention has been made in view of this point, and an object of the present invention is to provide an electronic balance in which a weight having a larger mass than before can be housed without taking up a large space within the housing.

<Means for Solving the Problems> In order to achieve the above object, in the present invention, as shown in FIG. A calibration weight 4 is disposed in the space, and a mechanism for loading/unloading the calibration weight 4 with respect to a weight receiver 5 formed near the upper end of the sample pan 2 or sensing member 3 (for example, a pusher) is provided. Raising rods 6a, 6b) are provided.

Here, instead of the space in which the calibration weight 4 is arranged to be the space formed between the upper surface of the housing 1 and the sample plate 2, as shown in FIG. It may also be a space at the upper end of the interior of the housing 1 that is formed to protrude into the recess on the lower surface of the dish 2 .

Note that the sample dish 2 referred to in this specification refers to not only one integrally formed of a single member but also one that is formed integrally with a third plate, for example.
As shown in the figure, it also includes one that is separated into a plate 2a and a plate holder 2b.

<Function> During normal measurements, the calibration weight built into the balance maintains a non-contact state with the sensitive member of the load detection mechanism and the sensitive parts of the sample plate connected to it, and during calibration, it The load must be applied without contacting other members. Further, as described above, it is desirable that the load be applied directly to the center of the sensing member without using a lever or the like.

The calibration weight 4 is made into a ring shape, for example, and the sensing member 3
The load inside the housing 1 can be reduced by placing the load on the sample pan 2 or the weight receiver 5 near the upper end of the sensing member 3. It is possible to use a large-volume calibration weight 4 without interfering with the detection mechanism or the like and without increasing the dimensions of the housing 1 itself.

As shown in FIG. 5, the calibration weight 4 is placed in the space inside the housing 1 created by protruding the top surface of the housing 1 into the recess on the bottom surface of the sample dish 2.
Even if it is arranged, there is no need to consider interference with other structural members in the housing 1, and a large-volume calibration weight 4 can be used without increasing the housing space other than the protrusion.

<Example> An example of the present invention will be described below based on the drawings.

FIG. 1 is a central vertical cross-sectional view showing the main structure of an embodiment of the present invention, in which a shows a normal measurement state and b shows a loaded state of the calibration weight 4.

A known load detection mechanism including a load sensor such as an electromagnetic force balance mechanism is disposed within the housing 1, 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 faces the outside through a hole 1a bored in the upper surface of the housing 1. The sample plate 2 is supported at the tip of the sensing member 3. A cup-shaped weight receiver 5 is formed near the upper end of the sensing member 3, for example, directly below the support portion of the sample plate 2.

The sample plate 2 is an integral plate having a disk shape as a whole, the peripheral edge of which is bent downward, and a hole into which the tip of the sensing member 3 is inserted is formed in the center of the lower surface. An annular calibration weight 4 is disposed in a space between the lower surface of the sample plate 2 and the upper surface of the housing 1, with the axis of the sensing member 3 as its center.

Inside the housing 1, push-up rods 6a and 6b are disposed which are moved up and down in conjunction with each other by a known simple up-and-down mechanism such as a cam mechanism or a crank mechanism. When the push-up bars 6a and 6b are at their rising ends, they come into contact with the bottom surface of the calibration weight 4 and push it up, as shown in FIG. The calibration weight 4 can be sandwiched and held between the weight 7 that has been adjusted. Note that the weight 7 has a tapered surface that opens downward, and when this tapered surface comes into contact with the tapered surface formed above the outer peripheral surface of the calibration weight 4, when it is pushed up by the push-up rods 6a and 6b, The center of the calibration weight 4 is positioned to coincide with the axis of the sensing member 3. In this state, the calibration weight 4 does not come into contact with any of the sample pan 2, sensing member 3, and weight receiver 5, and only the load placed on the sample pan 2 is detected by the load detection mechanism.

When the push-up bars 6a, 6b are at the lower end, they are no longer in contact with the calibration weight 4, as shown in FIG. 1b. That is, the push-up rods 6a, 6
The height of the tip of b is lower than the upper surface of the weight receiver 5 at its descending end, so the calibration weight 4 rests on the upper surface of the weight receiver 5 in this state. In this state, the calibration weight 4 is released from contact with the perpendicular weight 7, and its total mass is transmitted to the load detection mechanism via the weight receiver 5 and sensing member 3.

FIG. 2 is a central vertical cross-sectional view showing an example in which dustproof measures have been applied to the embodiment of FIG. 1.

That is, in this example, the weight per 7 is extended upward and a dustproof cover 7a extending further inward is integrally formed. This makes it possible to prevent the calibration weight 4 from becoming contaminated by dust in the atmosphere or by spilled samples. In FIG. 2, the same members as in FIG. 1 are given the same numbers.

The example shown in FIG. 3 is a modification of the dustproof measure shown in FIG. 2, and is an extremely practical example in consideration of ease of assembly and the like. Note that in this example, the sample plate 2 is replaced by the plate 2a.
This shows the type with separate plate support 2a.

In the example shown in FIG. 3, the hole 1a on the upper surface of the housing 1 is enlarged, and the lower dustproof cover 10 is provided to cover the hole 1a. Furthermore, an upper dustproof cover 71 that also serves as a weight is placed above it, and a calibration weight 4 is disposed in a space formed between the upper dustproof cover 71 and the lower dustproof cover 10. The push-up rod 6a is the lower dustproof cover 1.
The calibration weight 4 is configured to move up and down through the 0 point. Note that 60 is a push-up bar guide.

In this example, the sensing member 3 of the calibration weight 4 is
The positioning with respect to the axis of the calibration weight 4 is achieved by forming grooves 4a on the lower surface of the calibration weight 4 in correspondence with the positions of the push-up rods 6a and 6b.

To assemble the upper dustproof cover 71 to the housing 1, for example, the periphery of the hole 1a of the housing 1 is raised up, several protrusions 11 are provided on the outer periphery, and L-shaped notches are provided in the cover 71. , by placing the cover 71 over the rising portion of the housing 1 and twisting it so that it can be done with one touch. FIG. 4a shows an example of the notch 71a on the cover side, and FIG. 4b shows an example of the protrusion 11 on the housing 1 side. Note that a similar structure can be adopted for the lower dustproof cover 10 as well.

The example shown in Figure 5 is 7 per weight in Figure 1.
This is an example in which the dustproof cover 7a in FIG. 2 is also used by the wall of the housing 1.

In this example, the wall of the upper surface of the housing 1 is projected into the recess formed on the lower surface of the sample dish 2, centering on the hole 1a, and the space at the upper end inside the housing 1 is formed by this projection. A calibration weight 4 is disposed at . And push up rods 6a, 6b
At its rising end, the calibration weight 4 abuts against a flat surface 17 formed on the lower surface of the protrusion 12 of the housing 1 . In other words, the flat surface 17 of the housing 1 serves as the weight. Further, at the descending ends of the push-up bars 6a, 6b, the calibration weight 4 is placed on the weight receiver 5 provided at the upper end of the sensing member 3, as in FIG. Note that the positioning of the calibration weight 4 with respect to the axis of the sensing member 3 is done by forming grooves or recesses on the bottom surface of the calibration weight 4 corresponding to the positions of the push rods 6a and 6b, as in the example shown in FIG. This is dealt with by providing locations 4a and 4b.

In the example shown in FIG. 5, the calibration weight 4 is housed in the housing 1, but its housing position is in the space at the upper end of the interior obtained by protruding the housing 1 into the recess below the sample dish 2. because there is,
There is no need to consider interference with the load detection mechanism or the like within the housing 1, and a large-volume calibration weight 4 can be used without increasing the volume of the housing 1 other than the protrusion 12. Also, housing 1
The weight itself has the functions of a dustproof cover for the weight and the calibration weight 4, and the number of parts can be reduced.

In each of the embodiments described above, the number of push-up rods 6a, 6b may be three or more, and for example, as shown in FIG.
It is possible to move the calibration weight 4 up and down by using one push-up rod 6. Furthermore, when the cover 71 and the groove 4a are provided as shown in FIG. 3, the weight 4 can be moved up and down even with only one push-up bar 6a. In this case, the push-up rod 6a
When the amount of eccentricity of the weight 4 with respect to the weight increases and it becomes difficult to move up and down, appropriate measures can be taken accordingly, such as changing the shape of the weight 4 into a semicircular ring shape or a shape with a part of the ring cut out. .

The example shown in FIG. 7 shows an example in which the weight receiver 5 is provided on the sample pan 2 and the calibration weight 4 is housed inside the sample pan 2. As shown in FIG. In this figure, the left side of the center line shows the normal measurement state, and the right side shows the weight loaded state.

In this example, a weight receiver 5 is fixed to the downwardly bent end of the periphery of the sample dish 2, and covers almost the entire lower surface of the sample dish 2 except for the center. A calibration weight 4 is placed in the space between the sample plate 2 and the sample plate 2 . A push-up member 6d that can push up the calibration weight 4 through the central opening of the weight receiver 5 is provided in the housing 1. In normal measurement conditions, the calibration weight 4 is It contacts only the push-up member 6d and rides above it. Further, in the weight loaded state, the push-up member 6d descends, and the calibration weight 4 contacts only the weight receiver 5 and rides on it.
This example has the advantage that contamination of the calibration weight 4 can be prevented, similar to the example shown in FIG. 2, FIG. 3, or FIG. 5.

The example shown in FIG. 8 shows an example in which the mechanism for moving the calibration weight 4 up and down is simpler, and this mechanism is also provided outside the housing 1.

In this example, a cylindrical protrusion 61 with a wavy end face is provided on the upper surface of the hole 1a of the housing 1, and a ring-shaped weight support 62 with a wavy recess that fits into the protrusion 61 is provided.

FIG. 9 shows an exploded perspective view of the protrusion 61 and the weight support 62. Waveform formed on protrusion 61 and weight support 6
The waveforms formed in 2 have substantially the same pits, and the handle 62a provided on the weight support 62
When the weight support 62 is rotated, the weight support 6
2 is configured to move up and down.

The calibration weight 4 is placed above this weight support 62. Further, in this example, the weight receiver 5 is fixed to the sample plate 2 side.

In this example, at the upward displacement end of the weight support 62, the calibration weight 4 is supported on the upper surface of the weight support 62, as shown in FIG. Do not come in contact with any of them. From this state, use the handle 62a to hold the weight support 6.
2 is rotated and displaced downward, the calibration weight 4 is also displaced downward, but by the time the weight support 62 reaches the lower displacement end, the weight receiver 5
When the weight support 62 is at the lower displacement end, the calibration weight 4 contacts only the weight receiver 5,
Its entire mass is transmitted to the sensitive member 3.

The examples shown in FIGS. 10 to 18 are intended to move the calibration weight 4 up and down by rotating the calibration weight 4 itself, thereby loading/unloading the weight receiver 5. .

In the example shown in FIG. 10 as a central vertical sectional view and in FIG. 11 as an exploded perspective view of the main part, a cylindrical fixed weight support 63 having a wavy end face is formed on the upper surface of the housing 1 and centered around the hole 1a. ing. One notch 63b is formed at the top of each mountain portion 63a of this weight support 63, and pins 41 to 43 are made to protrude from the outer peripheral surface of the calibration weight 4 in correspondence with the notches 63b...63b. In addition, one of them, pin 41
is longer than the others to serve as a handle.

In the normal measurement state, as shown in FIG.
supported by. From this state, by holding the pin 41 and rotating the calibration weight 4, the calibration weight 4 gradually descends according to the waveform of the end face of the weight support 63, and eventually reaches the weight receiver 5. In this state, the depth of the trough of the waveform is determined so that the pins 41 to 43 do not come into contact with the weight support 63.

FIG. 12 shows a modification of the above-mentioned example, in which a fixed weight support 64 with a similarly corrugated end surface is formed on the upper surface of the housing 1, and a plurality of pins 44 are made to protrude from the outer peripheral surface of the calibration weight 4. . The feature of this example is that a special handle 45 for rotating the calibration weight 4 is fixed to the calibration weight 4, and the tip part 45 is fixed to the calibration weight 4.
A is made foldable using a hinge or the like so that it can be stored inside the sample dish 2 below. According to this example, the tip 45a of the handle 45 need only be pulled out to the outside of the sample dish 2 only when it is necessary to add or remove the calibration weight 4, and there is an advantage that the measurement work is not hindered.

In the example shown in FIG. 13, the means for rotating the calibration weight 4 is further modified.

That is, the fixed weight support 64 and the pin 44 of the calibration weight 4 are the same as in the previous example, but the calibration weight 4 is configured to be rotated via the dustproof cover 72. The dustproof cover 72 has a handle 72a that projects outward from below the sample dish 2, and is rotatably supported on a cylindrical cover support 64a that is connected to the weight support 64.
Furthermore, a fork 72b is projected from the lower surface of the dustproof cover 72, as shown in a perspective view in FIG. Then, the pin 4 provided on the calibration weight 4
4 is fitted into the recess of this fork 72b,
By rotating the dustproof cover 72 with the handle 72a, the calibration weight 4 is inserted through the fork 72b.
rotates and moves up and down. It is preferable to provide a plurality of pins 44 and forks 72b, for example three each. The width of the recess of the fork 72b is made wider than the outer diameter of the pin 44, and when the calibration weight 4 is loaded onto the weight receiver 5, a dust-proof It is necessary to turn the cover 72 slightly.

The examples shown in FIGS. 15 and 16 are examples in which the engagement relationship between the dustproof cover 72 and the calibration weight 4 and the mechanism for converting the rotation of the calibration weight 4 into vertical movement are respectively modified. In addition, a countermeasure has also been taken to semi-automate the fine movement and reversal of the dustproof cover 72 mentioned above. In addition, FIG. 15 is a central vertical cross-sectional view,
FIG. 16 is a plan sectional view of the main part of the calibration weight 4 taken just above the top surface.

In this example, the outer periphery of the calibration weight 4 is provided with, for example, about three notches 46, and each of the notches 46 is provided on the bottom surface of the dustproof cover 72.
A pin 72c inserted into the pin 72c is made to protrude.
The dustproof cover 72 is rotatably supported on a cover support 64a as in the example shown in FIG.
By rotating the dust-proof cover 72 with 2a, the calibration weight 4 is rotated while the pin 72c contacts the end surface of the notch 46.

This rotation of the calibration weight 4 is converted into vertical movement by a corrugated plate 47 fixed to the inner peripheral surface of the annular calibration weight 4 and a weight support 65 in a mating relationship with the corrugated plate 47. That is, a cylindrical weight support 65 having a wavy end surface is disposed around the hole 1a on the upper surface of the housing 1, and works in conjunction with the unevenness of the wavy plate 47 to respond to the rotation of the calibration weight 4. Move this up and down. When the calibration weight 4 is lowered, it is configured to rest on the weight receiver 5 via the corrugated plate 47.

In this example, a handle 7 is further provided on the top surface of the housing 1.
A return mechanism 8 is provided for slightly moving and reversing the dustproof cover 72 via 2a. This return mechanism 8
A piston 83 is provided within a cylinder 81 via a compression coil spring 82, and is disposed on the trajectory of the handle 72a during rotation. That is,
The mechanism 8 is arranged so that when the dust cover 72 is rotated by the handle 72a and the calibration weight 4 is loaded onto the weight receiver 5, the side surface of the handle 72a returns the piston 83 to the position where it is pushed into the cylinder 81. . In this state, as shown by the two-dot chain line in Figure 16,
The pin 72c is in contact with one side of the notch 46 of the calibration weight 4. When the handle 72a is released in this state, the piston 83 protrudes due to the elastic force of the compression coil spring 82, and the dustproof cover 72 is slightly reversed via the handle 72a. This causes pin 7
2c and the calibration weight 4 are released. Therefore, the measurer can simply press the handle 72a against the piston 83 and release it when the calibration weight 4 is loaded, and the dust cover 72 will automatically turn over by a minute amount.
The calibration weight 4 contacts only the weight receiver 5 and its entire mass is transmitted to the sensing member 3.

In the example shown in FIG. 17 and FIG.
2 and the calibration weight 4 is placed inside the protruding part 12 of the example shown in FIG. It is.

In this example, the calibration weight 4 in the protrusion 12 of the housing 1 is provided with multiple notches 46 as in the examples shown in FIGS. 15 and 16.
A claw 9a of a dedicated rotating member 9 is inserted inside, and the calibration weight 4 is rotated via the claw 9a.

Further, a cylindrical weight support 66 with a wavy end surface is provided inside the housing 1, and an annular groove 48 is provided in the lower surface of the calibration weight 4.
A wavy portion 49 is provided on the lower surface of the portion outside the groove 48. The wavy portion 49 rests on the wavy end surface of the weight support 66, and the calibration weight 4 is configured to move up and down in accordance with the rotational phase relationship between these portions.

19 and 20, respectively, are examples in which a mechanism for moving the weight receiver 5 up and down is used as a mechanism for loading/unloading the calibration weight 4. The left side shows normal measurement conditions, and the right side shows weight load conditions.

In the example shown in FIG. 19, a male thread 21 is formed on the outer periphery of the boss at the center of the lower surface of the sample pan 2, and a female thread 51 is formed on the center of the weight receiver 5. It is screwed into. The weight receiver 5 is also formed with a handle 52 that extends outward from below the sample plate 2 . By holding this handle 52 and rotating the weight receiver 5, the weight receiver 5 is configured to move up and down with respect to the sample plate 2.

In this example, there is a hole in the top surface of the housing 1.
A cylindrical weight support 1b is formed around a, and when the weight receiver 5 is in the lowered state, the calibration weight 4 is attached to the weight support 1b at the outer edge of its lower surface.
Only touch and ride on it. When loading the calibration weight 4, the weight receiver 5 is raised by holding the handle 52 and rotating the pan 2. As a result, the calibration weight 4 comes off from the weight support 1b, is clamped and fixed between the lower surface of the sample pan 2 and the weight receiver 5, becomes integrated with the sample pan 2, and transmits its entire mass to the sensing member 3. .

In the example shown in FIG. 20, a female thread 22 is cut inside the downwardly bent portion of the periphery of the sample dish 2, and a male thread 53 is cut on the outer periphery of the weight receiver 5, which is made into a disk shape. The male screw 53 is screwed into the female screw 22 of the sample pan 2, allowing the weight receiver 5 to move up and down with respect to the sample pan 2.

In this example, the weight support 1b is provided in the immediate vicinity of the hole 1a, and the weight support 1b is provided in the immediate vicinity of the hole 1a, similar to the example shown in FIG.
In the descending state, the calibration weight 4 rests on this weight support 1b. In addition, due to the rotation of the weight receiver 5, the calibration weight 4 moves between the sample pan 2 and the weight receiver 5.
They are sandwiched and fixed in between to become integrated.

According to the examples shown in FIGS. 19 and 20 above,
The loading/unloading mechanism for the calibration weight 4 is an extremely simple mechanism, which is disposed outside the housing 1, and has the advantage of having a small number of parts, being easy to process, and less likely to break down. .
Furthermore, in a loaded state where the weight receiver 5 is raised, the calibration weight 4 is tightly sandwiched between the sample pan 2 and the weight receiver 5, and can also be used as a weight locking mechanism during transportation. Furthermore, in the example shown in FIG.
The weight receiver 5 also functions as a dustproof cover.

In each of the examples shown in FIGS. 19 and 20, by making the screws 21 and 51 and the screws 22 and 53 multi-thread screws, or by using a helicoid instead of the screws, the The amount of vertical movement can be increased, improving operability.

The examples shown in FIGS. 21 to 25 show an example in which the calibration weight 4 is loaded/unloaded by moving the sample dish 2 up and down with respect to the sensing member 3.

In the example shown in FIG. 21, the sensing member 3 supports a dish support 31 having a male thread 31a carved on its outer periphery, and a female thread 23 is provided in the boss at the center of the sample dish 2 (pan holder 2b). It is screwed into the male thread 31a of the lever. In other words, the sample plate 2 is attached to the plate support 31.
By relatively rotating the sample plate 2 and the plate support 31, the sample plate 2 can be moved up and down with respect to the sensitive member 3. It is configured like this. Further, the weight receiver 5 is fixed to the outer periphery of the boss of the sample plate 2.

In this example, there is a hole in the top surface of the housing 1.
A cylindrical weight support 1b centered at point a is provided, and for example three protrusions P are provided on the top surface of the weight support 1b, and the sample plate 2 is in a downward state relative to the sensing member 3. Sometimes, the calibration weight 4 is supported by resting on the protrusion P. And sample plate 2
By raising the weight relative to the sensing member 3, the calibration weight 4 is placed on the weight receiver 5, and the weight is loaded. Here, for example, if two out of three protrusions P are electrically connected, loading/unloading of the calibration weight 4 can be electrically detected.

The example shown in FIG. 22 is an example in which dustproof measures are taken against the example shown in FIG. 21, and the structure for lifting the sample dish 2 is made more practical.

In this example, the hole 1a of the housing 1 is enlarged and a cylindrical cover support 1c is formed around the periphery of the hole 1a to support the dustproof cover 73. and,
The calibration weight 4 is disposed below the dustproof cover 73, and in normal measurement conditions is supported by a plurality of weight supports 1d protruding from the inner periphery of the hole 1a.

Further, a male thread 3a is carved at the tip of the sensing member 3, and a female thread 32a is formed in the center of the male thread 3a.
A cylindrical dish support 32 with a engraved mark thereon is screwed into it. The sample plate 2 (plate holder 2b) has a hole in the center of its boss, and is supported by the sensing member 3 with the outer periphery of the plate support 32 inserted into the hole.
Further, the weight receiver 5 is fixed to the pan support 32. Therefore, by rotating the plate support 32 and moving it up and down with respect to the sensing member 3, the sample plate 2
The weight receiver 5 moves up and down with respect to the sensing member 3, and the calibration weight 4 is configured to ride on the weight receiver 5 when the weight receiver 5 moves up and down.

In this embodiment, by fixing the stopper 3b to the upper end surface of the sensing member 3, the rising end of the plate support 32 can be restricted and the plate support 32 can be prevented from falling off.

The example shown in FIG. 23 is dust-proof like the example shown in FIG. 22, but shows an example in which the dust-proof cover of the weight receiver 5 is also used.

That is, a female thread 23 is provided at the center of the sample pan 2 (pan holder 2b) as in the example shown in FIG. 21, and a male thread 3a similar to the example shown in FIG. In the case where the sample dish 2 can be moved up and down with respect to the sensing member 3 by rotation, a weight is used that covers the entire bottom surface of the sample dish 2 except for the center, as shown in FIG. A receiver 5 is fixed to the downwardly bent end of the outer edge of the sample dish 2. In this case, the weight support 1e that supports the calibration weight 4 in a normal measurement state may have a cylindrical shape on the periphery of the hole 1a of the housing 1.

Vertical movement of the sample dish 2 and the dish support 31 shown in FIG. 21, the dish support 32 and the sensitive member 3 shown in FIG. 22, or the sample dish 2 and the sensitive member 3 shown in FIG. Similar to the examples shown in FIGS. 19 and 20, the mechanism can be replaced with a multi-thread screw or a helicoid, and as illustrated in FIG. Shaped guide groove G
The other side is provided with a protrusion that fits into the guide groove G, and by lifting the sample plate 2 or the plate support 32 upward and slightly rotating it, the protrusion is guided to the horizontal part of the guide groove G. It can also be configured so that it does not come down.

Furthermore, a lock-type ratchet mechanism that functions in the vertical direction is adopted, and by lifting a sample plate, etc. upwards to a predetermined height, it is locked in that position.
Various modifications are possible, such as configuring the sample plate to descend when lifted and released again from that state.

In the example shown in FIG. 25, the vertical movement of the sample dish 2 relative to the sensitive member 3 is made by movable the dish bearing shaft 33 of the sensitive member 3, instead of the vertical movement of the dish part using the screw in FIG. Shows examples of what has been achieved.

That is, the dish support shaft 33 is supported slidably in the vertical direction relative to the sensing member 3, and the dish support shaft 33 is supported as follows.
It is moved up and down by the rotation of a cam 9 built into the sensing member 3. A weight receiver 5 is fixed to the sample plate 2 supported on the tip of the plate support shaft 33 on the outside of the housing 1, and a calibration weight 4 is arranged in the space between the housing 1 and the sample plate 2.

According to this embodiment, although the mechanism is somewhat complicated, the operability of adding and removing the calibration weight 4 can be improved by rotating the cam 9 electrically by operating a switch or the like. This method is the 22nd
This can also be applied to FIG.

In addition, in each of the embodiments described above, the sample plate 2 is not limited to a circular shape and may be square. In that case, the calibration weight 4 may have a rectangular ring shape instead of an annular shape. This is preferable in that the space between 2 and the housing 1 can be used effectively.

Furthermore, in the case of a large-sized electronic balance, by using a plurality of sensing members to support the sample plate, the calibration weight can be stored between the sample plate and the top surface of the housing without having to make it annular. The structure example is shown in the second
Figures 6a and 6b show a longitudinal sectional view and a plan view of the vicinity of the sample dish. In addition, Fig. 26a is A-A in Fig. 26b.
FIG. In this example, load sensor 1
The sensing member 3 attached to the
~30d, each of which protrudes from the housing 1, and supports the sample dish 2 at its tip. Then, the calibration weight 4 is attached to these supports 30a-3.
It is housed between the sample plate 2 on the inside of 0d and the upper surface of the housing 1, and is configured to be moved up and down by four interlocking push-up rods 60a to 60d. 30 pillars each
A to 30d have weight receivers 50a to 50d, respectively.
are formed protrudingly, and the push-up rods 60a to 60d
When the calibration weight 4 is at the lowering end, the calibration weight 4 is supported by the weight receivers 50a to 50d at its four corners, and its entire mass is transmitted to the load sensor 100. In addition, in normal measurement conditions, the push-up rods 60a to 60d
is located at the rising end, and the calibration weight 4 contacts and is supported only by the push-up rods 60a to 60d.

Further, the present invention is not limited to the above-described embodiments, and various changes can be made, such as replacing a part of the configuration of each embodiment with each other.

<Effects of the Invention> As explained above, according to the present invention, the calibration weight is disposed between the upper surface of the housing and the sample plate to enable loading/unloading of the sensitive member, thereby making it possible to perform calibration. It is not necessary to provide a space in the housing for storing a calibration weight, and it is possible to house a large-volume, therefore large-mass, calibration weight, and the entire balance can be made compact. especially,
For balances with a large capacity, the calibration accuracy can be improved compared to conventional balances with built-in weights, which have to be calibrated using weights that are significantly lighter than the capacity.

In addition, by making the upper wall of the housing protrude into the recess on the lower surface of the sample plate and storing the calibration weight in the space formed by the protrusion at the upper end of the housing, it is possible to Calibration weights can be stored without considering interference with the mechanism, and the storage space for calibration weights is essentially wasted space below the sample plate.
This structure also provides the same effect as above.

Furthermore, if the calibration weight is configured to be loaded/unloaded by moving the weight receiver or sample pan up and down with respect to the sensitive member using a screw, etc.,
This means that not only the calibration weight but also its addition/extraction mechanism can be virtually eliminated from inside the housing, making it possible to obtain a balance with a built-in weight using the same housing as a balance that does not have a built-in calibration weight, contributing to compactness. It is large in size, and has the advantage of being extremely simple mechanically, resulting in fewer failures and lower costs.

This also applies to the type with a wavy weight support on the upper surface of the housing.

[Brief explanation of the drawing]

1 to 25 are explanatory diagrams of embodiments of the present invention, in which FIG. 1 is a central vertical cross-sectional view showing a basic structural example, and FIGS. 2 and 3 are central vertical cross-sectional views showing modified examples thereof. , FIG. 4 is an explanatory diagram of the main part of FIG. 3.
FIG. 5 is a central vertical sectional view showing an embodiment in which the calibration weight 4 is arranged in the space of the housing protrusion 12, FIG. 6 is an explanatory diagram of another embodiment of the vertical movement mechanism for the calibration weight 4, Figure 7 is a central longitudinal cross-sectional view of an example in which the calibration weight 4 is stored in the sample pan 2, and Figure 8 is a central longitudinal cross-sectional view of the calibration weight 4.
Central vertical sectional view of a modified example of the vertical movement mechanism, No. 9
The figure is an exploded perspective view of the main parts, and FIG. 10 is a central sectional view of a further modified example of the vertical movement mechanism of the calibration weight 4.
FIG. 11 is an exploded perspective view of the main part, FIGS. 12 to 15 are center longitudinal cross-sectional views showing modifications thereof, FIG. 16 is a plan sectional view of the main part of FIG. 15, and FIG.
FIG. 7 is a central vertical cross-sectional view showing a modified example, the first
Figure 8 is a plan view of the main part. 19 and 20 are central longitudinal sectional views showing an embodiment using a mechanism for moving the weight receiver 5 up and down. 21 to 25 are diagrams showing an embodiment using a mechanism for moving the sample dish 2 up and down, FIG. 21 is a central vertical sectional view showing an example of its basic structure, and FIGS. FIG. 24 is a vertical cross-sectional view of a main part of the modified example, and FIG. 25 is a central vertical cross-sectional view of the modified example. FIG. 26 is an explanatory diagram of an embodiment using a calibration weight other than a ring shape. DESCRIPTION OF SYMBOLS 1... Housing, 1a... Hole, 12... Protrusion part, 2... Sample plate, 2a... Dish, 2b... Dish holder, 3... Sensing member, 4... Calibration weight, 5...
Weight receiver, 6a, 6b...Pushing rod.

Claims (1)

[Scope of Claims] 1. A sensing member of a load detection mechanism disposed inside the housing faces the outside through a hole formed in the upper surface of the housing, and the sensing member is disposed outside the housing. In the balance, a calibration weight is disposed in the space formed between the upper surface of the housing and the sample plate, and the calibration weight is attached to the sample plate or the sensor plate. An electronic balance comprising a mechanism for loading/unloading a weight receiver formed near the upper end of the member. 2. The electronic balance according to claim 1, wherein the calibration weight is disposed in the following space instead of the space formed between the upper surface of the housing and the sample plate. A housing wall directly below the sample plate is made to protrude into a recess formed on the lower surface of the sample plate, and a space at the upper end of the interior of the housing is formed by the protrusion.