JP2867726B2 - Electronic balance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic balance having a built-in weight and a mechanism for adding and removing the weight, and having a function of automatically performing sensitivity calibration when a calibration command is issued.

[0002]

2. Description of the Related Art In general, an electronic balance has a function of calibrating a sensitivity by applying a weight having a known mass to a load detection mechanism for sensitivity calibration, and using the output of the load detection mechanism in that state and the mass of the weight. Have. Among electronic balances with such a sensitivity calibration function, a weight for sensitivity calibration is built in the balance case, and a weight adding / removing mechanism for loading / removing the built-in weight to / from the load detection mechanism is provided. , Or when the ambient temperature has changed by more than a predetermined temperature change, or when a predetermined time has elapsed since the previous sensitivity calibration time, the weight adjustment mechanism is automatically driven to load the built-in weight to the load detection mechanism, and the sensitivity calibration is performed. Some are configured to perform

[0003]

However, in an electronic balance called a general-purpose balance or the like, even if the electronic balance has a built-in calibration weight as described above, it surrounds a sample dish like a so-called analytical balance. Few of them have a weighing chamber. Therefore, even when the sensitivity calibration is performed by loading the internal weight, there is a possibility that accurate sensitivity calibration cannot be performed due to the influence of the wind through the sample dish.

In an electronic balance having a built-in weight,
Irrespective of the presence or absence of the weighing chamber, if a sample or the like is placed on the sample dish when the built-in weight is applied to the load detector, incorrect sensitivity calibration is performed. Therefore, there is a device having a function of prohibiting the sensitivity calibration operation when a load is acting on the sample dish. However, even with such a device, the sensitivity calibration operation is automatically performed after a predetermined time elapses. In some cases, such as when it is necessary to remove the sample from the sample dish and there is no worker nearby,
There is a problem that sensitivity calibration that should be performed is not performed.

[0005] The present invention has been made in view of such circumstances, and is hardly affected by wind at the time of sensitivity calibration, and accurate even when a load is applied to the sample dish at the time of sensitivity calibration. The purpose is to provide an electronic balance that can perform sensitivity calibration.

[0006]

Means for Solving the Problems To achieve the above object, an electronic balance of the present invention has a dish addition / detachment mechanism for separating / loading a sample dish from a load detection mechanism, and a built-in weight is generated by generating a calibration command. The sample dish is automatically separated from the load detection mechanism before the load is applied to the load detection mechanism, and the sample dish is automatically placed on the load detection mechanism after the sensitivity calibration operation is completed. Attached.

[0007]

[Function] The sample pan is automatically separated from the load detection mechanism before the built-in weight is applied to the load detection mechanism, so that the load detection mechanism is not affected by the wind through the sample pan. In addition, even if a load acts on the sample dish, the output of the load detecting mechanism is not affected.

[0008]

FIG. 1 is a front view of a balance case 1 according to an embodiment of the present invention, in which a part of the balance case 1 is cut away. FIG. 1A shows a normal measurement state, and FIG. This shows a loaded state. A hole 11 is formed on the upper surface of the balance case 1 so that a dish receiver 31 communicating with the load detecting mechanism 3 faces the outside. The sample dish 2 is placed.

In the balance case 1, an internal weight 4 is provided.
And a known weight adding / removing mechanism 5 including a lever 51 for adding and removing the built-in weight 4 to and from the load detecting mechanism 3 and a cam and a motor (neither of which is shown). Is generated, the built-in weight 4 is loaded on the load detecting mechanism 3, the output of the load detecting mechanism 3 is read in that state, and then the built-in weight 4 is removed from the load detecting mechanism 3 again. .

In the balance case 1, a sample dish 2 is also provided.
A dish addition / detachment mechanism 6 for adding / detaching to / from the dish receiver 31 is provided. The dish adding / detaching mechanism 6 has a substantially horseshoe-shaped dish support 61 with a circular part cut out, a vertical rack 62 fixed to a lower portion of the dish support 61, and guides the rack 62 in the vertical direction. The motor 65 includes a guide 63, a pinion gear 64 meshing with the rack 62, and a motor 65 for rotating the pinion gear 64.
Of the plate support 6 via the rack and pinion mechanism
1 is configured to move up and down.

As shown in FIG. 2 in a perspective view of a main part of the upper surface of the balance case 1, the upper surface of the balance case 1
A substantially horseshoe-shaped hole 12 for inserting and removing the dish support portion 61 is formed around the hole 11 for projecting the dish support 31, and in a state where the dish support portion 61 is raised to the upper limit,
As shown in FIG. 1B, the sample plate 2 is pushed up by the plate support portion 61, and the sample plate 2 can be separated from the plate receiver 31.

FIG. 3 is a flow chart showing the contents of the sensitivity calibration routine among the programs written in the ROM of the microcomputer constituting the control unit of the embodiment of the present invention. The operation of is described. This routine is executed when a predetermined time has elapsed since the previous calibration, and when a sensitivity calibration command generated automatically by a key operation or the like when a temperature change of a predetermined amount or more has occurred since the previous calibration. Is selected.

When a sensitivity calibration command is issued (ST1), first, an operation command is given to the dish adding and removing mechanism 6 to drive the motor 65 to raise the dish support 61 to the upper limit, as shown in FIG. 1 (B). The sample dish 2 is separated from the dish tray 31 (ST
2). Thereafter, an operation command is given to the weight adding / removing mechanism 5, and the built-in weight 4 is loaded on the load detecting mechanism 3 (ST3). Reading the output D ₁ of the load detection unit 3 in this state (ST4).

Next, an operation command is given to the weight adding / removing mechanism 5 again to remove the internal weight 4 from the load detecting mechanism 3 (ST).
5), reads the output D ₂ of the load detection mechanism 3 in that state (ST6). Next, the read data D ₁ and D ₂ ,
From the known mass M of the internal weight 4 and the known coefficient M, the sensitivity coefficient K is calculated by the following calculation, and the coefficient obtained in the previous calibration operation is updated (ST7).

K = M / (D ₁ -D ₂ ) Finally, a command is given to the dish addition / detachment mechanism 6 to drive the motor 65 to lower the dish support 61 to the lower limit (ST8).
End the sensitivity calibration operation. As described above, in the embodiment of the present invention, sensitivity calibration is always performed in a state where the sample dish 2 is separated from the load detection mechanism 3, and even if a sample or the like is placed on the sample dish 2, Does not affect the sensitivity calibration result.

The dish adding / removing mechanism 6 is not limited to the structure of the embodiment of the present invention described above, but may employ any known mechanism.

[0017]

As described above, according to the present invention, the sample dish is automatically separated from the load detection mechanism by the generation of the sensitivity calibration command, and in this state, the internal weight is loaded / removed on the load detection mechanism. Update operation of the sensitivity coefficient, it is possible to eliminate all the effects of disturbances such as wind on the load detection mechanism through the sample dish, and it is possible to always perform accurate sensitivity calibration, Even when a sample or the like is placed on the sample, sensitivity calibration can be automatically performed without lowering the sample.

As a result, compared to the conventional electronic balance with a built-in calibration weight, the advantage is utilized more effectively, and the operator is relieved of the trouble of dropping the sample at the time of the sensitivity calibration, and in particular, the passage of time. With electronic balances that have an automatic sensitivity calibration function that automatically performs sensitivity calibration, there is no need to display a warning or the like when an object is placed on the sample dish as in the past. Problems such as stoppage of operation are eliminated.

[Brief description of the drawings]

FIG. 1 is a front view of a balance case 1 according to an embodiment of the present invention, in which a part of the balance case 1 is cut away. FIG.
Shows a state in which the internal weight 4 is loaded on the load detection mechanism 3.

FIG. 2 is a perspective view of a main part of the upper surface of the balance case 1;

FIG. 3 shows the RO of the microcomputer according to the embodiment of the present invention;
Flow chart showing the contents of the sensitivity calibration routine among the programs written in M

[Explanation of symbols]

 1 ··· Balance case 11 ··· Dish receiving hole 12 ··· Dish support portion hole 2 ··· Sample dish 3 ··· Load detection mechanism 31 ··· Dish receiving 4 ·・ ・ ・ Built-in weight 5 ・ ・ ・ ・ ・ ・ Weight addition / detachment mechanism 51 ・ ・ ・ ・ ・ ・ Lever 6 ・ ・ ・ ・ Dish addition / detachment mechanism 61 ・ ・ ・ ・ ・ ・ Dish support part 62 ・ ・ ・ ・ ・ ・ Rack 63 ・ ・ ・ ・ ・ ・ Guide 64 ・ ・..Pinion gear 65 .... Motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01G 23/01

Claims (1)

(57) [Claims] An internal weight and a weight adding / removing mechanism for adding and removing the internal weight to and from a load detecting mechanism on which a sample dish is placed by generating a calibration command, and applying the internal weight to the load detecting mechanism. In the electronic balance provided with sensitivity calibration means for calibrating the sensitivity of the balance using the output of the load detection mechanism in the state where the load is detected and the mass value of the built-in weight, the sample dish is separated from the load detection mechanism. Having a dish adding / removing mechanism to be placed, automatically separating the sample dish from the load detecting mechanism before applying the built-in weight to the load detecting mechanism by the generation of the calibration command, and after completion of the sensitivity calibration operation An electronic balance, wherein the sample dish is configured to be automatically placed on a load detection mechanism.