JPS62168025A - Electronic weighing instrument - Google Patents

Abstract

PURPOSE:To measure long-time variation in welded value without any error by providing an electronic weighing device, a sample adding and removing mechanism, a calibration weight adding and removing mechanism, a control part, etc., and automatically updating a calibration coefficient at intervals of the specific number of times of weighing. CONSTITUTION:This instrument is provided with the electronic weighting device 1 which calculates the calibration coefficient (k) from the output of a load detection part 1 when a calibration weight C is placed as a load and the weighed value of a body S to be measured from the output of the detection part 11 when the body S to be weighed is placed as a load and the calibration coefficient (k), the sample adding and removing mechanism 2 which mounts and demounts the body S to be weighed on and from the detection part 11, and the calibration weight adding and removing mechanism 3 which mounts and demounts the weight (c) on and from the detection part 11. Then, a control part 4 is provided which controls the weighing device 1 and mechanisms 2 and 3 according to a set sequence, the body S to be measured is mounted and demounted automatically to weigh it plural times, and the weight is placed as the load automatically at intervals of the specific number of times to update the calibration coefficient (k). Consequently, the weighed value contains no error and this equipment is used to a test such as the investigation of variation in water content, etc., for a long time while ambient temperature is varied, thereby obtaining a high-accuracy measurement result.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electronic measuring device, and is particularly useful for investigating the absorption and hydrophilic properties of a sample, and for obtaining mass changes over a long period of time of an object to be measured. Concerning suitable weighing devices.

<Conventional technology> In general, the moisture content of the target material has a large effect on the trade of agricultural products and forest products, and in the processing of wood, tobacco, etc.
As the production of fibers such as paper and cloth becomes automated, the need to measure the moisture content of articles has increased, and the measurement technology has also improved.

By the way, there are many types of moisture content measurement devices currently in use, but among them, electronic measuring instruments such as so-called electronic balances are used for devices that measure slight changes in moisture content with high accuracy. There are many things.

Electronic scales are extremely easy to perform automatic measurements;
Moreover, it is suitable for use as described above in that it is possible to continuously record changes in measured values over time.

<Problems to be solved by the invention> However, electronic measuring instruments suffer from zero point drift or calibration value fluctuations (span fluctuations) due to changes in ambient temperature or pressure.
Therefore, a test in which changes in measured values are measured over a long period of time while changing atmospheric conditions is fraught with measurement errors. This zero point drift and calibration value fluctuation are characteristics of electronic measuring instruments, and it is impossible to completely eliminate them. Even if they are kept to an extremely small level, a large amount of cost will be incurred. It's not practical.

The present invention has been made in view of the above, and does not particularly suppress the characteristics of electronic measuring instruments such as zero point drift and calibration value fluctuation.
Therefore, it is an object of the present invention to provide an electronic weighing device that is capable of determining changes in measured values over a long period of time without error while changing the above-mentioned atmospheric conditions using an ordinary electronic weighing device.

Means for Solving the Problems> The configuration for achieving the above object will be explained with reference to FIG. 1, which is an embodiment drawing. Electronic weighing that calculates a calibration coefficient K from the output of the load detection section 11 and determines the weight value of the object to be weighed S based on the output of the load detection section 11 when the object to be weighed S is loaded and the calibration coefficient. a sample addition/removal mechanism 2 for attaching and removing an object to be measured 3 to and from a load detection unit 11;
A calibration weight addition/removal mechanism 3 for loading/unloading a calibration weight C is provided on the load detection section 11. A control unit 4 is provided to control the sample addition/removal mechanism 2 and calibration weight addition/removal mechanism 3 of the electronic scale 1 in accordance with a preset sequence, and the object to be weighed S is automatically loaded and unloaded multiple times. The configuration is such that the calibration weight C is automatically loaded and the calibration coefficient is updated every predetermined number of measurements.

<Function> Even if the electronic measuring instrument 1 has zero point drift or calibration value fluctuation,
Automatically calibrate for a predetermined number of times, for example, every time! r
If the calibration coefficient K is updated by loading 1C, the obtained measured value will not contain any errors. Therefore, changes in water content etc. can be investigated over a long period of time while changing the ambient temperature, pressure, etc. Highly accurate measurement results can be obtained by conducting such tests.

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

FIG. 1 is a block diagram of an embodiment of the present invention.

The electronic measuring instrument 1 includes a load detection section 11 and a calculation section 12. The load detection section 11 includes a rod mechanism 111 and a sensor section 112 of an electromagnetic force balance type or the like. A weighing container 13 containing a sample S is suspended from the rod mechanism 111 by a core 1.
4 and a hanging device 11 for hanging via the measuring hook 15.
1a, and a weight pan 111b on which a calibration weight C is placed. When a load acts on the rod mechanism 111, the sensor section 112 outputs digital data of an electric signal corresponding to the load, and the data is input into the calculation section 12 every moment.

The calculation unit 12 is mainly composed of a microcomputer, and includes CPUs 1.21. ROMI 22. RAM123,
Input/output control unit 124. and a digital display 125 for displaying measured values. In the ROM 122, a calibration coefficient calculation program and a measurement value determination program, which will be described later, are written.

The load detection unit 11 described above is housed in a vacuum container 5, and the vacuum container 5 lowers the internal pressure to near vacuum pressure by connecting the suction port 51a of the detachable reaction tube 51 to a vacuum pump. be able to. Inside this vacuum container 5, a measuring hook 15 is attached to a hanging tool 111a of a rod mechanism 111.
A sample addition/removal mechanism 2 for suspending and removing the calibration weight C, and a calibration weight addition/removal mechanism 3 for adding/removing the calibration weight C to/from the weight pan 111b of the rod mechanism 111 are provided. The sample addition/removal mechanism 2 and the calibration weight addition/removal mechanism 3 suspend the weighing hook 15 by vertically displacing the linear heads 22 and 32 using motors 21 and 31 provided outside the vacuum container 5 as drive sources, respectively. It is possible to lift/remove and add/remove the calibration weight C. These motors 2
1 and 31 are configured such that their driving is controlled by a command signal from the control section 4.

The control unit 4 is composed of a personal computer,
CPU41. ROM42. RAM43゜I/O control unit 4
4. An interface circuit 45° includes a keyboard 46, a CRT 47, etc., outputs command signals to the motors 21 and 31 from the interface circuit 45, and is connected to the input/output control unit 124° of the calculation unit 12 of the electronic measuring instrument 1. At 44, they are connected by a bidirectional information transmission path. Via this information transmission path, the control section 4 issues a command signal to the calculation section 12 of the electronic measuring instrument 1 to specify which of the above-mentioned measured value determination program or calibration coefficient calculation program is to be executed. The above motors 21, 31. The command signal to the calculation unit 12 is generated in a predetermined sequence based on the control program written in the ROM 42 and the control condition data stored in the RAM 43. Note that the data of this control condition can be input from the keyboard 45 in terms of the measurement cycle, the calibration interval, and the like.

Next, the operation of each part will be described. The initial positions of the linear heads 22 and 32 of the sample addition/removal mechanism 2 and the calibration weight addition/removal mechanism 3 are respectively at their upper limits, that is, the measuring hook 15 and the calibration weight C are not loaded on the rod mechanism 111. Prior to measurement, the above-mentioned control conditions are set.

Then, the reaction tube 51 is removed from the vacuum container 5, the sample S is put into the measuring container 13, and the reaction tube 51 is inserted again to adjust the atmosphere inside the vacuum container 5, thereby completing the preparation. In addition,
Measuring container 13. It is assumed that the total mass of the hanging core 14 and the measuring hook 15 is known, and its value T is stored in the control unit 4 in advance.

When a command to start measurement is given from the keyboard 45, each part operates under the set control conditions as shown in the timing chart in FIG. 2, for example. In the example shown in FIG. 2, the measurement cycle is 10 minutes and the calibration interval is 1, that is, the calibration is performed immediately before each measurement. That is, at the same time as the start, the control section 4 issues a zero set signal, stores the current output Do of the sensor section 112 of the electronic measuring instrument 1 in the RAM 123, and also stores the value D.
At O, the measured value, that is, the value displayed on the display 125 is set to zero. At the same time, it instructs the electronic measuring instrument 1 to execute a calibration coefficient calculation program among the programs written in the ROM 122. Further, a drive command is issued to the calibration weight addition/removal mechanism 3, and the calibration weight C is placed on the weight pan 111b.

In the calibration coefficient calculation program in the electronic measuring instrument 1, the calibration coefficient K is calculated by the following equation (1), and its (D value is
AM 123. Note that here, Wc is the known mass of the calibration weight C, and Dc is the output of the sensor unit 112 when the calibration weight C is loaded.

K=Wc/(Dc-Do)-(
11 After determining the calibration coefficient K, a command is issued to the calibration weight addition/removal mechanism 3 to remove the calibration weight C from the weight pan 111b, and at the same time, a command is issued to the sample addition/removal mechanism 2 to remove the calibration weight C from the weighing hook 1.
5 is hung on the hanging tool 111a.

Further, the electronic measuring device 1 is instructed to execute a measured value determination program.

In the measurement value determination program, the load mass W is calculated using the following equation (2). Here, D is the output of the sensor section 112 of the measuring hook 15) u hanging.

W=K(D-Do)-(21 Then, this W is displayed on the display 125 as a measured value, and the value is transferred to the control unit 4.

In the control unit 4, the transferred measurement value W and the previously stored measurement container 13. Hanging core 14. From the total mass T of the measuring hook 15, the mass Ws of the sample S
, W s = W - T...(
3) and stored in the RAM 43.

Next, a command is issued to the sample addition/removal mechanism 2, and the measuring hook 15 is
is removed from the hanging device 111a, and waits until the set period has elapsed. Then, at each cycle, the above-described procedure is repeated, and the mass Ws of the sample S is sequentially stored in the RAM 43.

As described above, according to the set control conditions, the sample S is automatically hung on and removed from the rod mechanism 111 to determine its mass Ws, and immediately before determining its quality IWs, the calibration weight C is attached to the rod mechanism 111. The calibration coefficient K is updated by multiplying and removing.

In the above embodiment, the sample addition/removal mechanism 2 and the calibration weight addition/removal mechanism 3 are provided with motors 21 and 31, respectively.
However, it is also possible to configure both adding and removing mechanisms to be driven by one motor. Furthermore, it goes without saying that equation (3) may be executed by the calculation unit 12 of the electronic measuring instrument 1.

<Effects> As explained above, according to the present invention, a sample addition/removal mechanism for loading and unloading a sample on the load detection section of an electronic scale and a calibration weight loading/unloading mechanism for loading and unloading a calibration weight on the load detection section are provided. In addition, a control unit is provided to control both of these mechanisms and the electronic scale under preset conditions, and a calibration weight is automatically loaded every predetermined number of sample measurements, for example, every time. to update the calibration coefficients.
Even if the electronic measuring instrument has zero point drift or calibration value fluctuation,
The measured value of the sample obtained does not include any error. Therefore, extremely accurate data can be obtained in tests that investigate changes in the mass of a sample over a long period of time, such as changes in water content, especially in tests that are performed while changing the ambient temperature and pressure. Furthermore, since there is no need to particularly suppress the zero point drift or calibration value fluctuation of the electronic measuring instrument, a normal commercially available electronic measuring instrument can be used, and the cost will not increase.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a timing chart showing the operation of each part thereof. 1... Electronic measuring instrument 11... Load detection section 12... Calculation section 111...
- Rod mechanism 112...Sensor section 2...Sample addition/removal mechanism 3...Calibration weight addition/removal mechanism 21.31...Motor 4...Control section C...Calibration weight S...Sample patent applicant
Japan Tobacco Inc. Shimadzu Corporation

Claims (1)

[Claims] Calibration coefficients are calculated from the output of the load detection section when a calibration weight with a known mass is loaded, and the output of the load detection section and the calibration coefficient when the object to be weighed is loaded to calculate the weighing of the object. an electronic scale that determines a value; a sample addition/removal mechanism that applies/removes the object to be measured to/from the load detection section; a calibration weight addition/removal mechanism that applies/removes the calibration weight to/from the load detection section; It is equipped with a control unit that controls the addition/extraction mechanism and the calibration weight addition/extraction mechanism based on a preset sequence, and the device automatically hangs and unloads the object to be weighed multiple times, and also controls the predetermined weighing process. An electronic weighing device configured to automatically update the calibration coefficient every time.