JP2002214032A - Electronic scale - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the mass of a weighed body without calibration using internal and external weights. SOLUTION: A measured value of the weighed body outputted from a weighting part 2 is outputted by a processing part 11 from a correction part 11 and corrected by using gravitational acceleration at the arrangement place of the electronic scale as a correction value, so that it is displayed as the mass at a display part 12. The correction part accurately finds the electronic scale arrangement place by a GPS reception part, finds the gravitational acceleration at the arrangement place of the electronic scale by a gravitational acceleration arithmetic part 6A with its latitude information and altitude information, and corrects the measured value the processing part 11 by using the gravitational acceleration as the correction value to find the mass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic balance, and more particularly, to detecting a position where the user is located, an altitude, and the like, thereby obtaining a gravitational acceleration at a point where the balance is placed, thereby accurately measuring the mass of an object to be measured. And an electronic balance configured to perform measurement.

[0002]

2. Description of the Related Art An electronic balance typified by an electromagnetic balance type weighing device called an electronic balance, a load cell type weighing device, or the like is configured to obtain the mass by measuring the weight of an object. Here, the weight is a value obtained as a result of the gravitational acceleration acting on the mass of the object. If the gravitational acceleration is different, the same mass is measured as a different weight.

FIG. 4 shows the mechanism of gravity. The symbol E is the earth conceptually shown, and S is the polar axis, that is, the rotation axis of the earth E. In this figure, the effect of gravity at a specific point P1 on the earth E can be explained as follows.
G is an attractive force acting toward the center of the earth E, code CF1
Is the centrifugal force generated in the direction perpendicular to the polar axis S by the rotation of the earth E about the polar axis S, and this point P1
It is this attractive force G that actually acts as gravity in
It becomes a vector V1 with the centrifugal force CF1. Therefore, the centrifugal force does not act at the extreme point, and only the attractive force G acts on the object. As a result, the weight of the object becomes the largest, and conversely, the centrifugal force acts the largest on the equator EQ having the largest turning radius. Therefore, the weight of the object is minimized.

[0004] Even if the point P2 has the same latitude as the point P1, if the point is far from the ground, it can be considered that the earth radius R has increased at that point by the distance r from the ground surface. . The attraction between the object and the earth is 2 of the distance
Since the weight becomes smaller in proportion to the power, the weight of an object having the same mass becomes smaller. In addition, since the distance from the center of the earth becomes large, the centrifugal force CF2 becomes slightly larger than the above-mentioned CF1,
Therefore, the vector V2 of the attractive force G and the centrifugal force CF2 is slightly smaller than V1. This also makes it easy for the weight of a small but massive object to be reduced.

[0005] The above points will be described in a practical example as follows. First, considering the latitude in Tokyo and Sapporo as an example, the gravitational acceleration in Tokyo is 9.798 m / S ² , and the gravitational acceleration in Sapporo, which has a higher latitude and less centrifugal force than Tokyo, has a gravitational acceleration of 9.805 m / S ² Becomes As a result, what is displayed as a weight (mass) of 100.000 g in Tokyo, for example, is displayed as 100.071 g in Sapporo.

Considering the altitude (altitude), for example, comparing the case at the ground surface and the case at a position 10 m above the ground surface (corresponding to the fourth floor of the building), the object at this position has an actual radius R of the earth of 10 m. The addition can be thought of as the radius of the earth. This means that, although the calculation formula is omitted, the weight of exactly 200.000 g on the ground surface is 199.99937 g at a position 10 m higher. In this description, the vector V2 is excluded from the calculation.

[0007]

As described above, since the gravitational accelerations at the points where the objects are located are different from each other, the objects having the same mass are measured as different weights depending on the arrangement points. This is a serious problem in a high-resolution weighing device such as an equilibrium weighing device.

In order to solve this problem, a weighing device having a built-in weight has been provided. In other words, with this built-in weight type weighing device, the same gravitational acceleration as the object to be measured also acts on the built-in weight. , Ie, regardless of the magnitude of the gravitational acceleration, the same weighing value (mass) can always be displayed.

As described above, a balance that calibrates using a built-in weight can basically measure the mass, but has some problems. First, a built-in weight, a mechanism for adding and removing the built-in weight to and from the measuring unit, and an electric motor and the like as driving means for operating the adding and removing mechanism are stored in the weighing device. The complexity of these mechanisms and the weight of the internal weight is increased by the weight of the entire apparatus.

In the case of an electromagnetic balance type weighing device, a weight transmission mechanism for transmitting the load of the weighed object to the electromagnetic portion is very delicately configured. Vibration, heat generation of the motor, and the like adversely affect the accuracy of the weighing device. Further, the deterioration of the built-in weight over time, the wear of the addition / removal mechanism, and the like also deteriorate the accuracy of the weighing device over time.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to an electronic balance constructed in view of the above problems, and is characterized in that it can measure the mass of an object without using a built-in weight. . That is, the present invention determines the gravitational acceleration at the point where the weighing device is placed, and uses this gravitational acceleration as a correction value,
This is an electronic balance configured to obtain a mass of an object by correcting a measurement value measured as a weight.

More specifically, the position on the earth where the weighing device is located, particularly the latitude, is detected by GPS, and if necessary, the altitude (hereinafter referred to as "altitude") of the placement portion is detected. Calculates the gravitational acceleration acting on the weighing device arrangement section from the detected latitude and altitude, and corrects the actually measured weight value using the calculated gravitational acceleration as a correction value to display the mass of the measurement target. An electronic balance characterized by the following.

In another configuration, in order to more accurately calculate the gravitational acceleration at the point, the data of the gravitational acceleration and repulsive force based on the celestial body operation from the data of the Bouguer anomaly at the point and the time data at the time of weight measurement are used. An electronic balance is configured to be used as a correction value for calculation.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An electronic balance has a built-in GPS
(Global Positioning System)
An external terminal such as a portable terminal having a PS function detects a position where the self is located, that is, a latitude and an altitude on the earth, stores the latitude data and the altitude data, and reads an electronic balance from the latitude data and the altitude data. Calculate the gravitational acceleration at the arranged point. The gravitational acceleration obtained from the latitude data and the altitude data is a value that is satisfied when the earth is regarded as a completely homogeneous sphere and forces other than the earth are ignored. Hereinafter, the gravitational acceleration obtained from the latitude data and the altitude data including the embodiment will be referred to as a “basic gravitational acceleration value” at that point.

The measured value (weight) of the weighed object measured by the measuring section
Is output to the processing unit. On the other hand, the basic value of the gravitational acceleration at the point where the electronic scale is located is calculated from the latitude and altitude of the point where the electronic balance is located based on the GPS position information. The standard gravitational acceleration at the point is determined by correcting the gravitational acceleration basic value with data specific to the point, such as a Bouguer anomaly value (details will be described later).

Using the standard gravitational acceleration as a correction value, the weight value output from the weighing unit is corrected, and a value that is closer to the mass of the weighed object is calculated. Note that, although a small amount, the standard gravitational acceleration is affected by the attraction, repulsion, etc. of the planets and satellites associated with the operation of the celestial body, and therefore, more strictly, the standard gravitational acceleration of the point changes with the time of the operation of the celestial body. If a value obtained by further correcting the standard gravitational acceleration by a factor is obtained and this value is used as a correction value for weight, the weighed value (weight) can be brought closer to the mass more accurately.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows a configuration example of an electronic balance according to the present invention. Regardless of the type of the electronic balance, such as an electromagnetic balance type or a load cell type, the mechanism itself for measuring the load of the weighed object is basically the same as the conventional configuration. The present invention is configured to obtain the mass of the weighed object by correcting the weight data of the weighed object weighed by the weighing unit 2 by the gravitational acceleration obtained by the correction unit 1.

First, the configuration of the correction unit 1 will be described.
Denotes a GPS receiving unit. The GPS receiving unit 3 is built in the electronic scale. In addition to this configuration, an external device 3 ′ such as a mobile phone having a GPS function or a GPS receiver used as a navigation system is provided. It may be configured to connect to and capture information.

Reference numeral 4 denotes a latitude information storage unit for storing the latitude information of the location of the electronic scale obtained by GPS, and reference numeral 5 denotes an altitude information storage unit for storing altitude (altitude) information of the location of the electronic balance. In addition, according to the GPS, it is possible to acquire not only the latitude information but also the longitude information. However, in the case of the present invention, since only the latitude affects the gravitational acceleration, basically only the latitude information is acquired. .

By the way, the GPS can calculate its own position (longitude and latitude) by the triangular intersection method by ranging to three satellites, and can also calculate its own altitude by ranging to four or more satellites. . If the altitude information cannot be obtained by GPS or the reliability is low, the altitude information 13 obtained from another information source such as the altitude of the map data of the point is directly used as the altitude information as the altitude information storage unit 5. May be output.

Reference numeral 6 denotes a correction value setting unit. In the case of the present invention, it is characterized in that the gravitational acceleration that acts is used as a correction value for the measured weight, but the weighing value measured as the weight includes buoyancy corresponding to the air density, electromagnetic balance weighing. In the case of the device, there are a plurality of factors for correcting the weighed value, such as a change in the electromagnetic force due to a change in the temperature of the electromagnetic unit (reference numeral 7).
This type of correction has been conventionally performed. In the present invention, since the conventional correction is naturally performed, only the correction using the gravitational acceleration obtained by the gravitational acceleration calculation unit 6A of the correction value setting unit 6 will be described below.

Reference numeral 8 denotes an auxiliary data storage unit which stores data (described later) for correcting the value of the gravitational acceleration obtained from the latitude information and the altitude information. 9
Is reset means. If the electronic scale is placed at a specific place, the latitude information and altitude information at this point are fixed unless the electronic scale is moved. In other words, when the electronic scale is moved, the data stored in the latitude information storage unit 4 and the altitude information storage unit 5 become unusable. The data stored in the storage unit 5 is canceled, and new latitude information and altitude information are acquired and stored via the GPS receiving unit 3 and the like.

The weighing data (weight) output from the weighing unit 12 is corrected using the gravitational acceleration obtained as described above as a correction value. That is, the weighing data output from the weighing unit 2 is digitally output to the processing unit 11 via the A / D conversion unit 10, and the weighing value is corrected in the processing unit 11 using the gravitational acceleration as a correction value, and the mass of the weighed object is calculated. It is displayed on the display unit 12. Here, the mass refers to a value obtained by correcting a weighing value as a weight and approximating the mass as much as possible. Incidentally, as described later, the force applied to the object is very complicated, and it is very difficult to measure the mass in a strict sense in physics.

Next, the means for obtaining the gravitational acceleration as a correction value will be described mainly with reference to FIG. The symbol D in the figure indicates data for calculating the gravitational acceleration at the location where the electronic balance is arranged. Among them, the gravitational acceleration data D1 with respect to the latitude and the gravitational acceleration data D2 with respect to the altitude can be obtained from the position information of the electronic scale acquired near the GPS. The gravitational acceleration data D1 for the latitude and the gravitational acceleration data D2 for the altitude are values derived when the earth E is assumed to be a homogeneous sphere, and the gravitational acceleration obtained from these data D1 and D2 is used as a gravitational acceleration basis. The value is assumed to be 14A. The weighing data (weight) output from the weighing unit 2 using the gravitational acceleration basic value 14A as a correction value.
May be corrected, but more precisely, a value obtained by further correcting the gravitational acceleration basic value 14A is used, or more accurate correction is performed.

First, the earth itself is not a homogeneous object, so that the gravitational acceleration on the earth is not necessarily a value itself corresponding to latitude when accurately considered. That is, on the earth, the gravity derived from the gravitational acceleration basic value 14A causes a considerable gravity anomaly such that the measured value is excessively large or too small depending on the measurement point. ing. The most significant of these gravity anomalies is thought to be the Bouguer anomaly originating from the underground structure at the measurement site.

The Bouguer anomaly is anomalous if an excessive mass exists underground, that is, the gravitational acceleration at that point becomes larger than the gravitational acceleration basic value, and if it is insufficient, the gravitational acceleration becomes smaller than the gravitational acceleration basic value. Become. This Bouguer anomaly has been examined quite closely in Japan. Broadly speaking, there is a negative anomaly on the Pacific coast of Honshu. This is due to the lack of mass in this region, as the massive Pacific Plate subducts on the Pacific coast of Honshu.

On the other hand, positive abnormalities are conspicuous in northeastern Japan compared to southwestern Japan. This is thought to be due to the fact that the dense mantle is rising in northeastern Japan and the crust, which has a smaller mass than the mantle, is thinner. In any case, since the Bouguer anomalies in various parts of Japan are known quite accurately, the Bouguer anomaly data D3 at the weighing device arrangement point is used as a correction value of the gravitational acceleration basic value 14A to obtain the standard of the weighing device arrangement point. The gravitational acceleration 14B is obtained. Of course,
Not only in Japan, but at a point where the Bouguer anomaly is accurately determined, accurate correction can be performed by using the Bouguer anomaly value.

Gravity acceleration data D for the above latitude
1. The gravitational acceleration data D2 with respect to altitude and the Bouguer anomaly data D3 are specific to the point, and are fixed data that does not need to be changed unless the arrangement point of the weighing device is moved (indicated by DS). The weighed value of the weighed object is corrected using the standard gravitational acceleration data 14B as a correction value.

Next, while the DS is fixed data at the point, the symbol DM indicates fluctuation data whose value changes depending on parameters such as time. The largest of the fluctuation data DM is a force such as an attractive force or a repulsive force acting on the earth by the operation of the celestial body such as the operation of the moon and the operation of the planet.

Since the force due to the celestial body operation changes with time, the celestial body operation data D4 at the time of weighing is obtained by using the time data D5, and the standard gravity acceleration data 14B is further corrected using the data D4. To obtain the data (referred to as “time corrected acceleration data”) 14C,
If the measured value of the weighed object is corrected using the data 14C as a correction value, the corrected value becomes closer to the mass of the weighed object. In this case, the GPS receiving unit 3
Extremely accurate time data transmitted from the atomic clock mounted on the S satellite can be obtained.

FIG. 3 shows an example of correction of the measured value of the weighed object. In this correction procedure, correction using time as a parameter is not performed. First, the electronic balance is activated (S1), and it is checked whether or not the electronic balance has been moved after the previous weighing operation (S2). If not, the fixed data DS (see FIG. 2) is not moved. Since there is no change, after weighing (S8), the weighing value is immediately corrected using this data (S8).
9).

On the other hand, when the arrangement position of the electronic balance is changed, new position information is obtained by GPS (S3), and the gravitational acceleration data D1 for latitude, the gravitational acceleration data D2 for altitude, If so, the Bouguer abnormal value data D3 is updated, and the updated standard gravity acceleration data 14B is changed to new data using the updated data (S4 to S6). In weighing the weighed material, the updated standard gravity acceleration data 14 is used.
B to correct the weighing value and display the corrected value (S
7 to S10).

[0033]

As described above, according to the present invention, information on a point where an electronic scale is placed can be obtained accurately by GPS, so that an accurate gravitational acceleration at the point can be obtained. Therefore, it is possible to determine the weight of the weighed object without using calibration with an external weight, or using a complicated addition / removal mechanism, or a built-in weight mechanism that causes problems over time such as heat or vibration during operation, or deterioration or wear. Becomes

Since there is no complicated built-in weight adding / removing mechanism,
The entire electronic balance can be reduced in size and weight.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a means for calculating a gravitational acceleration based on information on an electronic scale arrangement point obtained by GPS.

FIG. 3 is a flowchart illustrating an example of a method of correcting a weighing value.

FIG. 4 is a schematic diagram of the earth showing the state of gravitational acceleration at a predetermined point on the earth.

[Explanation of symbols]

 1 Correction unit 2 Measurement unit 3 GPS reception unit 4 Latitude information storage unit 5 Altitude information storage unit 6 Correction value setting unit 6A Gravitational acceleration calculation unit 11 Processing unit 12 Display unit 14A Gravity acceleration basic value 14B Standard gravity acceleration data 14C Time corrected gravity Acceleration data D1 Gravity acceleration data for latitude D2 Gravity acceleration data for altitude D3 Bouguer anomaly data D4 Astronomical operation data D5 Time data DS Fixed data DM Time fluctuation data

Claims (6)

[Claims] An electronic balance for displaying, via a processing unit, a measured value of a weighed object measured by a weighing unit, wherein the gravitational acceleration at a point where the electronic weighing unit is disposed is used as a correction value, and the weighed value is calculated. A means for correcting is provided, and the correcting means includes:
Means for detecting the location of the electronic balance by GPS;
Means for calculating a gravitational acceleration at the detected arrangement point, and correcting the weighed value of the weighed object using the obtained gravitational acceleration as a correction value. 2. The gravitational acceleration data based on the latitude information and the gravitational acceleration data with respect to the altitude at an electronic weighing scale arrangement point are fixed data of the point, and a gravitational acceleration reference value is set based on the fixed data. Claim 1
Electronic balance as described. 3. Bouguer anomaly data at the point is added to the gravitational acceleration data based on the latitude information and the altitude gravitational acceleration data at the altitude as the fixed data, and the Bouguer anomaly data at the point is corrected. 3. The electronic balance according to claim 2, wherein the gravitational acceleration reference value is corrected as a value to obtain standard gravitational acceleration data. 4. A means for acquiring, in addition to the fixed data, time variation data which influences the gravitational acceleration basic value or the standard gravitational acceleration data due to a change in time of the celestial body operation data, etc., 4. The gravitational acceleration data is further corrected to obtain time-corrected gravitational acceleration data, and the weighed value of the weighed object is corrected by the time-corrected gravitational acceleration data corresponding to weighing of the weighed object. Electronic balance according to 1. 5. The electronic balance according to claim 1, wherein the GPS receiving unit is incorporated in the electronic balance. 6. The electronic weigher according to claim 1, wherein said electronic weigher is provided with connecting means, and a GPS receiving terminal separately formed from said electronic weigher is connected via said connecting means.
An electronic balance according to any one of claims 1 to 4.