METHOD FOR JUDGING ENVIRONMENT OF BALANCE, AND APPARATUS FOR THE SAME

An electronic balance includes a weighing pan, a windshield, door opening and closing mechanisms configured to automatically open and close doors of the windshield, a weight sensor, a built-in weight, a weight applying and removing mechanism for the built-in weight, and a control unit, the control unit obtains a first standard deviation measured while the doors of the windshield are left closed, and a second standard deviation measured accompanied by a series of opening and closing operations consisting of opening the door by the door opening and closing mechanism, loading the built-in weight by the weight applying and removing mechanism, closing the door by the door opening and closing mechanism, acquiring weighing data of the built-in weight, opening the door by the door opening and closing mechanism, unloading the built-in weight by the weight applying and removing mechanism, and closing the door by the opening and closing mechanism.

TECHNICAL FIELD

The present invention relates to a method for judging a surrounding environment of an electronic balance, and an electronic balance for the same.

BACKGROUND ART

With a high-accuracy electronic balance whose weighed value minimum display (reading accuracy) is 0.1 mg or less, it is known that a surrounding environment of the balance influences the weighing accuracy. Therefore, in many cases, an electronic balance is provided with a windshield to prevent air flow around a weighing pan serving as one of the factors that lowers weighing accuracy (for example, Patent Literature 1). Further, many of the electronic balances include built-in weights whose mass is known, and have an automatic calibration function to automatically confirm the repeatability (standard deviation) of the balance (for example, Patent Literature 2).

CITATION LIST

Patent Literatures

SUMMARY OF INVENTION

Technical Problem

In a case of an electronic balance with a windshield, the confirmation of repeatability described above, that is, built-in weight applying and removing operations for obtaining a standard deviation of the built-in weight are performed in a state where the windshield is closed. However, at the time of actual weighing, a user performs weighing in a serial flow in which the user opens a door of the windshield and loads a to-be-weighed object, closes the door and measures weighing data of the to-be-weighed object, and opens the door and unloads the to-be-weighed object, so that door opening and closing are inevitable.

Therefore, there were many reports that the weighing performance guaranteed for the balance could not be obtained although the repeatability was confirmed before weighing, and there is a need to know to what extent the surrounding environment has influence under conditions of actual use by a user accompanied by the series of opening and closing operations.

The present invention was made to solve the problem described above, and an object thereof is to provide a method for judging an influence of a surrounding environment of an electronic balance under conditions close to actual use by a user, and an electronic balance for the same.

Solution to Problem

In order to solve the problem described above, an electronic balance according to an aspect of the present invention includes a weighing pan on which a to-be-weighed object is placed, a windshield surrounding the weighing pan, a door opening and closing mechanism configured to automatically open and close a door of the windshield, a weight sensor to which a load applied to the weighing pan is transmitted, a built-in weight to be loaded on and unloaded from the weight sensor, a weight applying and removing mechanism for the built-in weight, and a control unit configured to measure a standard deviation of the built-in weight and control the door opening and closing mechanism and the weight applying and removing mechanism, wherein the control unit obtains a first standard deviation measured while the door of the windshield is left closed, and a second standard deviation measured accompanied by a series of opening and closing operations consisting of opening the door by the door opening and closing mechanism, loading the built-in weight by the weight applying and removing mechanism, closing the door by the door opening and closing mechanism, acquiring weighing data of the built-in weight, opening the door by the door opening and closing mechanism, unloading the built-in weight by the weight applying and removing mechanism, and closing the door by the opening and closing mechanism.

In the aspect described above, it is also preferable that when the second standard deviation is larger than the first standard deviation, the control unit notifies a user that there is an influence from a surrounding environment caused by opening and closing of the door.

In the aspect described above, it is also preferable that the control unit ranks a difference value between the second standard deviation and the first standard deviation, or a square root value of a difference between the square of the second standard deviation and the square of the first standard deviation according to an evaluation threshold set in consideration of an internal design of the electronic balance, and evaluates an influence from a surrounding environment caused by opening and closing of the door.

In the aspect described above, it is also preferable that the control unit further measures a first stabilization time until fluctuation in weighing data of the built-in weight is stabilized when measuring the first standard deviation, and a second stabilization time until fluctuation in weighing data of the built-in weight is stabilized when measuring the second standard deviation, and when the second stabilization time is longer than the first stabilization time, calculates a time as an additional stabilization time by subtracting the first stabilization time from the second stabilization time, and notifies a user of the additional stabilization time.

In order to solve the problem described above, a method for judging a surrounding environment of an electronic balance according to an aspect of the present invention is a method for judging a surrounding environment of an electronic balance including a weighing pan on which a to-be-weighed object is placed, a windshield surrounding the weighing pan, a door opening and closing mechanism configured to automatically open and close a door of the windshield, a weight sensor to which a load applied to the weighing pan is transmitted, a built-in weight to be loaded on and unloaded from the weight sensor, a weight applying and removing mechanism for the built-in weight, and a control unit configured to measure a standard deviation of the built-in weight and control the door opening and closing mechanism and the weight applying and removing mechanism, and includes a step of measuring a first standard deviation of the built-in weight by repeating loading and unloading of the built-in weight by the weight applying and removing mechanism while the door of the windshield is left closed, and a step of measuring a second standard deviation of the built-in weight by repeating a series of opening and closing operations consisting of opening the door by the door opening and closing mechanism, loading the built-in weight by the weight applying and removing mechanism, closing the door by the door opening and closing mechanism, acquiring weighing data of the built-in weight, opening the door by the door opening and closing mechanism, unloading the built-in weight by the weight applying and removing mechanism, and closing the door by the opening and closing mechanism.

Advantageous Effects of Invention

According to the present invention, a surrounding environment of an electronic balance can be judged under conditions close to actual use by a user.

DESCRIPTION OF EMBODIMENTS

Next, preferred embodiments of the present invention will be described based on the drawings.

(Configuration of Electronic Balance)

FIG.1is a component block diagram of an electronic balance according to an embodiment of the present invention.FIG.2illustrates an example of an apparatus configuration of the electronic balance illustrated inFIG.1, and is a right-side perspective view of the same configuration example. As illustrated inFIG.1, an electronic balance1(hereinafter, simply referred to as a balance1) includes a weighing pan2, a windshield3, a balance main body4, an operation unit5, a display unit6, a timer8, a weight sensor11, a door opening and closing mechanism12, a built-in weight13, a weight applying and removing mechanism14, and a control unit15.FIG.2illustrates a configuration example embodying the balance1, and hereinafter, the components mentioned above will be described with reference toFIG.2.

The balance main body4is a case in which the weight sensor11, the door opening and closing mechanism12, the built-in weight13, the weight applying and removing mechanism14, the control unit15, and the timer8are included, and the weighing pan2is disposed at a center of an upper portion of the balance main body4.

The operation unit5and the display unit6are provided on a control panel7, and the control panel7is connected to the balance main body4by a cable. The operation unit5includes key switches necessary for operating the balance1, and on a screen of the display unit6, a menu and results relating to weighing, and further, a menu and results relating to surrounding environment judgment to be described later, are displayed. However, the control panel7and the balance main body4may be connected wirelessly. The operation unit5and the display unit6may be provided on the balance main body4. It is also preferable that the operation unit5includes a door opening and closing sensor (or button)51that triggers automatic opening and closing of the door opening and closing mechanism12to be described later.

The windshield3has a bottomless box shape, and is detachably attached to the balance main body4. For an attaching and detaching mechanism, a conventionally known configuration, for example, the configuration disclosed in Japanese Patent No. 5062880, etc., disclosed as a patent literature may be used. However, a configuration for which the windshield3and the balance main body4are integrated in a non-separable manner is also possible. The windshield3includes a front plate31at a front side, a back case32at a rear side, and opening and closing doors on left and right sides (hereinafter, the door on the left side is referred to as a left door33, and the door on the right side is referred to as a right door34), and an opening and closing door at an upper side (hereinafter, referred to as an upper door35). The front plate31, the back case32, the left door33, the right door34, and the upper door35define a weighing chamber surrounding the weighing pan2in all directions. Note that the expressions containing front, rear, left, upper/up, and lower/down used in the present description refer to directions indicated by the arrows Fr-Re (Front-Rear), Le-Ri (Left-Right), Up-Lo (Up-Down) illustrated inFIG.2, respectively.

The front plate31, the left door33, the right door34, and the upper door35are made of a transparent glass or resin so that an internal state can be observed. The back case32is made of, for example, glass, metal, or plastic. Each of the upper door35, the left door33, and the right door34is provided with a handle that assists door sliding. The upper door35can be manually opened and closed in the front-rear direction, and the left door33and the right door34can be automatically opened and closed in the front-rear direction by the door opening and closing mechanism12to be described later.

As the weight sensor11, an electromagnetic balance type, a strain gauge type, or a capacitive type is used. To the weight sensor11, a load of a to-be-weighed object placed on the weighing pan2is transmitted through a load transmitting mechanism (not illustrated) such as a beam. A load detected by the weight sensor11is output as weighing data to the control unit15. To the weight sensor11, the built-in weight13is also applied, and weighing data of the built-in weight13is also output to the control unit15.

The timer8acquires a current time (system time) of the balance1by calculating count values of a hardware timer and a software timer. The timer8may be a built-in clock of the control unit15.

The control unit15is, for example, a microcontroller configured by mounting a CPU and a memory, etc., on an integrated circuit. The control unit15includes a weighing unit151that calculates a weighed value from weighing data detected by the weight sensor11, a door opening and closing control unit152that controls the door opening and closing mechanism12, a weight applying and removing control unit153that controls the weight applying and removing mechanism14, and a surrounding environment judging unit154. These functional units151to154are configured by electronic circuits such as a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), and an PLD (Programmable Logic Device) such as FPGA (Field Programmable Gate Array).

The weighing unit151acquires weighing data of a to-be-weighed object by converting an analog signal detected by the weight sensor11into a digital signal. When a to-be-weighed object is placed on the weighing pan2, the weighing unit151waits for a predetermined period of time (hereinafter, referred to as an “acquisition time.” The acquisition time is set in advance, and stored in the memory of the control unit15) in which fluctuation in weighing data of the to-be-weighed object is expected to be stabilized, and calculates a weighed value by subtracting weighing data obtained in a state where the to-be-weighed object is not on the weighing pan2from the weighing data. Details of the functions of the door opening and closing control unit152, the weight applying and removing control unit153, and the surrounding environment judging unit154will be described later.

The built-in weight13is a weight whose weight is known disposed in the balance main body4for calibration of the balance. The known weight of the built-in weight13is stored in advance in the memory of the control unit15.

The built-in weight13is loaded on and unloaded from the weight sensor11by the weight applying and removing mechanism14.FIG.3illustrates a configuration example of the weight applying and removing mechanism14, and is a longitudinal sectional view of the same configuration example. The weight applying and removing mechanism14includes the built-in weight13, a weight holder141, a spring142, a load receiving portion143, an air bag144, a bag pressurization pump145, and a bag one-way solenoid valve146. The built-in weight13is held by the weight holder141, and the weight holder141is biased upward by the spring142. The air bag144is disposed at a position where the air bag pushes down the weight holder141downward, and the bag pressurization pump145and the bag one-way solenoid valve146are connected to the air bag144. The load receiving portion143is connected to the weight sensor11via a load transmitting mechanism (not illustrated) different from the weighing pan2.

The weight applying and removing mechanism14is controlled by the weight applying and removing control unit153of the control unit15. When loading the built-in weight13on the weight sensor11, the weight applying and removing control unit153activates the bag pressurization pump145to inflate the air bag144, push down the weight holder141against the biasing force of the spring142, apply a load of the built-in weight13to the load receiving portion143, and transmit the full load of the built-in weight13to the weight sensor11. On the other hand, when unloading the built-in weight13from the weight sensor11, the weight applying and removing control unit153opens the bag one-way solenoid valve146to the atmosphere to deflate the air bag144, push up the weight holder141by the biasing force of the spring142, and remove the load of the built-in weight from the load receiving portion143.

FIG.4illustrates a configuration example of the door opening and closing mechanism12, and is a block diagram of the same configuration example. The door opening and closing mechanism12is provided for each of the left door33and the right door34, and is independently controlled by the door opening and closing control unit152. Hereinafter, description will be given with use of the right door34.

For the right door34, the door opening and closing mechanism12includes a first pressurization pump121A, a second pressurization pump121B, a first pressure sensor122A, a second pressure sensor122B, a first one-way solenoid valve123A, a second one-way solenoid valve123B, and an air cylinder124. The first pressurization pump121A and the second pressurization pump121B are air pumps. Outlet sides of the first one-way solenoid valve123A and the second one-way solenoid valve123B are opened to the atmosphere, and by opening and closing the valves, air flowing and stoppage are controlled. The first pressure sensor122A monitors a pressure of air discharged from the first pressurization pump121A, and the second pressure sensor122B monitors a pressure of air discharged from the second pressurization pump121B. The first pressure sensor122A and the second pressure sensor122B are respectively connected to the air cylinder124, and monitor a pressure of air inside the air cylinder124. The air cylinder124is housed in an upper end portion of the right door34together with a piston rod125(FIG.2). Other components are housed in the back case32. Moreover, to the rear side of the air cylinder124, the first pressurization pump121A for advancing the right door34is connected, and to the front side of the air cylinder124, the second pressurization pump121B for retreating the right door34is connected.

The door opening and closing mechanism12is controlled by the door opening and closing control unit152of the control unit15. When opening the right door34(when moving the door rearward), the door opening and closing control unit152does not activate the first pressurization pump121A but opens the first one-way solenoid valve123A and closes the second one-way solenoid valve123B to pressurize the second pressurization pump121B, so as to retreat the right door34by air pressure of the second pressurization pump121B. On the other hand, when closing the right door34(when moving the door forward), the door opening and closing control unit152does not activate the second pressurization pump121B but opens the second one-way solenoid valve123B and closes the first one-way solenoid valve123A to pressurize the first pressurization pump121A, so as to advance the right door34by air pressure of the first pressurization pump121A. Each time the right door34is fully opened or fully closed, the pressure sensor122A,122B detects a sudden pressure increase, so that the door opening and closing control unit152stops the pressurization, opens the valves to release the air to the atmosphere, so as to stop the movement of the right door34.

Concerning the weight applying and removing mechanism14, details of the configuration illustrated inFIG.3are described in Japanese Patent No. 4851882 disclosed as a patent literature. However, the weight applying and removing mechanism14may be configured, for example, to load and unload the built-in weight13to and from the load receiving portion connected to the weight sensor11by a motor and a cam mechanism. Concerning the door opening and closing mechanism12, the configuration illustrated inFIG.4is described in detail in International Application No. PCT/JP 2020/011748. However, the door opening and closing mechanism12may be configured, for example, to move the door by a motor and a rack-and-pinion or a feed screw.

Next, a surrounding environment judgment method using the balance1described above will be described.FIG.5is a flowchart of surrounding environment judgment according to an embodiment of the present invention.

First, in Step S1, for example, when a user opens a surrounding environment judgment menu from the operation unit5and selects START, this triggers surrounding environment judgment to start. Alternatively, surrounding environment judgment may be configured to be automatically started before starting weighing, for example, when a user operates the door opening and closing sensor51to open the door.

When the surrounding environment judgment is started, first, a first measurement is performed in which measurements are made while the doors of the windshield3are left closed (Steps S2to S6).

As the processing shifts to Step S2, after an acquisition time elapses, the weighing unit151acquires weighing data in a state where neither the built-in weight13nor a to-be-weighed object is applied to the weight sensor11(hereinafter, referred to as “zero weighing data”).

Next, the processing shifts to Step S3, and the weight applying and removing control unit153controls the weight applying and removing mechanism14to load the built-in weight13on the load receiving portion143.

Next, the processing shifts to Step S4, and after the acquisition time elapses, the weighing unit151acquires weighing data of the built-in weight13(hereinafter, referred to as “full weighing data”).

Next, the processing shifts to Step S5, and the weight applying and removing control unit153controls the weight applying and removing mechanism14to unload the built-in weight13from the load receiving portion143.

Next, the processing shifts to Step S6, and the surrounding environment judging unit154counts up the number of measurements of the built-in weight13, and determines whether the number of measurements has reached the number of times (n times) set in advance. When the set number of times is not reached (No), the processing returns to Step S2. When the set number of times is reached (Yes), the processing shifts to Step S7. n is preferably 5 to 10.

As the first measurement is finished, next, a second measurement is performed in which measurements are made accompanied by opening and closing of the door of the windshield3(Steps S7to S15).

As the processing shifts to Step S7, after the acquisition time elapses, the weighing unit151acquires zero weighing data.

Next, in Step S8, the door opening and closing control unit152controls the door opening and closing mechanism12to open either the left or right door (which is to be set by a user. Hereinafter, description will be made with use of the right door34). Due to opening of the right door34, the environment in the weighing chamber is influenced by an environment outside the weighing chamber.

Next, the processing shifts to Step S9, and the weight applying and removing control unit153controls the weight applying and removing mechanism14to load the built-in weight13on the load receiving portion143.

Next, the processing shifts to Step S10, and the door opening and closing control unit152controls the door opening and closing mechanism12to close the right door34.

Next, the processing shifts to Step S11, and after the acquisition time elapses, the weighing unit151acquires full weighing data of the built-in weight13.

Next, the processing shifts to Step S12, and the door opening and closing control unit152controls the door opening and closing mechanism12to open the right door34. Due to opening of the right door34, the environment in the weighing chamber is influenced by an environment outside the weighing chamber again.

Next, the processing shifts to Step S13, and the weight applying and removing control unit153controls the weight applying and removing mechanism14to unload the built-in weight13from the load receiving portion143.

Next, the processing shifts to Step S14, and the door opening and closing control unit152controls the door opening and closing mechanism12to close the right door34.

Next, the processing shifts to Step S15, and the surrounding environment judging unit154counts up the number of measurements of the built-in weight13, and determines whether the number of measurements has reached the number of times (n times) set in advance. When the set number of times is not reached (No), the processing returns to Step S7. When the set number of times is reached (Yes), the processing shifts to Step S16. n is the same number as in the first measurement, and is preferably 5 to 10.

As the processing shifts to Step S16, the surrounding environment judging unit154calculates a span value (difference between full weighing data and zero weighing data) of each of the first measurement and the second measurement.

Next, the processing shifts to Step S17, and the surrounding environment judging unit154calculates a standard deviation of the span value of each of the first measurement and the second measurement.

Here, the standard deviation obtained in the first measurement (which is referred to as “first standard deviation”) represents the repeatability obtained in a state where the doors are closed, and can be grasped as the performance that the apparatus of the balance1can currently exhibit (performance that can be exhibited when there is no influence from the surrounding environment). Therefore, to the first standard deviation obtained in the first measurement, a reference sign “SDbp (standard deviation of balance performance)” is attached.

On the other hand, the standard deviation obtained in the second measurement (which is referred to as “second standard deviation”) represents the repeatability obtained at the time of loading and unloading of the built-in weight13accompanied by the series of opening and closing operations that are performed when weighing a to-be-weighed object in actuality, and can be grasped as the performance that the apparatus of the balance1exhibits under the influence of the surrounding environment. Therefore, hereinafter, to the second standard deviation obtained in the second measurement, a reference sign “SDep (standard deviation of environment performance) is attached.

Next, the processing shifts to Step S18, and the surrounding environment judging unit154judges the surrounding environment of the balance1by using the first standard deviation SDbp and the second standard deviation SDep.

In the surrounding environment judgment, the first standard deviation SDbp and the second standard deviation SDep are compared, and whether the second standard deviation SDep is larger than the first standard deviation SDbp is judged. When SDbp exceeds SDep, judgment is made impossible. However, it is considered that SDbp exceeding SDep rarely takes place. When SDep is larger than SDbp, due to the influence of the surrounding environment, the performance (repeatability) of the balance1at the time of actual weighing may possibly be inferior to the performance (repeatability) that the apparatus of the balance1can currently exhibit.

Next, the processing shifts to Step S19, and the surrounding environment judging unit154displays a result of the surrounding environment judgment in Step S18on the display unit6. As a result of the surrounding environment judgment, at least numerical values of the first standard deviation SDbp and the second standard deviation SDep are displayed on the display unit6.

Further, when the second standard deviation SDep is larger than the first standard deviation SDbp, the surrounding environment judging unit154preferably displays a comment for notifying a user that there is an influence from the surrounding environment caused by opening and closing of the door, for example, “Performance may be influenced by wind,” along with the numerical values. When the balance1includes a buzzer, a light, or the like, the notification to the user may be performed by sound or light.

It is known that as the accuracy of an electronic balance becomes higher, air flowing in the weighing chamber has greater influence on weighing. Therefore, for confirmation of the weighing performance, the electronic balance has an automatic calibration function to perform calibration by automatically applying and removing a built-in weight periodically or at the time of a user's operation. However, automatic application and removal of the built-in weight during calibration are performed in a state where the windshield is closed. Therefore, there were many reports that even after the calibration was performed, the weighing performance guaranteed for the balance could not be obtained at the time of weighing.

In contrast, according to the balance1and the surrounding environment judgment method of the balance1according to the present embodiment, two standard deviations are measured that are the repeatability (first standard deviation SDbp) in a state where the windshield3is closed and the repeatability (second standard deviation SDep) obtained accompanied by a series of opening and closing operations that are performed at the time of actual weighing of a to-be-weighed object by a user. By obtaining the repeatability without door opening and closing (first standard deviation SDbp) and the repeatability with door opening and closing (second standard deviation SDep), to what extent the surrounding environment has influence under conditions of actual use for weighing can be known.

Further, when the second standard deviation SDep is larger than the first standard deviation SDbp, by notifying the user that there is an influence from the surrounding environment caused by opening and closing of the door, the user himself/herself can be urged to take a response such as stopping the air conditioner, using a double windshield, or moving out of the wind.

Next, preferred modifications of the balance1according to the embodiment will be described. The same configuration as in the embodiment is provided with the same reference sign, and description thereof will be omitted.

An electronic balance1according to Modification 1 of the embodiment of the present invention has the same configuration as in the embodiment (FIG.1). Besides this configuration, the electronic balance1of Modification 1 also performs “evaluation” of the surrounding environment in addition.FIG.6is a flowchart of surrounding environment judgment according to Modification 1 of the embodiment of the present invention.

Steps S101to S118of Modification 1 are the same as Steps S1to S18of the embodiment (FIG.5). That is, when an option “Evaluate” is also selected on the surrounding environment judgment menu in Step S101, this triggers surrounding environment evaluation to start. The first measurement is performed in Steps S102to S106, the second measurement is performed in Steps S107to S115, and then, a first standard deviation SDbp obtained in a state where the doors of the windshield are closed and a second standard deviation SDep obtained accompanied by door opening and closing are measured in Steps S117and S118.

In Modification 1, in the next Step S119, for a difference between the second standard deviation SDep and the first standard deviation SDbp, the surrounding environment judging unit154sets an evaluation threshold in consideration of an internal design specific to the balance, and evaluates the surrounding environment of the balance. Specific examples of the surrounding environment evaluation are shown below.

(1) As an example, an evaluation threshold is set by using a display count of 1d of the balance (the display count of the balance means the smallest digit of a weighed value displayed on the display unit, and in a balance with minimum display of 1 μg, 1d=0.000001 g, and in a balance with minimum display of 0.1 mg, 1d is 0.0001 g).

(2) Assume an internal design specific to the balance1that the minimum display is 1 μg, in further consideration of a weighing capacity of the balance1, an evaluation threshold is set. For example, when the weighing capacity of the balance1is 20 g, an evaluation threshold for rank “A” is set to 2d, and when the weighing capacity of the balance1is 5 g, an evaluation threshold for rank “A” is set to a more stringent value of 1d.

(3) In a case where evaluation thresholds of the balance1are set as follows:Evaluation A: SDep−SDbp is 1d or lessEvaluation B: SDep−SDbp is more than 1d and not more than 3dEvaluation C: SDep−SDbp is more than 3d, and when a second standard deviation SDep=3.0 μg, and a first standard deviation SDbp=1.5 μg, are obtained in the balance1,

is obtained, and therefore, evaluation “B” is judged.

When SDbp exceeds SDep, evaluation is made impossible. However, it is considered that SDbp exceeding SDep rarely takes place.

On the assumption that the first standard deviation SDbp is the performance that the balance1can currently exhibit, the second standard deviation SDep obtained accompanied by the series of opening and closing operations can be considered to be a synthesis of the current performance of the balance (first standard deviation SDbp) and that corresponding to an influence of door opening and closing (standard deviation SDoc (open-close)). From additivity of variance, the square of SDep can be expressed as a sum of the square of SDbp and the square of SDoc. Therefore, the standard deviation SDoc corresponding to the influence of door opening and closing can be obtained by Numerical Formula 1:

For this standard deviation SDoc corresponding to the influence of door opening and closing, evaluation thresholds are set in consideration of an internal design specific to the balance, and a surrounding environment of the balance1is evaluated.

(1) As an example, evaluation thresholds are set by using a display count of 1d of the balance.

(2) In consideration of the internal design specific to the balance1, an evaluation threshold for rank “A” is set to a more stringent value of 0.5d.

(3) In a case where evaluation thresholds of the balance1are set as follows:Evaluation A: SDoc is 0.5d or lessEvaluation B: SDoc is more than 0.5d and not more than 1.0dEvaluation C: SDoc is more than 1.0d, and
when the standard deviation SDoc=1.92 μg corresponding to the influence of door opening and closing is obtained in the balance1, evaluation “C” is judged.

However, those described above are mere examples, and the values of evaluation thresholds and corresponding ranks shall be designed by comprehensively considering the internal design specific to the balance (including not only the minimum display and the weighing capacity, but also, for example, the type of the weight sensor of the balance, the internal structure and airtightness of the main body case, etc.). Further, in the examples described above, the display count of 1d used for setting of evaluation thresholds was used to convert the unit from 1 g (gram) into a smaller unit, and the setting may be made with the units of 1 g (gram) used without change, and this does not preclude using any other units.

Next, the processing shifts to Step S120, and the surrounding environment judging unit154displays, in addition to the numerical values of the respective standard deviations SDbp and SDep, an evaluated level and a comment corresponding to the level on the display unit6. As an example, the display unit6displays “No problem with surrounding environment” when evaluation A is judged, “Performance may be influenced by wind” when evaluation B is judged, and “Performance has deteriorated by wind. Take measure to avoid wind” when evaluation C is judged.FIG.7illustrates a display example of an evaluation result.

Note that it is also possible to output surrounding environment judgment and evaluation results from the balance1to an external device such as a printer or a personal computer by an RS232C cable, a USB, or BLE (Bluetooth low energy. Bluetooth is a registered trademark).FIG.8illustrates an output example of an evaluation result to a printer.

According to Modification 1, a surrounding environment is represented in the form of evaluation, so that a user can more easily understand and imagine the magnitude of an influence of the surrounding environment.

An electronic balance according to Modification 2 of the embodiment of the present invention has the same configuration as in the embodiment (FIG.1). Besides this configuration, the balance1of Modification 2 performs the following surrounding environment judgment.FIG.9is a flowchart of surrounding environment judgment according to Modification 2 of the embodiment of the present invention.

First, in Step S201, in the same manner as in the embodiment (FIG.5), when start is selected from the surrounding environment judgment menu, this triggers the surrounding environment judgment of Modification 2 to start.

As the surrounding environment judgment starts, first, the first measurement is performed in which measurements are made while the doors of the windshield3are left closed (Steps S202to S209).

In Step S202, after the acquisition time elapses, the weighing unit151acquires zero weighing data. Next, in Step S203, the weight applying and removing control unit153controls the weight applying and removing mechanism14to load the built-in weight13on the load receiving portion143.

Here, at the same time as loading of the built-in weight13, the surrounding environment judging unit154starts the timer8in Step S204.

Next, the processing shifts to Step S205, and the surrounding environment judging unit154determines whether fluctuation in full weighing data of the built-in weight13has been stabilized (whether the fluctuation in full weighing data has fallen within a predetermined range stored in advance in the memory). When the fluctuation is not stabilized (No), the processing continuously waits for stabilization, and when the fluctuation is stabilized (Yes), the processing shifts to Step S206.

As the processing shifts to Step S206, the surrounding environment judging unit154stops the timer8, and measures the time taken until the fluctuation in full weighing data is stabilized in the first measurement (hereinafter, referred to as a first stabilization time).

Next, in Step S207, the weighing unit151acquires full weighing data of the built-in weight after the first stabilization time T1elapses.

Next, in Step S208, the weight applying and removing control unit153controls the weight applying and removing mechanism14to unload the built-in weight13from the load receiving portion143. Next, in Step S209, the surrounding environment judging unit154determines whether the number of measurements has reached the number of times (n times) set in advance. When the set number of times is not reached (No), the processing returns to Step S202. When the set number of times is reached (Yes), the processing shifts to Step S210. n is preferably 5 to 10. At the second and subsequent times, zero weighing data may also be acquired after the first stabilization time T1.

As the first measurement is finished, next, the second measurement is performed in which measurements are made accompanied by opening and closing of the door of the windshield3(Steps S210to S221).

In Step S210, after the acquisition time elapses, the weighing unit151acquires zero weighing data. Next, in Step S211, the door opening and closing control unit152controls the door opening and closing mechanism12to open either the left or the right door (set by a user. Hereinafter, a case where the right door34is opened is described). Due to opening of the right door34, the environment in the weighing chamber is influenced by an environment outside the weighing chamber. Next, in Step S212, the weight applying and removing control unit153controls the weight applying and removing mechanism14to load the built-in weight13on the load receiving portion143.

Here, at the same time as loading of the built-in weight13, the surrounding environment judging unit154starts the timer8in Step S213.

Next, the processing shifts to Step S214, and the door opening and closing control unit152controls the door opening and closing mechanism12to close the right door34.

Next, the processing shifts to Step S215, and the surrounding environment judging unit154determines whether fluctuation in full weighing data of the built-in weight13has been stabilized (whether the fluctuation in the full weighing data has fallen within a predetermined range stored in advance in the memory). When the fluctuation is not stabilized (NO), the processing continuously waits for stabilization, and when the fluctuation is stabilized (YES), the processing shifts to Step S216.

As the processing shifts to Step S216, the surrounding environment judging unit154stops the timer8, and measures the time taken until the fluctuation in the full weighing data is stabilized in the second measurement (hereinafter, referred to as “second stabilization time”).

Next, in Step S217, the weighing unit151acquires full weighing data of the built-in weight13after the second stabilization time T2elapses. Next, in Step S218, the door opening and closing control unit152controls the door opening and closing mechanism12to open the right door34. Due to opening of the right door34, the environment in the weighing chamber is influenced by an environment outside the weighing chamber again. Next, in Step S219, the weight applying and removing control unit153controls the weight applying and removing mechanism14to unload the built-in weight13from the load receiving portion143. Next, in Step S220, the door opening and closing control unit152controls the door opening and closing mechanism12to close the right door34. Next, in Step S221, the surrounding environment judging unit154determines whether the number of measurements has reached the number of times (n times) set in advance. When the set number of times is not reached (No), the processing returns to Step S210. When the set number of times is reached (Yes), the processing shifts to Step S222. n is the same number as in the first measurement, and is preferably 5 to 10. At the second and subsequent times, zero weighing data may also be acquired after the second stabilization time T2.

Next, in Steps S222to S224, as in Steps S16to S18of the embodiment, the surrounding environment judging unit154calculates span values of the first measurement and the second measurement, calculates the first standard deviation SDbp and the second standard deviation SDep, and judges the surrounding environment by comparing SDbp and SDep.

Next, in Step S225, the surrounding environment judging unit154compares the first stabilization time T1and the second stabilization time T2, and when T2is longer than T1, calculates a time by subtracting the first stabilization time T1from the second stabilization time T2, as an “additional stabilization time dT” until stabilization of weighing data influenced by door opening and closing. When T1exceeds T2, calculation is made impossible. However, it is considered that T1exceeding T2rarely takes place.

Next, the processing shifts to Step S226, and the surrounding environment judging unit154displays the first stabilization time T1, the second stabilization time T2, and the additional stabilization time dT on the display unit6as well as the first standard deviation SDbp and the second standard deviation SDep. For example, on the display unit6, “Please wait for [additional stabilization time dT] more seconds until stabilization of weighed value influenced by surrounding environment due to door opening and closing” is displayed.

According to Modification 2, since numerical values of the first stabilization time T1, the second stabilization time T2, and the additional stabilization time dT are displayed, a user can be notified how long the user should wait until the influence of the surrounding environment decreases under actual use conditions at the time of weighing.

Preferred embodiments and modifications of the present invention have been described above, and each embodiment and each modification can be combined based on knowledge skilled in the art, and such a combined embodiment is included in the scope of the present invention.

REFERENCE SIGNS LIST