JP2011252740A - Balance and correction method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balance with which a measurement value of weight of an object to be measured can be corrected with sufficiently high accuracy in an arbitrary district while suppressing storage capacity needed.SOLUTION: The balance comprises a platform 1 on which an object to be measured is placed. The platform 1 comprises: a load cell 11 for converting a load into signals and outputting the same; a load measurement circuit 12 for measuring a load based on the signals output from the load cell 11; a CPU 13; and a storage part 14. The load cell 11, the load measurement circuit 12 and the CPU 13 function as a first measurement part which measures weight of the platform 1 and a second measurement part which measures weight of the object to be measured. The CPU 13 and the storage part 14 function as a ratio calculation part which calculates a ratio R of a measurement value W of the weight of the platform 1 and weight W' of the platform 1 under the specific gravitational acceleration; and a correction part for correcting a measurement value Wt of the weight of the object to be measured based on the ratio R.

Description

  The present invention relates to a scale for measuring the weight of an object to be measured and a correction method thereof.

  The weight of the object to be measured is the product of the mass of the object to be measured and the gravitational acceleration. Since the gravitational acceleration is small near the equator and large near the pole, the weight of the same object to be measured can vary between regions due to the difference in gravitational acceleration. However, if there are variations in the measured values of the weight of the same object to be measured, various inconveniences may occur in the real world. Therefore, in order to avoid the above-described variation, there has been proposed a balance that estimates and displays the measured value of the weight of the object to be measured under a specific gravitational acceleration.

  The scale described in Patent Document 1 (electronic weighing machine with gravity correction function) includes a memory that stores correction value data for each region, selects correction value data corresponding to the region specified by the switch, and selects the selected value. By correcting the measured value of the weight of the measured object with the correction value data, the measured value of the weight of the measured object under a specific gravitational acceleration is estimated, and the estimated value is displayed. Patent Document 2 discloses a scale (load cell scale) that automatically selects correction value data based on GPS signals.

JP-A-60-64224 JP 2001-59769 A

  In order to perform the above correction with sufficiently high accuracy using the scales described in Patent Documents 1 and 2, it is necessary to store correction value data for each sufficiently subdivided area. Therefore, the necessary storage capacity increases as the usable area increases, and increases as the correction accuracy increases. That is, in order to perform the above correction with a sufficiently high accuracy in an arbitrary area, a huge storage capacity is required.

  Accordingly, the present invention solves the problem of providing a scale capable of correcting the measured value of the weight of an object to be measured with a sufficiently high accuracy in an arbitrary region while suppressing the necessary storage capacity, and a correction method thereof. Let it be an issue.

  In order to solve the above-described problems, the present invention provides a table on which an object to be measured is placed, a first measurement unit that measures the weight of the table, a measured value of the weight of the table, and a specific gravitational acceleration. A ratio calculating unit for calculating a ratio of the weight of the table, a second measuring unit for measuring the weight of the measured object, and a correcting unit for correcting the measured value of the weight of the measured object based on the ratio A scale comprising:

  According to this scale, the weight of the platform was measured in a certain area, the ratio between this measured value and the weight of the platform under a specific gravitational acceleration was calculated, and based on this ratio, it was obtained in this area. The measured value of the weight of the object to be measured can be corrected. Since the above ratio is also the ratio of the gravitational acceleration in this region to the specific gravitational acceleration, this scale estimates the measured value of the weight of the object under the specific gravitational acceleration according to the above correction. can do.

  In addition, according to this scale, by measuring the weight of the platform in an arbitrary area, the above ratio according to the gravitational acceleration of the area can be calculated, so that the measured value of the weight of the object to be measured can be corrected. It is not necessary to store the data to be used for each region. Therefore, according to this scale, the measured value of the weight of the object to be measured can be corrected with sufficiently high accuracy in an arbitrary region while suppressing the necessary storage capacity.

  In the above-mentioned scale, a load converter that converts a load into a signal and outputs the load, and a load measurement circuit that measures a load applied to the load converter based on the signal output from the load converter, The first measuring unit includes a measured value (Wa) of the load measuring circuit based on a signal output from the load transducer when no load is applied to the load transducer, and the object to be measured on the table. Based on the measured value (Wb) of the load measuring circuit based on the signal output from the load converter when no load is applied to the load converter, The measurement value (W = Wb−Wa) is calculated, and the second measurement unit performs the load conversion when the object to be measured is not placed on the table and a load is applied to the load converter. The load measurement based on the signal output from the vessel The load measuring circuit based on the measured value (W0) of the road and the signal output from the load converter when the object to be measured is placed on the table and a load is applied to the load converter The measured value (Wt = Ws−W0) of the weight of the object to be measured may be calculated based on the measured value (Ws). In this case, even if the measured value (Wa) of the load measuring circuit based on the signal output from the load transducer when no load is applied to the load transducer is not zero, the weight of the table and the weight of the object to be measured are accurate. Can be measured. This contributes to an improvement in the accuracy of the correction.

  The scale includes an operation unit that is operated by a user, and the first measurement unit sends the measurement value of the load measurement circuit when the operation state of the operation unit is the first operation state to the load converter. The measurement value of the load measurement circuit based on the signal output from the load converter when no load is applied, and the measurement value of the load measurement circuit when the operation state of the operation unit is the second operation state, The measured value of the load measuring circuit is based on a signal output from the load converter when the object to be measured is not placed on the table and a load is applied to the load converter. Alternatively, a display unit for displaying information may be provided, and the first measurement unit may display a measurement value of the load measurement circuit when the display state of the display unit is in the first display state, and a load is applied to the load converter. The load transducer is The measured value of the load measuring circuit based on the received signal is used, and the measured value of the load measuring circuit when the display state of the operation unit is in the second display state is used. Instead, the measured value of the load measuring circuit based on the signal output from the load converter when a load is applied to the load converter may be used. In the former case, since the measurement necessary for calculating the ratio proceeds based on the operation state of the operation unit, useless waiting time can be eliminated. In the latter case, since it is not necessary to provide an operation unit for measurement necessary for calculating the ratio, the configuration of the scale can be simplified.

  In order to solve the above problems, the present invention provides a first weight measurement step for measuring the weight of a table on which an object to be measured is placed, a measured value of the weight of the table, and a specific gravitational acceleration. A ratio calculating step for calculating a ratio with the weight of the table, a second weight measuring step for measuring the weight of the object to be measured, and a correcting step for correcting a measured value of the weight of the object to be measured based on the ratio. A method for correcting a balance having the following is provided. According to this method, for the same reason as described above for the scale according to the present invention, the measured value of the weight of the object to be measured is corrected with sufficiently high accuracy in any region while suppressing the necessary storage capacity. can do.

1 is a plan view of a scale 10 according to an embodiment of the present invention. It is a block diagram which shows the electric constitution of the stand 1 with which the scale 10 is provided. It is AA 'sectional drawing (at the time of mounting) of FIG. It is AA 'sectional drawing of FIG. 1 (at the time of lifting). 3 is a flowchart showing a flow of setting processing executed by a scale 10; 4 is a flowchart showing a flow of measurement processing executed by the scale 10.

  A scale 10 according to an embodiment of the present invention is a weight measuring device that measures the weight of an object to be measured such as a human being, and includes a table 1 on which the object to be measured is placed, and a first that measures the weight of the table 1. A ratio for calculating a ratio R between a measurement unit (a load cell 11, a load measurement circuit 12, and a CPU (Central Processing Unit) 13 described later), a measured value of the weight of the table 1, and a weight of the table 1 under a specific gravity acceleration. Ratio of calculation unit (CPU 13 and storage unit 14 described later), second measurement unit (load cell 11, load measurement circuit 12 and CPU 13 described later) for measuring the weight of the object to be measured, and measurement value of the weight of the object to be measured A correction unit (a CPU 13 and a storage unit 14 to be described later) for correcting based on R is provided. The scale 10 has a setting mode for setting the ratio R and a measurement mode for measuring the weight of the object to be measured as its operation mode.

Hereinafter, the scale 10 will be described with reference to the drawings.
FIG. 1 is a plan view of the balance 10. As shown in this figure, the scale 10 includes a rectangular base 1 on which the object to be measured is placed and four legs 2 that support the base 1. The table 1 has an upper surface 1a in contact with the object to be measured and a lower surface (not shown), a display unit 15 having a part of the upper surface 1a as a display surface, and a setting switch 16 for switching between setting mode and measurement mode. In addition, an operation switch (operation unit) 17 for inputting a user instruction in the setting mode and a power button (not shown) for turning on / off the balance 10 are provided.

  The display unit 15 is a liquid crystal display device, for example. Each of the setting switch 16 and the operation switch 17 is a two-state switch that is turned on or off by being operated by a user, and outputs a signal corresponding to the state. However, when the setting switch 16 is operated, the state is switched and maintained until the next operation, whereas the operation switch 17 is normally maintained in the off state, and when operated, the state is changed. After turning it on temporarily, it returns to the off state. The operation mode of the scale 10 depends on the state of the setting switch 16 when the power is turned on. Specifically, in the on state, the setting mode is selected, and in the off state, the measurement mode is selected.

  FIG. 2 is a block diagram showing the electrical configuration of the table 1. As shown in this figure, the base 1 includes four load cells 11 corresponding to the four legs 2, a load measurement circuit 12, a CPU 13, and a storage unit 14. The load cell 11 is a load converter that converts a load into a signal and outputs the load. The load cell 11 includes a strain generating body that is distorted according to the load and a bridge circuit that outputs a signal according to the strain. Continue to output.

  The load measurement circuit 12 repeatedly executes the load measurement process. The load measurement process is a process of measuring the load applied to the four load cells 11 based on the signals output from the four load cells 11 and outputting a signal indicating the measured value. The load measured by the load measuring circuit 12 is a total of loads applied to each of the four load cells 11 (hereinafter referred to as “total load”). Since the load cell 11 continues to output a signal corresponding to the load, the load measuring circuit 12 repeatedly outputs a signal indicating the latest measured value of the total load.

  The storage unit 14 is a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable and Programmable Read Only Memory), and stores ratio data 141 indicating the ratio R. The storage unit 14 stores in advance table weight data 142 indicating the weight W ′ of the table 1 under a specific gravity acceleration. In the present embodiment, the standard gravitational acceleration is employed as the specific gravitational acceleration, but is not limited thereto.

  The CPU 13 includes an internal storage unit (not shown) that stores a table load data 143 indicating a measurement value Wb described later or a measurement value W0 described later, and receives a signal output from the load measurement circuit 12, ratio data 141, etc. In the storage unit 14, reading out various data such as the ratio data 141 and the weight data 142 from the storage unit 14, displaying various information such as character strings on the display unit 15, Based on the signal output from the setting switch 16, the state of the setting switch 16 (on state / off state) is determined, or based on the signal output from the operation switch 17, the state of the operation switch 17 (on state / off state). Off state).

  When the power is turned on, the CPU 13 determines the state of the setting switch 16 (on state / off state), and in the on state (setting mode), executes a setting process for setting the ratio R, Thereafter, the power is turned off, and in the off state (measurement mode), a measurement process for measuring the weight of the object to be measured is executed. The measurement process continues until the user turns off the power by operating the power button.

  3 and 4 are cross-sectional views taken along the line AA ′ of FIG. 1, and the vertical direction in FIGS. 3 and 4 coincides with the vertical direction. However, FIG. 3 shows a case where the balance 10 is placed on the floor 30, and FIG. 4 shows a case where the balance 10 is lifted by holding the platform 1. As is apparent from FIG. 3, the accommodation holes 18 opened downward are formed at the four corners of the table 1 one by one. Each accommodation hole 18 is configured with a part of the upper surface of the load cell 11 and accommodates the leg 2.

  The leg 2 is movable with respect to the table 1. However, as shown in FIG. 3, the movement of the leg 2 vertically upward is limited by the contact between the upper portion 21 of the leg 2 and the load cell 11, and the movement of the leg 2 vertically downward or in the horizontal direction is shown in FIG. As shown in FIG. 4, the contact is caused by the contact between the side portion 22 of the leg 2 and the contact portion 19 of the base 1. Therefore, even if the table 1 is grasped and the scale 10 is lifted, the leg 2 does not fall off the table 1. Of the parts of the base 1, only the load cell 11 is in contact with the upper part 21 of the leg 2, and among the parts of the leg 2, only the upper part 21 is in contact with the load cell 11.

  As shown in FIG. 3, even when the upper portion 21 of the leg 2 is in contact with the load cell 11, the lower portion 23 of the leg 2 protrudes from the opening of the accommodation hole 18. Therefore, when the scale 10 is placed on the floor 30, the table 1 is supported only by the four legs 2, and the total load applied to the four load cells 11 is the weight of the table 1 and the load placed on the table 1. This corresponds to the sum of the weight of the measurement object (hereinafter referred to as “total weight”). On the other hand, when the scale 1 is lifted by grasping the table 1, each load cell 11 does not come into contact with the leg 2 as shown in FIG. 4, so that the load applied to each load cell 11 is zero and the total load is zero. Become.

Next, the operation of the scale 10 will be described.
In the area where the scale 10 is used, the user first causes the CPU 13 to execute setting processing. Specifically, the power switch is pressed after the setting switch 16 is operated to turn it on. Thereby, the power is turned on and the setting process is executed. Next, the user causes the CPU 13 to execute measurement processing in the above-described region. Specifically, the power switch is pressed after the setting switch 16 is operated to turn it off. Thereby, the power is turned on and the measurement process is executed. The setting process is required only once for the first time, and it is not necessary to re-execute the setting process unless the area where the scale 10 is used is changed.

  FIG. 5 is a flowchart showing the flow of the setting process. As shown in this figure, in the setting process, the CPU 13 first executes a setting start process (S11). In the setting start process, the CPU 13 starts displaying instructions to the user. In this display, for example, on the display unit 15, “First, grab the platform and lift the scale and operate the operation switch 17. Next, place the scale on the floor and operate the operation switch 17.” Is displayed.

  Next, the CPU 13 determines whether or not the operation switch 17 is on (S12). If the determination result is “NO”, the process returns to step S12. Since the operation switch 17 is normally in the OFF state, step S12 is repeated for a while. On the other hand, according to the displayed instruction, the user grasps the table 1 to lift the balance 10 and operates the operation switch 17 as shown in FIG. As a result, the operation switch 17 is temporarily turned on, and the determination result in step S12 is “YES”.

  When the determination result in step S12 is “YES”, the CPU 13 receives the signal output from the load measurement circuit 12, and acquires the measurement value of the total load based on the received signal (S13). As described above, since the load measurement circuit 12 outputs a signal indicating the latest measurement value of the total load, what is acquired in step S13 is when the scale 10 is lifted by grasping the table 1 ( This is a measured value Wa of the total load (see FIG. 4). The measured value Wa is also a measured value of the load measuring circuit 12 based on signals output from the four load cells 11 when no load is applied to any of the four load cells 11. In step S13, the operation switch 17 returns to the off state.

  Next, the CPU 13 determines whether or not the operation switch 17 is on (S14). If the determination result is “NO”, the process returns to step S14. Since the operation switch 17 has already returned to the off state, step S14 is repeated for a while. On the other hand, the user places the scale 10 on the floor 30 and operates the operation switch 17 according to the displayed instruction as shown in FIG. As a result, the operation switch 17 is temporarily turned on, and the determination result of step S14 is “YES”.

  When the determination result in step S14 is “YES”, the CPU 13 receives the signal output from the load measurement circuit 12, and acquires the measurement value of the total load based on the received signal (S15). As described above, since the load measurement circuit 12 outputs a signal indicating the latest measurement value of the total load, the CPU 1 obtains the table 1 on which the object to be measured is not placed in step S15. This is a measured value Wb of the total load when being supported by four load cells 11 (see FIG. 3). The measurement value Wb is output from the four load cells 11 when the object to be measured is not placed on the table 1 and a load is applied to each of the four load cells 11 in the setting process. It is also a measurement value (measurement value at the time of setting) of the load measurement circuit 12 based on the signal. And the base load data 143 which shows measured value Wb is memorize | stored in the internal memory part of CPU13. In step S15, the display of instructions to the user ends.

  Next, the CPU 13 calculates the measured value W of the weight of the table 1 by subtracting the measured value Wa acquired in step S13 from the measured value Wb acquired in step S15 (S16). That is, the four load cells 11, the load measurement circuit 12, and the CPU 13 function as a first measurement unit that measures the weight of the table 1. Steps S13, S15, and S16 correspond to a first weight measurement step for measuring the weight of the table 1.

  Next, the CPU 13 calculates the ratio R based on the measured value W acquired in step S16 and the weight W ′ indicated by the table weight data 142 stored in the storage unit 14 (S17). The formula for calculating the ratio R is R = W ′ / W. Since the weight W ′ is the weight of the table 1 under a specific gravity acceleration, the CPU 13 and the storage unit 14 calculate the ratio R between the measured value of the weight of the table 1 and the weight of the table 1 under the specific gravity acceleration. It functions as a ratio calculation unit for calculating. Step S17 corresponds to a ratio calculation step for calculating the ratio R.

  Next, the CPU 13 stores the ratio data 141 indicating the ratio R calculated in step S17 in the storage unit 14 (S18). Thus, the setting process is completed and the power is shut off.

  FIG. 6 is a flowchart showing the flow of the measurement process. As shown in this figure, in the measurement process, the CPU 13 first acquires the measurement value W0 of the total load (S20). Specifically, first, for example, a character string “Please place the scale on the floor and operate the operation switch 17” is displayed on the display unit 15 and wait until the operation switch 17 is operated. Then, when the operation switch 17 is operated, a signal output from the load measurement circuit 12 is received, a measurement value of the total load is acquired based on the received signal, and table load data 143 indicating the acquired measurement value is obtained. The data is stored in the internal storage unit of the CPU 13 and the display unit 15 displays, for example, a character string “Please place the object to be measured on the scale”. Therefore, in step S20, in the measurement process, the total load measurement value (measurement value at the time of measurement) when the table 1 on which the object to be measured is not placed is supported by the four load cells 11 (see FIG. 3). W0 is acquired, and base load data 143 indicating the measured value W0 is stored in the internal storage unit of the CPU 13. That is, the table load data 143 is updated to the one indicating the measured value W0 acquired here.

  Thereafter, the CPU 13 obtains the measurement value Ws of the total load (S21) and subtracts the measurement value W0 obtained in step S20 from the measurement value Ws to calculate the measurement value Wt of the weight of the object to be measured ( S22), a process of correcting the measured value Wt with the ratio R indicated by the ratio data 141 stored in the storage unit 14 (S23), and a process of displaying the corrected measured value (estimated value) Wt ′ (S24). ) Are sequentially and repeatedly executed.

  The ratio R is also the ratio of a specific gravitational acceleration to the gravitational acceleration of the current location. Therefore, by multiplying the measured value Wt of the measured object weight under the gravitational acceleration of the current location by the ratio R, the measured value Wt ′ of the measured object weight under the specific gravity acceleration can be calculated. However, the measured value Wt ′ becomes a value other than zero only when the object to be measured is placed on the table 1.

  When the object to be measured is not placed on the table 1, the measured value Ws acquired in step S21 is the total when the table 1 on which the object to be measured is not placed is supported by the four load cells 11. It is a measured value of load. This coincides with the measured value W0 indicated by the table load data 143. Therefore, the measured value Wt = Ws−W0 calculated in step S22 is zero. Since nothing is multiplied by zero, the measured value Wt ′ = Wt × R calculated in step S23 becomes zero, and this zero is displayed on the display unit 15 in step S24.

  On the other hand, when the object to be measured is placed on the table 1, the measured value Ws acquired in step S <b> 21 is obtained when the table 1 on which the object to be measured is placed is supported by the four load cells 11. It is a measured value of the total load. On the other hand, the measured value W0 indicated by the table load data 143 is a measured value of the total load when the table 1 on which the object to be measured is not placed is supported by the four load cells 11. Therefore, the measured value Wt = Ws−W0 calculated in step S22 is a measured value of the weight of the object to be measured under the gravitational acceleration of the current location. That is, steps S21 and S22 correspond to a second weight measuring step for measuring the weight of the object to be measured, and the four load cells 11, the load measuring circuit 12, and the CPU 13 perform the second measurement for measuring the weight of the object to be measured. It functions as a part.

  In the subsequent step S23, the measured value Wt ′ of the weight of the object to be measured under a specific gravity acceleration is calculated by multiplying the measured value Wt and the ratio R. That is, step S23 corresponds to a correction step for correcting the measured value of the weight of the object to be measured based on the ratio, and the CPU 13 and the storage unit 14 correct the measured value of the weight of the object to be measured based on the ratio R. Functions as a correction unit. In this correction, the CPU 13 calculates the corrected measurement value Wt ′ using the measurement value Wt and the ratio R. The formula used for this calculation is Wt ′ = Wt × R. In step S24, the measured value Wt ′ is displayed on the display unit 15.

  As described above, according to the scale 10, the weight of the table 1 on which the object to be measured is placed is measured in a certain area, and the weight W ′ of the table 1 under a specific gravitational acceleration with respect to the measured value W. The ratio R is calculated, and based on this ratio R, the measured value Wt of the weight of the measured object obtained in this region is corrected, thereby measuring the weight of the measured object under a specific gravitational acceleration. The value Wt ′ can be calculated. That is, the scale 10 can estimate and display the measured value Wt ′ of the weight of the object to be measured under a specific gravity acceleration even under a gravity acceleration different from the specific gravity acceleration. Therefore, the scale 10 has an advantage that the measured value (estimated value) does not vary between regions due to the difference in gravitational acceleration.

  Further, according to the scale 10, since the ratio R according to the gravitational acceleration of the area can be calculated by measuring the weight of the table 1 in an arbitrary area, the measurement value Wt of the measured object weight is corrected. It is not necessary to store the data used for each region (gravity acceleration). Therefore, according to the scale 10, the measured value Wt of the weight of the object to be measured can be corrected with sufficiently high accuracy in an arbitrary region while suppressing the storage capacity required for the storage unit 14.

  Further, according to the scale 10, the first measurement unit that measures the weight of the table 1 holds the measured value Wa of the total load when the table 10 is lifted by holding the table 1, and the object to be measured is placed. Based on the measured value Wb of the total load when the non-supported table 1 is supported by the four load cells 11, the measured value W = Wb−Wa of the weight of the table 1 is calculated, and the weight of the object to be measured is calculated The second measuring unit to be measured includes the measured value W0 of the total load when the table 1 on which the object to be measured is not placed is supported by the four load cells 11, and the table on which the object to be measured is placed. Since the measured value Wt = Ws−W0 of the weight of the object to be measured is calculated based on the measured value Ws of the total load when 1 is supported by the four load cells 11, even if Wa = 0, The weight of the table 1 and the weight of the object to be measured can be accurately measured. This contributes to an improvement in the accuracy of correcting the measured value Wt of the weight of the object to be measured.

It should be noted that the present invention can include not only the above-described embodiment but also various forms obtained by applying the following modifications to the above-described embodiment, and any combination of these forms.
In the embodiment described above, the measurement value Wa is calculated by subtracting the measurement value Wa from the measurement value Wb. However, when the measurement value Wa is zero, the measurement value Wb is set as the measurement value W. Also good. That is, W = Wb may be used instead of W = Wb−Wa. In this case, it is not necessary to acquire the measurement value Wa.

In the embodiment described above, the CPU 13 as the first measurement unit calculates the measurement value of the load measurement circuit 12 when the operation state of the operation switch 17 is the first operation state (the number of operations in the setting process is one). The measured value Wa is based on the signals output from the four load cells 11 when the scale 10 is lifted by grasping the platform 1, and the operation state of the operation switch 17 is the second operation state (the number of operations in the setting process is 2). The measured value of the load measuring circuit 12 in the state of the rotation) is based on the signal output from each load cell 11 when the table 1 on which the object to be measured is not placed is supported by the four load cells 11 The measured value Wb.
By transforming this, the measured value of the load measuring circuit 12 when the number of operations in the setting process is one time is measured when the table 1 on which the object to be measured is not placed is supported by the four load cells 11. The measurement value Wb based on the signal output from the load cell 11 is used, and four measurement values of the load measurement circuit 12 when the number of operations in the setting process is two are held when the scale 10 is lifted by holding the table 1. The measured value Wa based on the signal output from the load cell 11 may be used. That is, step S13 and step S15 in FIG. 5 may be interchanged. In this embodiment, a state where the number of operations in the setting process is two corresponds to the “first operation state”, and a state where the number of operations in the setting process is one corresponds to the “second operation state”.
Further, for example, in the flowchart of FIG. 5, steps S12 and S14 are deleted, and step S11 is a step of causing the display unit 15 to display a character string “Please grab the platform and lift the scale” for a predetermined time. In addition, a step of displaying the character string “Place the scale on the floor” on the display unit 15 for a predetermined time may be inserted between steps S13 and S15.
That is, the CPU 13 as the first measurement unit is a load measurement circuit when the display state of the display unit 15 is in the first display state (when the display of the character string “grab the platform and lift the scale” ends). The measurement value 12 is the measurement value Wa based on the signals output from the four load cells 11 when the scale 10 is lifted while holding the platform 1, and the display state of the display unit 15 is the second display state (“ When the display of the character string “Place the scale on the floor” is completed), the table 1 on which the object to be measured is not placed is supported by the four load cells 11. The measured value Wb based on the signal output from each load cell 11 may be used.
In this case, since it is not necessary to operate the operation switch 17 in the setting process, the operation switch 17 can be deleted from the scale 10. That is, the configuration of the scale 10 can be simplified. On the other hand, in the above-described embodiment, since the measurement in the setting process proceeds based on the operation state of the operation switch 17, it is possible to eliminate a wasteful waiting time.
In addition, also about this form, the deformation | transformation which replaces step S13 and step S15 is possible. However, in this embodiment, step S11 is, for example, a step of displaying a character string “Place a scale on the floor” on the display unit 15 for a predetermined time, and inserting between steps S13 and S15. Is a step of displaying a character string “Please grab the platform and lift the scale” on the display unit 15 for a predetermined time. Even in this form, the end of the display of the character string “Please grab the platform and lift the scale” corresponds to the “first display state”, and the character string “Place the scale on the floor.” The end of the display corresponds to the “second display state”.

  In the above-described embodiment, the ratio R between the weight measurement value W of the table 1 and the weight W ′ of the table 1 under a specific gravity acceleration is as follows. Although the ratio of the weight W ′ of the table 1 is adopted, the ratio of the measured value W of the weight of the table 1 to the weight W ′ of the table 1 under a specific gravitational acceleration may be adopted. In this case, since R = W / W ′, the equation for calculating the corrected measured value Wt ′ is Wt ′ = Wt / R.

  In the embodiment described above, the base 1 is supported by the four load cells 11. However, the base 1 may be supported by the three or less load cells 11, or the base 1 may be supported by the five or more load cells 11. It is good also as a structure to support. In a configuration in which the table 1 is supported by one load cell 11, the load applied to the load cell 11 is the total load described above. Moreover, you may employ | adopt load converters other than a load cell.

1 unit 2 legs 10 scale 11 load cell 12 load measurement circuit 13 CPU
14 Storage unit 15 Display unit 16 Setting switch 17 Operation switch

Claims (5)

A table on which the object to be measured is placed;
A first measuring unit for measuring the weight of the table;
A ratio calculation unit for calculating a ratio between the measured value of the weight of the table and the weight of the table under a specific gravitational acceleration;
A second measuring unit for measuring the weight of the object to be measured;
And a correction unit that corrects a measured value of the weight of the object to be measured based on the ratio. A load converter that converts a load into a signal and outputs the signal;
A load measuring circuit for measuring a load applied to the load converter based on a signal output from the load converter;
The first measurement unit includes a measurement value of the load measurement circuit based on a signal output from the load converter when no load is applied to the load converter, and the object to be measured is placed on the table. And based on the measured value of the load measuring circuit based on the signal output from the load converter when a load is applied to the load converter, the measured value of the weight of the table is calculated,
The second measuring unit includes a load measuring circuit that is based on a signal output from the load converter when the object to be measured is not placed on the table and a load is applied to the load converter. The measured value and the measured value of the load measuring circuit based on the signal output from the load transducer when the object to be measured is placed on the table and a load is applied to the load transducer. Based on the measured value of the weight of the object to be measured,
The balance according to claim 1. It has an operation unit operated by the user,
The first measurement unit outputs the measurement value of the load measurement circuit when the operation state of the operation unit is in the first operation state, from the load converter when no load is applied to the load converter. The measurement value of the load measurement circuit based on the signal, the measurement value of the load measurement circuit when the operation state of the operation unit is the second operation state, the object to be measured is not placed on the table, When the load is applied to the load transducer, the load measurement circuit based on the signal output from the load transducer,
The balance according to claim 2. A display unit for displaying information;
The first measurement unit outputs the measurement value of the load measurement circuit when the display state of the display unit is in the first display state from the load converter when no load is applied to the load converter. The measurement value of the load measurement circuit based on the signal, the measurement value of the load measurement circuit when the display state of the operation unit is in the second display state, the object to be measured is not placed on the table, When the load is applied to the load transducer, the load measurement circuit based on the signal output from the load transducer,
The balance according to claim 2. A first weight measuring step for measuring the weight of a table on which the object to be measured is placed;
A ratio calculating step for calculating a ratio between the measured value of the weight of the table and the weight of the table under a specific gravitational acceleration;
A second weight measuring step for measuring the weight of the object to be measured;
And a correction step of correcting a measured value of the weight of the object to be measured based on the ratio.

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