Moisture meter

Abstract

To provide a heating and drying moisture meter that shows reliability for measurement results.SOLUTION: In order to solve the above problem, a moisture meter (100) is provided with: a mass sensor (2) for measuring the mass of a sample (11) placed on a weighing pan (1); a heating chamber (C) in which the weighing pan (1) is disposed; a heating unit (3) for heating the heating chamber (C); and a computation control unit (5) for controlling the heating unit (3) and calculating the moisture percentage of the sample from the sample mass (W) before heating and drying and the sample mass (D) after heating and drying. The computation control unit (5) shows the reliability of the moisture percentage on the basis of the minimum display of the mass sensor (2).SELECTED DRAWING: Figure 1

Description

Technical Field

[0002] , ,

[0001] The present invention relates to a moisture meter, and more particularly to a heat drying type moisture meter.

Background Art

[0002] As one of the devices for measuring the moisture content of a sample, a heat drying type moisture meter is known. The heat drying type moisture meter is a device that evaporates the moisture in a sample by heating the sample and measures the moisture content of the sample from the change (decrease) in the mass of the sample before and after heating. The moisture content MC [%] is obtained by Equation (3).

[0003] MC = (W - D) / W × 100 ···(3) However, W: Mass of the sample before drying, D: Mass of the sample after drying

[0004] As a method for examining the performance of a heat drying type moisture meter, a method using a standard substance whose ideal moisture content and change process are known in advance is known. For example, in the moisture meter of Patent Document 1, sodium tartrate dihydrate is used as the standard substance, the standard substance is actually heated, the measured moisture content and the measured heating time are measured, and these are compared with the ideal moisture content and the ideal heating time to automatically examine whether the moisture meter is functioning normally.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] While heat-drying type moisture meters can measure samples with low moisture content, such as resins, depending on the measurement conditions, the difference in mass before and after heating (moisture content) may be small compared to the minimum value (minimum display) at which the mass sensor can display weight. This can lead to measurement errors and inaccurate measurements.

[0007] For example, let's explain using the case where 2g of a sample with a moisture content of 0.05% is measured using a moisture meter with a minimum display of 0.001g. In the ideal case of this measurement, W (mass of sample before drying) = 2.000 g D (mass of sample after drying) = 1.999 g WD = 2.000g - 1.999g = 0.001g From equation (3), the moisture content is measured to be MC = 0.05 [%].

[0008] However, mass sensors are inevitably affected by the operating environment, such as vibration, wind, and sensor drift due to prolonged measurement, which can result in an error of up to 1 count (1 dig = 0.001 g) in the minimum display of the mass sensor. Therefore, as in the example above, when the difference between W and D is small, W (mass of sample before drying) = 2.000 g D (mass of sample after drying) = 1.999 g - (error 0.001 g) WD = 2.000g - 1.998g = 0.002g From equation (3), the moisture content is sometimes measured as MC = 0.10 [%]. This means that the moisture content measurement result will be off by as much as 0.05% per minimum display count (1 dig).

[0009] This problem can be solved by increasing the amount of sample being heated. For example, if you increase the W (sample mass before drying) of the sample in the above example from 2g to 10g, Ideal case W (mass of sample before drying) = 10,000 g D (mass of sample after drying) = 9.995 g WD = 0.005g MC = 0.05 [%] Cases including errors W (sample mass before drying) = 10,000 g D (mass of sample after drying) = 9.995g - (error 0.001g) WD = 0.006g MC = 0.06 [%] In this way, by increasing the sample size, the impact of error can be reduced to 0.01% per minimum display count (1 dig).

[0010] However, the fact that the moisture content measurement results in a heat-drying type moisture meter vary depending on the accuracy (minimum display) of the mass sensor is not generally well known. Therefore, even if a user suspects a measurement is inaccurate, it has been difficult for them to ascertain its reliability.

[0011] This invention was made to solve the aforementioned problems and aims to provide a heat-drying type moisture meter that presents the reliability of the measurement results. [Means for solving the problem]

[0012] To solve the above problems, a moisture meter according to one embodiment of the present invention comprises a mass sensor for measuring the mass of a sample placed on a weighing pan, a heating chamber in which the weighing pan is arranged, a heating unit for heating the heating chamber, and a calculation control unit for controlling the heating unit to calculate the moisture content of the sample from the sample mass W before heating and drying and the sample mass D after heating and drying, wherein the calculation control unit presents the reliability of the moisture content based on the minimum display of the mass sensor.

[0013] In the above embodiment, the calculation control unit can access a storage unit equipped with a reliability determination table that is divided into multiple regions in steps using thresholds created as multiples of the minimum display, and it is also preferable to apply the difference WD between the sample mass before heating and drying and the sample mass after heating and drying to the region, and indicate that the smaller the numerical value of the applied region, the lower the reliability.

[0014] In the above aspect, it is also preferable that the arithmetic control unit calculates the accuracy using an environmental coefficient determined according to the usage environment of the moisture meter, and presents the calculated accuracy as the reliability.

[0015] In the above aspect, it is also preferable that the arithmetic control unit receives an input of a numerical value of required accuracy for the moisture content rate using an environmental coefficient determined according to the usage environment of the moisture meter, calculates a recommended sample amount using Equation (2), and presents the recommended sample amount.

Effect of the Invention

[0016] According to the present invention, it is possible to provide a heat drying type moisture meter that presents the reliability with respect to the measurement result.

Brief Description of the Drawings

[0017] [Figure 1] It is a block diagram showing the configuration of a moisture meter according to the first embodiment of the present invention. [Figure 2] It is a perspective view showing a state where the lid of the heating chamber is opened in the same moisture meter. [Figure 3] It is a configuration example of a reliability determination table for the same moisture meter. [Figure 4] It is a block diagram showing the configuration of a moisture meter according to the second embodiment of the present invention. [Figure 5] It is a numerical example of the accuracy calculated according to the environmental coefficient in the same moisture meter. [Figure 6] It is a block diagram showing the configuration of a moisture meter according to the third embodiment of the present invention.

Modes for Carrying Out the Invention

[0018] Next, preferred embodiments of the present invention will be described based on the drawings. In this specification, unless otherwise specified, the moisture meter refers to a heat drying type moisture meter.

[0019] 1. First Embodiment Figure 1 is a block diagram showing the configuration of the moisture meter 100 according to the first embodiment, and Figure 2 is a perspective view showing the moisture meter 100 with the lid 9 of the heating chamber C open. As shown in Figure 1, the moisture meter 100 includes a weighing pan 1, a mass sensor 2, a heating unit 3, a calculation control unit 5, an input unit 6, a display unit 7, and a storage unit 8.

[0020] The mass sensor 2 is an electromagnetic balance type, strain gauge type, or capacitive type electronic sensor. The mass sensor 2 is housed inside the moisture meter body 10 (Figure 2) and connected to the weighing pan 1, and measures the mass of the sample 11 placed on the weighing pan 1.

[0021] The weighing pan 1 is located inside a heating chamber C, which is sealed by closing the hinged lid 9 (Figure 2). The weighing pan 1 has a handle and is configured to be detachable from the mass sensor 2. The heating chamber C is configured as a space defined by the upper part of the moisture meter body 10 and the lid 9, and houses the weighing pan 1.

[0022] The heating unit 3 includes a heating means 3a (Figure 2), such as a halogen lamp or a Joule-heating resistance wire, and a temperature sensor (not shown). The heating means 3a is controlled by the calculation control unit 5 based on the output from the temperature sensor to heat the heating chamber C (sample 11). The heating means 3a is housed inside the lid 9 of the heating chamber C. The lid 9 includes a container-shaped glass cover 9a (Figure 2) that covers the weighing dish 1 to prevent contact between the sample 11 and the heating means 3a.

[0023] The input unit 6 consists of buttons such as a measurement start button and a measurement stop button, and can issue instructions to the calculation control unit 5 to start and stop measurement.

[0024] The display unit 7 is a liquid crystal display and displays measurement results, etc. The input unit 6 and the display unit 7 may be integrated as a touch panel display.

[0025] The arithmetic control unit 5 is represented by a microcomputer that implements a CPU (Central Processing Unit) for arithmetic processing and ROM (Read-Only Memory) and RAM (Random Access Memory) as auxiliary storage units on an integrated circuit.

[0026] The calculation control unit 5 includes a mass measurement unit 51, a moisture content measurement unit 52, and a reliability determination unit 53. These functional units 51 to 53 are composed of electronic circuits such as a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), and a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array).

[0027] When the mass measuring unit 51 receives a notification to start measurement, it measures the mass (W) of the sample 11 before heating and drying, then heats the heating unit 3, and when the change in the mass of the sample 11 falls below a predetermined threshold, it terminates heating and measures the mass (D) of the sample 11 after heating and drying. The sample mass W before drying and the sample mass D after drying are stored in the storage unit 8, respectively.

[0028] The moisture content measuring unit 52 calculates the moisture content MC[%] of the sample 11 from equation (3) and displays the measurement result on the display unit 7.

[0029] The reliability determination unit 53 uses the reliability determination table 81, described later, to determine the reliability of the moisture content MC calculated by the moisture content measurement unit 52, and presents it to the user. The details of this will be described later.

[0030] The storage unit 8 is embodied, for example, by a non-volatile semiconductor memory such as flash memory. The storage unit 8 stores various programs for processing performed by the arithmetic control unit 5. The storage unit 8 stores a reliability determination table 81 (described later) for which the reliability determination unit 53 determines the reliability. However, the storage location of the reliability determination table 81 is not limited to the storage unit 8. The reliability determination table 81 may be stored in the storage unit of hardware such as a data logger attached to the moisture meter 100, or it may be stored in the management computer or management server of the moisture meter 100 and configured so that the moisture meter 100 can acquire it by communication.

[0031] The confidence level determination table 81 is divided into multiple regions in stages based on threshold values ​​(numerical values), with one confidence level assigned to each region. The confidence level is structured so that the smaller the numerical value of the region, the lower the confidence level.

[0032] The threshold values ​​that constitute the region are preferably set based on the "minimum display" of the mass sensor 2. The minimum display is the smallest value that the mass sensor 2 can display, and is the smallest unit of the numerical value displayed on the display unit 7. The minimum display uses a unit of 1 digit (1 dig), expressed as 1 dig = 0.001 g, etc. The minimum display of the mass sensor 2 is determined in advance according to the type of sensor and stored in the memory unit 8.

[0033] An example of the configuration of the confidence level determination table 81 is described below. For example, the threshold for the confidence level determination table 81 is set in units of mass [g], [mg], or [μg]. If the minimum display of the mass sensor 2 is 1 dig = 1 mg, then for example, three regions can be divided and set as follows: if it is 5 mg or less, the confidence level is C (low); if it is between 5 mg and 20 mg, the confidence level is B (average); if it is greater than 20 mg, the confidence level is A (good), and so on.

[0034] More preferably, the threshold for the reliability determination table 81 is set in units [dig] by a multiple of the minimum display of the mass sensor 2. Figure 3 shows an example of the configuration of the reliability determination table 81 for the moisture meter 100 when set in units [dig]. In Figure 3, three regions are divided, and the reliability is set as C (low) when it is 5 dig or less, B (average) when it is greater than 5 dig and 20 dig or less, and A (good) when it is greater than 20 dig. Using the reliability determination table 81 in Figure 3, for example, if the minimum display of the mass sensor 2 is 1 dig = 0.1 mg, then it is C when it is 0.5 mg or less, B when it is greater than 0.5 mg and 2 mg or less, and A when it is greater than 2 mg. If the minimum display of the mass sensor 2 is 1 dig = 1 mg, then it is C when it is 5 mg or less, B when it is greater than 5 mg and 20 mg or less, and A when it is greater than 20 mg. In this way, if the threshold of the reliability determination table 81 is set to a multiple of the minimum display of the mass sensor, the reliability evaluation criteria can be configured to change according to the accuracy of the mass sensor.

[0035] The above is just one example of how to configure the confidence level determination table 81. The number of regions is not limited to three; more regions may be used, and a configuration divided into two regions is also included in this form.

[0036] The reliability determination unit 53 determines the reliability by applying the difference WD between the sample mass W before heating and drying and the sample mass D after heating and drying to the region of the reliability determination table 81. For example, if the minimum display of the mass sensor 2 is 1 dig = 0.1 mg and the reliability determination table 81 in Figure 3 is used, the reliability determination unit 53 determines that when the difference WD is 10 mg, the difference WD = 10 mg falls in the region between 5 mg and 20 mg, so the reliability is determined to be B (normal). The reliability determination unit 53 displays the determined reliability along with the moisture content MC on the display unit 7 as an evaluation of the measurement result and presents it to the user.

[0037] Note that the above is an example explained using the example in Figure 3. The reliability determination unit 53 may present the reliability using "○", "△", "×", "Good", "Poor", or messages such as "Sufficiently reliable", "Reliable", or "Not reliable. Please review the measurement conditions" instead of "A", "B", or "C". Furthermore, the display of reliability is not limited to the display unit 7, but may also be configured to output to a data logger, management computer, or management server (none of which are shown) connected to the moisture meter 100 by wire or wireless.

[0038] In summary, this embodiment of the moisture meter 100 can provide an indication of the reliability of the measurement results (moisture content). Specifically, the moisture meter 100 determines that the reliability of the measurement results is low when the mass change of the sample 11 is small relative to the accuracy (minimum display) of the mass sensor 2. This allows the user to understand the reliability of the measurement results (moisture content).

[0039] 2. Second Embodiment Figure 4 is a block diagram showing the configuration of the moisture meter 100 according to the second embodiment. In the second embodiment, the calculation control unit 5 further includes an accuracy calculation unit 54. Other components are denoted by the same reference numerals, and the description in the first embodiment is referenced, with redundant explanations omitted.

[0040] The accuracy calculation unit 54 is composed of electronic circuits such as a CPU, ASIC, FPGA, and other PLDs, similar to the first embodiment. The accuracy calculation unit 54 calculates the accuracy (error) of the moisture content MC using the minimum display of the mass sensor 2 and an environmental coefficient determined according to the operating environment of the moisture meter 100.

[0041] The environmental coefficient is a natural number (unitless), and a smaller number indicates a better operating environment. An operating environment is considered good if there is no vibration or wind and the measurement can be completed in a short time, and a poor environment if it is susceptible to vibration and wind and requires a long measurement time.

[0042] Specifically, the environmental coefficient is determined, for example, as follows: Before measurement, the accuracy calculation unit 54 asks the user questions about the operating environment of the moisture meter 100, for example, via the display unit 7 and the input unit 6. The questions are, for example, "Are you using a vibration isolation table?", "Is the measurement platform close to a line of people's movement?", "Is there airflow on the moisture meter?", "Is the temperature of the air conditioner in the measurement room constant?", and "Is the measurement time 30 minutes or more?", and the user answers with "yes" or "no". The accuracy calculation unit 54 scores the answers to these questions and determines the environmental coefficient. The scoring can be calculated by adding 1 point for each "yes" answer to a question, and the total score becomes the environmental coefficient, or weighting may be applied depending on the question. Alternatively, the environmental coefficient can be automatically determined by the accuracy calculation unit 54 based on the values ​​of the vibration sensor, human presence sensor, and timer equipped in the moisture meter 100.

[0043] Once the environmental coefficient for the moisture meter 100 is determined, the accuracy calculation unit 54 calculates the accuracy of the moisture content MC (measurement result) using equation (1).

[0044] PE = ± A × B / W × 100 ... (1) however, PE: Accuracy (unit [%]) A: Environmental coefficient B: Minimum display (units should match Wr) W: Sample mass before heating and drying (units: [g], [mg], or [μg]) That is the case.

[0045] The accuracy calculation unit 54 displays the calculated accuracy PE, along with the moisture content MC, as an error component of the measurement result on the display unit 7. Similar to the first embodiment, the accuracy PE may be configured to be output to a data logger, a management computer, or a management server.

[0046] Figure 5 shows an example of the accuracy value calculated according to the environmental coefficient. From Figure 5, it can be seen that the accuracy [%] can be determined to increase as the sample mass W before heating and drying decreases and the environmental coefficient increases. Based on the results in Figure 5, it is preferable to determine the environmental coefficient to be allocated between 2 and 5, as this is in line with reality.

[0047] As described above, with this form of moisture meter 100, the accuracy (error [%]) of the measurement result (moisture content) is presented as a reliability level, taking into account the operating environment of the moisture meter 100. In this case, the moisture meter 100 also takes into account the accuracy (minimum display) of the mass sensor 2 (equation (1)), so it can present a more reliable accuracy level. The user can know the accuracy of the measurement result (moisture content) in detail, so they can roughly determine whether remeasurement is necessary, or how much the sample amount should be adjusted in remeasurement, depending on the required accuracy of the test content.

[0048] Furthermore, it is also preferable to combine the second embodiment with the first embodiment so that both the reliability determined by the reliability determination unit 53 and the accuracy calculated by the accuracy calculation unit 54 are presented for the moisture content MC.

[0049] 3. Third Embodiment Figure 6 is a block diagram showing the configuration of the moisture meter 100 according to the third embodiment. In the third embodiment, the calculation control unit 5 further includes a sample volume calculation unit 55. Other components are denoted by the same reference numerals, and descriptions from the first and second embodiments are referenced, with redundant explanations omitted.

[0050] The sample quantity calculation unit 55 is similarly composed of electronic circuits such as a CPU, ASIC, FPGA, or other PLD. The sample quantity calculation unit 55 receives a numerical value of the required accuracy for the moisture content MC from the user via the input unit 6 and calculates the recommended sample quantity (Wr) for the required accuracy.

[0051] The sample volume calculation unit 55 calculates the recommended sample volume Wr ​​using equation (2). Wr = A × B / AC × 100 ... (2) however, Wr: Recommended sample volume (units [g], [mg], or [μg]) A: Environmental coefficient B: Minimum display (units should match Wr) AC: Required precision (unit [%]) The environmental coefficient A is obtained by the accuracy calculation unit 54. The required accuracy AC is input by the user as "±0.1%", etc. The sample volume calculation unit 55 calculates the recommended sample volume Wr ​​from equation (2) and displays it on the display unit 7.

[0052] In summary, with this embodiment of the moisture meter 100, the user inputs the required accuracy into the moisture meter 100, and the recommended sample volume is specifically indicated. Generally, it is difficult for users to determine whether the sample volume is appropriate for the measurement results. This embodiment of the moisture meter 100 is convenient because it specifically indicates how much the sample volume should be increased.

[0053] Furthermore, the third embodiment may be presented together with the measurement result (moisture content) from the moisture content measurement unit 52, or it may be combined with the first embodiment and presented together with the reliability from the reliability determination unit 53. In addition, it may be combined with the second embodiment and presented together with the accuracy from the accuracy calculation unit 54.

[0054] Although preferred embodiments and modifications of the moisture meter of the present invention have been described above, these are merely examples of the present invention, and each form and each variation can be combined based on the knowledge of those skilled in the art, and such forms are also included within the scope of the present invention.

[0055] Furthermore, although this specification shows a heat-drying type moisture meter as a moisture meter, the present invention can also be applied to other types of moisture meters that are equipped with a mass sensor and calculate the moisture content by reading the change (decrease) in the mass of the sample before and after heating. [Explanation of Symbols]

[0056] 100 moisture meter C heating chamber 1 weighing dish 2 Mass Sensor 3 Heating section 5. Arithmetic Control Unit 51 Mass measurement section 52 Moisture content measuring section 53. Confidence Determination Unit 54 Accuracy Calculation Unit 55 Sample volume calculation unit 8 Memory section 81 Table for determining confidence level 11 samples

Claims

1. A mass sensor that measures the mass of a sample placed on a weighing dish, A heating chamber in which the weighing pan is placed inside, A heating unit for heating the aforementioned heating chamber, The system includes a calculation control unit that controls the heating unit and calculates the moisture content of the sample from the sample mass W before heating and drying and the sample mass D after heating and drying. The calculation control unit, Based on the minimum display of the mass sensor, the reliability of the moisture content is presented. The arithmetic control unit has access to a storage unit equipped with a reliability determination table that is divided into multiple regions in steps using thresholds created as multiples of the minimum display, A moisture meter characterized by applying the difference W-D between the sample mass before heating and drying and the sample mass after heating and drying to the given region, and indicating that the smaller the value in the applied region, the lower the reliability.

2. The moisture meter according to claim 1, characterized in that the calculation control unit calculates the accuracy using formula (1) with respect to an environmental coefficient determined according to the operating environment of the moisture meter, and presents the accuracy as the reliability. PE= ± A×B / W×100...(1) however, PE: Accuracy A: Environmental coefficient B: Minimum display W: Sample mass before heating and drying

3. The moisture meter according to claim 1 or 2, characterized in that the calculation control unit receives a numerical value with the required accuracy for the moisture content using an environmental coefficient determined according to the operating environment of the moisture meter, calculates a recommended sample amount using formula (2), and presents the recommended sample amount. Wr=A×B / AC×100...(2) however, Wr: Recommended sample volume A: Environmental coefficient B: Minimum display AC: Required accuracy

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