JP2002303572A - Moisture meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measuring accuracy in comparison to a conventional moisture meter, particularly a heat drying type moisture meter. SOLUTION: In the moisture meter, an inner case 25 comprising plate materials with low thermal conductivity enclosing a mass sensor 5 is adopted, a space between a top plate of the inner case 25 and a measuring tray 11 is provided as a heat insulating structure holding an air layer in between, air of the air layer is evacuated to the outside of the moisture meter, and a mass sensor output is processed by an individual signal processing circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture meter, and more particularly, to a heat-drying moisture meter. The present invention employs an inner case in which a mass sensor is surrounded by a plate material having a low thermal conductivity, and a heat insulating structure in which an air layer is interposed between a top plate and a weighing pan of the inner case. By exhausting the air of the layer out of the device and by processing the output of the mass sensor by a separate signal processing circuit,
Measurement accuracy can be improved as compared with the related art.

[0002]

2. Description of the Related Art Conventionally, in a heat-drying type moisture meter,
The water content of a sample is detected by measuring the change in mass by evaporating water by heating.
In such a moisture meter, by improving the measurement accuracy of mass, a desired measurement accuracy can be secured with a small amount of sample, and loss of a valuable sample can be reduced. In addition, the amount of waste generated by the measurement can be reduced, and the time required for the measurement can be reduced by reducing the sample amount of the sample.

For this reason, in this type of moisture meter, the mass of the sample is measured by an electromagnetic balance with high resolution, and the measurement result of the mass is not changed by heating or the like, thereby improving the accuracy of the mass measurement. It has been made to be.

FIG. 3 is a sectional view showing a moisture meter of this type viewed from the side. The moisture meter 1 includes a moisture meter main body 2 and a cover 3. Here, the moisture meter main body 2 is configured by housing a mass sensor 5, an analog signal processing circuit 6, a wiring board 7 including a digital signal processing circuit, an operation display unit 8, a power supply circuit unit 9, and the like in a predetermined case 4. .

[0005] Here, the mass sensor 5 is a sensor constituting an electromagnetic balance type balance, is connected to a weighing dish 11 via a predetermined connecting member 10, and a signal level changes according to a load by the connecting member 10. A load detection signal is output. Thus, in the moisture meter 1, the sample is arranged on the weighing dish 11, so that the mass sensor 5 generates a load detection signal based on an analog signal whose signal level changes according to the mass of the sample. It has been done. The analog signal processing circuit 6 performs an analog-to-digital conversion process on the load detection signal to generate load detection data. The digital signal processing circuit arranged on the wiring board 7 digitally processes the load detection data in response to the operation on the operation display unit 8 to detect the mass of the sample, and transmits the detection result to the operation display unit 8. indicate.
Further, a change in mass of the sample due to the heating of the heating source 13 described later is detected, and a moisture content is calculated from the detection result and displayed on the operation display unit 8. The power supply circuit section 9 generates power necessary for the operation of each section of the moisture meter 1 and supplies it to each section.

[0006] The cover 3 is configured to cover the weighing dish 11, and a heating source 13 such as a heater is disposed above the weighing dish 11. With such a configuration, the moisture meter 1 evaporates the moisture of the sample placed on the weighing dish 11 by heating by the heating source 13, and measures the change in the mass of the sample with the mass sensor 5 to reduce the moisture content of the sample. It has been made to detect.

In such a moisture meter 1, a case 4
By disposing the heat insulating member 14 between the weighing pan 11 and the mass sensor 5, and further by arranging the heat insulating member 15 between the case 4 and the weighing pan 11, In order to reduce the conduction, a heat insulating structure is provided between the mass sensor 5 and the weighing dish 11, so that the fluctuation of the measurement result due to the heating is also reduced.

[0008]

By the way, in a moisture meter, if the measurement accuracy can be further improved, it is considered that the measurement result can be obtained in a shorter time with a much smaller sample amount. In this case, weighing pan 1
It is considered that by further increasing the number of heat insulating structures between the mass sensor 5 and the mass sensor 5, the heat conduction from the weighing dish 11 to the mass sensor 5 can be further reduced, and the measurement accuracy can be improved.

However, if the heat insulating structure between the weighing dish 11 and the mass sensor 5 is further multi-layered as described above, there is a problem that the size of the entire configuration cannot be avoided.

Although the heat conduction from the weighing dish 11 to the mass sensor 5 can be reduced by the multi-layered heat insulation structure, the heat conduction to the mass sensor 5 cannot be completely prevented. In addition, due to such a multi-layered heat insulation structure, the heat radiation efficiency on the moisture meter main body 2 side tends to be rather lowered. Further, in the moisture meter 1, heat generating units such as an analog signal processing circuit 6 and a power supply circuit unit 9 are arranged on the moisture meter main body 2 side.

Even if the heat insulating structure is formed in multiple layers, the mass sensor 5 is sufficiently heated by the heat conduction from the weighing pan 11 to the mass sensor 5 and further by the heat generated by the power supply circuit 9 disposed on the moisture meter main body 2 side. 5 can not prevent the temperature change,
Accordingly, there has been a problem that the measurement accuracy cannot be sufficiently improved.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a moisture meter capable of effectively avoiding an increase in the overall shape and improving the measurement accuracy as compared with the prior art. Things.

[0013]

According to the first aspect of the present invention, there is provided a weighing dish on which a sample is placed, a heating source for heating the sample, and a weighing dish provided on the weighing dish. A mass sensor that outputs a load detection signal based on an analog signal whose signal level changes according to the mass. The load detection signal is processed by analog-to-digital conversion to generate load detection data, and the load detection data is processed by data processing. The present invention is applied to a moisture meter having a digital signal processing circuit for calculating a moisture content of a sample, and an inner case surrounding a mass sensor by a plate material having low thermal conductivity, a top plate of the inner case, and a weighing pan. And an exhaust mechanism for exhausting the air in the air layer to the outside of the apparatus.

According to a second aspect of the present invention, a weighing dish on which a sample is placed, a heating source for heating the sample, and an analog signal whose signal level changes in accordance with the mass of the sample placed on the weighing dish Mass sensor that outputs a load detection signal according to the above, and digital signal processing that calculates the moisture percentage of the sample by generating load detection data by converting this load detection signal from analog to digital, and processing this load detection data. When applied to a moisture meter having a circuit, the weighing dish, the heating source, and the mass sensor are held separately from the digital signal processing circuit.

[0015] According to the third aspect of the present invention, the second aspect is provided.
In the configuration of the above, an inner case that surrounds the mass sensor with a plate material having a low thermal conductivity, a heat insulating structure that is disposed between a top plate of the inner case, and a weighing pan, that sandwiches an air layer, And an exhaust mechanism for exhausting the air of the layer to the outside of the apparatus.

According to the fourth aspect of the present invention, there is provided the first aspect.
Alternatively, in the configuration of claim 3, the heat insulation structure includes at least an analog signal processing circuit, a digital signal processing circuit,
The top plate of the case that stores the inner case, and the top plate of the case and the top plate of the inner case are arranged between the top plate of the case and the top plate of the inner case. A partitioning heat insulating member (for example, for the purpose of heat radiation).

According to a fifth aspect of the present invention, in the first, third, or fourth aspect of the present invention, the exhaust mechanism includes a case for housing at least an analog signal processing circuit, a digital signal processing circuit, and an inner case. In the above, the exhaust port and the intake port are disposed above and below the case with the inner case interposed therebetween.

According to the structure of the first aspect, the inner case surrounding the mass sensor by a plate material having low thermal conductivity, and the air layer disposed between the top plate of the inner case and the weighing pan are interposed. By providing a heat insulation structure sandwiched between the weighing pan and the exhaust mechanism for exhausting the air in the air layer to the outside of the apparatus, the heat conduction from the weighing dish can be reduced by the inner case and the heat insulation structure.
In this way, even if the heat conduction is reduced, the accumulation of heat due to conduction heat and the accumulation of heat due to internal heat generation can be prevented by the exhaust by the exhaust mechanism. As a result, the adoption of a heat insulating mechanism having a simple configuration can prevent the overall shape from becoming large, and can significantly reduce the temperature change of the mass sensor as compared with the related art, thereby improving the measurement accuracy.

According to the second aspect of the present invention, the weighing dish, the heating source, and the mass sensor are held separately from the digital signal processing circuit, thereby preventing a temperature change of the mass sensor due to internal heat generation of the power supply circuit and the like. can do. As a result, the temperature change of the mass sensor can be reduced as compared with the conventional one simply by adopting the heat insulation structure to respond to the heat of the weighing pan side, and the overall shape is prevented from becoming larger,
In addition, the measurement accuracy can be improved as compared with the related art.

According to a third aspect of the present invention, in the configuration of the second aspect, the inner case surrounding the mass sensor by a plate having low thermal conductivity is disposed between the top plate of the inner case and the weighing pan. Heat insulation from the weighing pan side is reduced by the inner case and the heat insulation structure by providing the heat insulation structure that sandwiches the air layer and the exhaust mechanism that exhausts the air in the air layer to the outside of the device. In this way, even if the heat conduction is reduced, the heat storage of the conducted heat can be prevented by the exhaust by the exhaust mechanism. As a result, the adoption of a heat insulating mechanism having a simple configuration can prevent the overall shape from becoming large, and can significantly reduce the temperature change of the mass sensor as compared with the related art, thereby improving the measurement accuracy.

According to a fourth aspect of the present invention, in the configuration of the first or third aspect, the heat insulating structure is provided with at least an analog signal processing circuit, a digital signal processing circuit, and a top plate of a case for housing the inner case. And a heat insulating member disposed between the top plate of the case and the top plate of the inner case to divide the space between the top plate of the case and the top plate of the inner case into two (for example, for the purpose of heat dissipation). Therefore, a sufficient heat insulating effect can be achieved by a so-called multi-layered heat insulating structure, and heat storage can be sufficiently prevented by exhausting air from the air layer.

According to a fifth aspect of the present invention, there is provided the first aspect of the present invention.
In the configuration according to claim 3 or 4, the exhaust mechanism is provided at least in an upper side and a lower side of the case with the inner case sandwiched between at least the analog signal processing circuit, the digital signal processing circuit, and the case housing the inner case. With the exhaust port and the intake port arranged on the side, heat storage can be prevented by the flow of air that occurs naturally using the chimney effect, and the overall configuration can be simplified accordingly.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings as appropriate.

(1) First Embodiment FIG. 1 is a sectional view showing a moisture meter according to a first embodiment of the present invention as viewed from the side. In the configuration shown in FIG. 1, the same components as those of the moisture meter 1 described above with reference to FIG. 3 are denoted by the corresponding reference numerals, and redundant description will be omitted.

The moisture meter 21 includes a moisture meter body 22 and a cover 23. The moisture meter body 22 includes an electromagnetic balance type mass sensor 5, a wiring board 7, an operation display section 8, and a power supply circuit section 9B. It is arranged and arranged in the case 24.

The case 24 is made of a resin material having a relatively low thermal conductivity by injection molding. Case 2
4 is the depth side from the part where the weighing pan 11 is arranged.
The top plate is formed by a flat surface, and the top plate protrudes toward the cover portion 23 near the side surface on the back side, and is formed so as to be thick at the portion on the back side. The moisture sensor main body 22 has a mass sensor 5 attached to the inner case 25 at a deeper portion where the thickness becomes thicker than substantially below the portion where the weighing dish 11 is arranged.
It is stored and arranged in. The case 24 includes the weighing pan 1
A circular through hole for arranging the connecting member 26 is formed at a position where the first member 1 is arranged. The case 24 is configured such that the top plate functions as a heat insulating member that insulates the weighing dish 11 and the mass sensor 5 by these configurations, and this function reduces the temperature rise of the mass sensor 5 due to heating of the sample. ing.

On the other hand, the inner case 25 is made of a plate material having a low thermal conductivity and has a substantially hexahedral shape.
The mass sensor 5 is completely covered and hermetically closed except that a circular penetration is formed in a portion where the connecting member 26 is disposed. This also makes it difficult for the moisture meter main body 22 to transmit the heat of the weighing dish 11 to the mass sensor 5.

The height of the case 24 is selected so that a space having a predetermined thickness is formed between the inner case 25 and the top plate of the inner case 25. A heat insulating member 27 is arranged. Here, the heat insulating member 27
Are formed so as to substantially cover the top plate of the inner case 25, and to substantially equally divide the space between the top plate of the case 24 and the top plate of the inner case 25 in the thickness direction.
Is formed so that a circular through hole is formed in a portion where the is disposed. The heat insulating member 27 is held by the case 24 via, for example, a cylindrical spacer so that a predetermined gap is formed between the top plate of the case 24 and the top plate of the inner case 25. ing. Thereby, the moisture meter 21 is configured to make it difficult for the heat of the weighing dish 11 to be transmitted to the mass sensor 5 by the heat insulating member 26A.

Thus, the moisture meter 21 is moved to the inner case 25.
Between the top plate and the weighing pan 11 has a first air layer sandwiched between the case 24 and the heat insulating member 27, and a second air layer sandwiched between the heat insulating member 27 and the top plate of the inner case 25. It has an insulating structure so that the heat of the weighing dish 11 is hardly transmitted to the mass sensor 5.

The case 24 is an internal space on the side of the cover section 23 of the heat insulating member 27 arranged in this way, and the power supply circuit section 9B is provided in an internal space on the back side where the thickness is increased on the side of the cover section 23. An opening 29 which is disposed and forms an exhaust port is formed on the inner wall surface. Here, the power supply circuit section 9B
Is a power supply circuit for generating power for driving the moisture meter 21 except for driving the heating source 13, and is a circuit that generates the largest amount of heat among the circuits arranged in the moisture meter main body 2.

The case 24 is, as described above, the inner case 2
On the front side from the part where the 5 is arranged, the bottom plate side is formed so as to gradually decrease in thickness, and is formed so as to gradually decrease in thickness, and the obliquely inclined top plate side is operated. While the display unit 8 is arranged, an analog signal processing circuit 6 and a wiring board 7 of a digital signal processing circuit are arranged between the inner case 25 and the front wall surface. Case 24
Is formed by a shape in which the wall surface on the front side is inclined downward, and an opening 30 forming an air intake port is formed on the wall surface.
Are created.

Thus, in the moisture meter main body 22, each circuit block is arranged so that the internal space on the exhaust port 29 side becomes higher in temperature than the internal space on the intake port 30 side. As a result, the case 24 is moved from the intake port 30 to the case 24.
The outside air flows into the inside of the case 24, and the introduced outside air is discharged from the exhaust port 29, so that an air flow from the intake port 30 to the exhaust port 29 is formed inside the case 24. Furthermore, in the moisture meter main body 22, as compared with the intake port 30 into which the outside air flows,
By arranging the exhaust port 29 for discharging the internal air at a high position, the internal air flow is generated at a sufficient flow velocity by the so-called chimney effect.
In the moisture meter main body 22, the case 2
The inside of the case 4 is exhausted to prevent the temperature rise in the case 24 due to the heat generated by the analog signal processing circuit 6, the digital signal processing circuit, and the power supply circuit section 9B.

At the portion where the inner case 25 is disposed, the moisture meter main body 22 is arranged such that most of the air flow inside the inner case 25 flows on the upper and lower surfaces of the heat insulating member 27, that is, on the inner side and the lower side in the drawing. The inner case 25 is arranged such that the wall surface of the inner case 25 and the wall surface of the case 24 are substantially in close contact with each other, and on the bottom surface side, the bottom surface of the inner case 25 is in close contact with the bottom surface of the case 24. Thus, in the moisture meter main body 22, the heat insulating member 27, the inner surface of the top plate of the case 24 facing the heat insulating member 27, and the surface of the top plate of the inner case 25 are cooled by the airflow that prevents the temperature inside the case 24 from rising. In this way, the heat transmitted from the weighing dish 11 is not stored even after a long use.

In the main body 22 of the moisture meter, a heat insulating member 31 is further disposed between the top plate of the case 24 and the weighing pan 11 so that heat conduction from the weighing pan 11 side to the case 24 side is reduced. It has been done.

In the main body 22 of the moisture meter, the weighing pan 11
Is connected to the mass sensor 5, the heat insulating member 26 </ b> A having a low thermal conductivity is arranged in the middle, whereby the heat conduction of the connecting member 26 also causes the mass sensor 5 to move from the weighing dish 11 side to the mass sensor 5. Is designed to reduce the heat conduction.

On the other hand, in the moisture meter 21, the cover 23 has an inner space divided into two front and rear portions by a heat insulating wall 32 arranged on the back side, and the heating source 13 is driven in the space on the back side. The driving power supply circuit section 9A is disposed.
As a result, in the moisture meter 21, regarding the power source circuit other than the heat source 13 and the heat source having the largest heat value,
A power source for driving the heating source, which accounts for most of the heat generation, is arranged on the cover side, and accordingly, the heat generation on the moisture meter main body 22 side is reduced and the temperature change of the mass sensor 5 is reduced. .

(1-2) Operation of the First Embodiment In the above configuration, when the user sets a sample on the weighing dish 11 and operates the operation display section 8, the moisture meter 21 By the processing of the arranged digital signal processing circuit, a load detection signal whose signal level changes according to the load due to the mass of the sample is detected by the mass sensor 5,
This load detection signal is subjected to analog-to-digital conversion processing by the analog signal processing circuit 6 to generate load detection data. Further, the initial mass of the sample is detected by processing the load detection data in the digital signal processing circuit.

In the moisture meter 21, when the initial mass of the sample is detected in this way, the heating of the sample by the heating source 13 is started by the control of the power supply circuit 9A by the digital signal processing circuit, and the moisture of the sample is reduced. Evaporates slowly. Furthermore, when the moisture of the sample is completely scattered by the continuation of the heating, the change in the mass of the sample is stopped. The moisture meter 21 monitors the change in mass due to evaporation of the water in the same manner as in the case of detecting the initial mass, and calculates the water mass of the sample based on the change in the mass. The measurement is performed, and the measurement result is displayed on the operation display unit 8.

A heat insulating member 31 made of a material having a low thermal conductivity, a top plate of the case 24, and a heat insulating member 27 are sequentially arranged below the weighing pan 11, so that the heat on the weighing pan 11 is transferred to the mass sensor 5. And the temperature change of the mass sensor 5 is reduced. In addition, since the mass sensor 5 itself is surrounded by the plate material having low thermal conductivity and is housed in the inner case 25, the heat on the weighing dish 11 is hardly conducted to the mass sensor 5, and the temperature change of the mass sensor 5 is prevented. Is reduced. Further, the connecting member 26 that transmits the load of the weighing pan 11 to the mass sensor 5 also has a member 26A having a low thermal conductivity.
Is arranged in the middle, thereby making it difficult for the heat on the weighing pan 11 side to be conducted to the mass sensor 5, thereby reducing the temperature change of the mass sensor 5.

Even if it is difficult to conduct heat to the mass sensor 5 in this way, the heat of the weighing dish 11 is actually conducted to the mass sensor 5 side, and when this heat is stored, the mass sensor 5
In, the temperature rises. In addition, with respect to the internal heat generation of the moisture meter main body 22, when the heat insulating structure is employed in this way, the heat builds up rather, and the temperature of the mass sensor 5 rises.

In the moisture meter 21, an exhaust port 29 is formed on the rear side and upper side of the case, and the power supply circuit section 9B which generates the largest heat in the moisture meter body 22 is arranged inside the exhaust port 29, so that The air inside the case 24 heated by the heat generated by the power supply circuit section 9B is exhausted from the exhaust port 29. Further, the intake port 30 is disposed below the front side, which is the side opposite to the exhaust port 29 with the inner case 25 interposed therebetween, so that the air inside the case 24 is discharged from the exhaust port 29 in this manner. When the air is discharged, the outside air is introduced into the case 24 accordingly.

In the moisture meter 21, components that generate relatively little heat are arranged on the side of the intake port 30.
After the top plate of the case 30 is tilted obliquely upward, it becomes substantially flat at the inner case 25 and the cover portion 23 at the back side.
By protruding to the side and continuing to the exhaust port 29, a flow path is created so as to flow upward from below, whereby an air flow with a sufficient flow rate is formed by the chimney effect without providing a mechanism such as a fan. . Thereby, in the moisture meter 21, the air heated by the internal heat is efficiently discharged to the outside, and the temperature increase of the mass sensor 5 due to the internal heat is prevented.

In the moisture meter 21, the heat insulating structure between the weighing dish 11 and the mass sensor 5 is a first air layer between the top plate of the case 24 and the heat insulating member 27, and the heat insulating member 27 and the inner case 25. And a second air layer between the top plate and the top plate, and the air of the first and second air layers is supplied to the outside of the apparatus by the air flow from the intake port 30 to the exhaust port 29. The heat is prevented from being stored in the heat insulating structure.

That is, in the moisture meter 21, the flow path of the air exhausted to the outside in this manner is located below the weighing dish 11 in the space between the top plate of the case 24 and the top plate of the inner case 25. The case 2 is thus formed by the air flow that discharges waste heat due to internal heat to the outside.
The top plate 4, the heat insulating member 27, and the inner case 25 are cooled, and heat storage due to heat conduction from the weighing pan 11 is prevented.

Further, since the mass sensor 5 is completely housed in the inner case 25 formed of a plate material having a low thermal conductivity, the so-called inner case 25 and the like can be cooled while the so-called inner case 25 is cooled by a relatively active air flow. Even if the mass change is measured, the load detection signal can be output without being affected by such an air flow. Thus, in the moisture meter 21, the temperature change of the mass sensor 5 can be remarkably reduced as compared with the conventional case,
Accordingly, it is possible to effectively avoid an increase in the size of the entire shape, and to improve the measurement accuracy as compared with the related art.

(1-3) Effects of the First Embodiment According to the above configuration, the inner case 25 in which the mass sensor is surrounded by a plate material having a low thermal conductivity is employed. A heat insulation structure with an air layer interposed between the weighing pan and the air in this air layer is exhausted to the outside of the device. Heat storage due to heat conduction from the dish and heat storage due to internal heat generation can be prevented, thereby effectively avoiding an increase in the size of the entire shape and reducing a temperature change of the mass sensor 5. Accordingly, it is possible to effectively avoid an increase in the size of the entire shape, thereby improving the measurement accuracy as compared with the related art.

At this time, a heat insulating member 27 is disposed between the case 24 and the inner case 25 to form a heat insulating structure having two air layers interposed therebetween, so that heat conduction and heat storage are sufficiently reduced for practical use. can do.

By arranging the exhaust port and the intake port with the inner case 25 interposed therebetween, and forming the intake port and the exhaust port on the lower side and the upper side of the case 24, respectively, a natural so-called chimney effect is obtained. The air in the air layer can be exhausted to the outside of the apparatus by forming an air flow, and the measurement accuracy can be improved by a correspondingly simple configuration.

Also, by making most of such an air flow below the weighing pan into an air layer with a heat insulating structure, heat storage can be efficiently prevented by such an air flow. The measurement accuracy can be improved accordingly.

(2) Second Embodiment FIG. 2 is a sectional view showing a moisture meter according to a second embodiment of the present invention. The moisture meter 41 is configured by connecting a measurement unit 42 and a data processing unit 43 which are separately configured by a cable 44. In FIG. 2, the same components as those in FIGS. 1 and 3 are denoted by the corresponding reference numerals, and duplicate description will be omitted.

In the moisture meter 41, the measuring section 42
The heat source 13, the weighing dish 11, and the mass sensor 5 are arranged. Thus, in the moisture meter 41, the heating source 13, the weighing dish 11, and the mass sensor 5 are held separately from the analog signal processing circuit 6, the digital signal processing circuit, and the like, and the load is detected by the analog signal output from the mass sensor 5. The signal is transmitted to the data processing unit 43 via the cable 44 to detect the mass of the sample.
The power supply for driving the heating source 13 generated on the data processing unit 43 side is supplied to the measuring unit 42 via the control unit 4.

The measuring section 42 is arranged such that the mass sensor 5 is housed in the inner case 25 described in the first embodiment, and furthermore, the case 45, the heat insulating member 27, and the two air layers formed by the inner case 25. The heat insulation structure has the heat sink so that heat conduction from the weighing dish 11 side is reduced. In addition, a natural exhaust mechanism using a chimney effect of an intake port and an exhaust port (not shown) formed in the case 45 discharges air in the two air layers to prevent heat storage.
Further, the heat conduction to the mass sensor 5 is reduced by the heat insulation member 26A of the connection member 26 and also by the heat insulation member 15 arranged on the weighing dish 11 side.

In this way, if the heating source 13, the weighing pan 11, and the mass sensor 5 are held separately from the analog signal processing circuit 6, the digital signal processing circuit, etc., the weighing pan The measurement accuracy can be improved only by taking measures against heat generated by the heating source 13 which is heat from the 11 side. With this simple configuration, the measurement accuracy can be improved as compared with the related art.

In particular, in this embodiment, since the same heat countermeasures as in the first embodiment are provided on the measuring section 42 side, the second heat source is disposed separately. Compared with the first embodiment, the temperature change of the mass sensor 5 can be further reduced, and
Further, the measurement accuracy can be further improved.

Thus, in the moisture meter 41, the data processing unit 43 includes the wiring board 7 having the analog signal processing circuit 6 and the digital signal processing circuit arranged therein, the operation display unit 8, and the power supply circuit unit 9 in a predetermined case 47. Stored and configured. In this configuration, the data processing unit 43 divides the internal space of the case 47 into two by a heat insulating member 48 made of a plate material having low thermal conductivity, and the power supply circuit unit 9, the wiring board 7, The operation display unit 8 is arranged. Thereby, the moisture meter 41
In this configuration, a decrease in the measurement accuracy due to a temperature change in the analog signal processing circuit, which is a problem when the measurement accuracy is improved by reducing the temperature change of the mass sensor 5, is effectively avoided.

According to the second embodiment, the output of the mass sensor is processed by a separate signal processing circuit, so that the measurement accuracy can be improved as compared with the related art.

(3) Other Embodiments In the above-described first embodiment, the case where the power supply circuit section is divided into two and arranged on the cover side and the mass sensor side respectively has been described. The invention is not limited to this,
If necessary, they may be integrated and arranged on the cover side or the mass sensor side.

In the first embodiment described above,
Although the description has been given of the case where the power supply circuit section is disposed on the back side of the apparatus and on the cover side of the heat insulating member, and the analog signal processing circuit and the digital signal processing circuit are disposed on the front side, the present invention is not limited to this, and the present invention is not limited to this. If the temperature change of the mass sensor can be sufficiently prevented, the mass sensor can be arranged at various places.

Further, in the above-described embodiment, a case has been described in which a heat insulating structure having two air layers is used. However, the present invention is not limited to this, and the number of air layers may be variously changed as necessary. Can be selected.

In the above-described embodiment, the case where the moisture meter is constituted by the electromagnetic balance type mass sensor has been described. However, the present invention is not limited to this. For example, the moisture meter is constituted by a mass sensor using a strain gauge. It can be widely applied to cases and the like.

[0061]

As described above, according to the present invention, an inner case in which a mass sensor is surrounded by a plate having low thermal conductivity is employed, and an air space is provided between the top plate of the inner case and the weighing pan. The insulation accuracy is improved by exhausting the air in the air layer to the outside of the device and processing the output of the mass sensor by a separate signal processing circuit. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a moisture meter according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a moisture meter according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional moisture meter.

[Explanation of symbols]

1, 21, 41 ... moisture meter, 2, 22 ... moisture meter body,
3, 23 ... cover part, 4, 24, 45, 47 ... case 5, ... mass sensor 6, ... analog signal processing circuit, 9, 9A, 9B ... power supply circuit part, 11 ... weighing pan,
13 ... heating source, 14, 15, 27, 31, 48 ... heat insulating member, 25 ... inner case, 29 ... exhaust port, 30 ...
Intake port, 42 Measurement part, 43 Data processing part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naoto Izumo 1-243 Asahi, Kitamoto-shi, Saitama Inside A & D Corporation

Claims (5)

[Claims] 1. A weighing dish on which a sample is placed, a heating source for heating the sample, and a load detection signal based on an analog signal whose signal level changes according to the mass of the sample placed on the weighing dish. A mass sensor for outputting, and a digital signal processing circuit for calculating the moisture content of the sample by performing analog-to-digital conversion processing on the load detection signal to generate load detection data, and performing data processing on the load detection data. In the moisture meter, an inner case that surrounds the mass sensor with a plate material having a low thermal conductivity, a top plate of the inner case, and a heat insulating structure that is disposed between the weighing dish and an air layer. A moisture meter, comprising: an exhaust mechanism for exhausting the air in the air layer to the outside of the apparatus. 2. A weighing dish on which a sample is placed, a heating source for heating the sample, and a load detection signal based on an analog signal whose signal level changes according to the mass of the sample placed on the weighing dish. A mass sensor for outputting, and a digital signal processing circuit for calculating the moisture content of the sample by performing analog-to-digital conversion processing on the load detection signal to generate load detection data, and performing data processing on the load detection data. In the moisture analyzer, the weighing dish, the heating source, and the mass sensor are held separately from the digital signal processing circuit. 3. An inner case surrounding the mass sensor with a plate having low thermal conductivity; a heat insulating structure disposed between the top plate of the inner case and the weighing pan, with an air layer interposed therebetween. The moisture meter according to claim 2, further comprising an exhaust mechanism for exhausting the air in the air layer out of the apparatus. 4. The heat insulation structure includes at least a top plate of a case that houses the analog signal processing circuit, the digital signal processing circuit, and the inner case; a top plate of the case; and a top plate of the inner case. 4. The moisture meter according to claim 1, wherein the moisture meter is a heat insulating member disposed between the two to partition a space between the top plate of the case and the top plate of the inner case into two. 5. 5. The exhaust mechanism according to claim 1, wherein at least the analog signal processing circuit, the digital signal processing circuit, and the inner case are housed in the upper and lower sides of the case with the inner case interposed therebetween. The moisture meter according to claim 1, 3 or 4, wherein the exhaust port and the intake port are arranged.