WO1996032634A1

WO1996032634A1 - Moisture sensor for wooden material and automatic moisture content measuring device

Info

Publication number: WO1996032634A1
Application number: PCT/JP1996/000936
Authority: WO
Inventors: Masahiro Minoura; Hironori Watanabe; Masayuki Moriyama; Michio Noda
Original assignee: Sumitomo Forestry Co., Ltd.; Kett Electric Laboratory; Iida Kogyo Co., Ltd.
Priority date: 1995-04-13
Filing date: 1996-04-05
Publication date: 1996-10-17
Also published as: TW297092B; JP3686981B2

Abstract

A high-frequency capacitive moisture sensor comprises a first electrode in the form of a circular column adapted to rotate about an axis of rotation and having its diameter increasing gradually toward the center, and a second electrode provided opposed to the first electrode with a distance. An object to be measured is moved in contact with the first electrode for continuous measurement. In the case of a columnar object, the first electrodes of at least two moisture sensors are brought into contact with different sides of the object to continuously perform measurement so that a moisture content is found from measurements for the same cross section of the columnar object. At least one moisture sensor is disposed on the same plane of a relatively thin object, such as a cut stock for laminated lumber, sawing lumber products and the like.

Description

Description Moisture sensor for wood materials and automatic moisture content measuring device [Technical field]

The present invention relates to an apparatus for continuously measuring the moisture content of wood products produced at a wood processing plant or the like for solid wood, glued lumber, etc., and appropriately selecting the wood products.

[Background technology]

Conventional wood moisture sensors are classified into high-frequency resistance type, high-frequency capacity type, DC resistance type, etc. when classified by measurement method. Since the high-frequency resistance method and high-frequency capacitance method are non-broken, measurement can be performed without damaging the surface of the material, and since the depth of the electric field is deeper than that of the DC resistance method, moisture at a certain depth in the material is detected. It is possible to In many cases, the AC power supply is used as the power supply, and there are also types that are suitable for online measurement (continuous-type automatic moisture measurement device, Forestry Experiment Station Vol. 7, No. 5, 1993, etc.).

Also, from the viewpoint of the structure of the electrodes, as shown in Fig. 13, the method of arranging the anode and the cathode on the same plane, such as wood (hereinafter referred to as "material"), The method of making the cathode and the cathode face each other is the mainstream. In the former case, since the depth of the electric field is generally shallow, only water in the surface layer can be detected relatively. In the latter case, if the distance between the electrodes is not constant, the output signal will be unstable and the measurement accuracy will decrease.

Also, when measuring, the high-frequency method is influenced by the shape of the surface of the material, and it is necessary that the tip of the electrode and the surface of the material adhere to each other. If there is a gap, the apparent moisture value will be reduced due to the air gap. Tends to be too small. In addition, it is easily affected by the specific gravity, and the variation in the specific gravity of the measurement material tends to appear as the variation in the indicated value.

The DC resistance method is relatively unaffected by the specific gravity and is not easily affected by the surface shape of the material, but most of it is of the destructive type using needle electrodes, etc. Limited to some extent, so continuous measurement is not suitable. Due to the shallow force and depth of the electric field, the measurement material is limited to relatively thin ones.

The present invention illuminates the above circumstances, and the present invention adheres to a deformed material without damaging the material, and has an electrode structure that increases the measurement depth. An object of the present invention is to provide an automatic moisture content measuring device and a sorting device having high measurement accuracy. From the viewpoint of the electrode structure, the mainstream method is to arrange the anode and cathode on the same plane for both high-frequency and DC systems, and to oppose the anode and cathode. In the former case, since the depth of the electric field is generally shallow, only water in the surface layer can be detected relatively. In the latter case, the depth of the electric field is sufficient.If the distance between the electrodes and the size of the measurement material are not constant, the output signal will be unstable, and the dimensions and shape will be unstable or deformed. The measurement accuracy for the material, ie, the desiccant, is reduced.

When measuring a desiccant as described above, it is difficult to measure with the sensor at a fixed position, and it is necessary that the tip of the electrode and the surface of the material be in close contact. In other words, if there is a gap, the apparent moisture value becomes too small due to the air gap, or the specific gravity of the measurement material starts to affect, which tends to cause a variation in the indicated value.

As for the adhesion method, it is necessary to prevent the surface of the material from being damaged in order to perform continuous measurement, and it is necessary to position the material in the center of the material for accurate measurement. Furthermore, durability is required.

Since the high-frequency resistance method and the high-frequency capacitance method are non-destructive, measurement can be performed without damaging the material surface. However, the material in the drying process is deformed due to various stresses caused by fluctuations in moisture in the material, and changes in shape such as torsion occur, so conventional sensors follow the deformation and are located at the center of the material. It will be very difficult to do.

In addition, when performing continuous measurement, it is necessary to prevent the moving workpiece from fluctuating vertically and horizontally to stabilize the output signal.

The materials in the drying process have different moisture distributions in the length direction, and the state of the moisture distribution is different for each side surface. For this reason, the measurement accuracy decreases with a single sensor fixed type, and it becomes difficult to estimate the moisture state of the entire material.

In addition, when performing continuous measurement with multiple sensors, mutual interference occurs between the sensors, causing a large error in moisture measurement.

For this reason, it is necessary to consider the moisture sensors on each side so that mutual interference does not occur. Shifting the position of each sensor causes a shift in the measurement start time of each sensor, which makes it difficult to estimate the moisture value of each part of the material to be measured.

In addition, in a sawmill with drying equipment, the column material (105 cm (Angle to 12 O cm square) has a large distribution of moisture, and the resulting distribution of stress causes shape changes such as width, warp, and torsion. I know different things.

An apparatus for accurately measuring the moisture content of such a pillar has not yet been developed.

[Disclosure of the Invention]

The moisture sensor and the automatic moisture content measuring device of the present invention solve the above-mentioned drawbacks of the conventional moisture sensor, and accurately measure the moisture content (or moisture value) of a pillar material having a different dry state on each surface of the material. To be able to do so, a high-frequency capacitance method is used as the measurement method.

Furthermore, as shown in Fig. 1, electrode 1 (side in contact with the material) and electrode 2 (ground side) are three-dimensionally arranged. The shape of electrode 1 is a roller type with R processing as shown in the figure. did. Next, an air cylinder and a rack and pinion were used for horizontal movement in order to move the material to be measured stably.

Further, the sensors of this type were arranged on three opposite sides, that is, on the opposite side of the back-slit face of the material to be measured and on both sides perpendicular to the face. Next, in order to synchronize the detection signal from each sensor, a synchronization signal was obtained using an encoder built into one end of the above-described clamping device as shown in Fig. 5A and 5B, 15, 16, and 17. Thereafter, in order to further position the material in the longitudinal direction, the signal from each moisture sensor was synchronized by the measurement control unit 41 in the controller in FIG.

A comparison means for comparing the obtained moisture content with a predetermined value is provided, and the output of the comparison means is used to sort the material to be measured or to mark the material to be measured. I did it.

The sensor of the present invention uses a high-frequency measurement method for nondestructive, wide-range moisture measurement and continuous measurement. There are two types of high-frequency methods: resistance type and capacitance type.The high-frequency resistance type has a moisture measurement range that can be measured accurately regardless of the operating frequency range up to the maintenance saturation point. Therefore, a capacitance type that uses a frequency range that allows a wide range of moisture measurement was adopted.

The following measures were taken to improve the electric field depth and measurement accuracy. By arranging the anode and cathode three-dimensionally as shown in Fig. 1, the depth of the electric field becomes deeper, It has become possible to detect. The electric field emitted from the anode 1 has the highest electric field density between the negative electrode 2 on the opposite side, and the electric field on the opposite side has a slightly smaller electric field, but there is also an electric field flying at infinity. That is, as the thickness of the object to be measured is larger, the electric field passing through the object to be measured increases proportionately, and the effect becomes larger.

In order to follow the change in shape such as warpage and torsion during the drying process, the moisture measurement electrode was subjected to R processing so that it traveled in contact with the amount of cup (pillar in cross section in Fig. 3) such as a pillar. . However, the contact method for following wood is not limited to this method, and a plate-panel brush-like electrode, a roller using conductive rubber, or the like may be used.

Next, the material to be measured moving in the length direction uses an air cylinder and a rack and pinion, so that there is no wobble between the measurement sensor and the indicator roller, enabling stable moisture measurement. However, a close contact method using a hydraulic pressure or a motor may be used as a means for enabling the above measurement.

In addition, with a single sensor, only one side of the data is used, and the measurement accuracy is considerably reduced in practical use. When the sensors are arranged on two sides, the measurement accuracy is significantly improved. By arranging sensors on the three sides, the measurement accuracy can be further improved.

As a means to prevent mutual interference between the moisture sensors, this was dealt with by displacing the positions of the sensors, but by using one oscillating unit at the same position, the electrodes of each sensor were instantaneously switched by a switch. It doesn't matter if you switch to.

According to the present invention, moisture measurement can be continuously and accurately performed for the entire material, and conventional moisture quality control and sorting operations can be performed at high speed and accurately. In addition, automation is possible, resulting in significant labor savings.

[Brief description of drawings]

FIG. 1 is a diagram showing an electrode configuration of a moisture sensor according to the present invention.

FIG. 2 is a circuit diagram of the moisture sensor of the present invention.

FIG. 3 is a diagram showing an example of the arrangement of a moisture sensor according to the present invention.

FIG. 4 is an A view of FIG.

FIG. 5A is a plan view of the automatic moisture content measuring device of the present invention.

FIG. 5B is a side view of the automatic moisture content analyzer of the present invention. FIG. 6 is a system block diagram of the automatic moisture content measuring device of the present invention.

FIG. 7 is a view for explaining a method for determining the moisture content of a raw material using the automatic moisture content measuring device of the present invention.

FIGS. 8A to 8F show examples of the arrangement of a moisture sensor.

FIG. 8G is a plan view of the moisture sensor in the case of FIG. 8F.

FIG. 9A shows the measurement accuracy of the automatic moisture content measuring device of the present invention when three moisture sensors are used.

FIG. 9B shows the measurement accuracy of the automatic moisture content measuring device of the present invention when one moisture sensor is used.

FIG. 10 is a view showing actual measurement results by the automatic moisture content measuring device of the present invention.

FIG. 11A is a diagram showing an example when the moisture content of a column material is measured by one moisture sensor.

FIG. 11B is a diagram showing an example in which the moisture content of a pillar is measured by two moisture sensors.

FIG. 11C is a diagram showing an example in which the moisture content of a pillar is measured by three moisture sensors.

FIGS. 12A and 12B are diagrams showing an example of arrangement when two moisture sensors are provided.

FIG. 13 is a diagram showing a relationship between an electrode of a conventional moisture sensor and a material to be measured.

FIG. 14 is a diagram showing the relationship between the electrode of the conventional moisture sensor and the material to be measured.

[Best Mode for Carrying Out the Invention]

Fig. 1 shows the configuration of the electrodes of the moisture content measuring device (referred to as moisture sensor) for woody material of the present invention. 1 is the electrode (first electrode) that contacts the material. It has a cylindrical shape that rotates around a rotation axis. The diameter of the first electrode is formed so that the diameter gradually increases toward the center from the end. In other words, it has an outer shape that is R-shaped into a shape (ような shape) like the outer shape of a beat, so that it can cope with the warpage of the material. Reference numeral 2 denotes another electrode (second electrode), which is provided so as to be opposed to the electrode 1 by a support column 3 at a fixed distance. The second electrode may be flat or curved. Reference numeral 4 denotes an electric wire, which connects the output terminal of one third of the oscillating section 5 to the electrode I.c The oscillating section 5 is incorporated in the electrode 2, and the other end of the output of the oscillating section 5 is Connect to electrode 2 C / 96/936

6 铳The second electrode is grounded.

The electric field emitted from the electrode 1 has the highest electric field density between the electrode 2 on the opposite side and the opposite surface, that is, the side in contact with the material, although the electric field density is low, it flies indefinitely An electric field also exists. In other words, the electric field distribution is greatly widened, and as the thickness of the object under test becomes thicker, the electric field passing through the object under test increases, and by arranging the electrodes 1 and 2 three-dimensionally as shown in FIG. The depth can be made deeper, and it is now possible to detect moisture in the deep part of the material.

FIG. 2 is a circuit diagram of the moisture sensor of the present invention. The moisture measurement method of the present invention is a high-frequency capacitance type in order to realize non-destructive, continuous measurement, a wide measurement range, and to enable measurement of undried material. Oscillator 5 oscillates at an oscillation frequency of 0.1 MHz to 20 MHz. The oscillation frequency has a desirable range depending on the species of the material to be measured. For softwoods such as cedar plugs, the oscillation frequency is preferably 0.3 MHz to 2 MHz. More desirably, the frequency is 1.0 MHz ± 0.2 MHz for cedar wood and 0.5 MHz ± 0.2 Hz for hinoki wood. These frequencies are selected automatically according to the tree species or by the operator by switching the oscillation circuit by, for example, a switch. The electrodes 1 and 2 are connected to the oscillation unit 5. The oscillation frequency changes depending on the capacitance between the two electrodes. The oscillating unit 5 has an oscillating circuit unit composed of a ladder C or C and R, and the electrode 2 is connected in parallel with the capacitor C.

The oscillation frequency shifts when a dielectric material such as wood is brought close to or in contact with the electrode 1. Therefore, the amount of frequency shift is detected by the comparison circuit 6, and the output is sent to the measurement control unit as a detection signal. The detection signal is processed by the measurement control unit (Fig. 6) consisting of CPU54, ROM55, RAM56, etc., to determine the water content (moisture value) of the wood.

The obtained moisture value is used for the control signal of the material sorting device and marking device, and is displayed as necessary.

FIG. 3 shows the arrangement of the electrodes of the moisture sensor of the present invention. Fig. 4 is a view from A in Fig. 3. c8 is a pillar, and the electrodes 1 of the three moisture sensors 20, 21 and 22 are pressed against three surfaces except the back split surface of the material 8. Set to be applied. Since the electrode 1 is formed in a rectangular shape, even if the pillar 8 has a warp, it follows the shape of the warp. , Generated from electrode 1 and pillar The distribution of the electric field passing through the material 8 can be kept uniform, and the measurement accuracy can be improved.

As shown in FIG. 4, each moisture sensor is arranged at a predetermined distance so that electric fields generated by the respective electrodes do not affect each other.

When the electrode 1 rotates and the column 8 is moved in a certain direction, the electrode 1 rotates, so that each surface of the column 8 can be continuously measured.

FIG. 5A is a plan view of one embodiment of an automatic moisture content measuring device for continuously measuring the moisture content of a column using the moisture sensor of the present invention. FIG. 5B is a side view of FIG. 5A. The configuration and operation of the automatic moisture content measuring device of FIG.

When the material 8 to be measured is moved to the entrance of the automatic water content measuring device by the transfer device 7 with the spine of the material facing down, the elevator 9 moves down the drive motor 10 controlled by the inverter. The column 8 is sandwiched vertically and transported to the left at a constant speed.

In the figure, 101, 102, and 103 are one sensor unit that combines a sensor and an encoder. 11-1 to 14 are photoelectric switches, 15 to 17 are encoders 1 (rotary encoders), and 20 to 22 are moisture sensors. Fig. 4 shows the positional relationship between the moisture sensor-20-22 and the material to be measured.

When the material 8 is sent and the optical axis of the photoelectric switch 11 is interrupted, the photoelectric switch 11 is turned ON, pressure is applied to the air cylinder 18 and the measuring unit equipped with the first moisture sensor 20 is mounted. Insert the material 8 in the horizontal direction with the indicating roller 31.

When the column member 8 comes into contact with the support roller 31, the encoder 15 incorporated in the support roller 31 rotates in synchronization with the rotation of the support roller, and the position of the detection signal from the moisture sensor 20 is synchronized. Sent as a signal. (Refer to Fig. 6.) Further, the column member 8 is sent to the left, and when the optical axis of the photoelectric switch 12 is interrupted, the photoelectric switch 12 is turned ON.

When the photoelectric switch 12 is turned on, pressure is applied to the air cylinder 19, and the measuring section equipped with the second moisture sensor 21 is lowered, and the column member 8 is pressed downward. At this time, the support roller 32 provided below the moisture sensor 21 comes into contact with the lower surface of the metal member 8, and the encoder 16 incorporated in the support roller 32 rotates, and Sent as a position synchronization signal of the detection signal. Further, the column member 8 is sent to the left, and when the optical axis of the photoelectric switch 13 is blocked, the photoelectric switch 13 is turned on. When the photoelectric switch 13 is turned on, the air cylinder 23 is operated to move the measuring section equipped with the third moisture sensor 22 and to horizontally move the column member 8 together with the support roller 33 disposed opposite. In the direction. The support roller 33 comes into contact with the side surface of the column 8, and the encoder 17 incorporated in the support roller 33 rotates and is sent as a position synchronization signal of the detection signal from the moisture sensor 22.

The signal from the moisture sensor 20 is output at an appropriate position in synchronization with the photoelectric switches 11 to 14. In this embodiment, when the photoelectric switches 11 and 12 are in the ON state, the signal of the moisture sensor 20 is output. When the photoelectric switches 12 and 13 are in the ON state, the signal of the moisture sensor 21 is outputted. When the photoelectric switches 13 and 14 are ON, the signal of the moisture sensor 22 is output.

In another embodiment, the signals of the moisture sensors 120, 21 and 22 are output after a predetermined time has elapsed since each of the photoelectric switches 11 to 13 is turned on. Is also good.

When the end of the column member 8 passes through the optical axis of the photoelectric switch 12 and the light passes through, the photoelectric switch 11 becomes OFF. At this time, the air cylinder is returned by 18 force, and the measuring unit equipped with the first moisture sensor 20 pressing the column is released. Similarly, the end of the column member 8 passes through the optical axis of the photoelectric switch 12, and when the light passes through, the photoelectric switch 12 becomes OFF. At this time, the air cylinder 19 is lifted, and the measuring unit equipped with the second moisture sensor 121 pressing the material is released.

Further, when the terminal end of the column member 8 passes through the optical axis of the photoelectric switch 13 and the light passes therethrough, the photoelectric switch 13 becomes OFF. At this time, the air cylinder 23 is returned, and the measuring unit equipped with the third moisture sensor 22 pressing the column is released. When the tip of the column passes through the optical axis of the photoelectric switch 14, the photoelectric switch 14 is turned on, and the elevator 24 lowers the drive motor 25 controlled by the inverter, and digs up and down the material. , Discharge.

Each of the moisture sensors and support rollers described above have a mechanism that sandwiches the material to be measured between the air cylinder and the rack and pinion. The la is in contact with the center of each side surface of the material to be measured. The magnitude of the pinching pressure depends on the air pressure supplied to the air cylinder by the pressure adjustment regulator.

¾ 、 | ^ Adjustable.

The electrode of the moisture sensor of the present invention has a structure capable of deepening the electric field depth. For this reason, if the moisture sensors on each measurement surface are arranged at the same position, interference occurs between each moisture sensor and a large error occurs in the measured value. Therefore, these moisture sensors are arranged at a distance of about 5 Ocm where mutual interference does not occur, and the position of the detection signal from each moisture sensor is synchronized by the encoder. With such a configuration, a detection signal with a deep electric field depth independent of each surface can be obtained without being affected by drought, and the moisture content of the entire material to be measured can be measured with high accuracy.

FIG. 6 shows a system block diagram of the automatic moisture content measuring device of the present invention.

The signals from the photoelectric switches 11, 12, 13, and 14 are input to the transport control unit 42 and output to the drive unit 43.

The drive section 43 is composed of a conveyor mechanism section including a transport device 7 for transporting the material to be measured, and an electrode mechanism section for pressing an electrode against the material to be measured. The transport speed is variable so as to be compatible with workability, and the conveyor mechanism and the electrode mechanism are driven by control signals from the transport controller 42.

Encoders 15, 16, and 17 generate a number of pulses proportional to the amount of movement of the material to be measured, and these signals are used as position synchronization signals to control the measurement of the moisture sensor. The signals from the moisture sensors 20, 21, 22 are stored in the memories 51, 52, 53 of the measurement controller 41, respectively.

The moisture sensor 20, 21, 22 receives the output signal of the photoelectric switch 11, 1, 2, 13, 14 and the signal that combines the encoders 15, 16, 17 with human input and measures It is controlled so that the moisture sensor 1 is activated when the material comes to a position suitable for starting, or the output of the moisture sensor is sent to the measurement control unit 41.

In one embodiment of the present invention, when the measurement of one pillar is completed, the detection signal is converted into a moisture value by a detection signal-to-moisture ratio conversion table registered in the ROM 55 in advance.

In general, the moisture content Y of wood is represented by Equation 1 where the detected value is X. Y = ax ^a + bx '+ cx + d (1)

Coefficients a, b. C, d differ depending on the type of wood, and each coefficient is determined in advance by the least squares method. Therefore, part or all of the relationship between the coefficients a, b, c, and d, which differ depending on the type of wood, and the detection value x expressed by Equation 1 is registered in the ROM 55 as a detection signal-to-moisture conversion table. In advance, select the coefficients a, b, c, and d according to the type of wood to be measured, and determine the moisture value Y. This control is all performed by the CPU 54.

In the present invention, as shown in FIG. 7, the same cross-sectional positions (S 11, S 21, S 31), (S 12, S 22, S 32),… ( Sin, S2n, S3n), the average value Ml, M2, M3, ... Mn of the output of each moisture sensor 2 0, 2 1, 22 is calculated, and the average value Ml, M2, The average value of M3 to Mn is determined and used as the moisture content of the material to be measured.

The position-synchronized detection signal sent from each moisture sensor is stored in the RAM 56 as needed. The memory of the measurement controller 41 and the CPU 54 are connected by a bus 57. The moisture content of the material to be measured calculated by the measurement control unit 41 is determined based on a predetermined threshold value, converted into a classification signal indicating the degree of the moisture content, and input to the transport control unit 42. The transport control unit 42 receives the sorting signal and outputs a control signal to a sorting device 44 that sorts the material to be measured and a marking device 45 that marks the surface of the material to be measured according to the grade. I do.

In another embodiment of the automatic moisture content measuring apparatus of the present invention, the moisture sensor is placed at an appropriate interval so as to press different places on the plate material, that is, at a level that does not cause electric field interference that affects the measured value. By arranging them at intervals, the moisture content can be accurately measured even for a plate material. The interval is 10 cm or more on the same plane. It is preferably at least 15 cm. 8A to 8F show examples of the arrangement of the moisture sensor in this case. In the case of Fig. 8F, the sensor units 101 and 103 of Fig. 5 are installed in the same direction as the sensor unit 102, and the planar arrangement is as shown in Fig. 8G. Configure to measure the part. Similarly, in the case of Figs. 8A-8E, the measurement of Figs. 8A-8E becomes possible by changing the positions of the sensor units 101-103 according to the position of each sensor. Further, in another embodiment of the present invention, the moisture content at the same cross-sectional position of the material to be measured is calculated in real time while the material to be measured is being conveyed, and the moisture content as a final value is calculated by performing statistical processing. It may be.

FIGS. 9A and 9B show the measurement accuracy of the automatic moisture content measuring device of the present invention when three moisture sensors and two moisture sensors are used, respectively.

The horizontal axis (X-axis) indicates the total moisture content by dry method obtained according to the JIS standard, and the vertical axis (Y-axis) indicates the value obtained by converting the detection signal of this device into a moisture display. The X mark is the measurement data for one pillar.

In the comparison of Figures 11A, 11B, and 11C described later, when 3 sensors are mounted, the fluctuation is about 1/4 of the fluctuation when 1 sensor is mounted, and when 2 sensors are mounted, the fluctuation is There is a remarkable effect of using multiple moisture sensors between 1 sensor and 3 sensors. As shown in Fig. 9A, when 3 sensors are used, the standard deviation of the total dry moisture percentage is 6%. And satisfies practical accuracy. The standard deviation in the case of two sensors is 1.8% as shown in FIG. 9B, which also satisfies the practical accuracy.

FIG. 10 shows an example of the measurement results of the automatic moisture content measuring device of the present invention. The vertical axis indicates the level of the detection signal, and the horizontal axis indicates the measurement position.

Figures 11A, 11B, and 11C show the difference between the case where the moisture content of the column material was measured with one moisture sensor and the case where it was measured with two or three moisture sensors. The vertical axis shows the frequency (data number), and the horizontal axis shows the difference from the total dry method in%.

In the case of pillars, the drying condition on each side of the pillars varies depending on the state of stacking in the drying room, wind speed, ventilation, etc., and the water content varies. Therefore, when the material to be measured is a pillar, the data of one moisture sensor set on one side is as shown in Fig. 11A, and the moisture content cannot be measured with high accuracy. However, when two or more moisture sensors are used and the measurement results of at least two sides of the column are used, the moisture content can be determined almost exactly as shown in Figs. 11B and 11C. Even with two moisture sensors, the accuracy is much better than with one and is practical. When two moisture sensors are used, arrange the sensors as shown in Figs. 12A and 12B.

Wood cut wood for laminated wood (cut s tock for or lamined lumber) or thick like wood In the case of a plate having a thickness of not more than 50 mZm, there is little variation in the water content if the dry state is good. Therefore, in that case, measurement with practical accuracy is possible even with one moisture sensor.

In this case, measurement can be performed using only the sensor units 102 of FIGS. 5A and 5B.

The present invention is not limited to the above embodiments, but includes any embodiments included in the claims.

Claims

The scope of the claims

1. In a high-frequency capacitance-type moisture sensor that determines the moisture content of the material to be measured from the change in oscillation frequency due to the capacitance between the first and second electrodes provided in parallel with the capacitance C of the high-frequency oscillation circuit The first electrode is in contact with the material, the second electrode is a ground electrode, is configured to hold the first electrode, and both electrodes are provided in a pair facing each other. Wood material moisture sensor.

2. The moisture sensor according to claim 1, wherein the first electrode has a cylindrical shape that rotates about a rotation axis, and the diameter of the first electrode gradually decreases as going from the end toward the center. A wood-based moisture sensor characterized by being formed so as to be large.

3. The moisture sensor according to claim 1, wherein the high-frequency oscillation circuit includes frequency setting means for setting an oscillation frequency according to a type of the material to be measured.

4. The moisture sensor according to claim 3, wherein the frequency setting means includes means for setting a frequency in a range of 0.3 MHz to 1.2 MHz when the material to be measured is a softwood.

5. The moisture sensor according to claim 4, wherein the frequency setting means is 1.0 MHz ± 0.2 MHz when the material to be measured is cedar wood, and 0.5 MHz ± 0.2 MHz when the material to be measured is cypress wood. Includes means to set the frequency to MHz.

6. A high-frequency capacitance-type moisture sensor that determines the moisture content of the material to be measured from a change in the oscillation frequency due to the capacitance between the first and second electrodes provided in parallel with the capacitance C of the high-frequency oscillation circuit; In an automatic moisture content measuring device including a transport device for transporting a measurement material at a predetermined speed, a first electrode is configured to contact a material, a second electrode is a ground electrode, and a first electrode is connected to a material. An automatic moisture content measuring device for woody material, characterized in that it is configured to hold and that a pair of electrodes are provided facing each other.

7. The automatic moisture content measuring device according to claim 6, wherein the first electrode has a columnar shape rotating around a rotation axis, and the diameter of the first electrode is set to be more toward the center than the end. An automatic moisture content measuring device for woody materials, characterized in that the diameter is gradually increased.

8. The automatic moisture content measuring device according to claim 6, wherein the automatic moisture content measuring device includes a plurality of moisture sensors arranged at a predetermined distance so that electric fields do not interfere with each other. Means for contacting the respective first electrodes with the surface of the material to be measured, and means for continuously measuring the material to be measured while moving the material to be measured, at a plurality of the same cross-sectional positions of the material to be measured Means for determining the moisture content of the material to be measured from each measurement value.

9. The automatic moisture content measuring apparatus according to claim 8, wherein the moisture sensor is configured to contact each of the first electrodes with the same surface of the material to be measured. Moisture measurement device.

10. In the automatic moisture content measuring device according to claim 8, the number of moisture sensors is two, and the first electrode is provided on each of two surfaces of the column, namely, the opposite surface of the spine split and the one side surface perpendicular to the surface. An automatic moisture content measuring device for woody material, characterized in that it is configured to be in contact.

11. In the automatic moisture content measuring device according to claim 8, the number of moisture sensors is three, and the first electrodes are respectively provided on the three surfaces of the column opposite to the spine and on both sides in a direction perpendicular to the surface. An automatic moisture content measuring device for woody material, characterized in that it is configured to be in contact.

12. In the automatic moisture content measuring apparatus according to claim 8, the means for determining the moisture content is a means for determining the average value of the measured values of the respective moisture sensors at the same cross-sectional position of the material and a plurality of cross-sectional positions. Means for calculating the average of the average values of

13. The automatic moisture content measuring device according to claim 8, wherein the automatic moisture content measuring device includes a roller at a position facing each moisture sensor, and further outputs a pulse in synchronization with the rotation of the roller. A first electrode of each moisture sensor and a roller configured to press the side surface of the pillar by means of a roller; and a means for determining the same cross-sectional position of the pillar from the arrangement relationship of the moisture sensors and the output of each encoder. Including.

14. The automatic moisture content measuring device according to claim 8, wherein the first electrode of each moisture sensor is configured to contact a central portion of the pillar. .

15. The automatic moisture content measuring device according to claim 8 further includes a ratio reducing means for comparing the obtained moisture content with a predetermined 閛 value, and a means for selecting a material to be measured based on an output of the comparing means. .

16. The automatic moisture content measuring device according to claim 8, further comprising: comparing means for comparing the obtained moisture content with a predetermined threshold value; and a means for marking the material to be measured by the output of the comparing means. Including steps.

17. In the automatic moisture content measuring device according to claim 8, the high-frequency oscillation circuit includes frequency setting means for setting an oscillation frequency according to the type of the material to be measured.

18. The automatic moisture content measuring apparatus according to claim 17, wherein the frequency setting means includes means for setting a frequency in a range of 0.3 MHz to 1.2 MHz when the material to be measured is a softwood.

19. The automatic moisture content measuring apparatus according to claim 18, wherein the frequency setting means is 1.0 MHz ± 0.2 MHz when the material to be measured is cedar wood, and 0.5 MHz when the material to be measured is cypress wood. ± 0.

Includes means to set the frequency to 2 MHz.