JPS628741B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a microscopic system for determining and distinguishing the quality of wood by observing the knots and corresponding parts of wood, particularly sawn wood. Concerning a wave-based wood observation device. In particular, the present invention relates to a simple wood observation device of a size suitable for observing rapid changes in microwave energy caused by knots in wood.

(Prior Art) When distinguishing wood, it is important to distinguish knots in the wood. This has been done in a variety of ways in prior art devices. An example of conventional technology is to optically scan the surface of sawn wood using various devices, and use a photometer to detect the amount of light to determine the required detection based on the difference in color caused by the knots. I was doing it. Other methods utilize mechanical differences between knots and other parts of the wood to detect knots.

It was found that the nodes cause changes in the transmission of microwave energy in each part. Microwave energy transmitted through and reflected from the wood changes in amplitude and phase near the nodes. These changes are observed while comparing with the microwave energy transmitted through or reflected from the knotless parts of the wood, and if a sudden change occurs, it can be said that it is due to the knots.

Microwave energy transmitted through wood can be used to determine the average size of knots, while reflected microwave energy can be used to determine the location and size of visible knots on a given surface of wood. Therefore, by making similar measurements on the entire surface of the wood, it is possible to differentiate the wood based on its appearance and the average number of knots it contains. However, this type of conventional technology using microwave energy is not only large and complex in structure, but also has insufficient measurement accuracy.

(Problem to be Solved by the Invention) Therefore, the problem to be solved by the present invention is to solve the above-mentioned drawbacks of the prior art, namely, detecting the presence or absence of knots in wood and the condition of the knots using microwave energy. The question is how to make wood observation equipment smaller and simpler, and how to improve measurement accuracy.

(Means for Solving the Problems) It is an object of the present invention to have a small and simple structure suitable for measuring wood using microwave energy, and to have It is an object of the present invention to provide an industrially extremely advantageous observation device that can observe changes with sufficient measurement accuracy.

In order to achieve the above object, according to the present invention, a receiving antenna pair consisting of one transmitting antenna for microwave transmission and two receiving antennas arranged in close proximity, or a receiving antenna pair consisting of one transmitting antenna for microwave transmission and two receiving antennas arranged in close proximity A transmitting/receiving antenna device having a transmitting antenna pair consisting of two antennas for transmitting waves and one antenna for receiving, or a transmitting/receiving antenna device group combining a plurality of such transmitting/receiving antenna devices; Alternatively, it is emitted from an antenna pair consisting of two antennas, transmits through the observed wood, or is reflected from the wood, and is transmitted by one receiving antenna or two antennas of the receiving antenna pair of the transmitting/receiving antenna device or group of transmitting/receiving antenna devices. A wood observation device that classifies wood by sensing the presence of knots in the wood when a sudden change of a predetermined magnitude occurs in at least one of the amplitude, intensity, and phase of received microwaves. The microwaves transmitted from the one transmitting antenna or the pair of transmitting antennas and received by the pair of receiving antennas or the one receiving antenna are superimposed with a phase difference of 180 degrees, The superimposed microwaves are detected by a detector, and when either the receiving antenna pair or the transmitting antenna pair is facing a knotless part of the observed wood, the output from the detector is substantially zero. When either the receiving antenna pair or the transmitting antenna pair is facing the node of the observed wood, the output from the detector shows a value different from zero. It is characterized by detecting the presence of
A microwave wood observation device is provided.

For example, when microwave energy propagates through a medium, the change in energy is first determined by the dielectric constant and resistivity of the medium material. In wood, especially sawn wood, the above-mentioned properties are significantly different between knots and other parts of the wood, so the concentration of microwave energy is transferred from the knots of the wood to other parts of the wood or vice versa. Moving in the opposite direction produces a distinct change in the nature of the transmitted and reflected microwave energy. This change can then be observed by using a suitable antenna structure to measure the intensity and/or phase of the transmitted or reflected microwave energy. The wood quality in the area surrounding the knot differs from the normal characteristics of the rest of the wood, to the same degree as changes in the intensity and/or phase of the microwave energy transmitted or reflected through the wood in the vicinity of the knot. It can be observed by comparing it with the value measured in the knotless part of the wood.

In the present invention, such measurements are made by comparing the intensity and/or phase of the microwave energy in adjacent areas of a piece of wood, e.g. a board, and the output of the device is determined between these areas. In particular, in an equilibrium state with no nodes, there is no output or the output is minimum. Therefore, zero power indicates that the plate is uniform in the area of interest.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The apparatus of any embodiment may be used in conjunction with a suitable conveyor, in which case the wood may be conveyed relative to a stationary measuring point or, conversely, a movable measuring device may be moved relative to the wood being measured. In either case, the effects of the present invention remain the same. When moving wood, the wood is moved relative to the device, and such relative movement is possible by moving either the wood or the device.

The receiving apparatus of FIGS. 1 and 2 is equipped with a waveguide 11 as a receiving antenna, and this waveguide 11 has a front end portion, that is, a microwave transmitted from a single transmitter is At the entrance of the waveguide 11 that passes through the wood or is reflected from the wood, the waveguide 11 is divided into two by a separating material 13 placed on the H plane (magnetic interface of electromagnetic waves), and is divided into two separate pieces. A pair of receiving antennas is formed as a waveguide portion. A diode 12 serving as a detector is arranged at the rear end portion of the waveguide 11, and the two waveguide portions are configured to communicate in front of the detector 12. Although dividing into two parts does not directly affect the microwave energy passing through the waveguide 11, a delay member 14 made of a suitable material is placed in one of the two waveguide parts. The members 14 are selected to have a mutual relationship such that the waves propagating in one waveguide section are delayed by 180 degrees or an odd multiple of 180 degrees with respect to the waves propagating in the other waveguide. Made of material with electrical properties and length. When the waves that have passed through the two separate waveguide sections are superimposed, if the microwaves at each entrance of the two waveguide sections have the same phase and amplitude, then two The waves that pass through each waveguide section cancel each other out. Therefore, in the case of this measuring device, the output of the detector 12 is zero when in equilibrium, ie, when the sawn wood is uniform.

If the magnitudes or phase differences of the microwaves incident on the two waveguide sections differ due to the node or node region, a corresponding change will occur in the output from the detector 12, resulting in a non-zero output. It is easy to understand what you get. When radiating microenergy from antennas placed on opposite sides of the sawn wood, the average microwave energy transmission of the sawn wood will be A sudden change appears in the rate.
This is recognized as a clause. Similarly, by placing a transmitting antenna and a pair of receiving antennas similar to this example on the same side of the sawn wood, the microwave energy reflected from the wood can be monitored; This shows that the reflective properties of the wood change rapidly when there is an imbalance in the received energy of the receiving antenna. This reflective property is related to the surface of the wood, and the unbalanced condition in this case indicates that there are knot areas on each side of the wood that greatly affect the appearance of the sawn wood.

The dimensions of the delay element 14 are naturally related to the frequency used for the measurement. The length of this member 14 in the waveguide direction is such that the microwave propagating in the waveguide section where the member 14 is placed has a phase shift of 180 degrees or an odd multiple of 180 degrees as accurately as possible at the measurement frequency. must be chosen to receive it. Although this phase shift is determined depending on the frequency, it does not interfere with the measurement since the receiver is tuned to a predetermined frequency. Furthermore, the response characteristic curves obtained for various frequencies in equilibrium are sufficiently flat for the intended application of the device and the required accuracy.

3 and 4 show a second embodiment of the invention, in which a pair of receiving antennas are constructed as two waveguide sections 15, 16 of a waveguide, the arm sections being suitably close together. It is located. Although no extra bends are provided to simplify the drawing, the signal is received by arm portions 15 and 16 of the waveguide separated by a predetermined distance from each other, or by a horn antenna connected to these arm portions. As shown, the arm portions 15 and 16 are bent toward each other and connected in a horseshoe shape. Therefore, arm part 1
The microwave energy input from 5 and propagating reaches the center point of the horseshoe and faces the second arm portion 16 bent in the opposite direction. That is, if the microwave energies incident on the arm portions 15 and 16 are equal to each other, they will cancel out at the detector 12 located at the center of the horseshoe waveguide. The same result is obtained when the distance from the detector 12 to one end of the waveguide is longer than the distance from the detector 12 to the other end of the waveguide by an integral multiple of the wavelength.

To explain this process, electric field vectors are drawn with arrows in FIG. 3 to show the state of rotation of the vectors at the bends of the waveguide. From this illustration, it will be understood that in an equilibrium state, the electric fields are in opposite directions at the center of the horseshoe waveguide. Since the arm portions 15 and 16 of the waveguide can be arranged closer to each other if necessary, the apparatus of this embodiment also has the same structure as that shown in FIG.
It operates in exactly the same way as the device of FIG.

In the embodiment shown in FIG. 5, the energies received at both ends of the waveguide or the horn antennas connected thereto are superimposed with a phase difference of 180 degrees. The waveguide is bent at the wide side (H plane), and the detector 1
2 is placed in the waveguide at a position such that the distance to one end of the waveguide is a times a half wavelength and the distance to the other end is b times a half wavelength. b and a are odd numbers. As is known from microwave technology, if the wood to be measured is a uniform board, the output from the detector 12 is zero. In FIG. 6, the waveguide is replaced by a coaxial cable or other equivalent transmission line and a suitable antenna 17, 18 is connected at each end. In this case as well, if the coefficients b and a are odd numbers, the output from the detector 12 will be zero if the wood to be measured is a uniform board.

In Figure 7, the waveguide is also on the wide side (H plane).
The waveguide is bent to form a pair of receiving antennas, but the microwave energy input from each end of the waveguide passes through the E-plane T-junction, which is T-junctioned within the E-plane (electromagnetic wave's electric surface). It is detected by the detector 12. The length from the detector 12 to each end of the waveguide is m and n times the wavelength, and as is known from microwave technology, if m and n are integers, the wood to be measured is a uniform plate. In this case, the output of the detector 12 becomes zero.

The embodiment of FIG. 8 is for measuring reflected microwave energy according to the measuring principle. In this embodiment of the device, the transmitting and receiving antenna structures are assembled as a single device, for example by printed wiring techniques. Therefore, a device with a simple structure, low manufacturing cost, and small size can be obtained.

The transmitting antenna 21 is placed in the center of the device. In the illustrated printed circuit, the receiving antenna pair 22, 23 is arranged symmetrically with respect to the leads of the transmitting antenna. Therefore, if the reflective properties of the wood to be measured are uniform in the vicinity of both sides of the transmitting antenna, it is easy to obtain generally equal energy intensity for both pairs of receiving antennas. The interconnection of the receive antenna pair 22 and 23 is such that the microwave energy from both antenna leads has a 180 degree phase difference at the detector 12, so that the uniform reflected waves cancel each other out. be in a relationship. The transmitting antenna 21 and the pair of receiving antennas 22 and 23 are surrounded by a grounding member 25 to reduce interference between them.
This relationship is obtained when the distances from the detector 12 to the receiving antenna leads 22 and 23 are a and b times the half wavelength, respectively, and a and b are odd numbers, respectively. The transmitting antenna is connected to a suitable oscillator 24.

Transmitting antenna 21 and each receiving antenna 22, 23
When the distance between the transmitting antenna and the receiving antenna is relatively small and the input to the detector 21 is equal to the difference in the strength of the microwave energy incident on each receiving antenna, the transmitting antenna and the receiving antenna are It will be readily appreciated that a non-zero output will be obtained from the detector 12 if there is a conductor in the vicinity of the conductor.
It is known that when there is sufficient moisture in the wood being measured, such differences in reflective properties in the knot regions occur. Therefore, when the wood is conveyed past the transmitting and receiving antennas and the oscillator 24 is supplying microwave energy to the transmitting antennas,
If the detector 12 indicates an imbalance when the wood passes through the antenna pair, then the edge of the knot has passed through the antenna.

The figure shows a device in which the transmitting antenna and the receiving antenna pair are installed on the same side of the wood to be measured, that is, the device measures reflected waves from the wood, but the transmitting antenna side is disconnected and measured. It will be clear that modifications could be made to this example, such as moving to the other side of the wood and measuring the microwave energy that passes through the wood.

FIG. 9 shows an arrangement similar to FIG. 8, but in this embodiment two transmit antennas and one receive antenna are used. That is, the waves travel in the opposite direction when compared to the embodiment of FIG. This configuration is obtained by simply changing the supply from the oscillator 24 to be connected to the outer transmitting antenna conductors 26, 27 and connecting the detector 12 to the central receiving antenna 28. The method of feeding power from the oscillator 24 is similar to the detector arrangement in the previous embodiment, and the microwave energy radiated from the transmitting antenna pair has a phase difference of 180 degrees between the antenna sections on both sides.

The apparatus shown in FIG. 10 is similar in operating principle to the apparatus described above, but in this embodiment it is possible to show deviations in the grain direction of the sample, that is, the wood. antenna pair 29
and 30 are closely spaced and oriented so as to form an angle therebetween of a magnitude determined in accordance with principles described below. Antenna pair 29, 30
operates as either a transmitting antenna or a receiving antenna, but antenna 31 operates as either antenna 29 or 30.
It operates as a receiving antenna or a transmitting antenna depending on the operation of the antenna. Antennas 29 and 30 are provided symmetrically with respect to antenna 31 on either side thereof. In the reflected wave measurement, these antennas are attached to the same side of the wood 32, but in the transmitted wave measurement, the receiving antenna and the transmitting antenna are respectively placed on opposite sides of the wood to be measured. The angles of the antennas 29 and 30 are symmetrical with respect to the longitudinal plane of the antenna 31, and the angles are set so that the plane parallel to the electric field (so-called E plane) of the antennas 29 and 30 is α ₁ =−α ₂ with respect to the E plane. Form α ₁ and α ₂ . When measuring sawn wood, angles α ₁ and α ₂ are each +45 degrees,
-45 degrees is suitable.

By choosing 45 degrees like this, you can measure the maximum slope of the wood grain. This is because when the grain is slanted, the phase and amplitude of the different signals change between the signals, so the resulting difference signal increases progressively as the grain slope increases, and eventually This is because the slope is approximately at its maximum when the grain is parallel to the electric field of one antenna, i.e. at the same time when the grain is perpendicular to the electric field of the other antenna.

In addition to the above, the measurement signals of antenna pairs 29 and 30 are 180 degrees out of phase with each other. That is, the antenna pairs 29 and 30 are connected to the matching device 33 by means of a rectangular waveguide via a T-connection in the E plane, or alternatively the respective transmissions between the matching device 33 and the antenna pairs 29 and 30 are The electrical lengths of the paths are varied by half a wavelength or an odd number of half wavelengths. In this case, zero power is obtained from the receiver (neglecting noise) in equilibrium, ie when the grain of the wood to be measured passes through the active area of the antenna arranged symmetrically at equal angles. The reason for this is that at this time, the intensities of the respective signals from the wood to be measured cancel each other out due to the above-mentioned phase difference.

In addition, in the embodiments shown in FIGS. 3 to 7, even if the end of the waveguide is inclined as shown in FIG. 10, the intended purpose can be achieved if a twisted waveguide is used. You can get the configuration.

The transmitting device and corresponding receiving detector are illustrated as two "boxes" 33 and 34, although in some implementations one of 33, 34 may be the transmitter and the other may be the detector. Become.

As the wood 32 moves longitudinally relative to the detector, the deviation between the signals emitted or received by the antenna pair 29, 30 indicates a change in the quality of the wood. Depending on what you want to indicate, each unbalanced point can be shown as a flaw in the wood, a knot signal separated from the other signals, or the remaining signal can be sawn out. Indicates that the grain direction is distorted.

The microwave energy transmitter and detector 12 to be used in the apparatus of the present invention are devices familiar to those skilled in the wireless arts and do not require any special explanation. Therefore, based on the embodiments described above, it is possible to realize the present invention as defined in the claims of the present application.

Even in the case of a uniform plate, equilibrium can be broken due to slight distance differences between the antennas in an antenna pair or changes in the electrical length of the leads due to temperature changes, for example. When the leads connecting the antenna pair to the detector are of electrically unequal length,
A new equilibrium position is found by changing the transmission frequency slightly. For this purpose, for example, the transmission frequency may be continuously controlled, for example by means of an electronic device, so as to obtain a normal equilibrium state. If the time constant of the control circuit is chosen appropriately, the node will appear as a sudden increase in the control voltage, or if the time constant is small, as a sudden change in frequency.

Although the previous embodiments used a single receive antenna or a pair of receive antennas, several receive antennas may be installed in sequence to cover the entire width of the specimen or wood and to locate specific indications in close proximity. Of course, it is possible to show the knots or deviations in the grain direction at each point.

(Effects of the Invention) According to the present invention, microwaves received by a receiving antenna pair consisting of two antennas arranged close to each other are superimposed with a phase difference of 180 degrees, and this superposition is performed. The combined microwaves are detected by a detector, or the microwaves emitted with a phase difference of 180 degrees from a pair of transmitting antennas are received by a receiving antenna and detected by a detector, and then the microwaves are detected by a receiver. When the two microwave energies arriving at are equal, a zero output is obtained from the detector indicating balance, and when there is a node opposite one antenna of the antenna pair, an output different from zero is obtained.

Therefore, the wood can be distinguished immediately after it has passed through the area of action of the antenna, and automatic cutting is possible to separate and locate the valuable joints of the wood.

A preferred embodiment of the invention provides that a 180 degree phase difference is achieved by forming a waveguide whose front end portion is bisected by a separator to form two separate waveguide sections, but which communicate in front of the detector. As obtained by wave tubes, one of the separate waveguide sections is provided with a delay element which, depending on the electrical properties and length of the element, causes the microwaves propagating in one waveguide section to be delayed from the other. 180 degrees or
It is characterized by delaying by an odd multiple of 180 degrees. As a result, the signal incident on the receiving device is transmitted to the detector by means of a simple and advantageous structure.

Another embodiment of the present invention provides a method in which a 180 degree phase difference is achieved by connecting a receive antenna pair consisting of two antennas using waveguides, coaxial cables or other transmission paths of different lengths, each with a difference in electrical length of the path. is obtained by connecting to a common detector such that the measurement frequency is an odd multiple of a half wavelength. Therefore, it is possible to change the mutual spacing of the antennas. In addition, if the 180 degree phase difference is determined by connecting a pair of receiving antennas using a rectangular waveguide, the waveguide length from the antenna to the T-shaped connection point on the E plane is electrically equal or the electrical length is characterized in that it is obtained by connecting the T-junction points to a common detector in a series branch so as to differ by an integral multiple of wavelengths. This embodiment also allows the mutual spacing of the antennas to be varied.

A further embodiment of the invention is characterized in that the transmitting antenna and the receiving antenna pair are provided on the same side of the wood, the receiving antenna being arranged symmetrically on either side of the transmitting antenna. Thereby, not only the transmitting antenna but also the receiving antenna can be combined into one device. This configuration provides a simple and inexpensive device to manufacture. The device of this embodiment is for making measurements based on reflections from wood.

Yet another embodiment of the invention provides a device facing a uniform piece of wood with a 180 degree phase difference when the electrical lengths of the paths (i.e., waveguides, etc.) from the receiving antenna pair to the detector are different. A balanced state is maintained by electronically controlling the transmission frequency so as to obtain . Even if a uniform plate becomes unbalanced due to slightly different spacing of the antennas or changes in the electrical length of the path, e.g. due to temperature changes, the transmitted frequency can be e.g. Balance can be maintained with only small changes.

In another embodiment of the present invention, two transmitting antennas are provided, the microwaves from the pair of transmitting antennas have a phase difference of 180 degrees from each other, and the microwaves are received by the transmitted energy of the two transmitting antennas. The detected amount generated in the antenna is obtained as a zero output in a balanced state, and if there is a node facing any of the transmitting antennas, an output different from zero is obtained. Therefore, the device operates as before and the microwaves propagate in the opposite direction. This embodiment is suitable when the microwave energy is transmitted from a pair of antennas and received by antennas arranged symmetrically with respect to the pair. For this reason, in the mode of measurement using microwave energy transmitted through sawn wood, the transmitting antenna is placed as close as desired to one side of the wood and the receiving antenna is connected to the transmitting antenna on the other side. Place it at the midpoint of the pair. In the measurement method using reflected microwave energy from wood, a receiving antenna is placed in a suitable manner between two transmitting antennas. Since the microwave energy radiated by the transmitting antenna pair has a 180 degree phase difference, zero power is obtained at the receiving antenna for a uniform piece of wood.

Microwave energy supplied by an oscillator or equivalent is distributed to different transmitting antennas.
The transmission path that produces a phase difference of 180 degrees or an odd multiple of 180 degrees has different lengths for different antennas. Alternatively, in other modes, the phase difference is caused by the microwave energy radiated by the antenna pair. Another embodiment for creating such a phase difference, when considering possible aspects with reference to the various embodiments described above, can be found in the same way as creating the phase difference on the receiver side. realizable. It will be easy for those skilled in the art to modify the various embodiments described above so that a phase difference is generated on the transmitting antenna side.

Yet another embodiment of the invention provides that the first and second antennas constituting the antenna pair are provided symmetrically with respect to each other and inclined with respect to the third antenna of the apparatus and the main dimension of the sample, whereby the The present invention is characterized in that the amount of deviation of the grain direction from the main dimension direction is indicated by the phase difference or amplitude difference or both of the microwave range signals from the sample caused by the difference in wave direction. Therefore, according to this embodiment, the direction of the wood grain can be clarified and the wood can be distinguished. It is possible, for example, to differentiate pieces of wood, such as boards, immediately after they have passed through the antenna's active area, or to perform automatic cutting to separate and locate valuable joints in the wood. Zero output indicates that the board is uniform and the grain is straight in each area.

It is preferable that the angle at which the antenna pair is attached symmetrically and obliquely to the direction of the plate and the third antenna is 45 degrees.

[Brief explanation of the drawing]

1 and 2 are diagrams showing one embodiment of the receiving antenna of the device of the present invention, FIGS. 3 and 4 are diagrams showing other embodiments of the receiving antenna of the device of the present invention, and FIG.
7 to 7 are diagrams showing various embodiments of receiving antennas, FIGS. 8 and 9 are diagrams showing other embodiments of the present invention in which a transmitting antenna and a receiving antenna are configured as a single device, and FIGS. FIG. 10 is a diagram showing an embodiment of the device of the present invention applied to the measurement of the grain direction.

Claims (1)

[Claims] 1. A transmitting/receiving antenna device having a receiving antenna pair consisting of one transmitting antenna for microwave transmission and two receiving antennas arranged close to each other, or a plurality of such transmitting/receiving antenna devices. A combination of transmitting/receiving antenna devices is provided, and microwaves emitted from the transmitting antenna, transmitted through or reflected from the wood to be observed, and received by the receiving antenna pair of the transmitting/receiving antenna device or the transmitting/receiving antenna device group. A wood observation device that classifies wood by sensing the presence of knots in the wood when a sudden change of a predetermined magnitude occurs in at least one of amplitude, intensity, and phase, the receiving device The microwaves received by the two antennas of the antenna pair are superimposed with a phase difference of 180 degrees, the superimposed microwaves are detected by a detector, and the microwaves received by the two antennas of the receiving antenna pair are detected by a detector.
When either of the two receiving antennas is facing a solid part of the wood to be observed, the output from the detector is substantially zero, indicating an equilibrium state; A wood observation device using microwaves, characterized in that when facing a knot in observed wood, the presence of a knot is detected by the output from the detector showing a value different from zero. 2. In the device according to claim 1, the receiving antenna pair is constituted by a waveguide 11, and the front end portion of the waveguide 11 is divided into two by a separating material 13 in the H plane. Two separate waveguide sections are formed to form the receiving antenna pair and communicate with each other in front of the detector 12, one of the two waveguide sections having a delay member. 14 is provided, the delay member 14
By delaying the microwaves propagating in one waveguide section by 180 degrees or an odd multiple of 180 degrees with respect to the microwaves propagating in the other waveguide section, depending on the electrical properties and length of the waveguide section. A microwave wood observation device characterized by being configured to obtain a phase difference of 180 degrees. 3. The apparatus of claim 1, wherein the receiving antenna pairs are connected to the detector 12 using waveguides, coaxial cables, or other transmission paths of different lengths, and each receiving antenna pair is A microwave characterized in that the 180 degree phase difference is obtained by setting the electrical length difference from the microwave to the detector to be an odd multiple of a half wavelength of the microwave to be measured. Wood observation device by. 4. The device according to claim 1, wherein the 180 degree phase difference connects the receiving antenna pair to the detector in a series branch of a T-shaped junction in the E plane using a waveguide. The 180 degree phase difference is obtained by connecting the antennas and making sure that the electrical lengths of the waveguides from each antenna to the connection point are equal or different by an integral multiple of the wavelength. A microwave-based wood observation device. 5. In the device according to claim 1, 3, or 4, the transmitting antenna 21 and the receiving antenna pair 22, 23 are provided on the same side of the observed wood, and the receiving antenna pair A wood observation device using microwaves, characterized in that the two antennas are symmetrically provided on both sides of the transmitting antenna. 6. In the device according to claim 1, 3, or 5, when the waveguides or transmission paths from the receiving antenna pair to the detector 12 have electrically different lengths, A wood observation device using microwaves, characterized in that it is configured to maintain an equilibrium position by electronically controlling the microwave frequency so that the 180 degree phase difference is obtained for uniform wood. . 7 Claims 1 and 3 to 6
In the apparatus according to any one of the above items, the first and second antennas 29 and 30 constituting the receiving antenna pair are symmetrical to each other, and the third antenna for transmitting
The antenna 31 is provided at an angle with respect to the main plane of the observed wood, thereby eliminating the phase difference between the microwaves from the observed wood caused by the difference in polarization direction between the first and second antennas. 1. A microwave-based wood observation device, characterized in that it is configured to indicate the amount of deviation of the grain direction from the main surface direction by an amplitude difference or both. 8. In the device set forth in claim 7, the receiving antenna pair 29, 30 is installed symmetrically and obliquely with respect to the direction of the observed wood 32 and the third antenna 31 at an angle of 45 degrees. A characteristic microwave wood observation device. 9. Wood observation using microwaves in the apparatus according to claim 7 or 8, wherein the first, second, and third antennas 29, 30, and 31 are horn antennas. Device. 10 2 for microwave transmission placed in close proximity
A transmitting/receiving antenna device having a transmitting antenna pair consisting of two antennas and one receiving antenna, or a transmitting/receiving antenna device group combining a plurality of such transmitting/receiving antenna devices. When a sudden change of a predetermined magnitude occurs in at least one of the amplitude, intensity, and phase of the microwave transmitted through or reflected from the observed wood and received by the receiving antenna. The wood observation device detects the presence of knots in the wood to classify the wood, and the device sends microwaves emitted from each antenna of the pair of transmitting antennas with a phase difference of 180° to the receiving antenna. Therefore, when the simultaneously received waves are detected by a detector, and both of the two antennas of the transmitting antenna pair are facing a knotless part of the wood to be observed, the output from the detector is substantially The output from the detector exhibits a value different from zero when one of the antennas of the pair of transmitting antennas is facing the node of the observed wood. A microwave-based wood observation device characterized by detecting the presence of wood. 11. In the device according to claim 10, the transmitting antenna pair is constituted by a waveguide, and the front end portion of the waveguide is divided into two in the H plane by a separating material. The two separate waveguide sections are formed so as to form the transmitting antenna pair and to communicate with each other in front of the microwave transmitting section to the transmitting antenna pair, and one of the two waveguide sections A delay member is provided on one side of the waveguide, and depending on the electrical properties and length of the member, the microwave propagating in the one waveguide section is delayed by 180 degrees or 180 degrees with respect to the microwave propagating in the other waveguide section. A wood observation device using microwaves, characterized in that the device is configured to obtain the phase difference of 180 degrees by delaying by an odd number of degrees. 12. The apparatus of claim 10, wherein the pair of transmitting antennas are connected to a common oscillator using waveguides, coaxial cables, or other transmission paths of different lengths, and Microwave-generated wood characterized in that the 180 degree phase difference is obtained by setting the electrical length difference to the oscillator to be an odd multiple of a half wavelength of the measurement microwave. Observation equipment. 13. The apparatus of claim 10, wherein the 180 degree phase difference is achieved by connecting the transmitting antenna pair to the oscillator via a T-type connection in the E plane using a waveguide; A microwave characterized in that the electrical length from each transmitting antenna to the T-type connection is made equal to each other or different by an integral multiple of a wavelength to obtain the 180 degree phase difference. Wood observation device by. 14. In the device according to claim 10, 12, or 13, the transmitting antenna pair and the receiving antenna are provided on the same side of the observed wood, and the two antennas of the transmitting antenna pair A wood observation device using microwaves, characterized in that the antennas are arranged symmetrically on both sides of the receiving antenna. 15. In the device according to claim 10, 12 or 14, when each path from the oscillator to the two antennas of the transmitting antenna pair has a different electrical length, In the above
A microwave-based wood observation device characterized by being configured so that an equilibrium state is maintained by electronically controlling the transmitting microwave frequency so as to obtain a phase difference of 180 degrees. 16. In the device according to any one of claims 10 and 12 to 15, the first and second antennas 29 and 30 constituting the transmitting antenna pair are symmetrical to each other. and is provided at an angle with respect to the third reception antenna 31 and the main surface of the observed wood, thereby preventing the observed wood from being generated due to the difference in polarization direction between the first and second antennas. 1. A wood observation device using microwaves, characterized in that the device is configured to indicate the amount of deviation of the direction of the wood grain from the direction of the principal surface by the phase difference or amplitude difference or both of the microwaves. 17. In the device according to claim 16, the transmitting antenna pair 29, 30 is installed symmetrically and obliquely with respect to the direction of the observed wood 32 and the third antenna 31 at an angle of 45 degrees. A characteristic microwave wood observation device. 18. Wood observation using microwaves in the apparatus according to claim 16 or 17, wherein the first, second, and third antennas 29, 30, and 31 are horn antennas. Device.