JPS641631Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an apparatus for measuring the moisture content and basis weight of paper, fibers, etc., using microwaves.

As is well known, in this type of device, as shown in FIG. The antenna 13 provided in the receiving unit 13 receives microwaves frequency-modulated by sawtooth waves radiated from the antenna 12 ₁ provided in the receiver 13.
₁ , the moisture contained in the sheet-like object 14 to be measured is measured from the amount of attenuation of this microwave, and the basis weight is measured from the change in the resonance frequency of the cavity resonator.

By the way, there is a direction in which the fibers of paper and cloth line up.
It is known that microwave loss changes depending on the direction of the fiber and the direction of the microwave electric field. That is, in the conventional device, the transmitter 12
Since the microwaves emitted from the microwave are linearly polarized waves, if the direction of the fiber is parallel to the direction of the electric field shown by the solid line 21 in Figure 2, as shown by the dotted line 22 in the same figure, there will be a lot of loss. If the direction of the fibers is perpendicular to the direction of the electric field 21, as shown by the dotted line 23 in the figure, the loss will be reduced. Therefore, there is a disadvantage that the measured value changes depending on the direction of the fibers of the sheet-like object 14 for wave measurement.

This idea was made based on the above circumstances, and its purpose is to arrange first and second cavity resonators adjacent to each other in which the direction of the microwave electric field differs by 90 degrees, and to , by averaging the microwave attenuation measured by the second cavity resonator and the resonant frequency of the cavity resonator, the sheet can be accurately measured without being affected by the fiber direction of the sheet-like object. Moisture content of a sheet-like object that allows measurement of moisture content and basis weight of the sheet-like object,
The present invention aims to provide a basis weight measuring device.

An embodiment of this invention will be described below with reference to the drawings.

In FIG. 3, first and second cavity resonators 3
1 and 32 are arranged adjacent to each other. These first and second cavity resonators 31 and 32 are the first and second transmitting sections 31 ₁ and 32 1 and the first and second transmitting sections 31 ₁ and 32 1 respectively.
It consists of receiving sections 31 ₂ and 32 ₂ . These first and second transmitters 31 ₁ , 32 ₁ and the first and second transmitters 31 1 , 32 1 and
The receiving sections 31 ₂ and 32 ₂ are separated by a predetermined distance, and a sheet-like object 33 is inserted between them. Further, the first and second transmitting sections 31 ₁ and 32 ₁ are provided with transmitting antennas 34 1 and 34 ₁ orthogonally, respectively.
35 ₁ is provided, and the first and second receiving sections 31 ₂ , 3
2 ₂ is provided with receiving antennas 34 ₂ and 35 ₂ that are parallel to the antennas 34 ₁ and 35 ₁ of the corresponding transmitting sections 31 ₁ and 32 ₁ , respectively.

In the above configuration, when measuring the moisture content and basis weight of the sheet-like object 33, first, the first and second
transmitting sections 31 ₁ , 32 ₁ and first and second receiving sections 31
A sheet-like object 33 is inserted between ₂ and 32 ₂ , and in this state, microwaves frequency-modulated by sawtooth waves are radiated to the transmitting antennas 34 ₁ and 35 ₁ . The directions of the electric fields of these microwaves are different from each other by 90° inside the first and second cavity resonators 31 and 32. The microwaves radiated in this manner are received by the receiving antennas 34 ₂ and 35 ₂ of the first and second receiving sections 31 ₂ and 32 ₂ , respectively. Each of the received microwaves is displayed on an oscilloscope via a detector (not shown), and the attenuation of the microwave and the resonant frequency of the cavity resonator are determined from the screen of the oscilloscope. Measurements are made corresponding to the resonators 31 and 32. Then, the average value of these measured attenuation amounts is determined to determine the moisture content of the sheet-like object, and further, the average value of the measured resonance frequencies is determined to determine the basis weight of the sheet-like object 33. .

In this way, by averaging the attenuation amount and resonance frequency measured by microwaves whose electric field directions are different from each other by 90 degrees, it is possible to calculate the
The moisture content and basis weight of the sheet-like object 33 can be measured accurately.

In the above embodiment, the sheet-like object was sampled and measured, but it is also possible to install this device in, for example, a paper manufacturing process and measure running paper online.

Further, although an oscilloscope was used to measure the attenuation amount and resonance frequency of the microwave, the present invention is not limited to this. For example, the amount of attenuation can be determined by performing peak value detection on the output signals of the receiving antennas 34 ₂ and 35 ₂ . Furthermore, the resonance frequency can be measured by supplying the detection output signal to a frequency discrimination circuit or a frequency/voltage converter. Furthermore, the microwave attenuation and resonance frequency obtained for each cavity resonator 31, 32 in this way are converted into digital data, and this converted data is converted into an average value formed by an adder and a shift register, for example. By supplying it to an arithmetic circuit, the attenuation amount and resonance frequency can be automatically determined.

It goes without saying that various other modifications can be made without departing from the gist of the invention.

As detailed above, according to this invention, the moisture content of a sheet-like object allows accurate measurement of the moisture content and basis weight of the sheet-like object without being affected by the fiber direction of the sheet-like object. , a basis weight measuring device can be provided.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram showing an example of a conventional apparatus for measuring moisture content and basis weight of sheet-like objects, Figure 2 is a diagram shown to explain the relationship between the direction of the electric field and the direction of the fibers, and Figure 3 is FIG. 1 is a configuration diagram showing an embodiment of a moisture content and basis weight measuring device for a sheet-like object according to this invention. 31, 32...first and second cavity resonators, 31
₁ , 32 ₁ ...first and second transmitting sections, 31 ₂ , 32 ₂
...first and second receiving sections, 34 ₁ , 34 ₂ , 35 ₁ ,
35 ₂ ...Antenna, 33...Sheet-like object.

Claims (1)

[Scope of utility model registration request] Consisting of a first transmitter to which microwaves are supplied, and a first receiver to receive the microwaves supplied to the first transmitter, these first transmitters,
A first part in which a sheet-like object is inserted between the receiving parts.
a cavity resonator; a second transmitting unit to which microwaves are supplied with electric field directions that are 90° different from those of the microwaves supplied to the first transmitting unit; a second receiving section that receives microwaves; a second cavity resonator in which the sheet-like object is inserted between the second transmitting section and the receiving section; a first measuring means for measuring the moisture content of the sheet-like object by averaging the attenuation of the microwaves received by the receiving sections; and second measuring means for determining the average of the resonant frequencies of the first and second cavity resonators and measuring the basis weight of the sheet-like object. Quantity measuring device.