JPH051992A - Characteristic measuring device for sheet-like objects - Google Patents

Abstract

(57) [Summary] [Purpose] From thin paper to thick paper, transmission and scattering by paper are sufficiently performed, sensitivity is high, light attenuation is small, and measurement error is small with respect to axis deviation in the horizontal plane. Provided is a device for measuring the characteristics of a dovetail-shaped object. A sheet having a light receiving element for receiving light from a light projecting part through a sheet-shaped object, and measuring a physical characteristic of the sheet-shaped object based on a signal from the light receiving element. In a device for measuring characteristics of a sheet-shaped object, an upper reflector 30 and a lower reflector 31 each having a folded portion around the sheet-shaped object 3 are arranged, and both surfaces are provided between the sheet-shaped object and the lower reflector. A shield plate 32 having a mirror finish is arranged. Also,
A lens is provided to reduce the transmitted light by narrowing the transmitted light to reduce the return light and to make the outer diameters of the upper and lower reflection plates different. Also, the outer diameter is made variable, or the upper and lower reflectors are made rectangular so that the length of one is shorter than that of the other reflector and the long sides are arranged in the paper flow direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the amount of water contained in a sheet-like object.

[0002]

12 to 14 show a conventional example of a moisture meter for measuring the moisture content of a sheet-like object in a paper machine or the like.

In FIG. 12, 1 is a light projecting portion and 2 is a light receiving portion, which are arranged so as to face each other with a paper 3 as a measured object interposed therebetween. In the light projecting unit 1, the light from the light source 6 is collimated by the lens 7 and is made into intermittent light by the chopper / wheel 8, and then the paper 3 is irradiated through the irradiation window 4. The chopper / wheel 8 is absorbed by moisture 1.94μ
A filter 9 that transmits m light (M light) and a filter 10 that transmits 1.8 μm light (R light) that is not absorbed by moisture are provided, and the M light and the R light are alternately rotated according to the rotation. Irradiate the paper 3. In the light receiving section 2, the light transmitted through the paper 3 enters through the entrance window 5, is focused by the lens 11, and is received by the light receiving element 12.
Is focused on. The light receiving element 12 detects the M light and the R light in time series, gives them to the calculator 13 and calculates and outputs R / M.

In the conventional example shown in FIG. 13, the light from the light source 6 in the light projecting unit 1 is collimated by the lens 7 and the chopper
・ After making intermittent light with the wheel 8, irradiate the paper 3 through the irradiation window 4. The chopper / wheel 8 is not equipped with a filter as in the conventional example of FIG. 9, and the wheel is used only for removing the influence of stray light. Irradiation window 4
The white light emitted from the light source 3 is reflected multiple times across the paper 3 by the irregular reflection surfaces 16 and 17 provided on the opposing surfaces of the light projecting portion 1 and the light receiving portion 2, and an incident window provided at a position displaced from the irradiation window 4. It enters the light receiving part 2 from 5.

In the light receiving section 2, the incident light is divided into two by a beam splitter 18, one of which is guided to a light receiving element 12 through a filter 9 and a lens 11 which transmit M light, and the other of which is R.
The light is guided to the light receiving element 12 'through the filter 10 that transmits light and the lens 11'. The M light detected by the light receiving element 12 and the R light detected by the light receiving element 12 'are simultaneously given to the arithmetic unit 13, and the R / M calculation is performed and output.

FIG. 14 shows another embodiment of the prior art in which spherical mirrors 20 and 21 whose openings are covered with dustproof glasses 22 and 23 sandwiching the paper 3 are arranged. In this example, the light emitted from the light source 6 and interrupted by the chopper wheel 8 having the two types of filters is applied to the paper 3 through the irradiation window 5. Then, the light transmitted through the paper 3 or scattered by the paper is reflected by the inner surface of the sphere and irradiates the paper again, so that the light is transmitted through the paper a plurality of times and reaches the light receiving element 12. Similar to the example shown in FIG. 12, the detected light is subjected to R / M calculation by a calculator (not shown), and an electric signal related to the water content of the paper is output.

[0007]

Among the above-mentioned conventional devices, the structure shown in FIG. 12 has the advantages that the structure is simple and the attenuation of the light amount is small, but the object to be measured is one sheet of paper. If the paper is thin, there is a problem that it is not possible to obtain a highly sensitive one. Also, in the structure shown in FIG. 13, the light axes of the light projecting section and the light receiving section are offset from each other. Although the number of times of meeting with the paper increases, considering that the light scattered by the paper has a maximum spread of 180 °, the light that only meets with the paper once is included, and the sensitivity is not always satisfactory. It was In addition, there is a problem that the amount of light decreases when the amount of deviation of the optical axis is increased in order to reduce the effect of the transmitted light once (in the conventional example, the amount of deviation of the optical axis of the light projecting unit and the light receiving unit is about 60 mm. , The distance between the upper and lower reflectors is designed to be about 6 to 8 mm).

Further, in the case of the structure shown in FIG. 14, the light that has been transmitted and scattered by the paper a small number of times (light of low sensitivity that does not sufficiently associate with water molecules) is also included in the detection light. However, there is a problem that the moisture detection sensitivity is low. Furthermore, this method has a problem that the sensitivity of the thin paper and the thickness of the thick paper are different from each other, so that the influence of the paper quality becomes large. Further, in the above-mentioned conventional example, when the head for housing the light projecting portion and the light receiving portion is misaligned in the horizontal plane, an error is large, and mechanical and electrical correction means are required to correct the error. There was a problem. The present invention was made in order to solve the above-mentioned problems of the prior art. The thin and thick papers are sufficiently transmitted / scattered by the paper, and the sensitivity is high, the light attenuation is small, and the axis in the horizontal plane is small. It is an object of the present invention to provide a device having a small measurement error with respect to a deviation.

[0009]

According to a first aspect of the present invention for solving the above-mentioned problems, a light-receiving element for receiving light from a light-projecting portion through a sheet-like object is provided. A sheet-shaped object characteristic measuring device for measuring physical characteristics of the sheet-shaped object based on a signal from the light-receiving element, wherein an upper portion having a folded-back portion around the sheet-shaped object A reflecting plate and a lower reflecting plate are arranged, and a shielding plate having both surfaces mirror-finished is arranged between the sheet-like object and the lower reflecting plate.

According to a second aspect of the present invention, the light projecting section has a light source, a first means for collimating the light from the light source into parallel light, and a second means for narrowing the parallel light, and the light projecting from the upper reflector. It is characterized in that the diameter of the hole is formed so as not to be blocked near the focal point of the light narrowed down by the second means. Is characterized by having different outer diameters,

According to a fourth aspect of the present invention, the upper reflector and the lower reflector are formed in a rectangular shape or an elliptical shape, and at least one of the long sides and the short sides of the upper reflector and the lower reflector is one of the long sides. It is characterized in that it is formed to be short with respect to the plate, and its long side is arranged in the paper flow direction and its short side is arranged in a direction perpendicular to the paper flow.
It is characterized in that the ring diameter of at least one of the folded portions of the upper reflector and the lower reflector is made variable.

[0012]

According to the present invention, the light incident from the light projecting portion is transmitted through the paper or scattered by the paper and spreads in the outer peripheral direction between the upper reflection plate and the shielding plate. The light further propagates in the outer peripheral direction while repeating transmission / scattering between the upper reflecting plate, the paper, and the lower reflecting plate, is reflected by the folded portion, and further propagates / scattering toward the central portion. A part of this light is reflected by the lower reflection plate, then circulates to the back side of the shielding plate and is reflected between the lower reflection plate and the shielding plate to reach the light receiving element.

In the second aspect, the light from the light source
Since the light is reduced by the means and the light projecting hole of the upper reflection plate is formed so small that it does not block near the focal point of the light, the return light of the light reflected by the paper is reduced, and the effective reflection of the upper reflection plate on the paper is reduced. The area increases.

In the third aspect, since the upper reflector and the lower reflector are discs and have different outer diameters, the detected light amount is constant even if the axis is deviated. In the fourth aspect, since the upper and lower reflectors are rectangular and the short sides thereof are arranged at right angles to the paper flow direction, the measurement width can be reduced without lowering the sensitivity. In claim 5, since the ring diameter of at least one of the folded portions of the upper reflection plate and the lower reflection plate is made variable, it is possible to measure moisture from low basis weight paper to high basis weight paper without being affected by the basis weight. Is.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a cross section of a main part of an embodiment of the device of the present invention.
In the figure, reference numeral 30 denotes a mirror-finished upper reflecting plate on the side facing the paper, a light projecting hole 30a is formed in the center, and a folding ring 30b is formed on the outer peripheral portion. The folded ring 30b is a convex ring, and the inner circumference thereof has a hypotenuse whose cross section is about 60 ° with respect to the perpendicular of the mirror surface. Reference numeral 31 denotes a lower reflector having a mirror-finished side facing the paper, a light receiving hole 31a formed at the center, and a folded ring 31 at the outer peripheral portion.
b is formed. The folded ring 31b is a convex ring, and the inner periphery thereof has a hypotenuse having a cross section of about 60 ° with respect to the perpendicular of the mirror surface.

Reference numeral 32 is a shield plate having both surfaces mirror-finished and a conical protrusion (conical mirror) 33 whose surface is mirror-finished at the center of one surface. The shielding plate 32 has a plurality of columns (not shown) in the space between the lower reflection plate 31 and the paper 3.
Is fixed at the same height as the upper part of the folding ring 31b of the lower reflector, and the conical mirror 33 is arranged so as to face the light receiving hole 31a. The center of the shielding plate 32 is preferably aligned with the axes of the upper and lower reflection plates 30 and 31.

The upper and lower reflectors 30 and 31 are arranged as close as possible in consideration of the required allowable width with the paper 3 whose moisture content is to be measured sandwiched therebetween, and the light projecting space 34 and the light receiving space 35 are arranged. To form. FIG. 2 is a sectional view showing an embodiment according to claim 2 of the present invention. The same elements as those in FIG. 1 are designated by the same reference numerals, and overlapping description will be omitted. In FIG. 2, reference numeral 40 denotes a first light source 6 arranged inside, and a spherical reflecting mirror 41 and a first lens 7 arranged with the light source 6 interposed therebetween.
It is a cylinder. Reference numeral 42 denotes a second cylindrical body having one end fixed near the center of the upper reflecting plate 30 and having a second lens 7a inside thereof, and the other end having the first cylindrical body 40 through the chopper wheel 8.
Is arranged to face one end of the. At least two filters 10 provided in the chopper filter 8 are provided, and M light having a wavelength of 1.94 μm which is absorbed by water and water which is not absorbed by water as in the conventional example. It transmits R light of 8 μm. Here, the second lens 7a
The mounting position is preferably such that the focal point of the lens is located at the center of the exit of the light projecting hole 30a provided in the upper reflecting plate, and the diameter of the light projecting hole 30a is as small as possible so as not to block the condensed light. Form small.

In the above structure, the light emitted from the light source 6 including the light reflected by the spherical reflecting mirror 41 is included in the first lens 7
Is collimated into a parallel light beam, travels through the filter 10 provided on the chopper wheel 8 to the second cylindrical body 42, is narrowed down by the second lens 7a, and reaches the paper 3 through the light projecting hole 30a. In that case, a part of the light reflected by the paper 3 becomes return light and returns to the light source 6 side through the light projecting hole 30a. However, in the present invention, the diameter of the light projecting hole is formed small. The amount of returned light is reduced, and the amount of light received by the light receiving element 12 can be increased. Moreover, since the light projecting hole is small, the effective reflection area of the upper reflector 30 is large. as a result,
The number of times the light associates with the paper 3 increases, and the moisture detection sensitivity increases. Although not shown in the figure, the light receiving element 12 is provided in the subsequent stage with components necessary for the moisture measuring device, such as a computing unit for computing the moisture content based on the output of this element.

In such a structure, of the light radiated onto the paper surface from the light projecting portion, the light scattered on the surface of the paper is reflected by the upper reflecting plate 30, and the transmitted light is reflected by the shielding plate 32, and again the paper 3 is reflected. Returned to. The light thus transmitted / scattered by the paper 3 and propagated to the surroundings is mainly reflected by the reflection surface of the upper reflection plate 30 and returned to the central portion, and further transmitted / scattered by the paper 3 to be repeatedly received. Reach Cylinder mirror 3 under the shield 32
3 functions to effectively guide the light that has arrived to the light receiving element 12.

The applicant of the present invention has adopted the upper and lower reflectors 3
The outer diameter of 0, 31 is 60mm, and the upper folding ring 30a
Ring height h₁2.5mm, bottom folded ring 31
b ring height h₂5.0mm, folding ring 30
Gap between a and 30b and paper h ₃, H_FourRespectively 2.
0 mm, the diameter of the shading plate is 30 mm, paper from the surface of the shading plate
To 2.0 mm, the diameter of the light emitting hole is 3 mm, and the light receiving
The diameter of the hole was set to 18 mm, and the other conditions were the same.
I conducted an experiment.

FIGS. 3 and 4 show measurement signals (R / M) of six types of paper using the conventional apparatus shown in FIG. 10 and the apparatus of the present invention.
MW (moisture weight per unit area) is calculated from these values, and the moisture content of the paper (MW / BW × 100% ... BW = paper weight per unit area) is calculated from these values, with an accuracy of ± 0.1%. It shows the calibration curve when it is possible to measure within the range (Note that the accuracy of ± 0.1% here means that the measurement error is 4 when the water content is 5%, for example. .9
% To 5.1%, and (R / M) N is standardized based on the signal when there is no paper). That is, in the conventional apparatus, as shown in FIG. 3, five calibration curves were required to obtain an accuracy of ± 0.1%, but in the apparatus of the present invention, three calibration curves are required as shown in FIG. Can be measured at.

Generally, in the case of measuring the moisture content of paper online, the light emitting section and the light receiving section are arranged on two arms parallel to the paper, the paper runs between the arms, and the paper is further projected. The light section and the light receiving section run along the arm in a direction perpendicular to the running direction of the paper in order to measure the entire width of the paper. Therefore, the positions of the upper reflecting plate 30 arranged on the light projecting side and the lower reflecting plate 31 arranged on the light receiving side do not always coincide with each other, and for example, a shift occurs in the horizontal or vertical direction. Since a measurement error occurs when such a deviation occurs, various electrical and mechanical correction means have been proposed conventionally. And
Also in the structure of claim 1 of the present invention, the occurrence of a similar error due to such a shift is smaller than that of the conventional example, but some influence cannot be avoided. That is, when the upper and lower reflectors 30 and 31 are displaced in the horizontal direction, the effect of confining light deteriorates and the reflection condition with respect to the shield plate 32 also changes, so the amount of detected light decreases and the sensitivity also decreases.

FIG. 5 is a sectional view showing an embodiment of claim 3, which is intended to improve the horizontal deviation. The outer diameter of the upper reflector 30 is smaller than that of the lower reflector 31. Formed small. The lower reflector 31 is necessary to increase the amount of detected light, but since moisture detection is performed within the plane where the upper and lower surfaces are combined, the moisture measurement range is within the range of the upper reflector 30. According to the above configuration, as long as the upper reflector 30 moves in the horizontal direction inside the lower reflector 31, the moisture detection sensitivity and the light amount are maintained constant.

6 and 7 show upper and lower reflectors 30 and 31.
FIG. 6 shows the relationship between the deviation amount and the moisture content error when the outer diameters of the two are formed to have the same size (FIG. 6) and when the outer diameter of the upper reflector 30 is smaller than the outer diameter of the lower reflector 31 (FIG. 7). This is an example of an experiment using six kinds of paper inside, and the lower head is fixed, the upper head is moved by 1 mm from the center to obtain a signal, and the moisture content (MW / BW × 100% ... MW =
This is the result of obtaining the water content error per unit area, BW = paper weight per unit area), and obtaining the water content error based on the water content when there is no deviation (the axes match).

As is apparent from these figures, the running characteristics can be greatly improved by changing the diameters of the upper and lower reflectors 30 and 31 (generally, the deviation of the upper and lower heads is about ± 1.5 mm). However, in Fig. 6, the tracing papers NO.1 and NO.2 have an error of more than 0.2% with respect to the deviation of 2 mm, whereas in Fig. 7, all the papers are 0 when the deviation is 2 mm. Within the error of 0.2%, the moisture content error is improved).

In the experiment, the upper and lower reflectors 30 and 3
The outer diameters D ₁ and D ₂ of ₁ are both 40 mm,
The outer diameter D ₁ of the upper reflector 30 is 40 mm, the lower reflector 31
With an outer diameter D ₂ of 50 mm, the projection diameter d ₁ ,
Light receiving diameter d ₂ and shield plate diameter d ₃ are 3 mm and 18 m, respectively.
m and 22 mm were used as common dimensions. Also, the folding ring 3
The height h of the ring of 0a is 2.5 mm, the height h ₂ of the ring of the lower folding ring 30 b is 5.0 mm, the gaps h ₃ and h ₄ from the folding rings 30 a and 30 b to the paper are 2.0 mm, and the light is shielded. The diameter of the plate was 30 mm, and the gap from the surface of the light shielding plate to the paper was 2.0 mm.

FIG. 8 is a sectional perspective view showing an embodiment of claim 4 of the present invention in which the measurement width is shortened without decreasing the sensitivity. The same elements as those in FIG. 1 are designated by the same reference numerals, and overlapping description will be omitted. In this embodiment, the upper and lower reflectors are formed in a rectangular shape, and the upper reflector 30 has a long side length of 140 mm and a short side length of 40 mm.
The length of the long side of 1 is 150 mm, and the length of the short side is 50 mm. Heights h ₁ , h of the folding rings 30b, 31b
₂ is 9.6 mm from the reflecting surface for both the upper and lower reflectors. The diameter of the light projecting hole 30a is 3 mm, and the light receiving hole 31a is
Has a diameter of 18 mm. Further, in this example, the shield plate 3
2 has a square shape with one side of about 40 mm, both sides of the lower reflection plate 31 in the longitudinal direction are concave, and are bent in the shape of the end spread, and the bent portion is brought into contact with the lower reflection plate, and the opening is formed. Is fixed near the center of the lower reflector so that it is located in the paper flow direction. The device also fixes its longitudinal direction to the mounting head along the stream of paper.

With the above arrangement, the transmitted / scattered light does not enter from the width direction of the paper, and only the light transmitted / scattered along the opening in the flow direction of the paper is received. Generally, when measuring the water content of paper online, the measurement width in the paper width direction is more important than the measurement width in the paper flow direction. In this configuration, the width is short in the paper width direction and long in the paper flow direction, so the measurement width can be shortened without lowering the detection sensitivity. Although the upper reflector and the lower reflector are shown as rectangles in this embodiment, they may be formed in an elliptical shape with long sides being straight and short sides being semicircular.

9 (a) and 9 (b) are perspective views showing essential parts of an embodiment of claim 5 of the present invention. The embodiment of claim 1 has the following drawbacks because the diameter of the folded ring is fixed. That is, the diameter of the folded ring determines the number of times light propagates with the paper (propagation distance). Therefore, in low basis weight paper, when the ring diameter is large, the propagation distance increases and the sensitivity improves, and when the ring diameter is small, the sensitivity decreases. Also, in the case of high basis weight paper, when the ring diameter is large, the sensitivity does not change so much and the light quantity decreases and measurement becomes impossible. When the ring diameter is small, the light quantity increases.

In this example, the lower reflecting plate 31 and the folding ring 31b are formed as separate parts, and the folding ring 31 is divided into four equal parts. (A) The figure shows the folded ring 31b
The inner diameter D ₃ of the minimum condition, the outer periphery of the folded rings 31b in this state is positioned on the inner peripheral side of the lower reflector 31. FIG. 6B shows a state in which the ring diameter D ₃ is maximized, and the outer diameter D ₂ ′ of the ring matches the outer shape D ₂ of the lower reflector 31. In this case, a gap is created between the adjacent rings, but the gap is filled with the movable reflecting plate built into the folded ring. A mechanism for retracting or advancing the folding ring and moving the reflecting plate in and out of the split ring according to the gap can be manufactured by a known technique.

In the above structure, the folding ring 31b
High grammage paper (eg 200g / m ² )
The diameter of the folded ring (for example, 60 m) that can be used to obtain a sufficient amount of received light and a sufficient moisture detection sensitivity.
m) is determined. The ring diameter is the minimum diameter (the split ring has no gap). Next, the folding ring diameter (for example, 80 mm) is determined by using the paper with the lowest basis weight (for example, 20 g / m ² ) to obtain sufficient moisture detection sensitivity, and the maximum ring diameter is determined (the lower reflecting plate 31 is the folding ring. The outer diameter is determined according to the maximum diameter of the. The ring diameter is determined each time according to the basis weight of the paper, but the ring diameter refers to the cellulose (fiber) signal of the moisture meter. While deciding.

FIG. 10 and FIG. 11 show that when measuring the water content of low basis weight paper and high basis weight paper, it is possible to adjust the loop diameter by fixing the folded ring diameter (FIG. 10) and by changing the ring diameter each time. Fig. 11 shows the relationship between the indicated value and the water content (calibration curve) in the case of (Fig. 11). When the ring diameter is fixed, the respective calibration curves are relatively distant, but the ring diameter is variable. It shows that the calibration curve can be brought closer when it is adjustable and adjusted according to the basis weight, and only one calibration curve is required. The folding ring diameter may be changed stepwise according to the basis weight of the paper instead of being continuous. Further, in this embodiment, an example in which the ring diameter of the lower reflector is made variable is shown, but the folded ring diameter of the upper reflector may be made variable, or both the upper and lower folded ring diameters may be made variable.

[0033]

According to the present invention as specifically described in connection with the above embodiments, the light incident from the light projecting hole first transmits or scatters through the paper, but these lights are shielded and the upper reflector. Reflects between and associates with the paper multiple times. Then, when the light reaches the outer circumference of the shield plate, a part of the light reaches the light receiving element while repeatedly wrapping around the lower reflector and the back side of the shield plate and being reflected. On the other hand, the light that repeatedly associates with the paper toward the outer periphery of the reflector plate is returned by the folding ring and reaches the outer periphery of the shield plate again. . As a result, light with low moisture detection sensitivity that has passed through the paper only once does not reach the light receiving element side, so that the sensitivity is improved. The structure that returns the light to the light receiving element side (center direction) by the folding ring enhances the light confinement effect, and the amount of detected light is large, and the low basis weight paper (for example, about 30 g / m ² ) to high basis weight (for example, 150 g / M
Up to about ² ) can be measured with the same optical system. Light that is sufficiently associated with water molecules and that is sufficiently transmitted and scattered by paper from thin paper to thick paper is detected.
The influence of paper quality is reduced. Since the light is returned by the return ring, a small measurement area is required to obtain light with the same optical path length as in the past. Since the optical system of the upper and lower reflectors has a circular structure, it has excellent running characteristics with little influence when the head is displaced in the horizontal direction, and the outer diameters of the upper and lower reflectors are The difference can further reduce the occurrence of error. By making the upper and lower reflectors rectangular and arranging their short sides at right angles to the paper flow direction, the measurement width can be reduced without lowering the sensitivity. The amount of light returned can be reduced by reducing the size of the light-projecting hole with a lens to reduce the amount of light attenuation. Since the light projecting hole can be made small, the effective reflection area of the reflector is increased, and the moisture detection sensitivity is increased.
Since the ring diameter of at least one of the folded parts of the upper reflector and the lower reflector is made variable, it is possible to measure moisture with a single calibration curve from low basis weight paper to high basis weight paper without being affected by the basis weight. Is. And so on.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment according to claim 1 of the present invention.

FIG. 2 is a sectional configuration diagram showing an embodiment according to claim 2 of the present invention.

FIG. 3 is a diagram showing a relationship between a measurement signal (R / M), MW and a calibration curve in a conventional device.

FIG. 4 is a measurement signal (R / M) and M in the device of the present invention.
It is a figure which shows the relationship between W and a calibration curve.

FIG. 5 is a sectional configuration diagram showing an embodiment of claim 2;

FIG. 6 is a view showing a relationship between a deviation amount and a moisture content error when the outer diameters of the upper and lower reflection plates are formed to have the same size.

FIG. 7 is a diagram showing a relationship between a deviation amount and a moisture content error when the outer diameter of the upper reflector is smaller than the outer diameter of the lower reflector.

FIG. 8 is a sectional configuration diagram showing an embodiment of claim 3;

9 (a) and 9 (b) are perspective views of essential parts showing one embodiment of claim 5 of the present invention.

FIG. 10 is a diagram showing the relationship (calibration curve) between the indicated value and the water content when the diameter of the folded ring is fixed.

FIG. 11 is a diagram showing the relationship (calibration curve) between the indicated value and the water content when the diameter of the folded ring is variable.

FIG. 12 is a configuration diagram of a conventional device.

FIG. 13 is a configuration diagram showing another embodiment of the conventional device.

FIG. 14 is a configuration diagram showing another embodiment of the conventional device.

[Explanation of symbols]

3 sample paper 7 First lens 7a Second lens 8 chopper wheels 10 filters 30 upper reflector 30a Projection hole 30b folding ring 31 Lower reflector 31a Light receiving hole 31b Folding ring 32 Shield 33 Conical Miller 40 First cylinder 41 spherical reflector 42 Second cylinder 50 moving reflector

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Isozaki             2-9-32 Nakamachi, Musashino City, Tokyo Yokogawa             Electric Co., Ltd.

Claims (5)

[Claims] 1. A light receiving element for receiving light from a light projecting portion through a sheet-like object, and measuring a physical characteristic of the sheet-like object based on a signal from the light receiving element. In a sheet-shaped object characteristic measuring device, an upper reflector and a lower reflector having a folded-back portion are arranged around the sheet-shaped object, and both surfaces are provided between the sheet-shaped object and the lower reflector. An apparatus for measuring the characteristics of a sheet-like object, characterized in that a shield plate having a mirror finish is arranged. 2. The light projecting portion has a light source, a first means for collimating the light from the light source, and a second means for collimating the collimated light, and the diameter of the light projecting hole of the upper reflector is The second
2. The characteristic measuring device for a sheet-like object according to claim 1, wherein the measuring device is formed so small that it does not block near the focus of the light focused by the means. 3. The sheet according to claim 1, wherein the upper reflector and the lower reflector are formed in a disc shape, and the outer diameter of the upper reflector and the outer diameter of the lower reflector are different from each other. Device for measuring the characteristics of a tongue-shaped object. 4. The upper reflection plate and the lower reflection plate are formed in a rectangular shape or an elliptical shape, and at least one of the long sides and the short sides of the upper reflection plate and the lower reflection plate is with respect to one reflection plate. Form it short, with its long side in the paper flow direction,
2. The apparatus for measuring characteristics of a sheet-like object according to claim 1, wherein the short side is arranged in a direction perpendicular to the flow of paper. 5. The characteristic measuring device for a sheet-like object according to claim 1, wherein at least one of the folded portions of the upper reflector and the lower reflector has a variable ring diameter.