JPH03225258A - Instrument for measuring characteristics of sheet-like substance - Google Patents

Abstract

PURPOSE:To improve water detecting sensitivity and to measure water contents with high sensitivity especially in the case of thin paper by using paper transmitting light sufficiently associated with water molecules in the paper for the detection of water contents. CONSTITUTION:When light from a projecting optical fiber bundle 21 is projected to a projecting space 40, the light propagated into paper in the horizontal direction arrives at a light receiving space 41 and is made incident upon a light receiving optical fiber bundle 22 and the light reflected on the paper 3 advances in the outer peripheral direction while repeatedly reflected between the paper 3 and the end face of the fiber bundle 21 but can not advance to the space 41 by a shield plate 30. Since the light transmitted into the paper is reflected on a recessed part 26, the reflected light advances to the vicinity of the center of a ball but can not advance to the space 41. However, a part of the reflected light is made incident into the paper, turned to diffused propagation light by cellulose and projected to the space 4. The propagation light is reflected on a groove 27, transmitted into the paper, made incident upon the fiber bundle 22, and then projected to an optical system or a photodetecting element to execute arithmetic operation. In the case of measuring water contents of thin paper, the detection sensitivity can be improved by measuring the light propagated in the lateral direction as compared with a case utilizing transmitted light.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an apparatus for measuring the amount of moisture contained in a sheet-like object, and particularly to a measuring apparatus suitable for use in measuring the moisture content of thin paper.

<Prior Art> FIGS. 4 and 5 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. 4, 1 is a light projecting section, and 2 is a light receiving section, which are arranged opposite to each other with a paper 3, which is the object to be measured, sandwiched therebetween.

In the light projection unit 1, the light from the light source 6 is converted into parallel light by a lens 7, and further converted into intermittent light by a chopper wheel 8, and then
The paper 3 is irradiated through the irradiation window 4.

The chopper wheel 8 has 1 which is absorbed by moisture.
, a filter 9 that transmits 94 μm light (measurement light) and a filter 10 that transmits 1.8 μm light (comparison light) that is not absorbed by moisture are provided, and the measurement light and comparison light are alternately transmitted during one rotation. irradiate paper 3. In the light receiving section 2, light that has passed through the paper 3 enters through the entrance window 5, is focused by the lens 11, and is focused on the light receiving element 12. This light-receiving element detects the measurement light M and the comparison light R in time series, and supplies them to the calculator 13 to calculate R/M and output them.

In the conventional example shown in FIG.
After making the light into intermittent light, the paper 3 is irradiated through the irradiation window 4. This chopper wheel does not have a filter mounted thereon as in the conventional example shown in FIG. 4, and the wheel is used exclusively to remove all shadows of stray light. The white light irradiated from the irradiation window 4 is multiple-reflected on the diffuse reflection surfaces 16 and 17 provided on the opposing surfaces of the light projecting section 1 and the light receiving section 2 with the paper 3 sandwiched therebetween.

The light enters the light receiving section 2 through the entrance window 5 provided at a position shifted from the irradiation window 4.

In the light receiving section 2, the incident light is divided into two by a prism 18,
One is a filter 9 that transmits the measurement light. A filter 10 is guided through a lens 11 to a light receiving element 12, and the other is a filter 10 that transmits comparison light. The light is guided to a light receiving element 12' through a lens 11'. Measurement light M detected by the light receiving element 12 and the light receiving element 12'
The comparison light R detected by is simultaneously given to the arithmetic unit 13,
R/M calculation is performed and output.

<Problems to be Solved by the Invention> 1] Among the conventional devices described above, the one having the configuration not shown in FIG. Because it is.

If the thickness of this paper is thin, there is a problem that a product with good sensitivity cannot be obtained. In addition, the configuration shown in FIG.
The optical axes of the emitter and receiver are placed several tens of millimeters apart! Since the light reaches the light receiving section while passing through the paper and being scattered by the scattering surface, there is a problem in that the amount of light attenuation increases and the signal itself becomes smaller.

The present invention was made to solve the problems of the prior art described above, and focuses on the fact that light diffuses and propagates through the cellulose (cellulose) of paper. The purpose is to provide a device with a small quantity.

Means for Solving the Problems> The configuration of the present invention for solving the problems described in item 1 includes a light-receiving element that receives light from a light projecting section through a sheet-like object, and a signal from the light-receiving element is In the sheet-like object characteristic measuring device for measuring the physical properties of the sheet-like object based on the sheet-like object, the sheet-like object comprises: a light guide means having a light-emitting optical fiber bundle in the center and a light-receiving optical fiber bundle in the outer peripheral part; A concave portion having a semicircular cross section is disposed facing the end face of the light guiding means with a shaped object in between, and the concave portion has a semicircular cross section at a position facing the light emitting optical fiber bundle; A reflective member in which a groove with a semicircular cross section is formed surrounding the concave portion is fixed in a ring shape between a light-emitting optical fiber bundle and a light-receiving optical fiber bundle on the end face of the light guiding means, and comprising a shielding plate that prevents reflected light from entering the light receiving section,
The present invention is characterized in that, of the light emitted from the light projecting section, only the light that has propagated laterally within the sheet-like object is made to enter the light receiving section.

Effects> The light emitted from the projection optical fiber bundle is reflected or transmitted by the paper and also propagates in the lateral direction while being scattered by the cellulose of the paper. Among these lights, the light reflected from the paper surface is repeatedly reflected between the end face of the light emitting optical fiber bundle and travels to the east side of the light receiving optical fiber, but is blocked by the shielding plate and enters the light receiving optical fiber bundle. I can't. In addition, the light transmitted through the paper is reflected by the hemispherical recess, but since most of this reflected light goes toward the center of the hemisphere, this reflected light also does not enter the east receiving optical fiber. Only light that has propagated laterally inside is incident.

<Example> The present invention will be described below with reference to one drawing. FIG. 1 is a partial cross-sectional view of a main part of an embodiment of the apparatus of the present invention, and FIG. 2 is a cross-sectional view taken along line XX in FIG. In these figures 20
1 is a light guide means made of optical fibers, and a light-receiving optical fiber bundle 22 is arranged around a light-emitting optical fiber bundle 21 in the center.

These optical fiber bundles are arranged at a certain distance apart from each other by a member such as a resin 23 that absorbs infrared light (non-reflective), and their end surfaces are processed to be flush.

Reference numeral 25 denotes a reflecting member disposed at a position facing the end of the light guide means 20, and a recess 26 having a semicircular cross section is formed at a position facing the light emitting optical fiber bundle 21, and the light receiving optical fiber bundle A spring 27 having a semicircular cross section is formed at a position opposite to the spring 22 surrounding the four parts 26.

30 is a shielding plate fixed in a ring shape between the light-transmitting optical fiber bundle and the light-receiving optical fiber bundle, and 31 is a shielding plate fixed to the outer periphery of the light-receiving optical fiber bundle. Shielding plate 30.31
The convex parts A, A part and B, B'' parts formed between the tip of the reflective member and the four parts 26 and 27 of the reflective member are made by considering the necessary allowable width with the paper 3 whose moisture content is to be measured. The light emitting space 40 and the light receiving space 4 are arranged as close together as possible on the top.
form 1.

Although not shown in Figure 1, the light from the light source enters the other end of the light-emitting optical fiber bundle, and the other end of the light-receiving optical fiber bundle contains an optical system, a light-receiving element, a calculation unit, etc., and a moisture measuring device. It shall be equipped with the necessary components.

In the case of F, when the light from the light projection optical fiber bundle 21 is emitted into the light projection space 40, the light is reflected or transmitted by the paper 3, and a part of it propagates laterally through the cellulose of the paper. . Here, the light that has propagated through the paper in one direction is incident on the light receiving optical fiber bundle that has reached the light receiving space 41, but the paper 3
The light reflected by the projection optical fiber bundle 21 travels toward the outer circumference while repeating reflections with the end face of the light-emitting optical fiber bundle 21, but is blocked by the shielding plate 30 and cannot travel to the light-receiving space 41. Further, since the light transmitted through one sheet of paper is reflected by the concave portion (hemispherical surface) 26, the reflected light travels near the center of the sphere and cannot travel to the light receiving space 41. However, a part of this reflected light enters the paper and becomes diffusely propagated light due to cellulose and is emitted into the light receiving space. And what about the propagating light that is emitted into the light receiving space 41? The light is reflected by the II 27, passes through the paper, enters the light-receiving optical fiber bundle, and exits to an optical system or light-receiving element (not shown), where calculations similar to conventional ones are performed.

Figure 3 uses tissue vapor (thin paper) with a basis weight of 10 g/m' and high-quality paper with a basis weight of 1100 g/m', and calculates the water content ( According to Figure 0, which is a measurement of the output of the detector with respect to g/m2), when measuring the moisture content of thin paper such as tissue vapor, it is better to measure the light that propagates in the lateral direction rather than using the transmitted light. It can be seen that the detection sensitivity is much higher. This shows that the propagating light has a long propagation optical path in paper with a small basis weight, so water absorption is large (high sensitivity), and the transmitted light has a small absorption of the measurement light by water molecules.

<Effects of the Invention> According to the present invention as specifically explained above with the embodiments.

■ Moisture detection sensitivity is improved because the light propagating through the paper, which is fully associated with the water molecules in the paper, is used for detection, and the moisture content can be measured with high sensitivity, especially in the case of thin paper such as tissue vapor. .

■ As the light guiding means uses a concentric optical fiber bundle for transmitting light and a bundle of optical fibers for receiving light, the detection area can be reduced, more detailed moisture detection data can be obtained, and the edge of the paper can be Moisture detection up to nearby areas becomes possible.

[Brief explanation of drawings]

FIG. 1 is a partially cross-sectional perspective view showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view taken along the line X-X in FIG. 1, FIG. 3 is a diagram showing the relationship between the moisture content of paper and the output of the detector, and FIGS. 4 and 5 are configuration diagrams of the conventional apparatus. 20... Light guiding means, 21... Translucent optical fiber bundle. 22... Optical fiber bundle for light reception, 23... Resin, 25
...reflection block, 27 ... recess, 27 ... clear,
30.31... Shielding plate. Figure 3, a (amount ()/Inri Figure C Figure 3)

Claims (1)

[Claims] A sheet-like object characteristic measuring device that includes a light-receiving element that receives light from a light projecting section through a sheet-like object, and measures physical characteristics of the sheet-like object based on a signal from the light-receiving element. A light guiding means having a bundle of optical fibers for light projection in the center and a bundle of optical fibers for light reception at the outer periphery, and a light guiding means arranged opposite to the end face of the light guiding means with the sheet-like object in between, and the light transmitting light a reflecting member having a recess with a semicircular cross section at a position facing the fiber bundle, a groove having a semicircular cross section surrounding the recess at a position facing the light receiving optical fiber bundle, and the light guiding means. A shielding plate is fixed in a ring shape between the light-emitting optical fiber bundle and the light-receiving optical fiber bundle on the end face, and prevents the reflected light from the sheet-like object from entering the light-receiving section, and What is claimed is: 1. A characteristic measuring device for a sheet-like object, characterized in that, of the emitted light, only the light that has propagated laterally in the sheet-like object is made to enter the light receiving section.