JPH0315740A - Characteristic measuring instrument for sheet-shaped object - Google Patents

Abstract

PURPOSE:To improve the sensitivity by arranging a first light transmission means between a light throwing part and a sheet of paper and emitting the light from the light throwing part to an optical fiber through the sheet of paper and transmitting the light turned back by the optical fiber through the sheet of paper again and allowing the light to go and return plural times. CONSTITUTION:The light from the light throwing part is made incident on a first light transmission means 20 in the direction of an arrow (a), and a sheet 3 of paper is irradiated with this light. Though most of this light is transmitted through the sheet 3 of paper, a part of this light is propagated in the transverse direction while being scattered by cellulose of the sheet 3 of paper as shown by an arrow (b) and is made incident on a second light transmission means 21, which is arranged a certain length apart from the side face of the means 20, and is led in the direction of an arrow (c) and reaches a light receiving part. This certain length is different by relations to the distance from the light exit to the sheet 3 of paper and is set to such value that the direct reflected light from the sheet 3 of paper which is not related to moisture detection is not made incident on the light receiving part of the means 21. Thus, the sensitivity is improved and the extent of attenuation of light is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an apparatus for measuring physical properties such as moisture content or thickness of a sheet-like e+ body. <Prior art> Figures 14 and 15 are. A conventional example of a moisture meter that measures the moisture content of sheet-like objects in paper machines, etc. is shown below. In Figure 14. 1 is a light emitting part, and 2 is a light receiving part, and these are arranged opposite to each other with a paper 3, which is the object to be measured, sandwiched between them. In the light projecting section 1. After the light from the light source 6 is made into parallel light by the lens 7 and further made into intermittent light by the chopper wheel 8,
The paper 3 is irradiated through the irradiation window 4. The chopper wheel 8 includes a filter 9 that transmits 1.94 μm light (measurement light) that is absorbed by moisture, and a filter 10 that transmits 1.8 μm light (comparison light) that is not absorbed by moisture.
is provided, and irradiates the paper 3 with measurement light and comparison light alternately as it rotates. 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 arithmetic unit 13, which calculates M/R and outputs them. In the conventional example shown in No. 15. In the light projection unit 1, the light from the light source 6 is converted into parallel light by a lens 7, and the chopper wheel 8
’ to make the light intermittent, and then irradiate the paper 3 through the irradiation window 4. This chopper wheel is not equipped with a filter like the conventional example shown in Fig. 14, and the wheel is used exclusively to remove the effects 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 emitter 1 and the light receiver 2 while holding the paper 3 between them. The light-receiving section 2
Go inside. In the light receiving section 2. The incident light is split into two by the prism 18,
One is a filter 9 that transmits the measurement light. The light is guided to a light receiving element 12 through a lens 11, and the other light is guided to a light receiving element 12' through a filter 10 that transmits the comparison light, and a lens 11'. Measurement light M detected by light receiving element l2 and light receiving element 12'
The comparison light R detected at is simultaneously given to the arithmetic unit 13,
The M/H calculation is performed and output. Problems to be Solved by the Invention In the above conventional device. The configuration shown in Figure 14 has a simple structure. On the one hand, it has the advantage of less light attenuation, but on the other hand, the object to be measured is a single sheet of paper. If the thickness of this paper is thin, there is a problem that high sensitivity cannot be obtained.
Also. In the configuration shown in Figure 15, the optical axes of the light emitting part and the light receiving part are placed several tens of millimeters apart, and the light reaches the light receiving part while being transmitted and scattered through the paper by one scattering surface, so the amount of light attenuation is large. There was a problem that the signal itself became smaller. The present invention was made to solve the above-mentioned problems of the prior art, and utilizes the property that light that hits a sheet of paper propagates in the horizontal direction, and by folding the transmitted light and transmitting it multiple times, the S/N is improved. The ratio is high, and. The purpose is to provide a device with low attenuation. <Means for Solving the Problems> The present invention for solving the above problems is, with respect to claim 1, comprising a light-receiving element that receives light from a light projecting section through a sheet-shaped object. and a sheet-like object characteristic measuring device for measuring physical characteristics of the sheet-like object based on a signal from the light receiving element. It is arranged between the light projecting section and the sheet-like object. a first light guiding means that receives light from the light projecting section and emits the light toward the sheet-like object; The first light guiding means is disposed on the curved surface of the first light guiding means, and receives light emitted from the first light guiding means and propagated laterally in the sheet-like object. The present invention is characterized by comprising a second light guiding means for causing the light to enter the light receiving element, and with respect to claim 2, the light receiving element includes a light receiving element that receives light from the light projecting section via a sheet-like object. , in a sheet-like object characteristic measuring device that measures physical characteristics of the sheet-like object based on a signal from the light receiving element. It is arranged between the light projecting section and the sheet-like object. a first light guiding means that receives light from the light projecting section and emits it to the sheet-like object side;
at least one third light guide means for receiving the light emitted from the first light guide means and transmitting the light through the sheet-like object and emitting the light to the sheet-like object again; The present invention is characterized by comprising a second light guide means for receiving the light transmitted through the sheet-like object from the light means and making it enter the light receiving element. Regarding claim 3. The third light guide means is one. The light-receiving surface thereof is arranged at an angle with respect to the output surface of the first light-guiding means. Consists of bundles or optical fiber preforms. Light receiving ffl of each light guiding means
Should the diameter of (f41 part) be made larger than the diameter of the exit side?
or. The feature is that a condensing lens is provided on the receiving side of the optical fiber. Most of the light that is emitted from the first light guiding means and enters the paper passes through the paper, but especially for thin paper with a small basis weight, the optical propagation path length in the lateral direction of the paper Because it is long. A second light guiding means arranged on the surface of the first light guide means transmits the light from the lateral direction.
If the light is received through the light guiding means, a highly sensitive measurement signal can be obtained. Furthermore, since the light emitted from the first light guiding means passes through the paper multiple times through the third light guiding means having a folding portion, the j& degree becomes high. In that case, if there is only one third light guiding means and the light receiving surface of the third light guiding means is arranged at an angle with respect to the output surface of the first light guiding means, multiple types of paper with different basis weights can be printed on the same paper. It can be measured with the following equipment. Furthermore, the degree of attenuation of light can be reduced by increasing the diameter of the end of each light guiding means into which light enters, or by providing a condensing lens. Embodiment> An embodiment of the device of the present invention will be described below with reference to the drawings.
Figure 1 relates to claim 1, and Figure 14. The light projecting section shown in Fig. 15. FIG. 2 is a horizontal diagram showing the main parts of the present invention, with the light receiving section omitted. Reference numeral 20 denotes a first barrel light means, which is formed of, for example, an optical fiber bundle. 21 is a second light guiding means, which is also composed of an optical fiber bundle. 3 is the paper whose physical properties are to be measured. In the above-mentioned horizontal formation, light from a light projector (not shown) enters the first light guiding means 20 from the arrow A and illuminates the paper 3. Most of the light passes through the paper, but some of it propagates laterally through the paper, being scattered by the paper's cellulose, as shown by the arrows. The light enters the second light guiding means 21, which is arranged at a constant distance from the side surface of the second light guiding means, and is guided in the direction of the arrow C, reaching a light receiving section (not shown). In addition. The certain distance here differs depending on the relationship between the light output port and the paper, but it is a certain distance that does not directly reflect light from the paper that is not involved in moisture detection and enters the light receiving part of the second light guiding means. Let it be the distance. Figure 2 shows the water content (g /m2).According to the figure, when measuring the moisture content of thin paper like Teizchbeba, it is better to measure the light that propagates in the lateral direction than to use the transmitted light. It can be seen that the detection sensitivity is extremely high.This is because the propagating light has a long optical path in the paper with a small basis weight.The absorption of moisture is large (high sensitivity).
The transmitted light indicates that the absorption of the measurement light by water molecules is small.
Conversely, paper with a large basis weight has a short propagation path in the paper, so water absorption is small (low sensitivity). The transmitted light shows that the measurement light is highly absorbed by water molecules (high sensitivity). FIGS. 3 to 5 show other examples of the arrangement of the first and second light guide means when detecting light propagating laterally in this manner. That is, in FIGS. 3(a) and 3(b), a plurality of first light guide means 20 are connected to a plurality of second light guide means 21 while maintaining a constant distance.
The optical fibers forming these light guide means are bundled in an appropriate number and kept at constant intervals by a fixing member 5 made of infrared light absorbing (non-reflective) resin or the like. It is fixed. The other ends of these optical fiber bundles are each bundled and arranged to face a light emitting section and a light receiving section (not shown). In FIG. 4, the first and second light guiding means are arranged in an array via a fixing member 5 made of resin or the like that absorbs infrared light. Fifth
In the figure, a first light guiding means formed in a rod shape is surrounded by a second light guiding means formed in a cylindrical shape with the fixing member 5 interposed therebetween at a constant distance. According to the horizontal control shown in Figs. 3 to 5 above, it is possible to efficiently surprise up the components of the propagating light transmitted in the lateral direction. Figure 6. FIG. 7 shows an embodiment related to claim 2. 14 is an elliptical diagram showing the main parts with the light emitter and light receiver shown in FIGS. 4 and 15 omitted; FIG. In these figures, 20 and 21 are first and second light guiding means. 22 is a third light guiding means having a folded portion, and these are formed of an optical fiber bundle or an optical fiber preform. The diameter of the light guiding means is, for example, in the case of an optical fiber preform, the outer diameter of the cladding 24 being about 12 mm, and the outer diameter of the core 25 being about 10 mm, and in the case of an optical fiber bundle, it is about 12 mm. Also. The folded part is formed with a radius that does not allow light to leak. 3 is paper. In these figures, the output of the first light guide, the exit port of the third light guide, and the entrance of the second light guide are arranged to face each other with a sheet of paper in between. In the above configuration, the light from the light projecting section (not shown) is the first
The light enters the light guide means 20 from arrow A, passes through the paper 3, enters the third light guide means 22a, passes through the paper 3 again, and enters the third light guide means 22b. The light emitted from the third light guiding means 22b further passes through the paper 3 and enters the third light guiding means 22c. Further, the light passes through the paper 3 and is emitted to the second light guiding means 21. The ellipse is formed so that this light is emitted from the part shown by the arrow and illuminates a light-receiving element of a light-receiving section (not shown). According to the configuration shown in FIG. 6 above, the light from the light projector passes through the paper four times, and according to the configuration shown in FIG. 7, it passes through the paper eight times. the result. It is possible to improve the sensitivity of the measurement light M to the comparison light R mentioned in the conventional example. Furthermore, since the light emitted from the first light guiding means directly enters the other light guiding means through the paper, the degree of attenuation of the light can be reduced compared to the conventional example shown in FIG. In addition. in this case. If there is only one third light guiding means and the second light guiding means is placed in a position where it can receive the light emitted from the first light guiding means and propagates laterally through the paper, the same The device can measure the moisture content of papers with different basis weights. In addition,
The number of optical fibers that make up the light guiding means can be increased or decreased as appropriate, taking into account sensitivity and light attenuation. Figure 8 shows two types of paper, high-quality paper and tissue vapor, with varying moisture content (in this example, the humidity in the thermostatic chamber is 30%, 70%).
This shows the experimental results showing the relationship between the scattering distribution state of the measurement light after it passes through the paper and the relative light intensity when the moisture content is determined by leaving the paper in the paper for a long time. In the experiment, as shown in Figure 9, the optical fibers were placed facing each other with a piece of paper in between, and measurements were taken while tilting them at θ° as shown. According to the figure, when θ is O, there is no change in the output of the measurement light even if the humidity changes in the tissue vapor;
Changes in relative light intensity are observed in the 40° range. In addition, for high-quality paper, there is a sufficient change in relative light intensity when θ is O, but no change in relative light intensity is observed near 30°. FIG. 10 shows an embodiment related to claim 3, and is a diagram showing a configuration for efficiently detecting moisture in two types of paper based on the experimental results shown in FIG. 8 above. Here, the lth,
The light-receiving surface of the third light-guiding means is inclined at a predetermined angle (for example, 30 degrees) with respect to the light-emitting surface and the light-receiving surface of the second light-guiding means. According to such an ellipse, the light emitted from the first light guiding means and transmitted through the paper is 3 times larger than the third light guiding means.
It is incident at an angle of 0°±α (for example, lO°). As a result, it is possible to have sensitivity to 12 types of paper because it includes a portion where the relative light intensity of the two types of paper changes depending on moisture. One detection device can measure the moisture content of multiple types of paper. Also. In this case as well, if the second light guide is placed in a position where the light emitted from the first light guide can receive the light that propagates laterally through the paper, it will be more efficient, especially for thin paper. This makes it possible to measure moisture content. FIG. II and FIG. 12 show configuration diagrams related to claim 4. Elements that are the same as in Figure 1 are given the same reference numerals. Figure 11 shows an optical fiber preform used as the light guiding means. The diameter of the opening of the light receiving part is increased, for example, if the emitting part is 10 mm, the diameter of the opening of the light receiving part is increased.
It should be approximately 0mm. Figure 12 also shows an optical fiber bundle used as the guiding means. According to the configurations shown in FIGS. 11 and 12, the light transmitted through the paper 3 can be captured over a larger area, so that the degree of attenuation of the light can be reduced. Note that only one folding optical fiber 22 is shown to simplify the diagram, but the sixth
There may be one or more as shown in Figure 7. Also,
Although omitted in the figure, the large diameter portion can also be provided on the light receiving side of the second light guiding means 21. In addition. Processing to increase the diameter of the end can be done using a general technique that heats and stretches an optical fiber freeform to produce an optical fiber with a thickness of several tens of micrometers. Figure 13 shows an elliptical diagram regarding claim 6, and the first
Elements that are the same as those in the figure are given the same symbols. In this example, a condensing lens 11 with a diameter larger than that of the optical fiber is placed in front of the optical fiber to allow a wide range of light to enter the optical fiber, thereby reducing the degree of attenuation of the light. It has the same effect as the configuration shown in Figs. 11 and 12. Effects of the Invention> As specifically explained above with the embodiments, according to the present invention. A first guide means is arranged between the light projecting section and the paper, and the light from the light projecting section is emitted to the optical fiber side through the paper. The light that has been folded back by the optical fiber is further transmitted through the paper, so that the light travels back and forth through the paper multiple times. It is possible to improve sensitivity and reduce light attenuation. In addition, especially for thin paper, the measurement accuracy can be improved because it receives light that propagates in the lateral direction of the paper. Furthermore, since it receives propagating light and transmitted light from the lateral direction, it is possible to measure papers with different basis weights with a single detection device. Furthermore, by increasing the diameter of the light-receiving part of one optical fiber and placing a condenser lens in front of the light-receiving part, it is possible to realize a measuring device with less light attenuation.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of a characteristic measuring device for a sheet-like object related to claim 1 of the present invention, Fig. 2 is a diagram showing the relationship between water content of paper and detector output, and Figs. Figure 5 is a diagram showing another example of arrangement when detecting light propagating in the horizontal direction. FIGS. 6 and 7 are configuration diagrams showing an embodiment related to claim 2, and FIG. 8 is a diagram showing the relationship between the scattering distribution of the measurement light after passing through the paper and the relative light intensity. Figure 9 is a configuration diagram of an apparatus for measuring the relationship between the scattering distribution of measurement light and relative light intensity. FIG. 10 is a horizontal diagram showing an embodiment related to claim 3, and FIG. 11. FIG. 12 is a block diagram showing an embodiment related to claims 4 and 5, and FIG. 13 is a diagram 1 showing an embodiment related to claim 6.
Figures 14 and 15 are configuration diagrams of conventional equipment. 1...Light projection part. 2... Light receiving section, 3... Sheet-like object (paper), 5... Fixing member. 11... Condensing lens,
20...first light guide means, 21...second light guide means, 22nd! Figure 2 Figure b Figure 7 S Figure 9 Figure No. 0 Figure (c1) Figure 2 Figure l3 Figure (b)

Claims (1)

[Scope of Claims] 1) A sheet having a light-receiving element that receives light from a light projecting section via a sheet-like object, and measuring physical characteristics of the sheet-like object based on a signal from the light-receiving element. In the apparatus for measuring characteristics of a shaped object, a first light guiding means is arranged between the light projecting section and the sheet-like object, and receives light from the light projecting section and emits it to the sheet-like object side; disposed on a side surface of the first light guiding means, receiving light emitted from the first light guiding means and propagated laterally in the sheet-like object;
An apparatus for measuring characteristics of a sheet-like object, comprising a second light guiding means for causing light to be incident on the light-receiving element. 2) A characteristic measuring device for a sheet-like object, which has 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 first light guide means disposed between the light projector and the sheet-like object, which receives light from the light projector and emits it toward the sheet-like object; and the first light guide means. at least one third light guide means for receiving the light emitted from the sheet-like object and emitting the light to the sheet-like object again; An apparatus for measuring characteristics of a sheet-like object, comprising a second light guiding means that receives light transmitted through the sheet-like object and causes the light to enter the light-receiving element. 3) The third light guiding means is one, and the second light guiding means is located at a position where it can receive the light emitted from the first light guiding means and propagated laterally through the sheet-like object. 3. The apparatus for measuring characteristics of a sheet-like object according to claim 2, further comprising: a. 4) The sheet-shaped sheet according to claim 2 or 3, characterized in that the third light guide means is one, and the light receiving surface thereof is arranged at an angle with respect to the output surface of the first light guide means. Device for measuring properties of objects. 5) The apparatus for measuring characteristics of a sheet-like object according to claim 1 or 2, wherein the first to third light guiding means are formed of an optical fiber preform or an optical fiber bundle. 6) The apparatus for measuring properties of a sheet-like object according to claim 2, wherein the diameter of the light receiving side (end) of the third light guide means is larger than the diameter of the light emitting side. 7) The apparatus for measuring characteristics of a sheet-like object according to claim 2, characterized in that a condensing lens is provided on the light receiving side of the optical fiber, and the condensed light is made to enter the optical fiber.