JPH01316640A - Instrument for measuring characteristic of sheet-like object - Google Patents

Abstract

PURPOSE:To improve the sensitivity of the title instrument and, at the same time, to reduce the damping quantity of the light by providing reflecting member on both sides of a sheet-like object in a faced state and causing the light of a projector to make a round trip between the reflecting members through the sheet-like object. CONSTITUTION:The light of a projecting section enters a light input-output optical fiber bundle 24 of the 1st reflecting member 20 from the point indicated by the arrow (a) and the light from the fiber bundle 24 passes through paper 3 or becomes scattered light rays after the light is reflected by paper 3. The light rays passing through the paper 3 are made incident on and returned by the 2nd reflecting member 20a where doubled optical fiber bundles 24a are spread all over the member and made incident to the 1st member 20 after passing through the paper 3 again. The scattered light rays reflected by the paper 3 are also made incident on the 2nd member 20a and returned to the 1st member 20. Therefore, the light makes a round trip between the 1st and 2nd optical fiber bundles 24 and 24a through the paper 3 and part of the light is emitted from the port indicated by the arrow (b) of the fiber bundle 24a. Thus the sensitivity can be improved and damping of the signal can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an apparatus for measuring physical properties such as moisture content or thickness of a sheet-like object.

<Prior Art> FIGS. 6 and 7 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. 6, reference numeral 1 denotes a light projecting section 12 and 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 rt in time series, and supplies them to the arithmetic unit 13, which calculates M/R and outputs 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. 2, 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 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,
The calculation of M/H is performed and output.

<Problems to be Solved by the Invention> Among the conventional devices described above, the configuration shown in FIG.
It has the advantage of a simple structure and low light attenuation, but the measurement target is a single sheet of paper.

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 mm 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 in order to solve the problems of the prior art described above, and it is an object of the present invention to provide an apparatus in which light passes through paper several times 'Pl' and has a small amount of attenuation.

Means for Solving the Problems> The configuration of the present invention for solving the problems of the prior art described above includes a light receiving element that receives light from a light projecting section through a sheet-like object, and a light receiving element that receives light from the light receiving element through a sheet-like object. In the sheet-like object characteristic measuring device that measures the physical characteristics of the sheet-like object based on the signal of
It consists of a first and second reflecting member having an input/output optical fiber bundle whose one end constitutes a part of the semicircular sphere and which allows light to enter and exit from the other end, and the first reflecting member is connected to the light projecting section. and a sheet-like object, the second reflecting member is arranged opposite to the first reflecting member with the sheet-like object sandwiched therebetween, and the light from the light projecting part is reflected from the first reflecting member. It enters the input/output optical fiber bundle of the member and guides it to the inner surface of the first reflecting member, and also passes through the sheet-like object to the first. A part of the light reciprocating between the second reflecting members is emitted from the input/output optical fiber bundle and is made to enter the light receiving element.

Further, a property measuring device for a sheet-like object has a light-receiving element that receives light from the 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 third reflecting member formed in a hemispherical shape and having a refractive index distribution on its surface; an output optical fiber bundle in which optical fibers are formed in a tubular shape; and an output optical fiber bundle arranged near the center of the tube of the output optical fiber bundle. The input and output optical fibers are composed of a bundle of input optical fibers or an input optical fiber preform, and the input and output optical fibers are placed between the light projecting section and the sheet-like object, and the third reflecting member is placed between the sheet-like object and the input and output optical fibers. is arranged opposite to the input and output optical fibers with the light emitting unit in between, and the light from the light projecting section is incident on the input optical fiber bundle and reflected between the third reflecting members via the sheet-like object. The present invention is characterized in that the light is emitted from the output optical fiber bundle and is made to enter the light receiving element.

<Function> In claim 1, the light introduced into the first reflective member is transmitted through the paper, and is transmitted to the optical fiber constituting the second reflective member disposed opposite to the first reflective member. The light enters, turns around, and exits toward the first reflecting member again. This light is the second
The light enters the optical fiber constituting the second reflecting member, is turned back, and exits again to the second reflecting member. A portion of the light traveling back and forth in this manner is extracted from the output optical fiber and used as measurement light.

In claim 2, the light emitted from the incident optical fiber bundle or the incident optical fiber preform is transmitted through the paper, introduced into the interior from the surface of the semicircular third reflective member, and is reflected inside the reflective member. The emitted light passes through the paper again and is extracted from the output optical fiber bundle as a measurement port.

<Example> An embodiment of the present invention will be described below with reference to one drawing.

FIG. 1 is a cross-sectional configuration diagram showing essential parts of the present invention, with the light projecting section and light receiving section shown in FIGS. 6 and 7 omitted.

20 is a first reflecting member, and 20a is a second reflecting member.

Reference numerals 21 and 21a denote optical fiber fixing members, and these fixing members are formed in a hemispherical shape, and a plurality of holes are formed at high density from the outer surface toward the inside. Reference numeral 23 denotes a plurality of folded optical fiber bundles. Both ends of these optical fiber bundles 23 are inserted into the holes of the fixing member 20.20a, and their tips are fixed in a plane position on the inner surface of the fixing member (the dotted lines 23 indicate folded optical fiber bundles). 24. 24a is an input/output optical fiber bundle, one end of which is fixed to the inner surface of the fixing member in the same way as the folded optical fiber bundle. There is. In other words, the inner surface of the fixing member is densely packed with optical fiber ends.
These first. The second reflective members are arranged to face each other with the paper 3 interposed therebetween.

In the above configuration, the light from the light projecting unit 2 (not shown) enters the input/output optical fiber bundle 24 of the first reflecting member 20 from the arrow A, and the light from the input/output optical fiber bundle 24 is transmitted or reflected by the paper 3. It becomes scattered light. The transmitted light enters a second reflecting member in which a bundle of folded optical fibers is spread, is turned back, passes through the paper 3 again, and enters the first reflecting member. In addition, the reflected scattered light also enters the inside of the first reflecting member 20, is reflected, passes through the shield 3, enters the second reflecting member 20a, is reflected by this second reflecting member, and is reflected by the first reflecting member 2.
0.

According to the above configuration, the light is transmitted to the first . The light travels back and forth through the paper between the second optical fiber bundles, and a portion of the light is emitted from the arrow port of the input/output optical fiber east 24a.

With this configuration, sensitivity can be improved compared to the conventional example shown in FIG. 6, and signal attenuation can be reduced compared to the conventional example shown in FIG.

Furthermore, since one reflecting member is formed in a hemispherical shape, leakage of light from the measurement area can be reduced.

Note that in this embodiment, the folded optical fiber bundle was fixed to a hemispherical fixing member, but the tip of the optical fiber bundle may be fixed with an adhesive to form a hemispherical shape without using a fixing member. The shape of the optical fiber bundle and the positions of the entrance and exit ports are not limited to the illustrated example and may be arbitrary.

Further, an input/output optical fiber bundle for extracting a part of the reciprocating light may be provided on the first reflecting member side c1.

FIG. 2 shows an embodiment related to claim 2 of the present invention, in which (a) is a perspective view of the main part, and (b) is a side view of the main part.

In the figure, reference numeral 32 denotes an output optical fiber bundle in which a plurality of optical fibers are formed into a tubular shape, and an input optical fiber bundle 31 is disposed within this output optical fiber. Although not shown in the figure, a filling member is placed between the output optical fiber bundle and the input optical fiber bundle, and the input optical fiber is located at the center of the output optical fiber bundle and held so that its end surface is flush with the other optical fibers. There is. Note that the diametrical relationship between the input optical fiber bundle and the output optical fiber bundle is such that the light emitted from the input optical fiber bundle is reflected by the paper and is located at a position where the light does not directly enter the output optical fiber bundle. Preferably, 33 is a hemispherical third reflecting member, which is formed so that its refractive index distribution is different on the same plane.

FIG. 3 shows an example of the refractive index distribution of the third reflective member 33, in which (a) is a plan view and (b) is a sectional view taken along line XX in (a). In this example, quartz glass n1 with a high refractive index and quartz glass n2 with a low refractive index are arranged alternately in a hemispherical shape, and the light incident from the opening of arrow 41 propagates in the opposite direction in the reflective member. Emits light to the A1 and B sides. Similarly, light that enters from the honeypot side is also turned back and emitted to the opposite side.

Returning to FIG. 2, when light is emitted from the input optical fiber bundle 31, the light is transmitted through the paper or reflected from the surface. The transmitted light enters the third reflecting member 33.

In this case, due to the aperture angle, the light traveling straight passes through, but most of the light propagates inside the reflecting member 33, is turned back, passes through the paper again, enters the output optical fiber bundle 32, and enters the light receiving element (not shown). guided by. In addition.

Since the light that travels straight without hitting the water molecules contained in the paper has nothing to do with the measured quantity, the backside determination accuracy is improved.

Figures 4 and 5 show the side surface and refractive index distribution of the third reflecting member. Figure 4 shows the refractive index gradually increasing from the center of the hemisphere toward the outer circumference; Figure 5 shows a hemisphere with a higher refractive index at its center and outer periphery. Even if the refractive index is distributed in this way, the same effect as the reflective member shown in FIG. 3 can be obtained.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to claim 1 of the present invention, the hemispherical reflecting members are arranged facing each other while sandwiching a sheet-like object, and the light from the light projecting section is Because it is made to reciprocate through a sheet-like object.

It is possible to improve sensitivity and reduce the amount of attenuation of light.

Also, 1st. Since the second reflecting member is constituted by an optical fiber bundle, it can be made compact and the measurement area can be made small. As a result, the density of the amount of light can be improved, and therefore the measurement accuracy can be improved.

Furthermore, according to claim 2, the tip of the input/output optical fiber is flat, and the third reflecting member is formed in a hemispherical shape so that its entrance surface has a refractive index distribution. This makes production easier.

Since the light that travels straight through without hitting the water molecules of the paper is transmitted, the measurement accuracy can be increased.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional configuration diagram showing an embodiment related to claim 1 of the present invention, Fig. 2 is a perspective view (a) and side view (b) showing an embodiment related to claim 2, and Fig. 3 is a sectional view showing an embodiment related to claim 2. FIGS. 4 and 5 are side views showing an example of the structure of the third reflecting member, and FIGS. 6 and 7 are views of a conventional device. It is a figure showing an example of composition. 1... Light emitter, 2... Light receiver, 3... Paper, 20...
...First reflective member, 20a...Second reflective member, 2
1... Fixed member, 24.24a... Input/output optical fiber bundle. 3]... Input optical fiber bundle, 32... Output optical fiber Fig. f zO Z4α Fig. 6 J Fig. 7

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 an apparatus for measuring the characteristics of a shaped object, a plurality of optical fiber bundles are folded back and both ends of the optical fibers are brought together to form a semicircular sphere, and one end constitutes a part of the semicircular sphere, and light is emitted from the other end. A first and a second optical fiber bundle having an input/output optical fiber bundle capable of inputting and outputting the optical fibers.
The first reflecting member is arranged between the light projecting part and the sheet-like object, and the second reflecting member is arranged opposite to the first reflecting member with the sheet-like object interposed therebetween. , the light from the light projecting section enters the input/output optical fiber bundle of the first reflection member and guides it to the inner surface of the first reflection member, and the light is reflected by the first and second reflections via the sheet-like object. 1. An apparatus for measuring characteristics of a sheet-like object, characterized in that a part of the light reciprocating between members is emitted from the input/output optical fiber bundle and is 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 third reflecting member formed in a hemispherical shape and having a refractive index distribution on its surface; an output optical fiber bundle in which optical fibers are formed in a tubular shape; and an output optical fiber bundle arranged in the vicinity of the center of the tube of the output optical fiber bundle. The input/output optical fiber is composed of an input optical fiber bundle or an input optical fiber preform, and the input/output optical fiber is placed between a light projecting part and a sheet-like object, and the third reflecting member is sandwiched between the sheet-like object. is arranged to face the input/output optical fiber, and the light from the light projecting section is incident on the input optical fiber bundle, and the light reflected between the third reflecting member via the sheet-like object is reflected. An apparatus for measuring properties of a sheet-like object, characterized in that the apparatus is configured to emit light from the output optical fiber bundle and enter the light receiving element.