JP3237680B2 - Moisture measuring device for sheet-like objects - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a moisture meter for measuring the moisture of a sheet-like substance (for example, paper) online, and more specifically, to improve the accuracy of paper edge detection and simplify the apparatus. It relates to the measured moisture meter.

[0002]

2. Description of the Related Art FIG. 2 is an explanatory view showing a general structure of an apparatus for measuring the moisture of a sheet of paper. In the drawing, reference numeral 1 denotes paper traveling in a direction perpendicular to the paper surface of FIG. 2, and reference numerals 2 and 3 denote an upper head and a lower head which move left and right on the paper surface of FIG. 2 ', 3' are the positions of the upper head and the lower head which indicate a standby state when moisture is not measured, 4 is the upper beam supported by the upper head 2 to be gripped, 5 is the lower head 3 to be gripped. Lower beam supported.
6 and 7 are stands.

FIG. 3 is a diagram showing a general configuration of a moisture measuring device incorporated in the upper head and the lower head. In the figure, reference numeral 2 denotes an upper head (light-emitting unit), and 3 denotes a lower head (light-receiving unit), which are opposed to each other with the paper 1 as a measured object interposed therebetween. In the light projecting unit 2, the light from the light source 16 is
After being converted into parallel light by 7 and further converted into intermittent light by the chopper wheel 18, the light is irradiated onto the paper 1 through the irradiation window 19.
A filter 20 that transmits 1.94 μm light (M light) that is absorbed by moisture;
A filter 21 that transmits 1.8 μm light (R light) that is not absorbed by moisture is provided, and irradiates the paper 1 with M light and R light alternately according to rotation. In the light receiving section 3, the entrance window 22
The light that has passed through the paper 1 is incident, is focused by the lens 23, and is focused on the light receiving element 12. The light receiving element 12 detects the M light and the R light in a time-series manner and supplies the detected light to the arithmetic unit 13 with a value of V _R /
Output performs a calculation of V _M.

By the way, in such a measuring apparatus, a mechanism for detecting the end of the paper while the upper head 2 and the lower head 3 move in the left-right direction on the paper surface 1 is provided. FIG. 4 is a plan view (a) and a side sectional view (b) showing a conventional paper edge detecting device. The same elements as those in FIG. 3 are denoted by the same reference numerals, and only the main parts are shown.

In the drawing, reference numerals 31 and 32 denote irradiation windows 1 on a plane.
9, light-emitting windows provided therebetween, 33 , 33 a are light-emitting windows 3.
It is a light-emitting body (LED) that irradiates light through 1 and 32. 31b and 32b are light receiving elements for receiving light from the light emitting bodies 33 and 33a through the light receiving windows 31a and 32a.
Reference numeral 30 denotes a shutter that shuts off the light from the light source 16 in response to the detection of the paper edge.

The reason why the paper edge detection and the shutter mechanism are necessary in the above configuration will be described. That is, the upper head 2 and the lower head 3 move on the upper beam and the lower beam beyond the paper width during measurement. In this case, when there is no shutter, the light from the light source 16 is directly transmitted to the light receiving element 1 when the paper edge is released.
2 will be incident. As a result, the signal from the light receiving element 12 is saturated, the head is inverted, and the light receiving element 1
Even if 2 is interrupted by paper, measurement cannot be performed for a while.

According to the above configuration, for example, when the head moves in the direction of arrow B, the light receiving element 31b senses the light from the LED 33 at the moment when the head leaves the paper edge. The shutter 30 receives the signal from the light receiving element 31b and moves in the direction shown by the dotted line to block the light from the light source 16. Next instant light receiving element 32b
Also detects the paper edge, but the shutter remains closed at this time. When the head reverses and moves in the opposite direction, it is first detected that the light receiving element 32b is blocked by paper. At this time, the shutter is kept closed and the next time the light receiving element 31b detects the paper end. To open the shutter (move to the position indicated by the solid line).

When the head moves in the direction opposite to the arrow B, the shutter 30 operates in response to a signal from the light receiving element 32b. As a result, the light from the light source 16 does not directly irradiate the light receiving element 12.

[0009]

However, in the above-mentioned conventional apparatus, a light emitting element and a light receiving element for a paper edge detecting mechanism and a shutter mechanism which operates by receiving the signal are required. An abnormality in the measurement signal occurs, and a predetermined interval (actually, about 80 mm) is required between the detection elements 31b and 32b, so that the measurement width is restricted (that is, the measurement width is limited by the signal from the first light receiving element). (Because the shutter closes, it is not possible to measure about 40 mm from the end of the paper.) SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to realize a measuring apparatus which does not require a shutter or an optical switch and has no limitation on a measurement width.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a sheet-like object having a predetermined width,
A first head and a second head which are arranged to face each other across a predetermined gap with the sheet-shaped object interposed therebetween and reciprocate simultaneously in the width direction of the sheet-shaped object; and a predetermined head provided on the first and second heads. A sheet-like object provided with measuring means for irradiating measurement light and reference light having a wavelength of and measuring the moisture content of the sheet from the amount of attenuation of the light, and edge detection means for detecting an edge in the width direction of the sheet. In the apparatus, a polarizing filter that transmits light having a wavelength width from the measurement light to the reference light is arranged with a phase shifted by 90 ° with the sheet interposed therebetween.

[0011]

When there is no paper, the polarizing filters are arranged with a phase shift of 90 °, so that the measuring light and the reference light are prevented from irradiating the light receiving element. When paper is present, the light is scattered by the paper, so that the polarization is disturbed and the light passes through the polarizing filter and reaches the light receiving element.

[0012]

1A and 1B are main part configuration diagrams showing an embodiment of the present invention, wherein FIG. 1A is a plan view, FIG. 1B is a cross-sectional view when paper exists between heads, and FIG. Is a sectional view showing a state separated from the light receiving element. In these figures, FIG.
The same elements as those described above are denoted by the same reference numerals, and redundant description will be omitted.

Reference numerals 40 and 40a denote polarizing filters that transmit light having a wavelength ranging from measurement light (for example, light of 1.94 μm that is absorbed by moisture) to reference light (light of 1.8 μm that is not absorbed by moisture). These polarization filters are arranged so as to close the irradiation window 19 and the entrance window 22 and to shift the phase of their polarization planes by 90 °. A polarizing filter having such a predetermined transmission width is commercially available (the present invention is characterized in that the polarizing filter is used as a light shielding means of a moisture measuring device).

In the above configuration, there is a base paper between the light source 16 and the light receiving element 12 (b) In the case shown in the figure, the light is transmitted through the polarizing filter 40, hits the paper and is scattered there, and the polarization is disturbed. Through the paper. Then, the polarized light is transmitted through the polarizing filter 40a and reaches the light receiving element 12, and
The degree of attenuation of the measurement light corresponds to the water content of the paper. In FIG. 3C, since no paper exists, the light from the light source passes through the polarizing filter 40 but the phase of the polarization plane is 90 °.
The light does not reach the light receiving element because it is blocked by the polarizing filter 40b that is staggered. Further, according to the above configuration, the presence / absence of paper functions as a shutter for light that directly reaches the light receiving element, so that measurement can be made up to the very edge of the paper.

[0015]

As described above in detail with the embodiment, according to the moisture measuring apparatus of the present invention, the polarizing filter is shifted by 90 ° in place of the optical switch and the shutter, so that the configuration is simplified. Thus, it is possible to realize a measuring device which is free from failure and has no limitation on the measuring width.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a moisture measuring device of the present invention.

FIG. 2 is an explanatory diagram showing a general configuration of a moisture measuring device.

FIG. 3 is a diagram showing a general configuration of a moisture measuring device incorporated in an upper and lower head.

FIG. 4 is a configuration explanatory view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper 2 Upper head 3 Lower head 12 Light receiving element 16 Light source 19 Irradiation window 22 Incident window 40, 40a Polarizing filter

Claims (1)

(57) [Claims] 1. A sheet-like object running with a predetermined width and a sheet-like object arranged opposite to each other with a predetermined gap interposed between the sheet-like objects and simultaneously reciprocating in the width direction of the sheet-like object. A first head and a second head, measuring means provided on the first and second heads for irradiating measurement light and reference light of a predetermined wavelength and measuring the water content of the sheet from the attenuation of the light, and a width of the sheet In a moisture device for a sheet-like object provided with an end detecting means for detecting an end in a direction, a phase of a polarizing filter that transmits light having a wavelength width from the measurement light to the reference light is shifted by 90 ° across the sheet. A moisture measuring device for a sheet-like object, wherein the moisture measuring device is arranged in a manner to be arranged.