JPS6123499B2

JPS6123499B2 -

Info

Publication number: JPS6123499B2
Application number: JP10476680A
Authority: JP
Inventors: Akio Fujiwara; Seiji Takita; Seiichiro Kyobe
Original assignee: Yokogawa Hokushin Electric Corp
Current assignee: Yokogawa Electric Corp
Priority date: 1980-07-30
Filing date: 1980-07-30
Publication date: 1986-06-06
Also published as: JPS5729931A

Description

[Detailed description of the invention]

本発明はシート状の紙に近赤外線を照射し、そ
の紙と相互作用をもつた近赤外線を検出してシー
ト状の紙に含まれる又は吸着する水分量に関する
信号を得ると共に上記紙の坪量に関する信号を得
て、これらの信号を用いて水分量，水分率等を測
定する方法及び装置に関する。水分量に関する信号（以下、単に水分量信号）
を得る手段として、透過方式および多重散乱方式
がある。前者は、照射側光学系の光軸と受光側光学系の
光軸とをほぼ一致させて対向配設してなる照射部
および受光部を有し、これらの間にシート状の紙
を流して、照射部から約1.95μｍの赤外線（水分
の吸収波長領域の光。以下、この波長光を測定光
と称する）と約1.80μｍの赤外線（水分による吸
収がない波長領域の光。以下、この波長光を基準
光と称する）とを交互に紙に照射し、受光部で測
定光に対応する信号（以下、Ｍ信号と称する）お
よび基準光に対応する信号（以下、Ｒ信号と称す
る）を検出し、これらＭ信号およびＲ信号の商
（以下、Ｍ／Ｒ信号と称する）を水分量信号とす
る構成となつている。後者は、前者と以下の点について相違する。照射側光学系の光軸と受光側光学系の光軸とは
不一致な構成をなし、照射部からの測定光および
基準光は紙と複数回（前者に比べて格段に多い回
数）相互作用をなして受光部に到達するようにな
つている。ところで、水分量信号は、坪量の関数であるこ
とから、水分計に坪量検出部が併設されている場
合が多い。坪量検出部として、放射線、例えば、
β線を用いたものが実用されている。その測定原
理は、β線が紙を透過するとき減衰量が紙の坪量
に関係していることを利用している。上記した透過方式又は多重散乱方式において、
紙の原料配合が変わつたり、白色度、坪量、プレ
ス圧等、いわゆる紙の光学的諸条件が変わると、
Ｍ／Ｒ信号、すなわち、水分量信号に影響が現わ
れる。これらの影響を軽減するため、抄紙機のオ
ペレータは、紙の品種（銘柄）によつて水分の演
算式の定数を変更する操作をなしていたが、この
操作が煩雑であるばかりでなく、同一の銘柄であ
つても、上記光学的諸条件が変る場合もあるので
（しかもオペレータが知らないうちに）、従来の方
式では紙の水分量，水分率等を連続して精度良く
測定することが難しかつた。このような欠点を解決するため、次のような事
実に着目して後述のような構成の装置も試みられ
ていた（特開昭55−154439号公報参照）。この装
置の創作は、透過方式および多重散乱方式におけ
るＲ信号およびＭ信号が、紙の光学的特性を左右
する変数、即ち、層数ｎ，透過率ｆ，反射率ｒお
よび水分量MWの関数であつて、これらの変数が
各信号に対して次表のような感度を呈することに
着目してなされたものである。表において、
Rt，Mtは透過形水分計におけるＲ信号，Ｍ信号
を示し、Rn，Mnは多重散乱形水分計におけるＲ
信号，Ｍ信号を示す。 The present invention irradiates a sheet of paper with near-infrared rays, detects the near-infrared rays that interact with the paper, and obtains a signal regarding the amount of water contained or adsorbed in the sheet of paper, and also obtains a signal regarding the amount of water contained in or adsorbed to the sheet of paper. The present invention relates to a method and apparatus for obtaining signals related to water content and measuring moisture content, moisture content, etc. using these signals. Signal related to moisture content (hereinafter simply referred to as moisture content signal)
There are transmission methods and multiple scattering methods as means for obtaining this. The former has an irradiating part and a light receiving part which are arranged facing each other so that the optical axis of the irradiating optical system and the optical axis of the receiving optical system almost coincide, and a sheet of paper is passed between them. , infrared rays of approximately 1.95 μm (light in the wavelength region absorbed by moisture. Hereinafter, this wavelength light is referred to as measurement light) and infrared rays of approximately 1.80 μm (light in the wavelength region not absorbed by moisture. Hereinafter, this wavelength A signal corresponding to the measurement light (hereinafter referred to as the M signal) and a signal corresponding to the reference light (hereinafter referred to as the R signal) are detected by the light receiving section. However, the quotient of these M signal and R signal (hereinafter referred to as M/R signal) is configured to be a water amount signal. The latter differs from the former in the following points. The optical axis of the irradiation-side optical system and the optical axis of the light-receiving side optical system are configured so that they do not match, and the measurement light and reference light from the irradiation section interact with the paper multiple times (much more times than the former). It is designed so that the light reaches the light receiving section. By the way, since the moisture content signal is a function of basis weight, a moisture meter is often provided with a basis weight detection section. As the basis weight detection unit, radiation, for example,
Those using β-rays are in practical use. The measurement principle utilizes the fact that when beta rays pass through paper, the amount of attenuation is related to the basis weight of the paper. In the transmission method or multiple scattering method described above,
When the raw material composition of paper changes, or when the so-called optical conditions of paper such as whiteness, basis weight, press pressure, etc. change,
An influence appears on the M/R signal, that is, the water content signal. In order to reduce these effects, paper machine operators had to change the constants in the moisture calculation formula depending on the paper type (brand), but this operation was not only complicated, but also Even for paper brands, the optical conditions mentioned above may change (without the operator's knowledge), so with conventional methods, it is difficult to continuously and accurately measure paper moisture content, moisture percentage, etc. It was difficult. In order to solve these drawbacks, an apparatus having a structure as described below has been attempted, focusing on the following facts (see Japanese Patent Laid-Open No. 154439/1983). The creation of this device is based on the fact that the R and M signals in the transmission and multiple scattering systems are functions of the variables that govern the optical properties of the paper, namely the number of layers n, the transmittance f, the reflectance r and the moisture content MW. This was done by focusing on the fact that these variables exhibit sensitivities to each signal as shown in the table below. In the table,
Rt and Mt indicate the R signal and M signal in the transmission type moisture meter, and Rn and Mn indicate the R signal in the multiple scattering type moisture meter.
signal, M signal is shown.

【表】上記装置は、水分量信号としてMn／Rn信号
（水分量感度が大なる信号で、Rn／Mn信号でも
同じ）を用い、この信号に含まれる誤差要因を他
の信号で自動的に補償演算をなす構成となつてい
る。この具体例として、新聞紙の水分量，水分率
等の測定装置を挙げることができる。新聞紙は原
料パルプに故紙を含有させて抄造されるが、故紙
の含有率によつて透過率ｆが大きく変動し誤差要
因となつている。そこで、水分量信号Mn／Rn信
号はRn／Rt信号（透過率感度が大なる信号で
Rt／Rn信号でも同じ）で補償演算がなされる構
成となつている。このような装置において、
Mn／Rn信号およびRn／Rt信号が安定して得ら
れなければならない。ところが、実際の測定装置
にあつては、時間とともに、散乱面、照射窓、入
射窓等にダスト（紙粉やカーボン）が付着し、そ
の影響がRn、Mn、Rt、Mtの各信号に現れ、測
定精度を低下せしめる要因となつていた。ダスト
による影響について、第３図を参照して説明す
る。第３図は、ダストと信号の関係を示したもの
であり、以下に説明する検出ヘツド（第１図参
照）にゼロサンプルを供して得た実験データによ
るものである。第３図の縦軸はＫ値（＝Mn／Rn
信号値）、横軸はダスト量ｄを示し、グラフイは
ゼロサンプルを上ヘツド内に設置して得たグラフ
である。なお、検出ヘツドを据付ける環境にあつ
ては、ダストの付着量が、時間とともに比例的に
増加するので、第３図において、ダストの付着量
と校正回数とを対応して示してある。グラフイに
おいて、Ａ点は、上下ヘツドの散乱面、各窓等に
ダストが付着してない状態におけるＫ値でＫ_z0と
なつている。Ｂ点は、一定時間後の校正（これを
第１回目の校正という）における値をプロツトし
たもので、ダスト量ｄ＝d₁、Ｋ値＝Ｋ_z1となつて
いる。同様に、Ｃ点は第２回目の校正によるもの
で、ダスト量ｄ＝d₂、Ｋ値＝Ｋ_z2であり、Ｄ点は
第３回目の校正によるもので、ダスト量ｄ＝d₃、
Ｋ値＝Ｋ_z3である。一方、グラフロは、実際に、
被測定体であるシート状の紙を流す位置に、上記
グラフイを得たと同じ物性を有するシート状のサ
ンプルを配して得たデータに基づいて描いたもの
である。グラフロにおけるＡ点、B′点、C′点及
びD′点は、グラフイにおけるＡ点、Ｂ点、Ｃ点
及びＤ点に対応させてみればよい。このように、
サンプルを配設する位置によつてＫ値が異なる
（グラフイとロが得られる）のは、実際に紙を流
す位置にサンプルを配設した場合、多重散乱の度
合が、上ヘツド内にサンプルを配設した場合に比
べて極めて大きいためであると思われる。いま、Ｋ値について説明したが、実際の装定装
置におけるRn／Rt信号（これをＭ値という）や
Mt／Rt信号（これをＬ値という）についても同
様に、散乱面や各窓面に付着するダスト量による
影響を受ける。本発明は、かかる点に鑑みてなされたもので、
その目的は、上・下ヘツドの対向面である散乱面
や各窓面に付着するダストによる影響を自動的に
補正し、もつて、水分量、水分率等を精度良く測
定する方法及び装置を提供するにある。以下、図面を参照し本発明について詳しく説明
する。第１図は、本発明を説明するための、水分量、
水分率等の測定装置の検出ヘツドの構成説明図で
ある。第１図において、検出ヘツドは、照射窓１
１及び１２を有する上ヘツド１０と入射窓２１を
有する下ヘツド２０とを、シート状の紙３０を挾
んで対向配設する構成となつている。上・下ヘツ
ドの対向面は、反射被膜１３及び２２からなる散
乱面を構成している。また、上ヘツド１０は円板
状の板４１に貫通穴４２及び４３を設け、これら
貫通穴個々に基準光用光学フイルタ４２及び測定
光用光学フイルタ４３を埋設支承してなり連続し
た回転をする回転セクタ４０と、円板状の板６１
に複数の貫通穴を設け、その一部に標準サンプル
を埋設支承してなり、制御信号によつて定期的、
又は必要に応じて、間欠的に定められた回転角で
回転するホイール６０とを有し、回転セクタ４０
によつてランプ５０及びレンズ５１で作成され照
射窓１１を通路とする光路と、ランプ５０、ミラ
ー５３及びレンズ５２で作成され照射窓１２を通
路とする光とを間欠的に遮るようになつている。一方、下ヘツド２０はレンズ２３及びセンサ２
５を有し、入射窓２１を通過する光を検出し、次
段の演算部（図示せず）へ検出信号を送出する構
成となつている。ところで、各ヘツドの窓と回転セクタ４０との
関係及び各ヘツドの窓とホイール６０との関係
は、第２図の構成となつている。第２図のイ、
ロ、ハ及びニの各図は、第１図におけるイ−イ、
ロ−ロ、ハ−ハ及びニ−ニの断面図である（寸法
は必ずしも一致していない）。上ヘツド１０にあ
る照射窓１１と１２は、第２図のロ図のように、
紙の流れ方向（矢印で示す）に距離をもつて設け
られ、この照射窓１２と第２図のハ図で示した下
ヘツド２０の入射窓２１とが対向する状態で設置
されている。一方、回転セクタ４０の貫通穴４２及び４３
（光学フイルタ４２及び４３と同一）と照射窓１
１及び１２との位置関係は、第２図のイ図のよう
に、照射窓１１又は１２に係る光路に光学フイル
タ４２又は４３があるとき、他方の光路を板４１
の板面で遮断する構成、即ち、紙３０への照射光
を照射窓１１及び１２から同時に送出することが
ない構成となつている。また、ホイール６０は、
第２図のニ図のように、板６１の周縁部に貫通穴
６２，６５，６６，６７，６３及び６４を等間隔
に設け、貫通穴６５，６６，６７及び６４夫々
に、多重散乱用のゼロサンプル６５、スパンサン
プル６６、チエツクサンプル６７及び透過用のゼ
ロサンプル６４を埋設支承させてなる。そして、
通常の測定時にあつては、貫通穴６２を照射窓１
１に、貫通穴６３を照射窓１２に夫々対応させて
停止状態にある。校正時にあつては、第１の制御
信号によつて、ホイール６０にあらかじめ定めた
角度の回転を与え、照射窓１１に多重散乱用のゼ
ロサンプル６５を、照射窓１２に透過用のゼロサ
ンプル６４を夫々配設し、第２の制御信号によつ
て、多重散乱用のスパンサンプル６６を、第３の
制御信号によつて多重散乱用のチエツクサンプル
６７を順次照射窓１１に配設する。なお、第２及
び第３の制御信号発生時には、照射窓１２を遮光
する構成となつている（遮光手段は図示せず）。このような検出ヘツドで検出される時系列的な
Rn，Mn，Rt，Mtの各信号を演算部に与え、
Mn／Rn信号及びRn／Rt信号を作成し、所望の
演算をして、透過率ｆの影響を補正した水分量や
水分率を求めることができる。なお、装定装置
は、上記測定動作に入るにあたり、定期的、又
は、必要に応じて、サンプル６４〜６７等の標準
サンプルを用いて校正を自動的にやり、装置の精
度を維持している。本発明の一実施例による測定装置の演算部は、
上記信号の作成及び所望の演算をする機能に加え
て、校正時に、以下説明する補正演算をする機能
を有する。ゼロサンプルを用いた校正における特性は、先
に、第３図を参照して説明したように、サンプル
の設置位置によつてグラフイ又はグラフロとなる
ので、その位置による変動を考慮した補正演算を
施す必要がある。そこで、本発明者らは、上ヘツ
ド内にサンプルを設置した場合の校正（グラフイ
を得る）及び紙を流す位置にサンプルを設置した
場合の校正（グラフロを得る）によるダスト感度
比を一定とみなすこととし、(1)式〜(3)式の補正演
算式を導いた。Ｋ＝Kon−Ｋ_ｚ１−Ｋ_ｚ０／ＤＳＫ (1) Ｋ＝Kon−Ｋ_ｚ２−Ｋ_ｚ０／ＤＳＫ (2) Ｋ＝Kon−Ｋ_ｚ３−Ｋ_ｚ０／ＤＳＫ (3) 但し、Kon…測定状態（オンライン）におけ
るＫ値（Mn／Rn信号値） DSK…ダスト感度比上記各式において、右辺の第２項が補正量に相
当し、これを図示すれば第４図のグラフロとな
る。第４図は、補正量とダスト量の関係を示した
図であつて、縦軸がΔＫ値（補正量）、横軸がダ
スト量を示す。そして、グラフイは、第３図のグ
ラフロに夫々基づいて得たものである。補正演算は、最初、ダスト量が零のときゼロサ
ンプルを用いて求めたＫ値（これをＫ_z0とする）
を演算部に記憶することから始める。いま、校正
が定期的に第１回目、第２回目…と自動的になさ
れるものとすれば、測定装置は、第１回目の校正
が実行されるまでは、ダストによる影響はないと
して動作する。即ち、Mn／Rn信号（Ｋ値）はそ
のまま水分量や水分率を求める演算部に与えられ
る。次に、第１回目校正時にＫ＝Ｋ_z1を得て、演算
部で（Ｋ_z1−Ｋ_z0）／DSKの演算をし、この値を
保持して、以後、第２回目の校正時までの間の補
正量とする。即ち、(1)式に基づく演算をして補正
されたＫ値を求め、水分量や水分率を求める演算
部に与えられる。以下、第２回目の校正時にＫ＝Ｋ_z2、第３回目
の校正時にＫ＝Ｋ_z3を夫々得て、（Ｋ_z2−Ｋ_z0）／
DSK又は（Ｋ_z3−Ｋ_z0）DSKを求めると共にその
値を保持し、測定時に(2)式又は(3)式に基づく演算
をして補正されたＫ値を求めて、水分量や水分率
を求める演算部に与えられる。上記のように補正演算をＭ値（即ち、Rn／Rt
信号値）やＬ値（即ち、Mt／Rt信号値）につい
て実行し、補正されたＭ値やＬ値を水分量を求め
る演算部に与えることによつて、従来、１回／日
〜１回／週の頻度で上・下ヘツドの散乱面、各窓
面を清掃して得てきた精度を、全く精掃せずに得
ることができるようになつた。さらに、補正演算による効果を上げるには、補
正量を、第４図のグラフロ′に基づいて定めれば
よい。グラフロ′は、散乱面等のダスト付着量が
ほぼ一定の割合で増加してゆくものとみなして描
いてあるが、実際の上・下ヘツドにおける特性に
より近似していると言える。校正間隔が一定であ
る測定装置にあつては、グラフロ′に基づく信号
を作成することは容易なことである。さらに、本発明の他の実施例にあつては、(4)
式、(5)式及び(6)式に基づく補正演算を用いてい
る。Ｋ＝Kon−DK（epxΔＫ−１） (4) Ｌ＝Lon−DL（expΔＬ−１） (5) Ｍ＝Mon−DMln（ΔＭ＋１） (6) 但し、Kon，Lon，Mon…測定状態（オ
ンライン）におけるＫ値（Mn／Rn信号
値）、Ｌ値（Mt／Rt信号値）、Ｍ値（Rn／
Rt信号値） DK，DL，DM…実験データから求めた
定数 ΔＫ，ΔＬ，ΔＭ…校正時の信号値（ダ
スト付着状態）とダストの付着が零の時の
信号値との差このように、本発明による測定方法及び装置が
種々の補正演算式を用意しているのは、測定装置
の据付場所によつて検出信号特性が異なるためで
ある。換言すれば、付着するダストの性状の違い
によつて補正量が異なつてくるからである。なお、上記実施例において、検出ヘツドが多重
散乱形の光学系及び透過形の光学系を具備する構
成となつているが、本発明は、これに限定するも
のではなく、多重散乱形の光学系又は透過形の光
学系のみから成る検出ヘツドで構成される測定装
置をも含むものである。以上詳しく説明したように、本発明の測定方法
及び装置によれば、上ヘツド内又は下ヘツド内に
設置する標準試料を用いて、定期的に、又は必要
に応じて校正をして得る信号値と、あらかじめ求
めておいたダスト零信号値（ダスト付着量零のと
きの信号）との差を函数とする補正量を演算し、
この補正量で測定信号に含まれるダストによる影
響を自動的に補正するようになつているため、精
度の良い水分量、水分率等の信号を得ることがで
きる。[Table] The above device uses the Mn/Rn signal (a signal with high moisture content sensitivity, the same is true for Rn/Mn signals) as the moisture content signal, and automatically detects error factors contained in this signal using other signals. It is configured to perform compensation calculations. A specific example of this is a device for measuring moisture content, moisture content, etc. of newspaper. Newspaper is manufactured by incorporating waste paper into raw material pulp, but the transmittance f varies greatly depending on the content of waste paper, which is a cause of error. Therefore, the water content signal Mn/Rn signal is the Rn/Rt signal (signal with high transmittance sensitivity).
(The same applies to the Rt/Rn signals). In such a device,
The Mn/Rn signal and Rn/Rt signal must be stably obtained. However, in actual measurement equipment, dust (paper powder and carbon) adheres to the scattering surface, irradiation window, entrance window, etc. over time, and its influence appears on the Rn, Mn, Rt, and Mt signals. , which was a factor that reduced measurement accuracy. The influence of dust will be explained with reference to FIG. FIG. 3 shows the relationship between dust and signal, based on experimental data obtained by applying zero samples to the detection head (see FIG. 1) described below. The vertical axis in Figure 3 is the K value (=Mn/Rn
The horizontal axis shows the dust amount d, and the graph was obtained by installing a zero sample in the upper head. Note that in the environment in which the detection head is installed, the amount of dust adhesion increases proportionally with time, so in FIG. 3, the amount of dust adhesion and the number of calibrations are shown in correspondence. In the graph, point A has a K value of _Kz0 when no dust is attached to the scattering surfaces of the upper and lower heads, each window, etc. Point B is a plot of the values in the calibration after a certain period of time (this is referred to as the first calibration), and the dust amount d=d ₁ and the K value=K _z1 . Similarly, point C is due to the second calibration, dust amount d = d ₂ , K value = K _z2 , and point D is due to the third calibration, dust amount d = d ₃ ,
K value=K _z3 . On the other hand, Graflo actually
It is drawn based on data obtained by placing a sheet-like sample having the same physical properties as those used in the graph above at the position where the sheet-like paper, which is the object to be measured, is flowed. Points A, B', C', and D' in the graph can be made to correspond to points A, B, C, and D in the graph. in this way,
The reason why the K value differs depending on the position where the sample is placed (graphs 1 and 2) is that when the sample is placed at the position where the paper is actually flowed, the degree of multiple scattering is This seems to be because it is extremely large compared to the case where it is installed. I have just explained the K value, but the Rn/Rt signal (this is called the M value) in the actual mounting device
The Mt/Rt signal (this is called the L value) is similarly affected by the amount of dust adhering to the scattering surface and each window surface. The present invention has been made in view of these points,
The purpose is to automatically correct the effects of dust adhering to the scattering surfaces, which are the opposing surfaces of the upper and lower heads, and each window surface, and to develop a method and device that can accurately measure moisture content, moisture percentage, etc. It is on offer. Hereinafter, the present invention will be explained in detail with reference to the drawings. Figure 1 shows the water content,
FIG. 2 is an explanatory diagram of the configuration of a detection head of a device for measuring moisture content, etc. In FIG. 1, the detection head is located at the irradiation window 1.
An upper head 10 having windows 1 and 12 and a lower head 20 having an entrance window 21 are arranged facing each other with a sheet of paper 30 sandwiched therebetween. The opposing surfaces of the upper and lower heads constitute a scattering surface consisting of reflective coatings 13 and 22. Further, the upper head 10 has through holes 42 and 43 formed in a disc-shaped plate 41, and each of these through holes supports an optical filter 42 for reference light and an optical filter 43 for measurement light, and rotates continuously. Rotating sector 40 and disk-shaped plate 61
A standard sample is buried in several through-holes, and a standard sample is buried in some of the through-holes.
Or, if necessary, it has a wheel 60 that rotates intermittently at a determined rotation angle, and the rotating sector 40
The light path created by the lamp 50 and lens 51 and passing through the irradiation window 11 and the light created by the lamp 50, mirror 53 and lens 52 and passing through the irradiation window 12 are intermittently interrupted. There is. On the other hand, the lower head 20 includes a lens 23 and a sensor 2.
5, and is configured to detect light passing through the entrance window 21 and send a detection signal to the next stage calculation section (not shown). Incidentally, the relationship between the window of each head and the rotating sector 40 and the relationship between the window of each head and the wheel 60 are as shown in FIG. Figure 2 A,
Figures B, C, and D represent A, B, and B in Figure 1.
It is a sectional view of Ro-Ro, Ha-Ha, and Ni-Ni (dimensions do not necessarily match). The irradiation windows 11 and 12 in the upper head 10 are as shown in FIG.
The irradiation window 12 is provided at a distance in the paper flow direction (indicated by the arrow), and the irradiation window 12 and the entrance window 21 of the lower head 20 shown in FIG. On the other hand, the through holes 42 and 43 of the rotating sector 40
(same as optical filters 42 and 43) and irradiation window 1
1 and 12, as shown in FIG.
In other words, the light irradiated onto the paper 30 is not simultaneously sent out from the irradiation windows 11 and 12. Moreover, the wheel 60 is
As shown in FIG. 2, through holes 62, 65, 66, 67, 63, and 64 are provided at equal intervals on the peripheral edge of the plate 61, and through holes 65, 66, 67, and 64 are provided with holes for multiple scattering, respectively. A zero sample 65, a span sample 66, a check sample 67, and a zero sample 64 for transmission are embedded and supported. and,
During normal measurement, the through hole 62 is connected to the irradiation window 1.
1, the through holes 63 correspond to the irradiation windows 12 and are in a stopped state. During calibration, the wheel 60 is rotated by a predetermined angle using the first control signal, and a zero sample 65 for multiple scattering is placed in the irradiation window 11, and a zero sample 64 for transmission is placed in the irradiation window 12. A span sample 66 for multiple scattering is sequentially arranged in the irradiation window 11 according to the second control signal, and a check sample 67 for multiple scattering is sequentially arranged in the irradiation window 11 according to the third control signal. Note that when the second and third control signals are generated, the irradiation window 12 is configured to be shielded from light (the light shielding means is not shown). The time series detected by such a detection head
Give each signal Rn, Mn, Rt, Mt to the calculation section,
By creating the Mn/Rn signal and the Rn/Rt signal and performing desired calculations, it is possible to obtain the moisture content and moisture content corrected for the influence of the transmittance f. In addition, before entering the above-mentioned measurement operation, the mounting device automatically performs calibration using standard samples such as samples 64 to 67 periodically or as needed to maintain the accuracy of the device. The calculation unit of the measuring device according to an embodiment of the present invention includes:
In addition to the functions of creating the above-mentioned signals and performing desired calculations, it also has the function of performing correction calculations as described below during calibration. As explained earlier with reference to Figure 3, the characteristics of calibration using a zero sample will be graphi or grapho depending on the installation position of the sample, so a correction calculation should be performed that takes into account the variation due to the position. There is a need. Therefore, the inventors considered the dust sensitivity ratio to be constant due to the calibration when the sample is installed in the upper head (obtaining a graph) and the calibration when the sample is installed in the position where the paper flows (obtaining a graph). Therefore, we derived the correction calculation formulas (1) to (3). K=Kon-K _z1 -K _z0 /DSK (1) K=Kon-K _z2 -K _z0 /DSK (2) K=Kon-K _z3 -K _z0 /DSK (3) However, Kon...measurement status (online) ) K value (Mn/Rn signal value) DSK...Dust sensitivity ratio In each of the above equations, the second term on the right side corresponds to the correction amount, and this is illustrated as the graph in FIG. 4. FIG. 4 is a diagram showing the relationship between the correction amount and the dust amount, where the vertical axis shows the ΔK value (correction amount) and the horizontal axis shows the dust amount. The graphs were obtained based on the graphs shown in FIG. In the correction calculation, first, the K value obtained using zero samples when the amount of dust is zero (this is set as K _z0 )
Start by storing in the calculation section. Now, assuming that calibration is performed automatically for the first time, second time, etc. periodically, the measuring device operates as if there is no influence from dust until the first calibration is performed. . That is, the Mn/Rn signal (K value) is given as is to the calculation section that calculates the moisture content and moisture content. Next, obtain K=K _z1 during the first calibration, calculate (K _z1 - K _z0 )/DSK in the calculation section, hold this value, and use it from then on until the second calibration. The amount of correction between That is, the corrected K value is determined by calculation based on equation (1), and is provided to the calculation section that calculates the moisture content and moisture content. Hereinafter, K=K _z2 is obtained during the second calibration, K=K _z3 is obtained during the third calibration, and (K _z2 −K _z0 )/
Determine the DSK or (K _z3 - _{K z0} ) DSK, hold that value, calculate the corrected K value by calculating based on formula (2) or (3) at the time of measurement, and calculate the moisture content and moisture percentage. is given to the arithmetic unit that calculates . As mentioned above, the correction calculation is performed using the M value (i.e., Rn/Rt
conventionally, once a day to once a day The accuracy that was obtained by cleaning the scattering surfaces of the upper and lower heads and each window surface once a week can now be obtained without having to clean them at all. Furthermore, in order to increase the effect of the correction calculation, the correction amount may be determined based on the graph graph ' of FIG. 4. Although grapho' is drawn assuming that the amount of dust adhering to the scattering surface increases at a nearly constant rate, it can be said that it more closely approximates the actual characteristics of the upper and lower heads. For measuring devices with constant calibration intervals, it is easy to create a signal based on grapho'. Furthermore, in other embodiments of the present invention, (4)
A correction calculation based on equations (5) and (6) is used. K=Kon−DK(epxΔK−1) (4) L=Lon−DL(expΔL−1) (5) M=Mon−DMln(ΔM+1) (6) However, Kon, Lon, Mon…Measurement status (online) K value (Mn/Rn signal value), L value (Mt/Rt signal value), M value (Rn/Rn signal value) at
Rt signal value) DK, DL, DM...constants obtained from experimental data ΔK, ΔL, ΔM...difference between the signal value at the time of calibration (dust adhesion state) and the signal value when the dust adhesion is zero, The reason why the measuring method and device according to the present invention provides various correction calculation formulas is because the detection signal characteristics differ depending on the installation location of the measuring device. In other words, the amount of correction varies depending on the properties of the attached dust. In the above embodiment, the detection head is configured to include a multiple scattering type optical system and a transmission type optical system, but the present invention is not limited to this, and the present invention is not limited to this. Alternatively, it also includes a measuring device consisting of a detection head consisting only of a transmission type optical system. As explained in detail above, according to the measurement method and apparatus of the present invention, signal values obtained by calibrating periodically or as necessary using a standard sample installed in the upper head or lower head. and a predetermined dust zero signal value (signal when the amount of dust adhesion is zero) is calculated as a function,
Since the influence of dust included in the measurement signal is automatically corrected using this correction amount, highly accurate signals such as moisture content and moisture content can be obtained.

[Brief explanation of the drawing]

第１図は、本発明の一実施例による装置の検出
ヘツドの構成説明図、第２図イ，ロ，ハ及びニ
は、第１図におけるイ−イ、ロ−ロ、ハ−ハ及び
ニ−ニの各断面図、第３図は、Ｋ値−ダスト特性
図、第４図は、補正量−ダスト特性図である。１０……上ヘツド、１１及び１２……照射窓、
１３及び２２……反射被膜（散乱面）、２０……
下ヘツド、２１……入射窓、２５……光感応素
子、３０……被測定体（紙）、４０……回転セク
タ、６０……ホイール、５０……ランプ、５１，
５２及び２３……レンズ、５３……ミラー。 FIG. 1 is an explanatory diagram of the configuration of a detection head of an apparatus according to an embodiment of the present invention, and FIG. 3 is a K value-dust characteristic diagram, and FIG. 4 is a correction amount-dust characteristic diagram. 10... upper head, 11 and 12... irradiation window,
13 and 22... Reflective coating (scattering surface), 20...
Lower head, 21... Entrance window, 25... Photosensitive element, 30... Measured object (paper), 40... Rotating sector, 60... Wheel, 50... Lamp, 51,
52 and 23...lens, 53...mirror.

Claims

[Scope of Claims] 1. An upper head and a lower head are disposed facing each other to constitute both a multiple scattering type optical system and a transmission type optical system, or a multiple scattering type optical system is formed by the upper and lower heads. A sheet of paper is poured into the gap where the paper is exposed, and the paper is irradiated with measurement light that is light in a wavelength range that is absorbed by water and reference light that is light in a wavelength range that is not absorbed by water. The measurement light and the reference light that interact with the paper are guided to a photosensitive element and detected, and the measurement signal and the reference signal output from the photosensitive element corresponding to the measurement light and the reference light are used for calculation. Therefore, in the method of measuring the moisture content or moisture percentage contained in the paper, dust is not attached to any of the scattering surfaces formed on the opposing surfaces of the upper and lower heads, the irradiation window, and the entrance window. A measurement signal related to the multiple scattering optical system when the amount of dust adhesion is zero, which is obtained using a standard sample installed in the upper head or lower head after removing a sheet of paper from the gap when the dust is not present.
Dust zero signal Kzo consisting of the ratio of Mn and reference signal Rn
is stored in advance, the sheet of paper is removed from the gap, and a calibration operation is performed periodically or as necessary using the standard sample to obtain the measurement signal Mn and reference signal Rn for the multiple scattering optical system.
Find the calibration signal Kzn, which is the ratio of
When performing DSK, a signal (Kzn−Kzo)/ which is a function of the difference between the calibration signal Kzn and the dust zero signal Kzo
A method for measuring the water content or moisture percentage of paper, which comprises creating a DSK and using the signal to correct errors caused by dust adhesion. 2. The upper head and the lower head are arranged facing each other to constitute both a multiple scattering type optical system and a transmission type optical system, or a multiple scattering type optical system, and a sheet-shaped optical system is formed in the gap formed by the upper and lower heads. A piece of paper is passed through the paper, and the paper is irradiated with measurement light, which is light in a wavelength range that is absorbed by water, and reference light, which is light in a wavelength range that is not absorbed by water, to interact with the paper. The measurement light and the reference light are guided to a photosensitive element and detected, and the information contained in the paper is calculated by using the measurement signal and the reference signal output from the photosensitive element in response to the measurement light and the reference light, respectively. A standard installed in the upper head or lower head and inserted into the optical path of the multiple scattering type or transmission type optical system in response to an external calibration operation signal. Regarding the multiple scattering optical system obtained using the standard sample when no dust is attached to the sample, the scattering surfaces formed on the opposing surfaces of the upper and lower heads, the irradiation window, and the entrance window. Dust zero signal Kzo, which is the ratio of the measurement signal Mn and the reference signal Rn
means for storing in advance a dust sensitivity ratio; means for generating a control signal for removing a sheet of paper from the gap and performing a calibration operation of the apparatus periodically or as needed using the standard sample; When DSK is used, a signal (Kzn −
1. An apparatus for measuring the moisture content or moisture percentage of paper, comprising means for generating a signal (Kzo)/DSK and using the signal to perform correction calculations for errors caused by dust adhesion.