JPS6222006A - Measuring instrument for film thickness - Google Patents

Abstract

PURPOSE:To take an accurate measurement without contacting nor the influence of a shift in the position of a film to be measured by calculating the quantities of absorption in the object film for light beams which are transmitted through two band-ass filters and differ in wavelength and then calculating the film thickness from the quantities of absorption. CONSTITUTION:Light from a light source 2 is transmitted through a magnetic tape 1, transmitted through two different-wavelength band-pass filters 8b and 8c through a rotary disk 8, and converted by a photodetector 4 photoelectrically. The magnetic film 1b of the tape 1 has wavelength dependency, so the output of the photodetector 4, i.e. the quantities of different-wavelength transmitted light beams are converted into digital values in series by an A/D converter 5 and a processing circuit 6 calculates the ratio of the both or the gradient of transmission characteristics between the two wavelengths to find its transmission start wavelength, thereby obtaining an output proportional to the film thickness. Consequently, an accurate measurement is taken without contacting nor the influence of a shift in the position of the film.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 この発明は例えば磁気テープ等の製造ラインにおける塗
工機の制御、監視を行うための塗膜の膜厚を測定する膜
厚測定装置に関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a film thickness measuring device for measuring the film thickness of a coating film for controlling and monitoring a coating machine in a manufacturing line for, for example, magnetic tape. It is.

〔従来の技術〕[Conventional technology]

第４図は従来の渦電流式膜厚測定装置の構成図で、（１
）は磁気テープで、ポリエステル等の母材（１ａ）の上
に磁性体の塗膜（１ｂ）がついている。ＣＩυは検出器
で、コア（ｌｌａ）に励磁巻線（ｌｔｂ）を巻き、発振
器四で励磁している。Figure 4 is a configuration diagram of a conventional eddy current type film thickness measuring device.
) is a magnetic tape, which has a coating film (1b) of magnetic material on a base material (1a) such as polyester. CIυ is a detector, which has an excitation winding (ltb) wound around a core (lla), and is excited by an oscillator 4.

次に動作について説明する。コア（ｌｌａ）の開放端間
には励磁の磁界が発生しているが、接近した位置に磁性
体があると励磁インピーダンスが変わる。この変化は磁
性体の時性、サイズ、位置等により変化するため、この
インピーダンスの変化を検出すれば一定特性、一定位置
、一定幅の条件下で磁性体の厚みが検出できることとな
る。Next, the operation will be explained. An excitation magnetic field is generated between the open ends of the core (lla), but the excitation impedance changes if a magnetic body is located close to the core (lla). This change varies depending on the time, size, position, etc. of the magnetic body, so if this change in impedance is detected, the thickness of the magnetic body can be detected under conditions of constant characteristics, constant position, and constant width.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

従来の膜厚測定装置は被測定膜と検出器との距離を一定
に、しかも接近２通常は接触させなければ感度良く、安
定に測定できず、製造ライン中に組込むことができなか
った。Conventional film thickness measuring devices cannot be sensitively and stably measured unless the distance between the film to be measured and the detector is kept constant and the film and the detector are in close contact with each other, and cannot be incorporated into a production line.

本発明は上記のような問題点を解消するためになされた
もので、非接触にしかも、被測定膜の位置が変化しても
影春を受けない膜厚測定装置を提供する。The present invention has been made to solve the above-mentioned problems, and provides a film thickness measuring device that is non-contact and is not affected by changes in the position of the film to be measured.

〔問題点を解決するための手段〕[Means for solving problems]

この発明に係る膜厚測定装置は、光源と、この光源から
の光を被測定膜に透過させその光を受光する受光器と、
この光路上に設けられ第１及び第２の狭帯域フィルタ部
と遮光部とを有する回転板と、受光器の出力から膜厚を
演算する処理回路とを備えたものである。The film thickness measuring device according to the present invention includes: a light source; a light receiver that transmits light from the light source to a film to be measured and receives the light;
The apparatus includes a rotary plate provided on the optical path and having first and second narrow band filter sections and a light shielding section, and a processing circuit that calculates the film thickness from the output of the light receiver.

〔作用〕[Effect]

この発明における膜厚測定装置は処理回路が各狭帯域フ
ィルタを透過した光の被測定膜での吸収量を求め、この
吸収量から膜厚を演算する。In the film thickness measuring device according to the present invention, a processing circuit determines the amount of light absorbed by the film to be measured after passing through each narrowband filter, and calculates the film thickness from this amount of absorption.

〔発明の実施例〕[Embodiments of the invention]

以下、この発明の一実施例を図について説明する。第１
図は本発明の構成図で、第４図と同一番　　　０号のも
のは同一のものを示す。（幻は磁気テープ（１）を透過
する波長帯を持つ光源、（３）はレンズ、（４）は受光
器、（５）はＡ／Ｄ変換器、（６）はディジタル処理回
路、（７）はモータ、（８）はモータ（７）の軸に取付
けられた回転板で、その平面凶を第２図に示す。第２図
において、斜線部の（８ａ）は光を透過させない遮光部
、白い部分の（８ｂ）は第１の狭帯域フィルタ部、ドツ
トを付した部分の（８ｃ）’は前のフィルタ部（８ｂ）
とは波長の異なる第２の狭帯域フィルタ部である。An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram of the present invention, and the same number 0 as in Fig. 4 indicates the same thing. (The illusion is a light source with a wavelength band that passes through the magnetic tape (1), (3) is a lens, (4) is a light receiver, (5) is an A/D converter, (6) is a digital processing circuit, (7) ) is the motor, and (8) is the rotary plate attached to the shaft of the motor (7), whose plan view is shown in Figure 2. In Figure 2, the shaded area (8a) is the light shielding part that does not transmit light. , the white part (8b) is the first narrow band filter part, and the dotted part (8c)' is the previous filter part (8b).
is a second narrow band filter section having a different wavelength.

第１図にもどり、（９）はモータ（７）を駆動するとと
もに、回転板（８）の位置情報をディジタル処理回路（
６）に出力するパルス駆動回路である。第３図は磁気テ
ープ（１）の光の透過率の波長依存性を示す特性図であ
る。Returning to Fig. 1, (9) drives the motor (7) and transmits the position information of the rotary plate (8) to the digital processing circuit (
This is a pulse drive circuit that outputs to 6). FIG. 3 is a characteristic diagram showing the wavelength dependence of the light transmittance of the magnetic tape (1).

次に動作について説明する。Next, the operation will be explained.

光源（２）から出た光はレンズ（３）で集光し、磁気テ
ープ（１）を透過させる。この透過光は回転板（８）の
位置により、光かじゃへいされたり、異なる波長の狭帯
域フィルタ（８ｂ）（８ｃ）を透過する。この透過した
光を受光器（４）で光電変換する。ところで磁気テープ
（１）は母材（１ａ）と塗膜（１ｂ）とで構成さｎるが
、母材（１ａ）はポリエステル等透明な材料であるので
ほぼ１００％光が透過し、塗膜（１ｂ）の透過特性は第
２因に示す実線で表わした特性のように波長依存性を持
つ。しかもその特性は膜厚により厚い場合は一点鎖線、
薄い場合は点線のように厚みによりその透過開始波長が
異なる。一方光源（２）等の光強度の変化は透過開始波
長か同じであるが、その傾斜が異なる。従って前記受光
器（４）の出力を異なる波長の透過量を時系列でＡ／Ｄ
変換器（５）でディジタル値に変換し、ディジタル処理
回路（６）で両者の比又は２波長間の透過特性の傾きを
計算し、その透過開始波長を求めることで膜厚に比例し
た出力を安定に得ることができる。ところでモータ（７
）をパルス駆動回路（９ンで駆動するとともに、その情
報をディジタル処理回路（６）に入力することで光が受
光器（４）に入らない時と、狭帯域フィルタ（８ｂ）の
透過光が入っている時及びフィルタ（８ｃ）の透過光が
入っている時の関係がわかり、それぞれ光が入らない時
との差をとり、これを真の値とすることで暗電流の影響
を受けないものとなる。The light emitted from the light source (2) is focused by a lens (3) and transmitted through the magnetic tape (1). Depending on the position of the rotary plate (8), this transmitted light is blocked or transmitted through narrow band filters (8b) (8c) of different wavelengths. This transmitted light is photoelectrically converted by a light receiver (4). By the way, the magnetic tape (1) is composed of a base material (1a) and a coating film (1b).Since the base material (1a) is a transparent material such as polyester, almost 100% of light passes through it, and the coating film The transmission characteristic of (1b) has wavelength dependence as shown by the solid line in the second factor. Moreover, the characteristics are as shown by the dashed dot line when the film is thicker.
When it is thin, the transmission start wavelength differs depending on the thickness, as shown by the dotted line. On the other hand, the change in the light intensity of the light source (2), etc. is the same as the transmission start wavelength, but the slope is different. Therefore, the output of the photoreceiver (4) is measured by A/D in time series to measure the amount of transmission of different wavelengths.
The converter (5) converts it into a digital value, and the digital processing circuit (6) calculates the ratio of the two or the slope of the transmission characteristic between the two wavelengths, and then determines the transmission start wavelength to generate an output proportional to the film thickness. can be obtained stably. By the way, the motor (7
) is driven by the pulse drive circuit (9) and the information is input to the digital processing circuit (6) to detect when the light does not enter the receiver (4) and when the light transmitted through the narrow band filter (8b) You can understand the relationship between when light is entering the filter (8c) and when light is passing through the filter (8c), and by taking the difference from when no light is entering, and taking this as the true value, it is not affected by dark current. Become something.

〔発明の効果〕〔Effect of the invention〕

以上のように・この発明によれば被測定膜の光の透過率
の波長依存性から膜厚を求めるので、被測定膜の位置が
変化しても、また受光器の暗電流の影響を受けず、正確
に膜厚が測定できる。As described above, according to the present invention, the film thickness is determined from the wavelength dependence of the light transmittance of the film to be measured, so even if the position of the film to be measured changes, it is not affected by the dark current of the photoreceptor. The film thickness can be measured accurately.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の一実施例における膜厚測定装置の構成
図、第２図は第１図における回転板の平面図、第３図は
磁気テープの透過率の波長依存性特性図、第４図は従来
の膜厚測定装置の構成図である。 図において、（ｌｂ）は被測定膜としての磁性体の塗膜
、（２）は光源、（４）は受光器、（５）　（６）は処
理回路としてのそれぞれＡ／Ｄ変換器及びディジタル処
理回路、（８）は回転板、（８ａ）は遮光部、（８ｂ）
は第１の狭帯域フィルタ部、（８ｃ）は第２の狭帯域フ
ィルタ部である。 なお、各図中同一符号は同一または相当部分を示す。FIG. 1 is a block diagram of a film thickness measuring device according to an embodiment of the present invention, FIG. 2 is a plan view of the rotary plate in FIG. FIG. 4 is a configuration diagram of a conventional film thickness measuring device. In the figure, (lb) is a magnetic coating film as a film to be measured, (2) is a light source, (4) is a light receiver, (5) and (6) are an A/D converter and a digital processing circuit, respectively. Processing circuit, (8) rotating plate, (8a) light shielding part, (8b)
(8c) is a first narrowband filter section, and (8c) is a second narrowband filter section. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (6)

【特許請求の範囲】[Claims] （１）被測定膜を透過する波長帯の光を出射する光源、
この光源からの光を上記被測定膜に透過させこの透過し
た光を受光して光電変換する受光器、第１の波長の光を
透過させる第１の狭帯域フィルタ部と第２の波長の光を
透過させる第２の狭帯域フィルタ部と光を透過させない
遮光部とを周方向に順次配置し回転することによつて上
記光の通路上に上記各部が順次介在するように構成され
た回転板、上記受光器の出力から上記両波長における上
記被測定膜での光の吸収量を求めこの吸収量から被測定
膜の膜厚を演算する処理回路を備えた膜厚測定装置。(1) A light source that emits light in a wavelength band that passes through the film to be measured;
a light receiver that transmits light from the light source through the film to be measured, receives the transmitted light, and converts it photoelectrically; a first narrow band filter section that transmits light of a first wavelength; and a light receiver that transmits light of a first wavelength; A rotary plate configured such that a second narrow band filter section that transmits light and a light shielding section that does not transmit light are sequentially arranged in the circumferential direction and rotated so that the respective sections are sequentially interposed on the path of the light. . A film thickness measuring device comprising a processing circuit for determining the amount of light absorbed by the film to be measured at both wavelengths from the output of the light receiver and calculating the thickness of the film to be measured from the absorption amount. （２）被測定膜を入射光の方向と直角の方向に移動させ
る構成とし、膜厚を連続的に測定するようにしたことを
特徴とする特許請求の範囲第１項記載の膜厚測定装置。(2) A film thickness measuring device according to claim 1, characterized in that the film to be measured is moved in a direction perpendicular to the direction of incident light, and the film thickness is continuously measured. . （３）処理回路は受光器の出力をＡ／Ｄ変換するＡ／Ｄ
変換器とこのＡ／Ｄ変換器の出力をディジタル処理して
膜厚を演算するディジタル処理回路とからなることを特
徴とする特許請求の範囲第１項または第２項記載の膜厚
測定装置。(3) The processing circuit is an A/D converter that converts the output of the photoreceiver.
3. The film thickness measuring device according to claim 1, comprising a converter and a digital processing circuit that digitally processes the output of the A/D converter to calculate the film thickness. （４）ディジタル処理回路は各波長の光の透過量の比を
演算しこれから膜厚を演算することを特徴とする特許請
求の範囲第３項記載の膜厚測定装置。(4) The film thickness measuring device according to claim 3, wherein the digital processing circuit calculates the ratio of the amount of light transmitted at each wavelength and calculates the film thickness from the ratio. （５）ディジタル処理回路は各波長の光の透過量の２波
長間の傾きからその透過開始波長を演算しこれから膜厚
を演算することを特徴とする特許請求の範囲第３項記載
の膜厚測定装置。(5) The film thickness according to claim 3, wherein the digital processing circuit calculates the transmission start wavelength from the slope of the amount of light transmitted at each wavelength between two wavelengths, and calculates the film thickness from this. measuring device. （６）ディジタル処理回路は遮光部における値と各狭帯
域フィルタ部における値との差を使用して演算すること
を特徴とする特許請求の範囲第４項または第５項記載の
膜厚測定装置。(6) The film thickness measuring device according to claim 4 or 5, wherein the digital processing circuit performs calculations using the difference between the value in the light shielding part and the value in each narrow band filter part. .