TW201621312A - Non-contact eddy-current detecting device and controlling method thereof - Google Patents
Non-contact eddy-current detecting device and controlling method thereof Download PDFInfo
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本揭露是有關於一種非接觸式渦電流檢測裝置及其控制方法。 The present disclosure relates to a non-contact eddy current detecting device and a control method thereof.
利用捲對捲(Roll to Roll,R2R)製程來製作電子產品的技術越來越蓬勃,例如:軟性印刷電路板、導電薄膜…等等。其中,導電薄膜會在基材上快速地被沉積,且導電薄膜之阻抗的均勻性將直接影響到後續電子產品的特性表現,因此必須針對沉積後所形成之導電薄膜的阻抗進行量測。針對導電薄膜進行量測的裝置可以被區分成多種類型,其中非接觸式量測裝置可在不破壞待測樣品的情況下,檢測出待測樣品的特性與缺陷,非接觸式量測裝置的感應方式有許多種類型,其中一種是利用渦電流原理來進行感測。渦電流(Eddy Current)的作用原理是透過一交變磁場(一次磁場)與待測樣品進行耦合,以致使待測樣品感應出漩渦式 的電流,待測樣品的特性會造成渦電流流向的改變,且渦電流會形成二次磁場抵抗交變磁場(一次磁場)的變化,因此可藉由待測樣品所造成之耦合特性的變化來檢測待測樣品的特性。然而於捲對捲機台運作過程,非接觸式探頭需能克服機台上下振動及對溫度變化敏感的問題。 The use of roll-to-roll (R2R) processes to make electronic products is growing, such as flexible printed circuit boards, conductive films, and so on. Among them, the conductive film is rapidly deposited on the substrate, and the uniformity of the impedance of the conductive film directly affects the characteristic performance of the subsequent electronic product, and therefore the impedance of the conductive film formed after deposition must be measured. The device for measuring the conductive film can be divided into a plurality of types, wherein the non-contact measuring device can detect the characteristics and defects of the sample to be tested without destroying the sample to be tested, and the non-contact measuring device There are many types of sensing methods, one of which is to use the eddy current principle for sensing. The principle of Eddy Current is to couple with the sample to be tested through an alternating magnetic field (primary magnetic field), so that the sample to be tested is induced to vortex. The current, the characteristics of the sample to be tested will cause the change of the eddy current flow direction, and the eddy current will form a secondary magnetic field to resist the change of the alternating magnetic field (primary magnetic field), so the coupling characteristics caused by the sample to be tested can be changed. The characteristics of the sample to be tested are detected. However, in the operation of the roll-to-roll machine, the non-contact probe needs to be able to overcome the vibration of the machine up and down and sensitive to temperature changes.
傳統雙側串接式探頭使用兩探頭線圈串聯方式連接,但此種串接方式線圈對外接線受限於機構,較適用於小尺寸樣品或大尺寸樣品邊緣之片電阻檢測;當用於大尺寸樣品量測時,兩組探頭串聯線圈之中間連線需配合待測物尺寸而加長,導線易因動態機台扯動或振動造成線圈等效電感值變化,此電感值變化將造成片電阻量測誤差。 The traditional two-side series probe is connected in series by using two probe coils, but the external connection of the series connection coil is limited by the mechanism, and is suitable for the sheet resistance detection of small-sized samples or large-sized sample edges; when used for large size When the sample is measured, the middle connection between the two sets of probe series coils needs to be lengthened according to the size of the object to be tested. The wire is easy to change due to the dynamic inductance of the dynamic machine table. The change of the inductance value will cause the sheet resistance. Measuring error.
本揭露係有關於一種非接觸式渦電流檢測裝置及控制方法。 The disclosure relates to a non-contact eddy current detecting device and a control method.
根據本揭露提出一非接觸式渦電流檢測裝置。一第一線圈的第一端點與一第一功率放大器之第二端點及一第二功率放大器之第一端點耦合;一第二線圈的第一端點與第二功率放大器之第二端點及第一功率放大器之第一端點耦合;第一功率放大器之第一端點及第二功率放大器之第一端點與一負回授裝置之第一端點耦合,第一功率放大器之第三端點及第二功率放大器之第三端點與負回授裝置之第三端點耦合;一電流檢出器的第一 端點與第一線圈的第二端點與第二線圈的第二端點耦合,電流檢出器的第二端點輸出一檢出訊號。 According to the present disclosure, a non-contact eddy current detecting device is proposed. a first end of a first coil is coupled to a second end of a first power amplifier and a first end of a second power amplifier; a first end of the second coil and a second end of the second power amplifier The first end of the first power amplifier is coupled to the first end of the first power amplifier; the first end of the first power amplifier and the first end of the second power amplifier are coupled to the first end of a negative feedback device, the first power amplifier The third end point and the third end of the second power amplifier are coupled to the third end of the negative feedback device; the first of the current detector The end point is coupled to the second end of the first coil and the second end of the second coil, and the second end of the current detector outputs a detection signal.
根據本揭露另提出一非接觸式渦電流檢測方法。控制方法包括以下步驟。使用一第一線圈與一第二線圈感應待測物之一交流訊號;藉由第一線圈與第二線圈分別與一第一功率放大與一第二功率放大器之輸出相耦合,形成一正回授;第一功率放大器與第二功率放大器之輸入受一負回授裝置控制其振幅於一定值;將交流訊號經一電流檢出器產生一檢出訊號為直流。 According to the present disclosure, a non-contact eddy current detecting method is also proposed. The control method includes the following steps. Using a first coil and a second coil to sense an alternating current signal of the object to be tested; and coupling the first coil and the second coil to a first power amplifier and an output of the second power amplifier to form a positive return The input of the first power amplifier and the second power amplifier is controlled by a negative feedback device to have a certain amplitude; the AC signal is generated by a current detector to generate a detection signal of DC.
為了對本發明之上述及其他方面有更佳的瞭解,下文特舉若干實施範例,並配合所附圖式,作詳細說明如下: In order to better understand the above and other aspects of the present invention, a few embodiments are described below, and in conjunction with the drawings, the detailed description is as follows:
第1圖繪示非接觸式渦電流檢測裝置之一實施範例方塊圖之示意圖。 FIG. 1 is a schematic diagram showing an example block diagram of an embodiment of a non-contact eddy current detecting device.
第2A圖繪示一正回授NMOS實施範例之示意圖。 FIG. 2A is a schematic diagram showing an example of a positive feedback NMOS implementation.
第2B圖繪示一正回授PMOS實施範例之示意圖。 FIG. 2B is a schematic diagram showing an example of a positive feedback PMOS implementation.
第3圖繪示消除溫度效應之示例圖。 Figure 3 shows an example diagram of the effect of eliminating temperature.
第4圖繪示先前技術與本技術於樣品試片偏離探頭中心不同距離時輸出訊號產生誤差之比較示意圖。 FIG. 4 is a schematic diagram showing the comparison between the prior art and the prior art when the sample test piece is separated from the center of the probe by a different distance.
第5圖繪示先前技術單測頭對不同位移產生輸出訊號變化之示意圖。 FIG. 5 is a schematic diagram showing the change of the output signal generated by the prior art single probe for different displacements.
第6圖繪示於時間100秒後樣品振動產生量測誤差變化量之 示意圖。 Figure 6 shows the amount of change in the measurement error of the sample vibration after 100 seconds. schematic diagram.
第7圖繪示非接觸式渦電流檢測方法之一實施範例方塊圖之示意圖。 FIG. 7 is a schematic diagram showing a block diagram of an embodiment of a non-contact eddy current detecting method.
請參照第1圖,其繪示非接觸式渦電流檢測裝置1之方塊圖之示意圖。其中,磁蕊100a(第一探頭)與110a導線形成第一線圈10a,磁蕊100b(第二探頭)與導線110b形成第二線圈10b,待測物200置於第一線圈10a與第二線圈10b之間,其中該第一線圈10a與該第二線圈10b可為對稱式,第一線圈10a與該第二線圈10b可統稱探頭10。第一功率放大器120a輸出端耦合至第一線圈10a之第一端點,並輸出至第二功率放大器120b輸入端(第一端點);第二探頭第二功率放大器120b輸出端(第二端點)耦合至第二線圈10b之第一端點,並輸出第一功率放大器120a輸入端(第一端點),第一功率放大器120a與第二功率放大器120b形成正回授,正回授形成電路之自振盪,使該第一線圈10a與第二線圈10b在同一振盪迴路中,且工作於同一振盪頻率;功率放大器120輸出電流驅動探頭10產生一交變磁場(亦即一次磁場),當交變磁場通過待測物200,待測物200將感應出一渦電流(為一交流訊號),且渦電流的大小和待測物200的導電特性,例如:導電率、導磁率、厚度、缺陷…等有關。此外,待測物200所感應出的渦電流會輻射出二次磁場,以抵抗探頭10所產生之交變磁 場(亦即一次磁場)的變化。兩線圈分別接於獨立之功率放大器電路(例:第一功率放大器120a與第二功率放大器120b),降低線圈電感因機台扯動(相當於振動)造成振盪頻率改變而對於渦電流誤差之影響。 Please refer to FIG. 1 , which is a schematic diagram of a block diagram of the non-contact eddy current detecting device 1 . Wherein, the magnetic core 100a (first probe) and the 110a wire form a first coil 10a, the magnetic core 100b (second probe) and the wire 110b form a second coil 10b, and the object to be tested 200 is placed in the first coil 10a and the second coil Between 10b, the first coil 10a and the second coil 10b may be symmetric, and the first coil 10a and the second coil 10b may be collectively referred to as the probe 10. The output of the first power amplifier 120a is coupled to the first end of the first coil 10a and is output to the input of the second power amplifier 120b (first end point); the output of the second probe second power amplifier 120b (the second end) Point) coupled to the first end of the second coil 10b, and outputting the input end (first end point) of the first power amplifier 120a, the first power amplifier 120a and the second power amplifier 120b form a positive feedback, positive feedback forming The self-oscillation of the circuit causes the first coil 10a and the second coil 10b to be in the same oscillating circuit and operates at the same oscillating frequency; the output current of the power amplifier 120 drives the probe 10 to generate an alternating magnetic field (ie, a primary magnetic field). The alternating magnetic field passes through the object to be tested 200, and the object to be tested 200 induces an eddy current (which is an alternating current signal), and the magnitude of the eddy current and the conductive characteristics of the object to be tested 200, for example, electrical conductivity, magnetic permeability, thickness, Defects...etc. In addition, the eddy current induced by the object to be tested 200 radiates a secondary magnetic field to resist the alternating magnetic force generated by the probe 10. A change in the field (ie, a magnetic field). The two coils are respectively connected to independent power amplifier circuits (for example, the first power amplifier 120a and the second power amplifier 120b), thereby reducing the influence of the oscillation frequency of the coil inductance caused by the machine pulling (equivalent to vibration) on the eddy current error. .
負回授裝置300之迴路由差動放大器130、檢波器140、誤差比較器160與振幅電壓調制器170所組成。其中,功率放大器120輸出由一組差動放大器130相減後送至檢波器140轉為直流訊號,誤差比較器160將基準電壓產生器150輸出之直流電壓與檢波器140直流訊號差值相比較後,透過振幅電壓調制器170輸出至功率放大器120之第三端點,即第一功率放大器120a與第二功率放大器120b之第三端點,負回裝置300之迴路控制探頭10振盪電壓之振幅控制於定值。依回授控制理論,當差動放大器130、檢波器140與誤差比較器160增益乘積極大時,線圈電壓振幅約等於基準電壓產生器電壓除以振幅電壓調制器170增益,且線圈電流振幅等於線圈電壓振幅除以線圈電阻。基準電壓產生器150的電壓設定會因待測物的渦電流訊號強弱而改變,比如:若待測渦電流訊號弱,可調整基準電壓產生器150產生較高之電壓;若待測渦電流訊號強,可調整基準電壓產生器150產生較低之電壓。 The loop of the negative feedback device 300 is comprised of a differential amplifier 130, a detector 140, an error comparator 160, and an amplitude voltage modulator 170. The output of the power amplifier 120 is subtracted by a set of differential amplifiers 130 and sent to the detector 140 for conversion to a DC signal. The error comparator 160 compares the DC voltage output by the reference voltage generator 150 with the DC signal difference of the detector 140. Afterwards, the amplitude voltage modulator 170 outputs to the third terminal of the power amplifier 120, that is, the third terminal of the first power amplifier 120a and the second power amplifier 120b, and the loop of the negative return device 300 controls the amplitude of the oscillating voltage of the probe 10. Controlled by the fixed value. According to the feedback control theory, when the differential amplifier 130, the detector 140 and the error comparator 160 are multiplied by the gain, the coil voltage amplitude is approximately equal to the reference voltage generator voltage divided by the amplitude voltage modulator 170 gain, and the coil current amplitude is equal to The coil voltage amplitude is divided by the coil resistance. The voltage setting of the reference voltage generator 150 may change due to the intensity of the eddy current signal of the object to be tested. For example, if the eddy current signal to be measured is weak, the reference voltage generator 150 may be adjusted to generate a higher voltage; if the eddy current signal is to be measured The strong, adjustable reference voltage generator 150 produces a lower voltage.
線圈電流變化之渦電流由電流檢出器180將交流訊號轉換為直流之檢出訊號SD,由第一10a與第二線圈10b連至電流檢出器180之線路長短,並不會因待測物200之大小而需做調 整。 The eddy current of the coil current change is converted by the current detector 180 into the DC detection signal SD, and the length of the line connecting the first 10a and the second coil 10b to the current detector 180 is not to be measured. The size of the object 200 needs to be adjusted whole.
圖二A為本揭露之一正回授實施範例,其中,磁蕊100a(第一探頭)與導線110a以L1代表,磁蕊100b(第二探頭)與導線110b以L2代表,功率放大器120a及120b分別使用NMOS電晶體Q1與Q2構成,例如:為匹配電晶體;差動放大器130輸入訊號為VD1與VD2。當溫度上昇時,第一級NMOS電晶體Q1與Q2臨界電壓Vt隨溫度上昇而下降,Vt隨溫度變化約-2mV/℃,因此Q1與Q2汲極電流ID及根據公式(1)ID=1/2 μnCox(W/L)(VGS-Vt)2…………………(1). FIG. 2A is a positive feedback embodiment of the present disclosure, wherein the magnetic core 100a (first probe) and the wire 110a are represented by L1, the magnetic core 100b (second probe) and the wire 110b are represented by L2, and the power amplifier 120a and 120b is formed by using NMOS transistors Q1 and Q2, respectively, for example, to match the transistor; and the differential amplifier 130 inputs signals VD1 and VD2. When the temperature rises, the threshold voltage Vt of the first-stage NMOS transistors Q1 and Q2 decreases as the temperature rises, and Vt varies by -2mV/°C with temperature, so the Q1 and Q2 gate currents I D and according to formula (1) I D =1/2 μ n C ox (W/L)(V GS -V t ) 2 .....................(1).
將同時上昇。其中,μn為電子移動率,Cox為氧化層電容,W為通道寬度,L為通道長度。差動放大器相比較抵銷溫度對Q1與Q2汲極電流上昇造成之飄移,故與溫度無關,由圖三可知,溫度效應被抵銷,即由圖左之±2.5%減少至圖右之±0.35%。圖二B為PMOS功率放大器之實施例,作用方式與NMOS類似,不再贅述。 Will rise at the same time. Where μ n is the electron mobility, C ox is the oxide capacitance, W is the channel width, and L is the channel length. The differential amplifier compares the offset temperature to the drift of the Q1 and Q2 bungee currents, so it has nothing to do with the temperature. As shown in Figure 3, the temperature effect is offset, that is, ±2.5% from the left of the figure to ± on the right side of the figure. 0.35%. Figure 2B shows an embodiment of a PMOS power amplifier. The mode of operation is similar to that of an NMOS and will not be described again.
圖4繪示先前技術與本技術於樣品試片偏離探頭中心不同距離時輸出訊號產生誤差之比較示意圖。顯示待測物於垂直方向上之位移關係。圖左為先前技術,某些阻片會因距離改變而有較大之誤差,如途中箭頭所標示點。圖右為我們發明之實驗數據,無圖左之缺點。第5圖繪示先前技術單測頭對不同位移產生輸出訊號變化之示意圖。其中有5片試片片電阻,每片導電度不同,顯示水平位移對待測物之影響。其中x軸為不同導電性之 樣品,y軸為輸出訊號SD電壓值,圖中符號為待測物偏離中心之距離d,即d為探頭與待測物間之距離。SD值希望隨d之變化,越小越好。第6圖繪示於時間100秒後樣品振動產生量測誤差變化量之示意圖。顯示樣品振動對待測物之影響。在振動下,仍可維持±1.5%的誤差。繪示非接觸式渦電流檢測方法之一實施範例方塊圖之示意圖。 FIG. 4 is a schematic diagram showing a comparison between the prior art and the prior art when the sample test piece is separated from the center of the probe by a different distance. The displacement relationship of the object to be tested in the vertical direction is displayed. The left side of the figure is the prior art, and some of the obstructions have large errors due to distance changes, such as the points indicated by the arrows on the way. The right side of the picture shows the experimental data of our invention, and there is no shortcoming of the left figure. FIG. 5 is a schematic diagram showing the change of the output signal generated by the prior art single probe for different displacements. There are 5 test piece resistances, each with different conductivity, showing the effect of horizontal displacement on the object to be tested. Where the x-axis is different in conductivity For the sample, the y-axis is the output signal SD voltage value, and the symbol in the figure is the distance d from the center of the object to be tested, that is, d is the distance between the probe and the object to be tested. The SD value is expected to vary with d, the smaller the better. Figure 6 is a schematic diagram showing the amount of change in the measurement error of the sample vibration after 100 seconds. Shows the effect of sample vibration on the object to be tested. Under vibration, an error of ±1.5% can still be maintained. A schematic diagram showing an example block diagram of one of the non-contact eddy current detecting methods.
根據本揭露之另一方面,提出一種非接觸式渦電流檢測方法。參考第7圖,繪示非接觸式渦電流檢測方法之一實施範例方塊圖之示意圖,本揭露利用第一與第二線圈感應待測物之一交流訊號802,此交流訊號為一渦電流;第一與第二線圈分別與第一與第二功率放大器之輸出相耦合,形成一正回授804;第一與第二功率放大器受一負回授裝置控制其振幅於定值806,將此交流訊號經電流檢出器產生一檢出訊號為直流808;負回授裝置由差動放大器、檢波器、誤差比較器與振幅電壓調制器所組成。其中,差動放大器消除溫度效應,誤差比較器適度調整待測物與基準電壓間之誤差,讓振幅調制器可提供一定值振幅給功率放大器。 According to another aspect of the present disclosure, a non-contact eddy current detecting method is proposed. Referring to FIG. 7 , a schematic block diagram of an embodiment of a non-contact eddy current detecting method is illustrated. The present disclosure utilizes the first and second coils to sense an alternating current signal 802 of the object to be tested, and the alternating current signal is an eddy current; The first and second coils are coupled to the outputs of the first and second power amplifiers respectively to form a positive feedback 804; the first and second power amplifiers are controlled by a negative feedback device to have an amplitude at a fixed value 806. The AC signal is generated by the current detector and the detection signal is DC 808; the negative feedback device is composed of a differential amplifier, a detector, an error comparator and an amplitude voltage modulator. Among them, the differential amplifier eliminates the temperature effect, and the error comparator moderately adjusts the error between the object to be tested and the reference voltage, so that the amplitude modulator can provide a certain amplitude to the power amplifier.
本揭露之裝置與方法於雙側非接觸式渦電流探頭透過對稱型線圈與放大電路構成正回授,產生自振盪電路,並透過差動放大電路將輸出訊號相比較降低共模溫飄之影響,同時於電路中使用兩組功率放大器分別提供對應探頭之線圈電流,以降低線圈線路過長受干擾與振動之影響。 The device and method disclosed in the present invention form a positive feedback by a symmetric non-contact eddy current probe through a symmetrical coil and an amplifying circuit, and generate a self-oscillating circuit, and compare the output signals through a differential amplifying circuit to reduce the influence of the common mode temperature drift. At the same time, two sets of power amplifiers are used in the circuit to respectively provide the coil current of the corresponding probe to reduce the influence of the interference and vibration of the coil line.
本揭露使用兩磁蕊運用兩獨立功率放大器分別推動各磁蕊之線圈,降低線圈繞線之長度,且於兩功率放大電路輸出由一組差動放大器將其比較後送至檢波器,藉由此差動放大器降低兩功率放大器對於溫度飄移之影響,兩個磁蕊上兩組線圈與兩個功率放大器形成正回授自振盪電路,自振盪電路使兩探頭於同一振盪迴路中且工作於同一振盪頻率,兩探頭分別接於獨立之功率放大器電路,降低線圈電感因機台扯動造成振盪頻率改變而對於檢測渦電流誤差之影響,同時藉由差動放大器降低共模溫度飄移之影響。 The disclosure uses two magnetic cores to respectively drive the coils of the magnetic cores to reduce the length of the coil windings, and the two power amplifier circuit outputs are compared by a set of differential amplifiers and sent to the detector. The differential amplifier reduces the influence of the two power amplifiers on the temperature drift. The two sets of coils and the two power amplifiers on the two magnetic cores form a positive feedback self-oscillation circuit, and the self-oscillation circuit makes the two probes in the same oscillation circuit and works in the same The oscillating frequency, the two probes are respectively connected to the independent power amplifier circuit, which reduces the influence of the oscillating frequency change caused by the oscillating frequency change of the coil inductance, and reduces the influence of the common mode temperature drift by the differential amplifier.
綜上所述,雖然本發明已以實施例揭露如上,然其並非用以限定本發明。本發明所屬技術領域中具有通常知識者,在不脫離本發明之精神和範圍內,當可作各種之更動與潤飾。因此,本發明之保護範圍當視後附之申請專利範圍所界定者為準。 In conclusion, the present invention has been disclosed in the above embodiments, but it is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.
1‧‧‧非接觸式渦電流檢測裝置 1‧‧‧ Non-contact eddy current testing device
10‧‧‧探頭 10‧‧‧ probe
10a、10b‧‧‧第一、第二線圈 10a, 10b‧‧‧ first and second coils
100a、100b‧‧‧第一、第二磁蕊 100a, 100b‧‧‧ first and second magnetic core
110a、110b‧‧‧第一、第二導線 110a, 110b‧‧‧first and second conductors
120‧‧‧功率放大器 120‧‧‧Power Amplifier
120a、120b‧‧‧第一、第二功率放大器 120a, 120b‧‧‧ first and second power amplifiers
130‧‧‧差動放大器 130‧‧‧Differential Amplifier
140‧‧‧檢波器 140‧‧‧Detector
150‧‧‧基準電壓產生器 150‧‧‧reference voltage generator
160‧‧‧誤差比較器 160‧‧‧Error Comparator
170‧‧‧振幅電壓控制器 170‧‧‧Amplitude voltage controller
180‧‧‧電流檢出器 180‧‧‧current detector
180‧‧‧電流檢出器 180‧‧‧current detector
200‧‧‧待測物 200‧‧‧Test object
300‧‧‧負回授裝置 300‧‧‧negative feedback device
SD‧‧‧檢出訊號 SD‧‧‧Detection signal
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