TWI284730B - Detector - Google Patents

Abstract

A detector is configured substantially vertical to a non-ferrous metal test article. The detector comprises: a coil frame, a main coil which is coaxially installed on the coil frame, a first secondary coil and a second secondary coil. The first and the second secondary coils are respectively located at two sides of the main coil, and the first secondary coil are farther from the non-ferrous metal test article than the second secondary coil. If the main coil is excited by an AC voltage, then the first and the second secondary coils respectively generate a first and a second induction voltages. When the distance between the detector and the non-ferrous metal test article is long, the first induction voltage is smaller than the second induction voltage, and the root-mean-square value of difference is not smaller than 3.5 mV. The difference will first approaches to zero and next increases as the distance is shortened.

Description

1284730 •九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種探測器，特別是指一種用於量測 距離的探測器。 【先前技術】 ~ 渦流（Eddy Current )是由變化的磁場在導體内感應產 生的電流’可被應用於金屬偵測、金屬分類、厚度量測、 距離量測及缺陷檢測等。 t 參閱圖1，日本發明專利特許第1424933號揭露了一種 差動回授型渦流距離計。該距離計包含一交流電源81、一 正回授放大器82、一探測器83及一交流電壓放大器84， 並用於量測該探測器83與一金屬待測物85間的距離。 該探測器83垂直該金屬待測物85，且包括一線圈架 83 1及同軸設置在該線圈架83 1上的一主線圈832、一第一 次線圈833和一第二次線圈834。該等次線圈833、834具 有相同的匝數，並以相同的距離分別位於該主線圈832的 ® 二側，且該第一次線圈833較該第二次線圈834遠離該金 屬待測物85。 該交流電源81輸出一具有預設頻率及預設振幅的交流 電壓到該正回授放大器82。該探測器83及該交流電壓放大 器84設置在該正回授放大器82的回授路徑上。 該正回授放大器82的輸出電壓激發該主線圈832，並 藉此分別在該第一、第二次線圈833、834内感應產生一第 一感應電壓及一第二感應電壓。該等次線圈833、834以差 I284730 % 動方式電連接。該交流電壓放大器84放大該第一、第二感 、應電壓的差異，並回授到該正回授放大器82。 在理想狀況下，該主線圈832產生的交流磁場會在該 . 第一、弟二次線圈833、834内感應產生相同的電壓。 * 參閱圖2 ’橫軸代表該探測器83與該金屬待測物85間 的距離，而曲線91是該第一、第二感應電壓的差異的均方 根（Root Mean Square，RMS)值經歸一化（Normalize)的 • 結果。當該探測器83與該金屬待測物85間的距離很長時 ’該主線圈832產生的交流磁場不會在該金屬待測物85内 感應產生渦流，此時，該第一、第二感應電壓的差異為〇。1284730 • Nine, invention description: [Technical field to which the invention pertains] The present invention relates to a detector, and more particularly to a detector for measuring a distance. [Prior Art] ~ Eddy Current is a current induced by a varying magnetic field in a conductor. It can be applied to metal detection, metal classification, thickness measurement, distance measurement, and defect detection. t Referring to Fig. 1, a differential feedback type eddy current distance meter is disclosed in Japanese Patent No. 1424933. The distance meter includes an AC power source 81, a positive feedback amplifier 82, a detector 83, and an AC voltage amplifier 84, and is used to measure the distance between the detector 83 and a metal object to be tested 85. The detector 83 is perpendicular to the metal object to be tested 85, and includes a bobbin 83 1 and a main coil 832, a first coil 833 and a second coil 834 coaxially disposed on the bobbin 83 1 . The secondary coils 833, 834 have the same number of turns and are respectively located on the two sides of the main coil 832 at the same distance, and the first coil 833 is away from the metal object to be tested 85 from the second coil 834. . The AC power source 81 outputs an AC voltage having a preset frequency and a preset amplitude to the positive feedback amplifier 82. The detector 83 and the AC voltage amplifier 84 are disposed on a feedback path of the positive feedback amplifier 82. The output voltage of the positive feedback amplifier 82 activates the main coil 832, and thereby inducing a first induced voltage and a second induced voltage in the first and second secondary coils 833, 834, respectively. The secondary coils 833, 834 are electrically connected in a dynamic manner with a difference of I284730%. The AC voltage amplifier 84 amplifies the difference between the first and second sensed voltages and returns it to the positive feedback amplifier 82. Under ideal conditions, the alternating magnetic field generated by the primary coil 832 induces the same voltage in the first and second secondary coils 833, 834. * Referring to Figure 2, the horizontal axis represents the distance between the detector 83 and the metal object to be tested 85, and the curve 91 is the Root Mean Square (RMS) value of the difference between the first and second induced voltages. Normalized • Results. When the distance between the detector 83 and the metal object to be tested 85 is long, the alternating magnetic field generated by the main coil 832 does not induce eddy currents in the metal object to be tested 85. At this time, the first and second The difference in induced voltage is 〇.

Ik著该探測器83與該金屬待測物85間的距離逐漸縮短， 該主線圈832產生的交流磁場會在該金屬待測物85内感應 產生渦流，而渦流會產生另一交流磁場（與該主線圈832 產生的父流磁％的方向相反），使得該第一、第二感應電壓 變小’且該第二感應電壓變小的速率大於該第一感應電壓 變小的速率，此時，該第一、第二感應電壓的差異逐漸變 •大。 參閱圖3，橫軸代表該探測器83與該金屬待測物85間 的距離，而曲線92是該正回授放大器82的輸出電壓的 RMS值。由於該第一、第二感應電壓間的差異隨著該探測 斋83與該金屬待測物85間的距離而改變，使得該正回授 放大器82的輸出電壓也隨著該探測器83與該金屬待測物 85間的距離而改變，因此藉由偵測該正回授放大器82的輸 出電壓，可以量測該探測器83與該金屬待測物85間的距 6 1284730 然而，隨著該探測器83與該金屬待測物85間的距離 逐漸加長，該第一、第二感應電壓的差異的改變量逐漸變 小（如圖2所示）。當改變量太小時，該距離計將無法量測 到正確的距離。因此，該距離計可量測的距離是受限的， 一般來說不大於120mm。 再者，在實際狀況下，難以製作該等次線圈833、834 ’使得在該探測器83與該金屬待測物85間的距離很長時 邊第一、第二感應電壓相同，而即使做成，隨著該等次線 圈833、834的老化也不易長期維持。以下分別以兩個例子 說明在距離很長時該第一、第二感應電壓不相同的情形。 參閱圖4，橫軸代表該探測器83與該金屬待測物85間 的距離，而曲線93是該第一、第二感應電壓的差異的RMS 值經歸一化的結果。當該探測器83與該金屬待測物85間 的距離很長時，該第一感應電壓大於該第二感應電壓，且 一者的差異的RMS值一般來說不大於1 mv。隨著該探測器 83與該金屬待測物85間的距離逐漸縮短，該第一、第二感 應電壓的差異呈單調遞增。此情形與圖2的理想狀況類似 ’因此’该距離計可量測的距離與理想狀況相同，一般來 說不大於120mm。 參閱圖5，橫軸代表該探測器83與該金屬待測物85間 的距離，而曲線94是該第一、第二感應電壓的差異的RMS 值經歸一化的結果。當該探測器83與該金屬待測物85間 的距離很長時’該第一感應電壓小於該第二感應電壓，且 1284730 二者的差異的RMS值一般來說不大於imV。隨著該探測器 83與該金屬待測物85間的距離逐漸縮短，該第一、第二感 應電壓的差異會先遞減到〇再遞增，且遞減部分與遞增部 分之相位相差180度。如果同時偵測該正回授放大器82的 輸出電壓的振幅及相位，該距離計可量測的距離與理想狀 況相同’一般來說不大於120mm。而如果只偵測該正回授 放大器82的輸出電壓的振幅，一電壓可能會對應到二距離 。為了避免量測距離上的困難，可以只使用隨著距離逐漸 縮短而電壓遞增的部分進行量測，但如此一來，將會更進 一步限制該距離計可量測的距離，一般來說不大於8〇mm。 另外，每一探測器83的特性（如圖2所示）不會完全 相同’且會隨著老化而偏移。因此，每隔一段時間或在置 換該探測器83時，該距離計都必須校正該正回授放大器82 的輸出電壓與距離的關係（如圖3所示），以量測到正確的 距離。 【發明内容】 因此，本發明之目的即在提供一種可以用於量測距離 之探測器。 於是，本發明探測器實質上垂直該非鐵金屬待測物， 且包括一線圈架及同軸設置在該線圈架上的一主線圈、一 第一次線圈和一第二次線圈。該第一及第二次線圈分別位 於該主線圈的二側，且該第一次線圈較該第二次線圈遠離 該非鐵金屬待測物。 當該主線圈被一交流電壓激發時，該第一及第二次線 1284730 圈分別感應產生一第一感應電壓及一第二感應電壓。當該 探測器與該非鐵金屬待測物間的距離很長時，該第一感應 電壓小於該第二感應電壓，且二者的差異的均方根值不小 於3 ·5ηιν，而隨著該距離逐漸縮短，該差異會先遞減到〇再 遞增。 本發明藉由使用隨著該距離逐漸縮短而該差異遞減的 部分，可以達到量測距離的功效。 【實施方式】Ik the distance between the detector 83 and the metal object to be tested 85 is gradually shortened, the alternating magnetic field generated by the main coil 832 induces eddy currents in the metal object to be tested 85, and the eddy current generates another alternating magnetic field (and The main coil 832 generates a reverse direction of the parent flux %, such that the first and second induced voltages become smaller, and the rate at which the second induced voltage becomes smaller is greater than the rate at which the first induced voltage becomes smaller. The difference between the first and second induced voltages gradually becomes larger. Referring to Fig. 3, the horizontal axis represents the distance between the detector 83 and the metal object to be tested 85, and the curve 92 represents the RMS value of the output voltage of the positive feedback amplifier 82. Since the difference between the first and second induced voltages varies with the distance between the detection gate 83 and the metal object to be tested 85, the output voltage of the positive feedback amplifier 82 also follows the detector 83 and the The distance between the metal test objects 85 changes. Therefore, by detecting the output voltage of the positive feedback amplifier 82, the distance between the detector 83 and the metal object to be tested 85 can be measured 6 1284730, however, The distance between the detector 83 and the metal object to be tested 85 is gradually lengthened, and the amount of change in the difference between the first and second induced voltages is gradually reduced (as shown in FIG. 2). When the amount of change is too small, the distance meter will not be able to measure the correct distance. Therefore, the distance that the distance meter can measure is limited, and is generally not more than 120 mm. Furthermore, under actual conditions, it is difficult to fabricate the secondary coils 833, 834' such that the first and second induced voltages are the same when the distance between the detector 83 and the metal object to be tested 85 is long, and even if As the secondary coils 833, 834 age, it is not easy to maintain for a long time. The following two examples illustrate the case where the first and second induced voltages are different when the distance is long. Referring to Fig. 4, the horizontal axis represents the distance between the detector 83 and the metal object to be tested 85, and the curve 93 is the normalized result of the RMS value of the difference between the first and second induced voltages. When the distance between the detector 83 and the metal object to be tested 85 is long, the first induced voltage is greater than the second induced voltage, and the RMS value of the difference is generally not more than 1 mv. As the distance between the detector 83 and the metal object to be tested 85 is gradually shortened, the difference between the first and second inductive voltages increases monotonically. This situation is similar to the ideal situation of Figure 2. Thus, the distance that the distance meter can measure is the same as the ideal condition, and is generally no more than 120 mm. Referring to Fig. 5, the horizontal axis represents the distance between the detector 83 and the metal object to be tested 85, and the curve 94 is the normalized result of the RMS value of the difference between the first and second induced voltages. When the distance between the detector 83 and the metal object to be tested 85 is long, the first induced voltage is less than the second induced voltage, and the RMS value of the difference between 1284730 is generally not more than imV. As the distance between the detector 83 and the metal object to be tested 85 is gradually shortened, the difference between the first and second inductive voltages is first decreased to 〇 and then incremented, and the decreasing portion is 180 degrees out of phase with the increasing portion. If the amplitude and phase of the output voltage of the positive feedback amplifier 82 are simultaneously detected, the distance that the distance meter can measure is the same as the ideal condition 'generally no more than 120 mm. If only the amplitude of the output voltage of the positive feedback amplifier 82 is detected, a voltage may correspond to two distances. In order to avoid the difficulty in measuring the distance, it is possible to measure only the portion with the voltage increasing as the distance is gradually shortened, but in this way, the distance that the distance meter can measure can be further limited, generally not greater than 8〇mm. In addition, the characteristics of each detector 83 (shown in Figure 2) will not be exactly the same 'and will shift with ageing. Therefore, at intervals or when the detector 83 is being replaced, the distance meter must correct the relationship between the output voltage of the positive feedback amplifier 82 and the distance (as shown in Figure 3) to measure the correct distance. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a detector that can be used to measure distances. Thus, the detector of the present invention is substantially perpendicular to the non-ferrous metal object to be tested, and includes a bobbin and a main coil coaxially disposed on the bobbin, a first coil and a second coil. The first and second coils are respectively located on two sides of the main coil, and the first coil is away from the non-ferrous metal object to be tested than the second coil. When the main coil is excited by an alternating current voltage, the first and second secondary lines 1284730 respectively induce a first induced voltage and a second induced voltage. When the distance between the detector and the non-ferrous metal object to be tested is long, the first induced voltage is smaller than the second induced voltage, and the root mean square value of the difference between the two is not less than 3·5ηιν, and The distance is gradually shortened, and the difference is first decremented to 〇 and then incremented. The present invention achieves the effect of measuring the distance by using a portion where the difference is gradually decreased as the distance is gradually shortened. [Embodiment]

有關本發明之前述及其他技術内容、特點與功效，在 以下配合參考圖式之一個較佳實施例的詳細說明中，將可 清楚地呈現。 參閱圖6,本發明利用渦流的量測裝置之較佳實施例包 含一交流訊號產生單元11、一探測器12、一差動放大單元 13、一父流至直流轉換單元15、一偏置電壓合成單元16及 一對數放大單元17，並用於量測該探測器12與一非鐵金屬 待測物2間的距離。該非鐵金屬待測物2可以是固態或液 態，例如：煉鋼連續澆鑄作業中鑄模内的鋼液。 該探測器12實質上垂直該非鐵金屬待測物2，且包括 一線圈架121及同軸設置在該線圈架121上的一主線圈122 、一第一次線圈123和一第二次線圈124。該等次線圈123 、124分別位於該主線圈122的二側，且該第一次線圈123 較該第二次線圈124遠離該非鐵金屬待測物。 該交流《產生單元11輸丨―具有預設頻率及預設振 幅的交流電壓到該探測器12的主線圈122，並激發該主線 1284730 圈1^2 ’且藉此分別在該第一、第二次線圈ι23、ι24内感 應產生一第一感應電壓及一第二感應電壓。 爹閱圖7,橫軸代表該探測器12與該非鐵金屬待測物 2間的距離，而曲線3 i是該第一、第二感應電壓的差異的 RMS值經歸一化的結果。當該探測器12與該非鐵金屬待測 物2間的距離很長（不小於4〇〇mm)時，該第一感應電壓 小方；該第二感應電壓，且二者的差異的rms值不小於 . 3.5mV。隨著該探測器12與該非鐵金屬待測物2間的距離 逐漸縮短，該第一、第二感應電壓的差異會先遞減到〇再 遞增。該第一、第二感應電壓的差異為〇時，該探測器12 與該非鐵金屬待測物2間的距離落在1〇mm〜5〇mm的範圍内 〇 值得注意的是’本發明是使用隨著距離逐漸縮短而電 壓遞減的部分進行量測，與習知不同。然而，隨著該探測 器12與該非鐵金屬待測物2間的距離逐漸加長，該第一、 • 第二感應電壓的差異的改變量逐漸變小。當改變量太小時 ，將無法量測到正確的距離。因此，可量測的距離是受限 的，一般來說不大於12〇mm，與習知相同。為了解決此問 題，本發明藉由使改變量大的部分有較小的增益而改變量 小的部分有較大的增益（詳細情形如以下所述），能增加可 量測的距離，一般來說不大於300mm。 麥閱圖6，在本實施例中，該線圈架121的直徑為 28mm，該主線圈122的阻數為52區，該第一、第二次線圈 I23、U4羚匝數皆為72匝，而該第一、第二次線圈、 10 1284730 124與該主線圈122的距離皆為9mm。 較佳地’當本發明用於高溫環境時，該線圈架⑵是 選用熱膨脹係數低的絕緣材質。 該差動放大單元13從該探測器U的第-、第二次線 圈123、124接收該第…第二感應電M，並放大該第_、，、 弟-感應電壓的差異後輸出到該交流至直流轉換單元Η。 該交流至直流轉換單元15將接收到的交流電壓轉換成 可反應該交流電壓之振幅的直流電壓（如圖8的曲線32所 示）後輸出到該偏置電壓合成單元16。 在本實施财’該交流至直轉換單元15是計算該交 流電壓的RMS值以得到該直流電壓。 省偏置電壓合成單元16將一偏置電壓（如圖8的曲線 33所示）減去接收到的電壓後（如圖9的曲線34所示）輸 出到㈣㈣大單元17。該偏置電壓大於在該探測器_ 该非鐵金屬待測物2 _距純長時接㈣的電壓。 。亥對數放大單兀17將接收到的電壓對數放大（即較小 的電壓有較大的增益而較大的電壓有較小的增益）後輸出 〇 參閱圖10，橫軸代表該探測器12與該非鐵金屬待測物 1的距離’而曲線3 5是該對數放大單元丨7的輸出電壓。 =由仙該對數放大單元17的輸出電壓，可以量測該探測 為12與該非鐵金屬待測物2間的距離。 值得注意的是，當本發明用於量測較短距離（即不大 於12〇mm)時，可以不需要該偏置電壓合成單元16及該對 1284730 數放大單元17。此時，Μ 士 /占、3丨斗a上丄 稭由偵測该交流至直流轉換單元1 5 的輸出電壓（如圖8的曲綠 口曲線32所不），可以量測該探測器 12與該非鐵金屬待測物2間的距離。 然而，每-探測器12的特性（如圖7所示）不會完全 相同且θ 著老化而偏移。因此，每隔—段時間或在置 換該探測器12時’都必須校正該對數放大單元17的輸出 電壓與距離的關係（如圖1G所示），以量測到正確的距離The foregoing and other technical features, features and advantages of the present invention will be apparent from Referring to FIG. 6, a preferred embodiment of the eddy current measuring device of the present invention comprises an AC signal generating unit 11, a detector 12, a differential amplifying unit 13, a parent to DC converting unit 15, and a bias voltage. The synthesizing unit 16 and the pair of amplifying units 17 are used to measure the distance between the detector 12 and a non-ferrous metal object to be tested 2. The non-ferrous metal analyte 2 may be solid or liquid, for example, molten steel in a mold in a continuous steel casting operation. The detector 12 is substantially perpendicular to the non-ferrous metal object 2, and includes a bobbin 121 and a main coil 122, a first sub-coil 123 and a second sub-coil 124 coaxially disposed on the bobbin 121. The secondary coils 123 and 124 are respectively located on two sides of the main coil 122, and the first coil 123 is farther away from the non-ferrous metal object to be tested than the second coil 124. The communication "generating unit 11 transmits" an alternating voltage having a preset frequency and a preset amplitude to the main coil 122 of the detector 12, and exciting the main line 1284730 to the circle 1^2' and thereby respectively in the first and the A first induced voltage and a second induced voltage are induced in the secondary coils ι23 and ι24. Referring to Fig. 7, the horizontal axis represents the distance between the detector 12 and the non-ferrous metal analyte 2, and the curve 3 i is the normalized result of the RMS value of the difference between the first and second induced voltages. When the distance between the detector 12 and the non-ferrous metal analyte 2 is long (not less than 4 〇〇mm), the first induced voltage is small; the second induced voltage, and the rms value of the difference between the two Not less than 3.5mV. As the distance between the detector 12 and the non-ferrous metal object 2 is gradually shortened, the difference between the first and second induced voltages is first decreased to 〇 and then increased. When the difference between the first and second induced voltages is 〇, the distance between the detector 12 and the non-ferrous metal analyte 2 falls within a range of 1 〇 mm to 5 〇 mm, and it is noted that the present invention is The measurement is performed using a portion where the voltage is gradually decreased as the distance is gradually shortened, which is different from the conventional one. However, as the distance between the detector 12 and the non-ferrous metal analyte 2 is gradually lengthened, the amount of change in the difference between the first and second induced voltages gradually becomes smaller. When the amount of change is too small, the correct distance cannot be measured. Therefore, the measurable distance is limited, generally no more than 12 〇 mm, as is conventional. In order to solve this problem, the present invention can increase the measurable distance by making the portion with a large change amount have a small gain and the small portion having a small gain (details are as described below), generally Said no more than 300mm. In the present embodiment, the diameter of the bobbin 121 is 28 mm, the resistance of the main coil 122 is 52, and the number of the first and second coils I23 and U4 is 72 匝. The distance between the first and second coils, 10 1284730 124 and the main coil 122 is 9 mm. Preferably, when the present invention is used in a high temperature environment, the bobbin (2) is made of an insulating material having a low coefficient of thermal expansion. The differential amplifying unit 13 receives the second electric induction M from the first and second coils 123 and 124 of the detector U, and amplifies the difference between the _, 、, 弟-induced voltage and outputs the difference AC to DC conversion unitΗ. The AC-to-DC conversion unit 15 converts the received AC voltage into a DC voltage (shown by a curve 32 in Fig. 8) that can reflect the amplitude of the AC voltage, and outputs it to the bias voltage synthesizing unit 16. In the present embodiment, the AC to DC conversion unit 15 calculates the RMS value of the AC voltage to obtain the DC voltage. The provincial bias voltage synthesizing unit 16 outputs a bias voltage (shown as curve 33 of FIG. 8) to the received voltage (as shown by curve 34 in FIG. 9) to (4) (d) large cell 17. The bias voltage is greater than the voltage at the detector _ the non-ferrous metal test object 2 _ from the pure length (four). . The logarithmic amplification unit 17 amplifies the received voltage logarithm (ie, a larger voltage has a larger gain and a larger voltage has a smaller gain). The output is referred to FIG. 10, and the horizontal axis represents the detector 12 and The distance θ of the non-ferrous metal test object 1 and the curve 35 are the output voltage of the logarithmic amplification unit 丨7. = The output voltage of the logarithmic amplification unit 17 can be measured as the distance between the detection 12 and the non-ferrous metal analyte 2. It is to be noted that the bias voltage synthesizing unit 16 and the pair of 1284730 magnifying units 17 may not be required when the present invention is used to measure a short distance (i.e., no more than 12 mm). At this time, the detector 12 can be measured by detecting the output voltage of the AC to DC conversion unit 15 (not shown in the curve of the green curve 32 of FIG. 8). The distance from the non-ferrous metal analyte 2 . However, the characteristics of each detector 12 (as shown in Figure 7) are not exactly the same and θ is aging and offset. Therefore, the relationship between the output voltage of the logarithmic amplification unit 17 and the distance (as shown in Fig. 1G) must be corrected every other time or when the detector 12 is replaced (to measure the correct distance).

。回歸參閱圖6,較佳地，本發明可以更包含一處理單元 18以進行校正。 该處理皁兀18儲存既有之該對數放大單元17的輪出 電壓與距離的關係，以當作基本特徵數據。在進行量測前 ^亥處理單it 18先調整該偏置電壓，以在該探測器12與 该非鐵金屬待測物2間的距離很長時，使該對數放大單元 17的輸出電壓與其儲存的電壓實質上相同。然後，該處理 單元18固定該偏置電壓，並取得另一距離時該對數放大單 =17的輸出電壓。在進行量測時，該處理單元18根據取 得的電壓與儲存的數據，將該對數放大單元17的輸出電壓 以等比内差法換算成距離。如此一來，可以提高量測的正 確性。 在本實施例中，該處理單元18儲存距離在〇〜4〇〇mm 範圍内每改變10mm時該對數放大單元17的輸出電壓，其 值用Vb(i)表示，且卜〇〜40。在進行量測前，該處理單元18 先調整該偏置電壓，以在距離為4〇〇mm (即卜4〇)時，使 該對數放大單元17的輸出電壓Vn(4〇)與其儲存的電壓 12 1284730. Referring back to Figure 6, preferably, the present invention may further comprise a processing unit 18 for performing the correction. The treated saponin 18 stores the relationship between the round-out voltage and the distance of the logarithmic amplification unit 17 as the basic characteristic data. Before the measurement is performed, the bias voltage is first adjusted to adjust the output voltage of the logarithmic amplification unit 17 when the distance between the detector 12 and the non-ferrous metal analyte 2 is long. The stored voltages are substantially the same. Then, the processing unit 18 fixes the bias voltage and obtains an output voltage of the logarithm = 17 at another distance. When the measurement is performed, the processing unit 18 converts the output voltage of the logarithmic amplification unit 17 into a distance by a proportional internal difference method based on the obtained voltage and the stored data. In this way, the accuracy of the measurement can be improved. In the present embodiment, the processing unit 18 stores the output voltage of the logarithmic amplification unit 17 every 10 mm in the range of 〇~4 〇〇mm, the value of which is represented by Vb(i), and 〇40. Before performing the measurement, the processing unit 18 first adjusts the bias voltage to cause the output voltage Vn (4〇) of the logarithmic amplification unit 17 to be stored with the distance when the distance is 4 〇〇mm (ie, 4 〇) Voltage 12 1284730

Vb(4〇)實質上相同。然後，該處理單元 ，並取得距離為⑽匪（即卜10)時 固定該偏—置電壓 輸出電壓Vn(lG)，並根據下式計算取^^早70 17的 據間的比例A : 、甩堊與儲存的數 α^ΥΜζΣΜ G ㈣-F“10) 在進行量測時，該處理單元18根 像下式計算距離/: \Avb{i+\yAvb(i)+\ 其中，V是偵測到的該對數放大單 且AVb(WAVb(i+1)。 早U7的輸出電壓， =地’本發明可以更包含一帶通據波單元14，用於 ^ ψ ^ ^ 罨1中的回頻及低頻雜訊後Vb (4〇) is substantially the same. Then, the processing unit fixes the bias voltage output voltage Vn(lG) when the distance is (10) 匪 (ie, 10), and calculates the ratio A of the data of the early 70 17 according to the following formula:甩垩 and stored number α^ΥΜζΣΜ G (4)-F "10) When measuring, the processing unit 18 calculates the distance / as follows: \Avb{i+\yAvb(i)+\ where V is the Detect The logarithm of the logarithm is amplified and AVb (WAVb(i+1). The output voltage of early U7, = ground'. The present invention may further include a bandpass data unit 14 for the frequency hopping in ^ ψ ^ ^ 罨1 And low frequency noise

輸出到s亥父流至直流轉換單AH 正確性。 乂更進步如南量測的 ::二述，本發明藉由使用該探測器12隨著距離逐漸 部分進行量測，能解決習知可量測距離 的問題，而藉由該偏置電塵合成單…該對 …早7^ 17 ’能增加可量測距離，再藉由該處理單元18 仃校正，能提高量測的正確性。因此，確實可 發明的目的。 Α+ 、所述者，僅為本發明之較佳實施例而已，合不 能以此限定本發明每妳 田 月A鈿之靶圍，即大凡依本發明申請專Output to s Hai parent flow to DC conversion single AH correctness.乂 进步 如 如 南 : : : : : : : : : : : : : : : : : 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南 南Synthetic single...the pair...the early 7^17' can increase the measurable distance, and then the correction by the processing unit 18 , can improve the accuracy of the measurement. Therefore, it is indeed possible to invent the object. Α+, the above is only a preferred embodiment of the present invention, and it is not possible to limit the target circumference of each of the fields of the present invention, that is, the application for the invention according to the present invention.

13 1284730 範圍及發明說明内容所作之簡單的等效變化與修錦，皆仍 屬本發明專利涵蓋之範圍内。 【圖式簡單說明】 圖1是一電路圖，說明習知的差動回授型渦流距離計 ， 圖2是一特性曲線圖，說明在理想狀況下該距離計的 一探測器的感應電壓差與距離的關係； .圖3是一特性曲線圖，說明該距離計的輸出電壓與距 離的關係； 圖4是一特性曲線圖，說明在實際狀況下該探測器的 感應電壓差與距離的一關係； 圖5是一特性曲線圖，說明在實際狀況下該探測器的 感應電壓差與距離的另一關係； 圖6是一電路圖，說明本發明渦流量測距離的裳置的 較佳實施例； • 圖7是一特性曲線圖，說明該較佳實施例的一探測器 的感應電壓差與距離的關係； 圖8是一特性曲線圖，說明該較佳實施例的一交流至 直流轉換單元的輸出電壓與距離及一偏置電壓的關係； 圖9是一特性曲線圖，說明該較佳實施例的一偏置電 壓合成單元的輸出電壓與距離的關係；及 圖1 〇是一特性曲線圖，說明該較佳實施例的一對數放 大單元的輸出電壓與距離的關係。 14 1284730 【主要元件符號說明】13 1284730 The scope of the invention and the simple equivalent changes and modifications made by the description of the invention are still within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram illustrating a conventional differential feedback type eddy current distance meter, and FIG. 2 is a characteristic diagram illustrating an induced voltage difference of a detector of the distance meter under ideal conditions. The relationship between distances; Fig. 3 is a characteristic graph illustrating the relationship between the output voltage and the distance of the distance meter; Fig. 4 is a characteristic graph illustrating the relationship between the induced voltage difference and the distance of the detector under actual conditions. FIG. 5 is a characteristic diagram illustrating another relationship between the induced voltage difference and the distance of the detector under actual conditions; FIG. 6 is a circuit diagram illustrating a preferred embodiment of the vortex flow distance of the present invention; Figure 7 is a characteristic diagram illustrating the relationship between the induced voltage difference and the distance of a detector of the preferred embodiment; Figure 8 is a characteristic diagram illustrating an AC to DC conversion unit of the preferred embodiment. The relationship between the output voltage and the distance and a bias voltage; FIG. 9 is a characteristic diagram illustrating the relationship between the output voltage and the distance of a bias voltage synthesizing unit of the preferred embodiment; and FIG. Exemplary graph illustrating the relationship between a pair of numbers of the preferred embodiment of the amplification unit output voltage and distance. 14 1284730 [Description of main component symbols]

11 * ^ ^y ^y * -交流訊號產生單元 1 <- i * ^ * ΐ -探測器 1 *r * ^ * · …差動放大單元 4 ·ν + » ♦ X + K +，帶通濾波單元 1 ¢. p * * * f < 交流至直流轉換單元 1 ¢: * κ ♦ *i + …偏置電壓合成單元 17。…… "對數放大單元 1 y * y * y ^ ν …處理單元 2……" "非鐵金屬待測物 31〜35。 μ曲線 1511 * ^ ^y ^y * - alternating signal generating unit 1 <- i * ^ * ΐ - detector 1 *r * ^ * · ... differential amplifying unit 4 · ν + » ♦ X + K +, band pass Filter unit 1 ¢. p * * * f < AC to DC conversion unit 1 ¢: * κ ♦ *i + ... bias voltage synthesizing unit 17. ... "Logarithmic Amplification Unit 1 y * y * y ^ ν ...Processing Unit 2..."" Non-ferrous metal test object 31~35. μ curve 15

Claims (1)

l28473〇 申請專利範圍： 種％ /則為’貫質上垂直一非鐵金屬待測物，且包含： —線圈架； —主線圈； —第一次線圈；及 —第二次線圈，與該主線圈和該第一次線圈同轴設 置在該線圈架上，該第一及第二次線圈分別位於該主 的二側，且該第一次線圈較該第二次線圈遠離該非鐵 金屬待測物； 當該主線圈被一交流電壓激發時，該第一及第二次 =圈分別感應產生一第一感應電壓及一第二感應電壓， 田忒捺測器與該非鐵金屬待測物間的距離很長時，該第 〜感應電壓小於該第二感應電壓，且二者的差異的均方 拫值不小於3.5mV，而隨著該距離逐漸縮短，該差異會 先遞減到0再遞增。 曰 2 % ·=據申請專利範圍第丨項所述之探測器，其中，在該第 〜及第二感應電壓的差異為0時，該探測器與該非鐵金 屬待測物間的距離落在l〇mm〜5〇mm的範圍内。 3.依據申請專利範圍S丨項所述之探測器，其中，該第— 及第二次線圈的匝數相同。 該第一 該線圈 4·依據申請專利範圍第丨項所述之探測器，其中 及苐_次線圈與該主線圈的距離相同。 5.依據申請專利範圍第i項所述之探測器，其中 架是選用熱膨脹係數低的絕緣材質。 16 1284730 6.依據申請專利範圍第1項所述之探測器，其中，當距離 不小於400mm時代表距離很長。L28473〇 Patent application scope: Species % / then 'permeally perpendicular to a non-ferrous metal test object, and includes: - coil bobbin; - main coil; - first coil; and - second coil, and The main coil and the first coil are coaxially disposed on the bobbin, the first and second coils are respectively located on two sides of the main body, and the first coil is away from the non-ferrous metal than the second coil When the main coil is excited by an alternating current voltage, the first and second times=circle respectively induce a first induced voltage and a second induced voltage, and the field detector and the non-ferrous metal object to be tested When the distance between the two is long, the first induced voltage is smaller than the second induced voltage, and the mean square value of the difference between the two is not less than 3.5 mV, and as the distance is gradually shortened, the difference is first decreased to 0. Increment.曰2 % ·= The detector according to the scope of the application of the patent application, wherein the distance between the detector and the non-ferrous metal object to be tested falls when the difference between the first and second induced voltages is zero L〇mm~5〇mm. 3. The detector according to claim S, wherein the first and second coils have the same number of turns. The first coil 4 is the detector according to the scope of the invention, wherein the 苐-second coil is the same distance from the main coil. 5. The detector according to item i of the patent application scope, wherein the frame is made of an insulating material having a low coefficient of thermal expansion. 16 1284730 6. The detector of claim 1, wherein the distance is a long distance when the distance is not less than 400 mm.