201011308 九、發明說明： 【發明所屬之技術領域】 本發明係為一種量測電容的電容值或是電容值的變化 量的方法與電路，尤其是有關於一種以電容積分電路量測 電容的電容值或是電容值的變化量的方法與電路。 【先前技術】 美國專利6, 466, 036號中揭示一種如何利用電荷移 轉技術用來偵測或是量測待測電容的電容值變化的方法與 電路。如圖（一）所示，該技術透過將待測電容内的電荷移 轉到一個參考電容内，經過移轉多次之後，參考電容内的 電荷會逐漸升高，參考電容的電壓也會跟著升高，藉由量 測參考電容上的電壓變化，因而計算待測電容的電容值變 化。 該技術有一個缺點，就是每次由待測電容移轉到參考 電容電荷量都不相同，後一次比前一次移轉較少的電荷， 經過累計多次之後，最後幾次移轉的電荷相對第一次來 說，已經少很多，參考電容的電壓上升，越到後面變得上 升越慢，因此造成量測待測電容的時間較久及精確度較差 等衍生之問題。 緣此，本案之發明人係研究出一種一種量測電容的電 容值或是電容值的變化量的方法與電路，尤其是有關於一 種依一已知電容值及三個開關以電容積分電路量測一未知 電容的電容值或是其的變化量的方法與電路，其係可改善 習知技術中之量測待測電容的時間較久及精確度較差之現 201011308 狀0 【發明内容】 本發明係關於一種量測雷☆ 化量的方法與電路，其係電容值或是電容值的變 精確電容值或是電容值的分電路’進而達成高 J雙化篁感測之目的 該方法至少包括 電容一端接地，另 (a)將該未知 端開路，同時，將該已知雷办& — …一… 放大器之負輸入端與輪出端=短路，並連接到一運算 入端連接到一第一參考電中’該運算放大器之正輪 _放大益之負：端連接到該已知電容的-端，該運 算放大器之輸出端連接到診p ▲ $ % 連 σ ^ 孑已知電容的另一端；（C)將該未 .式―恭广收ϋ 參考電壓使該未知電容充電至 一預定電壓；（d)將該未知曾办 電令另—端開路；以及（e)將該 未知電容另一端以一類比間J C開關導通的方式與該運算放大器 之負輸入端連接。 參 較佳的，該電路至少包 匕祜.一已知電容，一第一參考 電壓；-不同於該第-參考電壓之第二參考電壓；一第一 開關其端係輕接於該未知對地電容未接地之一端係 控制對該未知對地電容充電到該第二參考電壓·’一第二開 關，其一端係耦接於該未知對地電容未接地之一端，係控 制對該已知電容充電；一第三開關，係控制對該已知電容 放電；一電容積分電路，係包含該已知電容，運算放大器， 第一參考電壓及該第三開關，使用該第/參考電壓量讓第 二開關兩端有一個固定的電廢差，提供/個固定電流對已 201011308 知電容充電；一電壓量測電路，用來量測運算放大器輸出 端電壓，此電壓一為參考電容其中一端的電壓以及一訊號 處理及控制電路，係用來控制該第一、第二、第三開關， 並對電壓量測電路的量測結果做處理，以測該未知待測電 容的電容值或是電容值的變化量。 為使貴審查委員對於本發明之結構目的和功效有更 進一步之了解與認同，茲配合圖示範例詳細說明如後。 【實施方式】 圖二係為本發明較佳實施例之電路圖。 本發明電路的一開關201用來對待測電容211 (如金屬 導體平板對地的電容）作初始化，該開關201導通時會初 始化待測電容211的電位，將該待測電容211充電到一電 壓212，初始化完成時，把該蘭關201斷開，讓待測電容 2Π兩端的電壓保持在該電壓212。 本發明電路的一開關203用來對參考電容207作初始 化，開關203導通時會初始化參考電容207，將參考電容 207兩端的電壓放電到0伏特，初始化完成時，把開關203 斷開。 其中，本發明主要特性是利用一參考電容積分電路 220，來量測待測電容211的電容值或是電容值的變化量。 該待測電容可為一金屬球狀物或金屬平板。電容積分電路 220可以透過各種電路完成，本發明使用一個運算放大器 206, —個參考電壓204及一個參考電容207完成，參考電 容207兩端連接到運算放大器206的反向輸入端及輸出端。 201011308 當參考電容207充電完成時，一電壓量測電路208用來 量測運算放大器輸出端的電壓205，再經由一訊號處理及控 制電路209處理所量測的訊號，以計算待測電容211的電 容值或是電容值的變化量。該訊號處理及控制電路其功能 包含三個開關元件的控制，控制啟動電壓量測電路2〇8, 讀取電壓量測電路的結果，及處理量測待測電容211的計 算。 較佳者，該電壓量測電路2〇8可為一類比數位轉換器或 馨一比較器。該訊號處理及控制電路209可由微控制器，微 處理器，數位訊號處理器，FPGA，或是積體電路中選擇 —種〇 較佳者，本發明電路可以由積體電路製造的方式做在一 顆積體電路内，亦可以由數個積體電路所構成。本發明電 路亦可用來量測電容的電容值或是電容值的變化量，也可 以篁測其他元件含有電容的特性的電容值或是電容值的變 化量，特別適合量測任何物體的對地的電容值，包含人體 參的各個部位，因接觸或是靠近某個感應平面而產生電容值 的變化量因此可運用為觸碰式開關。而該觸碰式開關可為 多通道開關。 … 較佳者，本發明的待測電容2 i i，可為一金屬平板或是 積體電路的-個或是一個以上的接腳所產生的電容 以是印刷電路板(PCB)上導線所形成之寄生電容，或是將導 線製作成圓形或是其他形狀所形成的電容，也可以是因人 體或是其他物體接觸或是靠近該印刷電路板(pCB)上導線 或導線形成的平面213所產生的電容。 201011308 較佳者，該參考電壓204,可以使用各種方式實現，可 以在積體電路内由積體電路的電源產生，或是利用其他電 阻、電容、電晶體等元件所實現產生。電壓204的電壓值 可以是任意電壓，但是不同於參考電壓212。此參考電壓 204接在運算放大器2〇6的正端輸入，因運算放大器2〇6操 作在負回授的緣故，運算放大器206的正端與運算放大器 的負端為虛擬短路，所以運算放大器2〇6的負端電壓相等 於參考電壓204的電壓。 φ 圖二的實施步驟如下，其中步驟a〜e見於圖三： a. 先將本實施例電路設定在一個初始化的狀態開關2〇1 及202斷開，開關203導通，將積分電路上的參考電容207 初始化，將參考電容207上兩端的電壓放電到〇v;由圖三 可知電容211開路，參考電容207短路； b. 將開關203斷開，由圖三可知參考電容2〇7開路； c. 將開關201導通，將待測電容211初始化，待測電容上 211的電壓充電到參考電壓212 ; φ d.將開關201斷開，由圖三可知電容211再次開路； e.將開關202導通一個固定時間（△ 〇後，再將開關202 斷開； f·重複步驟c，d，e N次之後，到下一步驟g ; g·電壓量測電路208量測205的電壓值；以及 h_利用電壓量測電路208的量測結果，以一訊號處理及控制 電路計算待測電容211的電容值或是電容值的變化量。 此實施例的說明如下： 一個金屬圓型導體平面213及連接此金屬圓型導體平 201011308 面213到積體電路的接腳上所產生的寄生電容211，當人的 手指靠近或是接近此金屬圓型導體平面213時，會增加待 測電容211的電容值。所以量測待測電容211的電容值增 加的量，就可以判斷出是否人的手指是否靠近或是接近此 金屬圓型導體平面213。 在執行完步驟a，b參考電容207兩端的電壓為0V; 執行完步驟c，d待測電容211對地的電壓為固定的電 壓 212; 執行完步驟e，參考電容207兩端的電壓會被充電到一個 △ V; 此 Δν = Ι*Δΐ/〇8; I為參考電壓212，204相減，除以開關202導通時的電 阻值。 △ t為開關202導通的時間；201011308 IX. Description of the Invention: [Technical Field] The present invention relates to a method and a circuit for measuring a capacitance value of a capacitor or a variation of a capacitance value, and more particularly to a capacitance measuring a capacitance by a capacitance integrating circuit Method and circuit for changing the value or capacitance value. [Prior Art] A method and circuit for using a charge transfer technique to detect or measure a change in capacitance of a capacitor to be measured is disclosed in U.S. Patent No. 6,466,036. As shown in (1), the technique shifts the charge in the capacitor to be tested into a reference capacitor. After multiple shifts, the charge in the reference capacitor gradually increases, and the voltage of the reference capacitor also follows. Ascending, by measuring the voltage change on the reference capacitor, the capacitance value of the capacitor to be measured is calculated. One disadvantage of this technique is that each time the capacitance to be measured is transferred to the reference capacitor, the amount of charge is different. The latter time is less than the previous charge. After a cumulative number of times, the last few transferred charges are relative. For the first time, it is much less. The voltage of the reference capacitor rises, and the slower the rise becomes later, which causes the problem of measuring the time of the capacitor to be tested and the accuracy. Therefore, the inventor of the present invention has developed a method and circuit for measuring the capacitance value of a capacitor or the amount of change in a capacitance value, in particular, a method according to a known capacitance value and a capacitance of three switches to a capacitance integration circuit. A method and a circuit for measuring a capacitance value of an unknown capacitor or a variation thereof, which can improve the time and accuracy of measuring the capacitance to be tested in the prior art. 201011308 shape 0 [Summary] The invention relates to a method and a circuit for measuring the amount of lightning ☆, which is a sub-circuit of a capacitance value or a capacitance value of a capacitance value or a capacitance value, and further achieves the purpose of high-J bismuth 篁 sensing. Including one end of the capacitor is grounded, and (a) the unknown end is open, and at the same time, the negative input of the known thunder & a... amplifier is shorted to the wheel end and connected to an arithmetic input terminal In a first reference circuit, the positive wheel of the operational amplifier is negative: the terminal is connected to the - terminal of the known capacitor, and the output of the operational amplifier is connected to the diagnosis p ▲ $ % σ σ ^ 孑 known capacitance The other end (C) omitting the reference voltage to charge the unknown capacitor to a predetermined voltage; (d) opening the unknown to the other end; and (e) the other end of the unknown capacitor Connected to the negative input of the operational amplifier in a manner that a ratio of JC switches are turned on. Preferably, the circuit includes at least a known capacitor, a first reference voltage, a second reference voltage different from the first reference voltage, and a first switch whose end is lightly connected to the unknown pair. One end of the ground capacitor is not grounded to charge the unknown ground capacitance to the second reference voltage, and a second switch is coupled to one end of the unknown grounded capacitor that is not grounded. Capacitor charging; a third switch is for controlling discharge of the known capacitor; a capacitor integrating circuit includes the known capacitor, an operational amplifier, a first reference voltage, and the third switch, using the first/reference voltage amount There is a fixed electrical waste difference at both ends of the second switch, and a fixed current is supplied to the capacitor of 201011308. A voltage measuring circuit is used to measure the voltage of the output terminal of the operational amplifier. This voltage is one end of the reference capacitor. The voltage and a signal processing and control circuit are used to control the first, second, and third switches, and process the measurement result of the voltage measuring circuit to measure the capacitance of the unknown capacitor to be tested. Or the amount of change of the capacitance value. In order to enable the reviewing committee to have a better understanding and recognition of the structural purpose and efficacy of the present invention, the following examples are described in detail with reference to the illustrated examples. Embodiments Fig. 2 is a circuit diagram of a preferred embodiment of the present invention. A switch 201 of the circuit of the present invention is used to initialize the capacitor 211 (such as the capacitance of the metal conductor plate to the ground). When the switch 201 is turned on, the potential of the capacitor 211 to be tested is initialized, and the capacitor 211 to be tested is charged to a voltage. 212. When the initialization is completed, the blue off 201 is turned off, and the voltage across the capacitor 2Π to be tested is maintained at the voltage 212. A switch 203 of the circuit of the present invention is used to initialize the reference capacitor 207. When the switch 203 is turned on, the reference capacitor 207 is initialized, and the voltage across the reference capacitor 207 is discharged to 0 volts. When the initialization is completed, the switch 203 is turned off. The main feature of the present invention is that a reference capacitance integrating circuit 220 is used to measure the capacitance value of the capacitor 211 to be measured or the amount of change in the capacitance value. The capacitance to be tested can be a metal ball or a metal plate. The capacitance integrating circuit 220 can be implemented by various circuits. The present invention uses an operational amplifier 206, a reference voltage 204 and a reference capacitor 207. The reference capacitor 207 is connected across the inverting input and output of the operational amplifier 206. When the reference capacitor 207 is fully charged, a voltage measuring circuit 208 is used to measure the voltage 205 at the output of the operational amplifier, and then the measured signal is processed by a signal processing and control circuit 209 to calculate the capacitance of the capacitor 211 to be tested. The value or the amount of change in the capacitance value. The function of the signal processing and control circuit includes the control of three switching elements, the control of the starting voltage measuring circuit 2〇8, the reading of the result of the voltage measuring circuit, and the processing of the measurement of the capacitance 211 to be measured. Preferably, the voltage measuring circuit 2〇8 can be an analog-to-digital converter or a comparator. The signal processing and control circuit 209 can be selected from a microcontroller, a microprocessor, a digital signal processor, an FPGA, or an integrated circuit. The circuit of the present invention can be manufactured by an integrated circuit. In an integrated circuit, it can also be composed of several integrated circuits. The circuit of the invention can also be used for measuring the capacitance value of the capacitor or the variation of the capacitance value, and can also measure the capacitance value of the characteristic of the other component or the variation of the capacitance value, and is particularly suitable for measuring the grounding of any object. The capacitance value, which includes various parts of the human body ginseng, can be used as a touch switch due to the amount of change in capacitance caused by contact or proximity to a sensing plane. The touch switch can be a multi-channel switch. Preferably, the capacitor 2 ii to be tested in the present invention can be a metal plate or a capacitor of one or more pins or a capacitor formed by a lead on a printed circuit board (PCB). The parasitic capacitance, or the capacitance formed by making the wire into a circular shape or other shape, may also be a plane 213 formed by a human body or other object contacting or close to a wire or wire on the printed circuit board (pCB). The resulting capacitance. 201011308 Preferably, the reference voltage 204 can be implemented in various manners, and can be generated by the power supply of the integrated circuit in the integrated circuit, or by using other resistors, capacitors, transistors, and the like. The voltage value of voltage 204 can be any voltage, but different than reference voltage 212. The reference voltage 204 is connected to the positive terminal input of the operational amplifier 2〇6. Since the operational amplifier 2〇6 operates under the negative feedback, the positive terminal of the operational amplifier 206 and the negative terminal of the operational amplifier are virtual short circuits, so the operational amplifier 2 The negative terminal voltage of 〇6 is equal to the voltage of reference voltage 204. The implementation steps of Fig. 2 are as follows, wherein steps a to e are shown in Fig. 3: a. First, the circuit of this embodiment is set in an initial state, switches 2〇1 and 202 are turned off, and switch 203 is turned on, and the reference on the integrating circuit is used. The capacitor 207 is initialized, and the voltage at both ends of the reference capacitor 207 is discharged to 〇v; as shown in FIG. 3, the capacitor 211 is open, and the reference capacitor 207 is short-circuited; b. The switch 203 is turned off, and the reference capacitor 2〇7 is open from FIG. 3; Turning on the switch 201, the capacitor 211 to be tested is initialized, and the voltage of the capacitor 211 to be measured is charged to the reference voltage 212; φ d. The switch 201 is turned off, and the capacitor 211 is opened again by the third figure; e. the switch 202 is turned on. After a fixed time (Δ〇, then switch 202 is turned off; f· repeat steps c, d, e N times, to the next step g; g·voltage measuring circuit 208 measures the voltage value of 205; and h Using the measurement result of the voltage measuring circuit 208, the signal value of the capacitor 211 to be measured or the amount of change of the capacitance value is calculated by a signal processing and control circuit. The description of this embodiment is as follows: A metal circular conductor plane 213 and Connect this metal circular guide The parasitic capacitance 211 generated on the pin of the integrated circuit of the 201011308 surface 213 to the integrated circuit, when the human finger approaches or approaches the metal circular conductor plane 213, increases the capacitance value of the capacitor 211 to be tested. By measuring the amount of increase in the capacitance of the capacitor 211, it can be determined whether the human finger is close to or close to the metal circular conductor plane 213. After performing step a, the voltage across the reference capacitor 207 is 0V; c, d The voltage of the capacitor 211 to be tested is a fixed voltage 212; after step e is performed, the voltage across the reference capacitor 207 is charged to a ΔV; Δν = Ι*Δΐ/〇8; I is the reference voltage 212, 204 is subtracted, divided by the resistance value when the switch 202 is turned on. Δt is the time when the switch 202 is turned on;
Cs為參考電容207的電容值。 又因為待測電容211執行完步驟e所儲存的電荷變化量為 AQcx = Cx^AVcx = Ι*Δΐ; △ Qcx為待測電容211的電荷變化量；Cs is the capacitance value of the reference capacitor 207. The amount of charge change stored in step e of the capacitor 211 to be tested is AQcx = Cx^AVcx = Ι*Δΐ; ΔQcx is the amount of charge change of the capacitor 211 to be tested;
Cx為待測電容211的電容值； △ Vex為At時間中，待測電容211上的電壓變化； 所以 △ V=I*At/Cs = Cx*AVcx / Cs。 執行完步驟f，參考電容207兩端的電壓會被充電到一個 NAV; △ Vcs =Ν* △ V=NI* △ t /Cs = NCx* △ Vcx/Cs。--------（公 201011308 •式一） △ Vcs為參考電容207兩端的電壓變化。 由（公式一）來看，參考電容207兩端的電壓會與Cx有關， 所以當N，AVcx, Cs不變時，Cx改變，會改變參考電 容207兩端的電壓差。 執行完步驟g，205的電壓值會被量到，因參考電容207 其中一端接到運算放大器206的負端，此電壓因運算放大 器206虛擬短路的關係，會與運算放大器206的正端相同， φ 為參考電壓204,參考電容207的另一端接到205,亦即為 電壓量測電路208所量到的電壓。所以，參考電容207兩 端的電壓差又等於參考電壓204與電壓量測電路208所量 到的電壓相減的值，所以Cx is the capacitance value of the capacitor 211 to be tested; ΔVex is the voltage change of the capacitor 211 to be tested in At time; therefore, ΔV=I*At/Cs = Cx*AVcx / Cs. After step f is performed, the voltage across the reference capacitor 207 is charged to a NAV; Δ Vcs = Ν * Δ V = NI * Δ t / Cs = NCx * Δ Vcx / Cs. -------- (public 201011308 • Equation 1) △ Vcs is the voltage change across the reference capacitor 207. From (Formula 1), the voltage across the reference capacitor 207 will be related to Cx, so when N, AVcx, Cs are unchanged, Cx changes, changing the voltage difference across the reference capacitor 207. After the execution of steps g, 205, the voltage value is measured, because one end of the reference capacitor 207 is connected to the negative terminal of the operational amplifier 206. This voltage is the same as the positive terminal of the operational amplifier 206 due to the virtual short circuit of the operational amplifier 206. φ is the reference voltage 204, and the other end of the reference capacitor 207 is connected to 205, that is, the voltage measured by the voltage measuring circuit 208. Therefore, the voltage difference between the two ends of the reference capacitor 207 is equal to the value subtracted by the reference voltage 204 and the voltage measured by the voltage measuring circuit 208, so
Vopout = Vb - Δ Vcs = Vb - N* Cx * Δ Vex / Cs *Vopout = Vb - Δ Vcs = Vb - N* Cx * Δ Vex / Cs *
Vopout為205的電壓值，Vopout is the voltage value of 205,
Vb為參考電壓204， 執行完步驟h，經由電壓量測電路208的量測結果，透過 _ 一直在監控205的電壓值，可以偵測到Cx的變化，進而 馨 ^ 求得待測電容211的電容值或是電容值的變化量。 此特性有如下的優點： 1. 因為電容積分電路220的參考電容207的電壓是線性改 變，所以只要控制N的大小，就可以很容易控制電容積 分電路220的參考電容207的電壓在一個範圍内，電壓 量測電路208可以量到比較精確的電壓值。 2. 改變電容積分電路220的參考電容207的電容值大小， 就可以改變ΔΥ大小，因為： 201011308 △ V=I △ t /Cs = Cx △ Vex / Cs，△ V 與 Cs 成反比，Cs 愈小則△V愈大，△V愈大，則N就可以較小，則量 測待測電容221的電容值的時間就可以縮短。 3.因為電容積分電路220的參考電容207的電壓是線性改 變，所以容易控制及處理，且解析度也比較高。 同理，本發明之運作原理亦可運用於多通道的未知電 容測量如圖四所示，圖四增加一組未知電容211 a/b及開關 201a/b及202a/b，當開關201a/b及202a/b被四個交錯的時 脈所驅動則熟於該項技藝者可輕易依前述揭示内容測得未 知電容21 la/b之電容值或變化量在此不再贅述。 唯以上所述者，僅為本發明之範例實施態樣爾，當不 能以之限定本發明所實施之範圍。即大凡依本發明申請專 利範圍所作之均等變化與修飾，皆應仍屬於本發明專利涵 蓋之範圍内，謹請貴審查委員明鑑，並祈惠准，是所至 禱0 【圖式簡單說明】 圖一A/— B係為先前技藝之示意圖； 圖二係為用於本發明之範例示意圖； 圖三係為圖二之等效電路圖；以及 圖四係為本發明之多通道範例示意圖。 【主要元件符號說明】 201, 201a, 201b, 202, 202a, 202b, 203 開關 204 電壓 12 201011308 206 運算放大器 205 運算放大器輸出端 207, 211, 211a, 211b 電容 208 電壓量測電路 209 訊號處理及控制電路 212 電壓 213, 213a, 213b 導體平面 220 參考電容積分電路 13Vb is the reference voltage 204. After the step h is performed, the measurement result of the voltage measuring circuit 208, through the voltage value of the monitoring 205, can detect the change of Cx, and then the capacitor 211 is obtained. The value of the capacitance or the amount of change in the capacitance value. This feature has the following advantages: 1. Since the voltage of the reference capacitor 207 of the capacitance integrating circuit 220 is linearly changed, the voltage of the reference capacitor 207 of the capacitance integrating circuit 220 can be easily controlled within a range as long as the magnitude of N is controlled. The voltage measurement circuit 208 can measure a relatively accurate voltage value. 2. By changing the capacitance value of the reference capacitor 207 of the capacitance integrating circuit 220, the ΔΥ size can be changed because: 201011308 Δ V=I Δ t /Cs = Cx Δ Vex / Cs, Δ V is inversely proportional to Cs, and the smaller the Cs Then, the larger the ΔV is, the larger the ΔV is, the smaller N can be, and the time for measuring the capacitance value of the capacitor 221 to be measured can be shortened. 3. Since the voltage of the reference capacitor 207 of the capacitance integrating circuit 220 is linearly changed, it is easy to control and process, and the resolution is also relatively high. Similarly, the operating principle of the present invention can also be applied to multi-channel unknown capacitance measurement as shown in FIG. 4, and FIG. 4 adds a set of unknown capacitors 211 a/b and switches 201a/b and 202a/b, when the switch 201a/b And 202a/b is driven by four interleaved clocks, and the skilled person can easily detect the capacitance value or the variation of the unknown capacitor 21 la/b according to the foregoing disclosure, and will not be described herein. The above description is only exemplary of the invention, and is not intended to limit the scope of the invention. That is to say, the equivalent changes and modifications made by the applicants in accordance with the scope of the patent application of the present invention should still fall within the scope of the patent of the present invention. Please ask the reviewing committee for the examination, and pray for the best. It is the prayer to the zero. [Simplified explanation] Figure 1 is a schematic diagram of a prior art; Figure 2 is a schematic diagram of an example used in the present invention; Figure 3 is an equivalent circuit diagram of Figure 2; and Figure 4 is a schematic diagram of a multi-channel example of the present invention. [Main component symbol description] 201, 201a, 201b, 202, 202a, 202b, 203 Switch 204 Voltage 12 201011308 206 Operational amplifier 205 Operational amplifier output 207, 211, 211a, 211b Capacitance 208 Voltage measurement circuit 209 Signal processing and control Circuit 212 voltage 213, 213a, 213b conductor plane 220 reference capacitance integrating circuit 13