201205090 六、發明說明： 【發明所屬之技術領域】 本發明係有關一種感測器，特別是關於一種觸控感測電路 及方法。 【先前技術】 觸控功能已廣泛應用在智慧型手機、筆記型電腦、多媒體 播放器及資訊家電等範_，而電容式的觸控感應由於能達到高 鲁 感度及低成本，使得市場相繼採用。在資訊家電的產品使用電 容式的觸控按鍵可將產品外觀塑造的更有現代感與設計感，也 可讓操作方式更貼近使用者的習性，但需要考慮資訊家電的使 用環境，因此對雜訊抑制須特別注意。另一方面，近距離感應 (proximity detection)的功能可讓產品設計得更低耗電，讓使用 者在罪近時即提早喚醒電器產品，不需等待喚醒時間，響應節 能低碳的環保政策。 · • 【發明内容】 本發明的目的之一，在於提出一種感測電路及方法。 本發明的目的之一，在於提出一種可應用於電容式觸控按 鍵的感測電路及方法。 本發明的目的之一，在於提出一種可應用於近距離感應的 感測電路及方法。 根據本發明，一種感測電路包含偵測端點供連接電容式觸 控按鍵或天線’初始化開關連接在該偵測端點與初始化電壓端 3 201205090 之間’主《電開關控制主充電電流源對該偵測端點充電，取樣 開關控制取樣電容對__關取樣，衝該取 樣電壓，以及量測電路根據該取樣電壓產生量測數值。 根據本發明’-種_電路包含_端點供連接電容式觸 控按鍵或天線，初純_連接在該_端點與初始化電壓端 之間’主放電關㈣主放電電流職·_點放電，取樣 開關控·樣電容對該伽端‘點的取樣，電壓緩衝驗衝該取 樣電壓，以及量測電路根據該取樣電壓產生量測數值。 根據本發明’一種感測電路包含偵測端點供連接電容式觸 控按鍵或天線，第-初始化開關在第—時相控繼制端點的 初始化’主充電關在該第—時相控制主充電魏源對該偵測 端點充電’第一取樣開關在該第一時相控制第一取樣電容對該 偵測端點的取樣，第一電壓緩衝器緩衝該第一取樣電壓，第二 初始化開關在第二時相控制該偵測端點的初始化，主放電開關 在該第一時相控制主放電電流源讓該偵測端點放電，第二取樣 開關在該第二時相控制第二取樣電容對該偵測端點的取樣，第 一電壓緩衝器緩衝該第二取樣電壓’以及量測電路根據該第一 及第一取樣電壓產生量測數值。 根據本發明，一種感測方法包含提供偵測端點俾連接電容 式觸控按鍵或天線，設定該偵測端點的電壓，對該偵測端點充 電並取樣得到取樣電壓，儲存該取樣電壓到量測電容，以及讓 3亥里測電容放電到低於參考電壓’因而從其放電時間得到量測 數值。 根據本發明，一種感測方法包含提供偵測端點俾連接電容 201205090 式觸控按鍵或天線’設定該伽端_電壓，讓鋪測端點放 電並取樣得到取樣電壓，儲存該取樣電壓到量測電容，以及讓 S玄畺測電谷充電到南於參考電壓，因而從其充電時間得到量測 數值。 根據本發明，-贼财法包含触細端麟連接電容 式難按鍵或天線’在第-時相中，設定該侧端點的電壓， 對該偵測端點充電並取樣得到第一取樣電壓儲存到第一量測 電容’在第二時相巾，設定該侧端闕電壓，讓該偵測端點 • 放電並取樣得到第二取樣電壓儲存到第二量測電容，以及根據 該第一及第二取樣電壓取得量測數值。 【實施方式】 圖1係電容式的觸控感應的示意圖。電容式觸控按鍵10 係由兩彼此絕緣的電極板構成，通常是在印刷電路板上的跡線 (trace)，可為任何形狀，此構造形成一個感應電容，若有物件 接近或觸碰，則該感應電容的電容值會改變。感測電路12感 • 測該感應電容的結果經數位處理器14運算，可供判斷是否有 物件接近或觸碰，或作其他用途。 圖2係本發明之感測電路12的第一實施例，感測電路12 有偵測端點Vx供連接電容式觸控按鍵10，Cx表示電容式觸 控按鍵1〇的感應電容。感測電路12在感測時，先連通初始化 開關SUPINT ’將偵測端點Vx拉到接地端GND的電壓準位， 因而對感應電容Cx進行電荷初始化。接下來切斷初始化開關 SUHNT ’連通主充電開關SUP、取樣開關SWUPDN1及量測 201205090 開關SWUPDN2 ’因此主充電電流源2〇對偵測端點νχ充電， 其電壓Vx被取樣電容csmi取樣制取樣電壓VSM1並力口以 儲存。由於Vx的值與cx的值有關，因此取樣電麼VSM1實 質上包含Cx的值’亦即包&Cx的變量資訊。鎌切斷主充 電開關SUP，開關SWUPDN卜SWUPDN2保持連通一段時間， 讓取樣電壓VSM1經過電壓緩衝器22緩衝，以及經過低通滤 波器30的延遲時間’儲存到量測電容CT1。依序切斷開關 SWUPDN2、SWUPDN1，讓量測電路24量測量測電容CT1 儲存的取樣f壓VSM1。首紐職觀制_ SUpDN，同 時觸發-個開始計數信號(圖中未示)通知圖！中的數位處理器 14或外部的微處理單元開始計數。量測電容⑶被從屬放電 電流源26以小電流慢慢的放電，直到其電壓彳氏於參考電壓Vref 時，比較器28觸發高準位信號通知圖丨中的數位處理器14或 外部的微處理|元停止計數。由開始計數到停止計數之間的計 數時間差，即係對感應電容Cx的量測數值。若量測電容cT1 具較大電容值’則可得聰準度較高的制數值。電壓隨搞器 32從電壓Vx產生電壓VF〇UT施加到電容式觸控按鍵1〇的 另-電極板，此等電位操作將使電容式觸控按鍵⑽的兩電極 板看到的越效應f額失，因而猶該兩電極板之間的水膜 或其他附絲(如林祕)所形細雜錢電容。 圖3係本發明之感測電路12的第二實施例，其原理與圖 2的實施例她’但是縣充電秋電的对改為先放電再充 電。連it初始化開關SDNINT時，该測端點νχ被拉到電源端 VLDO的電壓準位，進行感應電|Cx的電荷初始化。接下來 201205090 切斷初始化開關SDNINT，連通主放電開關SDN、取樣開關 SWDNUP1及量測開關SWDNUP2，因此主放電電流源34讓 感應電谷Cx放電’取樣電谷Csm2取樣得到取樣電廢 並加以儲存。然後切斷主放電開關SDN，開關SWDNUP1、 SWDNUP2保持連通一段時間’讓取樣電壓VSM2經過電壓缓 衝器22緩衝，以及低通濾波器30的延遲時間，儲存到量測電 容CT2。依序切斷開關SWDNUP2、SWDNUP卜讓量測電路 36量測量測電容on儲存的取樣電壓VSM2。連通從屬充電 開關SDNUP時觸發一個開始計數信號(圖中未示)通知圖j中 的數位處理器14或外部的微處理單元開始計數。從屬充電電 流源38以小電流對量測電容CT2慢慢的充電，直到其電壓高 於參考電壓Vref時，比較器40觸發高準位信號通知圖丨中的 數位處理器14或外部的微處理單元停止計數。由開始計數到 停止計數之間的計數時間差，即係對感應電容Cx的量測數值。 合併圖2及圖3的電路成為圖4的擬差動(^^40 differential)架構’可改善感測電路12對抗低頻私莫雜訊及比 較器偏移電屋的能力。圖5係此實施例的時序圖，其一次感測 操作包含兩個時相’時相Phasel躲級放職，依循圖2 的模式得到第-計數值，時相phase2為快放慢充週期，依循 圖3的模式得到第二計數值。&係相關開關的保持時間，记 係低通齡1 3G的賴咖。制料44會料相外咖卜 Phase2分別測得的第一及第二計數值相加(圖中未示)作為量測 數值。若取樣電容Csml、Csm2具有相等的電容值，量測電 容CH、CT2具有相_電容值，主錢電流源如和主放電 201205090 電流源34的電流量相同，從屬放電電流源26和從屬充電電流 源38的電流量相同，比較器28、40相同，則將兩時相phasel、 Phase2分別測得的第一及第二計數值相加，便可抑制低頻共模 雜訊以及減低比較器的偏移電壓帶來的誤差，得到較準確的量 測數值。 圖6係上述消除低頻共模雜訊與比較器偏移電壓的示意 圖。在量測電容充電或放電至參考電壓Vref時，比較器會發 生高低準位轉換。若比較器有偏移電壓v〇s存在，則會造成時 • 相Phasel的計數值變為tl-Atos，時相Phase2的計數值變為 t2+Atos，但二者相加結果為tl+t2，因而消除了偏移電壓v〇s 造成的誤差Atos。由於低頻雜訊無法被低通濾波器濾除，因此 在取樣時會提供雜訊電壓Δνηο^到量測電容，造成時相 Phasel的計數值變為tl+Atn ’時相Phase2的計數值變為 t2-Atn ’但二者相加結果為tl+t2，因而消除了低頻雜訊造成的 誤差Atn。所以圖4的實施例能消除低頻共模雜訊及比較器偏 移電壓所產生的誤差。 ® 除了數位方式的相加運算以外，亦可透過類比方式的相加 運鼻來消除雜訊。只要將兩時相得到的取樣電壓VSM1、VSM2 相加’再由後端的計數器得到計數值，即能達到相同的功能。 圖7係本發明之感測電路12的第四實施例，圖8係其時序圖。 除了量測電路50以外，此實施例的電路和圖4的實施例是相 同的，產生及儲存取樣電壓VS1VQ、VSM2到量測電容CH、 CT2的過程也是相同的’但是量測電路5〇的量測過程不同。 量測電路50利用開關電路52讓量測電容CT1、CT2電荷平 8 201205090 衡’達到類比式的相加運算。在經過兩時相Phasel、Phase2 後，先連通開關S2 —段時間，再連通開關S3 —段時間，在切 斷開關S3以前連通開關S1，如此，將量測電容CT2倒置和量 測電容CT1並聯，因而將量測電容CT1得到的電壓變化量和 量測電容CT2得到的電壓變化量相加。連通從屬放電開關 SUPDN，讓從屬放電電流源26使量測電容CT1 ' CT2放電到 低於參考電壓Vref，由後端的電路計數得到量測數值。在另一 實施例中’開關電路52改為將量測電容CT1倒置和量測電容 CT2並聯，再經從屬充電電流源充電到高於參考電壓Vref，亦 可得到相同的結果。這種類比式的運算一樣可以抑制低頻共模 雜訊與比較器偏移電壓的誤差。 在上述所有實施例中，濾波器30係主動式或被動式的濾 波器，其目的在於濾除取樣電壓的高頻雜訊。若不在意高頻雜 訊的影響’則可省略低通濾波II 3G，而將電壓緩衝$ 22提供 的取樣電壓直接送入量測電容。‘ ’、 '于、了應用在電谷式觸控按鍵，本發明之感測電路12也可 以應用在天線實現近距離感應。如圖9所示，當圖2、圖4或 圖7的感測電路12對偵測端點νχ充電，會產生瞬間電流。 而手6〇在空間中的移動會造成天線62或66的電感值變化 △L，因此感應電壓 公式1 AVmut = AL.·^， dt 201205090 仏成取樣電容Csml得到的取樣電壓VSM1產生變化，從其得 到的里測數值也跟著變化^同理，當圖3、圖4或圖7的感測 電路12讓_端點Vx放電，會產生瞬間電流。而手6〇在空 間中的移動造成的電感值變化AL使取樣電容Csm2得到的取 I電壓VSM2產賴化，從其得綱量繼值也跟著變化。 不同結構的域林@的磁場分布，例如目9上方的單導絲 天線62得到以其為中心的同心圓磁力線64，圖9下方的;t累旋 線圈天線66得到集中於上下方向的磁力線68。當手6〇接近 天線62 ’或經過天線66的上方或下方，將破壞其磁力線分布， 導致電值變彳b AL，目域測電路便能由AVniut得到變 化的昼測數值，因而實現近距離感應。若是將電容式觸控按鍵 10的電極板經過特別的設計，使其具有天線的效果，則感測 電路12能同時執行近距離感應的功能。 以上對於本發明之較佳實施例所作的敘述係為闡明之目 的而無,¾限定本發明精確地為所揭露的形式，基於以上的教 導或從本發明的實施例學習而作修改或變化是可能的，實施例 係為解說本發明絲理以及讓熟㈣項技術者以各種實施例 利用本發明在實際應上而選擇及敘述，本發明的技術思想企 圖由以下的申請專利範圍及其均等來決定。 【圖式簡單說明】 圖1係電容式的觸控感應的示意圖； 圖2係本發明之感測電路的第—實施例； 圖3係本發明之感測電路的第二實施例； 10 201205090 圖4係本發明之感測電路的第三實施例 圖5係圖4的時序圖， 圖6係消除低頻共模雜訊與比較器偏移電壓的示意圖； 圖7係本發明之感測電路的第四實施例； 圖8係圖7的時序圖；以及 圖9係本發明之感測電路應用於近距離感應的示意圖。 【主要元件符號說明】201205090 VI. Description of the Invention: [Technical Field] The present invention relates to a sensor, and more particularly to a touch sensing circuit and method. [Prior Art] Touch functions have been widely used in smart phones, notebook computers, multimedia players, and information appliances. Capacitive touch sensors have been adopted in the market because of their high sensitivity and low cost. . The use of capacitive touch buttons in the products of information appliances can make the appearance of the products more modern and design, and also make the operation method closer to the user's habits, but it is necessary to consider the use environment of information appliances, so it is miscellaneous. Signal suppression must pay special attention. On the other hand, the function of proximity detection allows the product to be designed with lower power consumption, allowing the user to wake up the electrical product early when the crime is near, without waiting for the wake-up time, and responding to the low-carbon environmental policy. · SUMMARY OF THE INVENTION One object of the present invention is to provide a sensing circuit and method. One of the objects of the present invention is to provide a sensing circuit and method that can be applied to a capacitive touch button. One of the objects of the present invention is to provide a sensing circuit and method that can be applied to proximity sensing. According to the present invention, a sensing circuit includes a detection terminal for connecting a capacitive touch button or an antenna 'initialization switch is connected between the detection terminal and the initialization voltage terminal 3 201205090' main "electric switch control main charging current source The detection terminal is charged, the sampling switch controls the sampling capacitor to sample __ off, rushes the sampling voltage, and the measuring circuit generates a measured value according to the sampling voltage. According to the invention, the '--circuit includes _end point for connecting a capacitive touch button or an antenna, and the initial pure _ is connected between the _end and the initialization voltage terminal' main discharge off (four) main discharge current _ point discharge The sampling switch controls the sample capacitor to sample the gamma end point, the voltage buffer checks the sampling voltage, and the measuring circuit generates the measured value according to the sampling voltage. According to the present invention, a sensing circuit includes a detection terminal for connecting a capacitive touch button or an antenna, and an initialization of the first-initial switch at the first-phase phase-controlled relay terminal 'main charge off' in the first-phase phase control The main charging Wei source charges the detecting end point. The first sampling switch controls the sampling of the detecting end point by the first sampling capacitor in the first phase, the first voltage buffer buffers the first sampling voltage, and the second initialization The switch controls the initialization of the detection terminal in the second phase, the main discharge switch controls the main discharge current source to discharge the detection terminal in the first phase, and the second sampling switch controls the second phase in the second phase The sampling capacitor samples the detection endpoint, the first voltage buffer buffers the second sampling voltage 'and the measurement circuit generates a measured value according to the first and first sampling voltages. According to the present invention, a sensing method includes providing a detecting end point, connecting a capacitive touch button or an antenna, setting a voltage of the detecting end point, charging and sampling the detecting end point to obtain a sampling voltage, and storing the sampling voltage. To measure the capacitance, and let the 3 mile capacitance drop below the reference voltage' thus get the measured value from its discharge time. According to the present invention, a sensing method includes providing a detection terminal 俾 connection capacitor 201205090 type touch button or antenna 'setting the gamma _ voltage, causing the measurement terminal to discharge and sampling to obtain a sampling voltage, and storing the sampling voltage to the amount Measure the capacitance, and let the S Xuanzhen test valley charge to the south reference voltage, so get the measured value from its charging time. According to the present invention, the thief money method includes a contact terminal or a capacitive button or an antenna. In the first phase, the voltage of the terminal is set, and the detection terminal is charged and sampled to obtain a first sampling voltage. Storing to the first measuring capacitor 'in the second phase, setting the side voltage, allowing the detecting end point to be discharged and sampling to obtain the second sampling voltage to be stored in the second measuring capacitor, and according to the first And the second sampling voltage obtains the measured value. Embodiment 1 FIG. 1 is a schematic diagram of a capacitive touch sensing. The capacitive touch button 10 is composed of two electrode plates insulated from each other, usually a trace on a printed circuit board, and can be any shape. The structure forms an inductive capacitor. If an object approaches or touches, Then the capacitance value of the sensing capacitor will change. The sensing circuit 12 senses the result of measuring the sensing capacitance by the digital processor 14 to determine whether an object is approaching or touching, or for other purposes. 2 is a first embodiment of the sensing circuit 12 of the present invention. The sensing circuit 12 has a detecting terminal Vx for connecting the capacitive touch button 10, and Cx for sensing capacitance of the capacitive touch button 1〇. When sensing, the sensing circuit 12 first connects the initialization switch SUPINT ’ to pull the detection terminal Vx to the voltage level of the ground GND, thereby performing charge initialization on the sensing capacitor Cx. Next, the initialization switch SUHNT 'connects the main charging switch SUP, the sampling switch SWUPDN1, and the measurement 201205090 switch SWUPDN2'. Therefore, the main charging current source 2〇 charges the detecting terminal νχ, and the voltage Vx is sampled by the sampling capacitor csmi. The VSM1 is connected to the port for storage. Since the value of Vx is related to the value of cx, the sampling power VSM1 substantially contains the value of Cx', that is, the variable information of the packet & Cx.镰 The main charging switch SUP is turned off, the switch SWUPDN BUUPDN2 is kept connected for a period of time, the sampling voltage VSM1 is buffered by the voltage buffer 22, and the delay time 'passed by the low-pass filter 30' is stored to the measuring capacitor CT1. The switches SWUPDN2 and SWUPDN1 are sequentially turned off, and the measuring circuit 24 measures the sampling f voltage VSM1 stored in the measuring capacitor CT1. The first job title system _ SUpDN, at the same time trigger - a start counting signal (not shown) notification map! The digital processor 14 or an external microprocessor unit starts counting. The measuring capacitor (3) is slowly discharged by the slave discharge current source 26 with a small current until its voltage is at the reference voltage Vref, and the comparator 28 triggers the high level signal to notify the digital processor 14 or the external micro in the figure. Processing | meta stop counting. The counted time difference between the start count and the stop count is the measured value of the sense capacitor Cx. If the measuring capacitance cT1 has a large capacitance value, then a higher value of the accuracy can be obtained. The voltage follower 32 applies a voltage VF〇UT from the voltage Vx to the other electrode plate of the capacitive touch button 1,, and the equipotential operation causes the two electrodes of the capacitive touch button (10) to see the effect f The amount is lost, so the water film or other wire (such as the forest secret) between the two electrode plates is shaped as a junk capacitor. Fig. 3 is a second embodiment of the sensing circuit 12 of the present invention, the principle of which is the same as that of the embodiment of Fig. 2, but the pair of county charging electric power is replaced by first discharging and recharging. When it initializes the switch SDNINT, the measured terminal νχ is pulled to the voltage level of the power supply terminal VLDO, and the charge of the induced power |Cx is initialized. Next, 201205090 cuts off the initialization switch SDNINT, connects the main discharge switch SDN, the sampling switch SWDNUP1 and the measurement switch SWDNUP2, so the main discharge current source 34 causes the induced electric valley Cx to discharge the sampled electric valley Csm2 to sample and collect the electric waste and store it. Then, the main discharge switch SDN is turned off, and the switches SWDNUP1, SWDNUP2 are kept in communication for a while. The sampling voltage VSM2 is buffered by the voltage buffer 22, and the delay time of the low-pass filter 30 is stored in the measurement capacitor CT2. The switches SWDNUP2 and SWDNUP are sequentially turned off, and the measurement circuit 36 measures the sampling voltage VSM2 stored on the capacitance. When the slave charging switch SDNUP is connected, a start count signal (not shown) is triggered to notify the digital processor 14 in Fig. j or an external microprocessor unit to start counting. The slave charging current source 38 slowly charges the measuring capacitor CT2 with a small current until its voltage is higher than the reference voltage Vref, and the comparator 40 triggers the high level signal to notify the digital processor 14 in the figure or external micro processing. The unit stops counting. The count time difference between the start count and the stop count is the measured value of the sense capacitor Cx. Combining the circuits of Figures 2 and 3 to become the pseudo-differential architecture of Figure 4 improves the ability of the sensing circuit 12 to combat low frequency private noise and comparators. FIG. 5 is a timing diagram of the embodiment, wherein one sensing operation includes two phases, phase Phasel, and the first counter value is obtained according to the mode of FIG. 2, and the phase phase 2 is a fast-discharging and slow-charging cycle. The second count value is obtained following the pattern of FIG. & is the retention time of the relevant switch, and records the Lagage with a low pass age of 1 3G. The material 44 will be out of phase. The first and second count values respectively measured by Phase 2 are added (not shown) as the measured values. If the sampling capacitors Csml and Csm2 have equal capacitance values, the measurement capacitors CH and CT2 have phase-capacitance values, and the main-source current source has the same current amount as the main discharge 201205090 current source 34, the slave discharge current source 26 and the slave charging current. The current amount of the source 38 is the same, and the comparators 28 and 40 are the same, and the first and second count values respectively measured by the two phase phases phase1 and phase2 are added, thereby suppressing the low frequency common mode noise and reducing the bias of the comparator. The error caused by the voltage shifting results in a more accurate measurement value. Figure 6 is a schematic illustration of the above-described elimination of low frequency common mode noise and comparator offset voltage. When the measuring capacitor is charged or discharged to the reference voltage Vref, the comparator will have a high and low level transition. If the comparator has an offset voltage v〇s, it will cause the count value of phase Phasel to become tl-Atos, and the count value of Phase2 will become t2+Atos, but the result of the addition is tl+t2 Therefore, the error Atos caused by the offset voltage v〇s is eliminated. Since the low-frequency noise cannot be filtered by the low-pass filter, the noise voltage Δνηο^ is supplied to the measurement capacitor during sampling, causing the count value of the phase phase Phasel to become tl+Atn' when the count value of phase Phase2 becomes t2-Atn 'but the result of the addition is tl+t2, thus eliminating the error Atn caused by low frequency noise. Therefore, the embodiment of Figure 4 eliminates the errors caused by low frequency common mode noise and comparator offset voltage. ® In addition to the digital addition, it is also possible to eliminate noise by adding the analogy. As long as the sampling voltages VSM1 and VSM2 obtained by the two phases are added together and the counter value is obtained by the counter at the back end, the same function can be achieved. Fig. 7 is a fourth embodiment of the sensing circuit 12 of the present invention, and Fig. 8 is a timing chart thereof. The circuit of this embodiment is identical to the embodiment of FIG. 4 except for the measurement circuit 50. The process of generating and storing the sampling voltages VS1VQ, VSM2 to the measurement capacitances CH, CT2 is also the same 'but the measurement circuit 5' The measurement process is different. The measuring circuit 50 uses the switching circuit 52 to make the measuring capacitances CT1, CT2 charge equal to the analogy type of addition operation. After passing through the two phases Phasel and Phase2, first connect the switch S2 for a period of time, then connect the switch S3 for a period of time, and then connect the switch S1 before the switch S3 is cut off. Thus, the measuring capacitance CT2 is inverted and the measuring capacitance CT1 is connected in parallel. Therefore, the amount of voltage change obtained by measuring the capacitance CT1 is added to the amount of voltage change obtained by the measurement capacitor CT2. The slave discharge switch SUPDN is connected to cause the slave discharge current source 26 to discharge the measurement capacitor CT1 'CT2 below the reference voltage Vref, and the measured value is obtained by the circuit at the back end. In another embodiment, the switching circuit 52 instead inverts the measuring capacitor CT1 in parallel with the measuring capacitor CT2, and then charges the subordinate charging current source above the reference voltage Vref to obtain the same result. This analogy operation suppresses the error of the low frequency common mode noise and the comparator offset voltage. In all of the above embodiments, the filter 30 is an active or passive filter whose purpose is to filter out high frequency noise of the sampled voltage. If you don't care about the effects of high-frequency noise, you can omit the low-pass filter II 3G and send the sampled voltage from the voltage buffer $ 22 directly to the measurement capacitor. The sensing circuit 12 of the present invention can also be applied to the antenna for near-distance sensing, as applied to the electric valley type touch button. As shown in FIG. 9, when the sensing circuit 12 of FIG. 2, FIG. 4 or FIG. 7 charges the detection terminal ν, an instantaneous current is generated. The movement of the hand 6〇 in the space causes the inductance value of the antenna 62 or 66 to change by ΔL, so the induced voltage formula 1 AVmut = AL.·^, dt 201205090 The sampling voltage VSM1 obtained by the sampling capacitor Csml changes, from The measured value obtained by the same is also the same as the change. When the sensing circuit 12 of FIG. 3, FIG. 4 or FIG. 7 discharges the _terminal Vx, an instantaneous current is generated. The change in the inductance value caused by the movement of the hand 6〇 in the space causes the I voltage VSM2 obtained by the sampling capacitor Csm2 to be produced, and the value of the relay value is also changed. The magnetic field distribution of the domain forest of different structures, for example, the single-wire antenna 62 above the mesh 9 obtains a concentric circular magnetic field 64 centered thereon, the lower portion of FIG. 9; the t-rotating coil antenna 66 is obtained by the magnetic field lines 68 concentrated in the up-and-down direction. . When the hand 6〇 approaches the antenna 62' or passes above or below the antenna 66, the magnetic field line distribution will be destroyed, resulting in the electric value 彳b AL, and the field measurement circuit can obtain the changed measured value by the AVniut, thereby achieving the close range. induction. If the electrode plate of the capacitive touch button 10 is specially designed to have an antenna effect, the sensing circuit 12 can simultaneously perform the function of proximity sensing. The above description of the preferred embodiments of the present invention is intended to be illustrative, and is not intended to limit the scope of the present invention. The invention is modified or changed based on the above teachings or from the embodiments of the present invention. The embodiments of the present invention are selected and described in the actual application of the present invention in various embodiments, and the technical idea of the present invention is intended to be equivalent to the scope of the following claims and their equals. To decide. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of capacitive touch sensing; FIG. 2 is a first embodiment of a sensing circuit of the present invention; FIG. 3 is a second embodiment of a sensing circuit of the present invention; 10 201205090 4 is a timing diagram of the sensing circuit of the present invention, FIG. 5 is a timing diagram of FIG. 4, and FIG. 6 is a schematic diagram of eliminating low frequency common mode noise and comparator offset voltage; FIG. 7 is a sensing circuit of the present invention. Fourth Embodiment; FIG. 8 is a timing chart of FIG. 7; and FIG. 9 is a schematic diagram of the sensing circuit of the present invention applied to proximity sensing. [Main component symbol description]
10 電容式觸控按鍵 12 感測電路 14 數位處理器 20 主充電電流源 22 電壓緩衝器 24 量測電路 26 從屬放電電流源 28 比較器 30 低通濾波器 32 電壓隨耦器 34 主放電電流源 36 量測電路 38 從屬充電電流源 40 比較器 44 量測電路 50 量測電路 201205090 52 開關電路 60 手 62 單導線條天線 64 磁力線 66 螺旋線圈天線 68 磁力線10 Capacitive touch button 12 Sensing circuit 14 Digital processor 20 Main charging current source 22 Voltage buffer 24 Measuring circuit 26 Slave discharge current source 28 Comparator 30 Low pass filter 32 Voltage follower 34 Main discharge current source 36 Measuring circuit 38 Slave charging current source 40 Comparator 44 Measuring circuit 50 Measuring circuit 201205090 52 Switching circuit 60 Hand 62 Single wire strip antenna 64 Magnetic line 66 Spiral coil antenna 68 Magnetic field line
i S] 12i S] 12