CN103324366A

CN103324366A - Capacitor detection device and capacitive touch system applying same

Info

Publication number: CN103324366A
Application number: CN2012100745956A
Authority: CN
Inventors: 何闿廷; 洪国强
Original assignee: MSTAR SEMICONDUCTOR CO Ltd; MStar Software R&D Shenzhen Ltd
Current assignee: MediaTek Inc; MStar Semiconductor Inc Taiwan
Priority date: 2012-03-20
Filing date: 2012-03-20
Publication date: 2013-09-25
Anticipated expiration: 2032-03-20
Also published as: CN103324366B

Abstract

The invention provides a capacitance detection device connected to a capacitance to be measured, including a first capacitance, a second capacitance, a control module and a judgment module. The first capacitor and the second capacitor are connected to the capacitor under test through an input node. The control module is used for providing a first voltage change of the first capacitor and providing a second voltage change of the capacitance to be measured, thereby causing a third voltage change of the second capacitor. The first cross-voltage change and the second cross-voltage change make the charges flowing from the first capacitor to the input node and the charges flowing from the input node into the capacitor to be measured positive and negative. The judging module is used for judging the capacitance of the capacitor under test according to the capacitance of the first capacitor, the capacitance of the second capacitor, the first change in voltage across, the change in second voltage across and the change in third voltage across capacity.

Description

Capacitance detection device and capacitive touch system using the capacitance detection device

技术领域 technical field

本发明与测量技术相关，并且尤其与测量电容值的电路改良相关。The present invention relates to measurement technology and in particular to the improvement of circuits for measuring capacitance values.

背景技术 Background technique

随着科技日益进步，近年来各种电子产品的操作介面都愈来愈人性化。举例而言，透过触控屏幕，使用者可直接以手指或触控笔在屏幕上操作程序、输入讯息/文字/图样，省去使用键盘或按键等输入装置的麻烦。实际上，触控屏幕通常是由感应面板及设置于感应面板后方的显示器组成。电子装置可根据使用者在感应面板上所触碰的位置，以及当时显示器所呈现的画面，来判断该次触碰的意涵并执行相对应的操作结果。With the advancement of technology, the operation interfaces of various electronic products have become more and more user-friendly in recent years. For example, through a touch screen, users can directly operate programs and input messages/texts/patterns on the screen with their fingers or a stylus, saving the trouble of using input devices such as keyboards or buttons. In fact, the touch screen is usually composed of a sensing panel and a display disposed behind the sensing panel. The electronic device can judge the meaning of the touch according to the position touched by the user on the sensing panel and the picture displayed on the display at that time, and execute the corresponding operation result.

就电容式触控装置而言，使用者的触碰会影响被触碰点的电场，进而造成相对应的电容值变化。测量电容值变化的电路的灵敏度和正确性因此至关重要。图1(A)中的区块100为一电容检测电路范例。此检测电路包含运算放大器12、焊垫(pad)14、回授电容Cfb、两个第一开关SW1和一个第二开关SW2。焊垫14用以将位在检测电路100外部的待测电容Cx连接至运算放大器12。待测电容Cx位在感应面板中，会随着使用者是否触碰而变化。As far as the capacitive touch device is concerned, the user's touch will affect the electric field of the touched point, thereby causing a corresponding change in capacitance value. The sensitivity and correctness of circuits that measure changes in capacitance value are therefore critical. Block 100 in FIG. 1(A) is an example of a capacitance detection circuit. The detection circuit includes an operational amplifier 12, a pad 14, a feedback capacitor Cfb, two first switches SW1 and a second switch SW2. The bonding pad 14 is used for connecting the capacitor Cx to be measured outside the detection circuit 100 to the operational amplifier 12 . The capacitance Cx to be measured is located in the sensing panel, which will change according to whether the user touches it or not.

在检测过程的第一阶段，两个第一开关SW1被设定为通路，第二开关SW2被设定为断路；图1(A)中的电路等同于图1(B)所示的电路。在这个情况下，运算放大器12的输出端(Vout)和正负输入端的电压都会等于参考电压VL。回授电容Cfb因此被放电至不存有电荷，待测电容Cx则是被充电至存有电荷Cx*VL。随后，在检测过程的第二阶段，两个第一开关SW1被切换为断路，第二开关SW2被切换为通路；图1(A)中的电路等同于图1(C)所示。在这个情况下，运算放大器12的正负输入端的电压都会变为参考电压VH。电荷经重新分配后，输出端的电压可表示如下：In the first stage of the detection process, the two first switches SW1 are set to ON and the second switch SW2 is set to OFF; the circuit in FIG. 1(A) is equivalent to the circuit shown in FIG. 1(B). In this case, the voltages at the output terminal (Vout) and the positive and negative input terminals of the operational amplifier 12 are equal to the reference voltage VL. Therefore, the feedback capacitor Cfb is discharged until there is no charge, and the capacitor Cx under test is charged to have a charge Cx*VL. Subsequently, in the second stage of the detection process, the two first switches SW1 are switched off, and the second switch SW2 is switched on; the circuit in FIG. 1(A) is equivalent to that shown in FIG. 1(C). In this case, the voltages of the positive and negative input terminals of the operational amplifier 12 both become the reference voltage VH. After charge has been redistributed, the voltage at the output can be expressed as:

$Vout Vout = = VH VH + + ((VH VH - - VL VL)) * * \frac{Cx Cx}{Cfb Cfb} . . - - - - - - ((11))$

由于参考电压VL、VH和回授电容Cfb的数值皆为已知，根据输出电压Vout即可推算出待测电容Cx的大小。若将待测电容Cx进一步拆解为未受使用者影响前即存在的背景电容Cbg及因使用者碰触产生的电容变化量Csig的总和，式(1)可被改写为：Since the values of the reference voltages VL, VH and the feedback capacitor Cfb are known, the value of the capacitor Cx to be tested can be calculated according to the output voltage Vout. If the capacitance Cx to be measured is further disassembled into the sum of the background capacitance Cbg that existed before being affected by the user and the capacitance change Csig caused by the user's touch, formula (1) can be rewritten as:

$Vout Vout = = VH VH + + ((VH VH - - VL VL)) * * \frac{Cbg Cbg}{Cfb Cfb} + + ((VH VH - - VL VL)) * * \frac{Csig Csig}{Cfb Cfb} . . - - - - - - ((22))$

实际上背景电容Cbg大致为定值。因此，主要的测量对象是电容变化量Csig。为了避免输出电压Vout饱和，回授电容Cfb不能被设计得太小。然而，由式(2)的最后一项可看出，回授电容Cfb愈大，测量电容变化量Csig的解析度就愈差。In fact, the background capacitance Cbg is approximately constant. Therefore, the main measurement object is the capacitance variation Csig. In order to avoid saturation of the output voltage Vout, the feedback capacitor Cfb cannot be designed too small. However, it can be seen from the last term of the formula (2), that the larger the feedback capacitance Cfb is, the worse the resolution of measuring the capacitance variation Csig is.

发明内容 Contents of the invention

为解决上述问题，本发明数个实施例提出一种新的电容检测装置及应用该电容检测装置的电容式触控系统。藉由在回授电容的外新增一个电容来适当供应待测电容在电荷重新分配过程中需要的电荷量，根据本发明数个实施例的电容检测装置可克服先前技术中难以兼顾测量解析度和避免输出电压饱和的问题。值得注意的是，可采用原电路板上连接线与屏蔽层之间的寄生电容做为该新增电容，藉此达到节省芯片面积的效果。In order to solve the above problems, several embodiments of the present invention provide a new capacitance detection device and a capacitive touch system using the capacitance detection device. By adding a new capacitor outside the feedback capacitor to properly supply the amount of charge required by the capacitor under test during the charge redistribution process, the capacitance detection device according to several embodiments of the present invention can overcome the difficulties in measuring resolution in the prior art and avoid the problem of output voltage saturation. It is worth noting that the parasitic capacitance between the connection line and the shielding layer on the original circuit board can be used as the added capacitance, thereby achieving the effect of saving chip area.

根据本发明的一具体实施例为一种电容检测装置，连接于一待测电容，该电容检测装置包含一第一电容、一第二电容、一控制模块及一判断模块。该第一电容和该第二电容透过一输入节点连接至该待测电容。该控制模块用以提供该第一电容一第一跨压变化，并提供该待测电容一第二跨压变化，藉此使该第二电容产生一第三跨压变化。该第一跨压变化与该第二跨压变化使自该第一电容流向该输入节点的电荷与自该输入节点流入该待测电容的电荷正负相同。该判断模块用以根据该第一电容的电容量、该第二电容的电容量、该第一跨压变化、该第二跨压变化及该第三跨压变化，判断该待测电容的电容量。According to a specific embodiment of the present invention, a capacitance detection device is connected to a capacitor to be tested, and the capacitance detection device includes a first capacitor, a second capacitor, a control module and a judgment module. The first capacitor and the second capacitor are connected to the capacitor under test through an input node. The control module is used for providing a first voltage change of the first capacitor and providing a second voltage change of the capacitance to be measured, thereby causing a third voltage change of the second capacitor. The first cross-voltage change and the second cross-voltage change make the charges flowing from the first capacitor to the input node and the charges flowing from the input node into the capacitor to be measured positive and negative. The judging module is used for judging the capacitance of the capacitor under test according to the capacitance of the first capacitor, the capacitance of the second capacitor, the first change in voltage across, the change in second voltage across and the change in third voltage across capacity.

根据本发明的另一具体实施例为一种电容式触控系统，其中包含一显示器、多个感应电容、一第一电容、一第二电容、一控制模块及一判断模块。该多个感应电容各自对应于该显示器上的一实体位置。该第一电容和该第二电容透过一输入节点连接至该多个感应电容其中之一作为一待测电容。该控制模块用以提供该第一电容一第一跨压变化，并提供该待测电容一第二跨压变化，藉此使该第二电容产生一第三跨压变化。该第一跨压变化与该第二跨压变化使自该第一电容流向该输入节点的电荷与自该输入节点流入该待测电容的电荷正负相同。该判断模块用以根据该第一电容的电容量、该第二电容的电容量、该第一跨压变化、该第二跨压变化及该第三跨压变化，判断该待测电容的电容量。Another specific embodiment according to the present invention is a capacitive touch system, which includes a display, a plurality of sensing capacitors, a first capacitor, a second capacitor, a control module and a judgment module. Each of the sensing capacitors corresponds to a physical location on the display. The first capacitor and the second capacitor are connected to one of the plurality of sensing capacitors through an input node as a capacitor to be measured. The control module is used for providing a first voltage change of the first capacitor and providing a second voltage change of the capacitor to be measured, thereby causing a third voltage change of the second capacitor. The first cross-voltage change and the second cross-voltage change make the charges flowing from the first capacitor to the input node and the charges flowing from the input node into the capacitor to be measured positive and negative. The judging module is used for judging the capacitance of the capacitor under test according to the capacitance of the first capacitor, the capacitance of the second capacitor, the first change in voltage across, the change in second voltage across and the change in third voltage across capacity.

关于本发明数个实施例的优点与精神可以藉由以下发明详述及附图得到进一步的了解。The advantages and spirits of several embodiments of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

附图说明 Description of drawings

图1(A)～图1(C)绘示先前技术中的电容检测电路。1(A) to 1(C) illustrate capacitance detection circuits in the prior art.

图2(A)～图2(C)为根据本发明的一实施例中的电容检测装置及其状态变化示意图。2(A) to 2(C) are schematic diagrams of a capacitance detection device and its state changes according to an embodiment of the present invention.

图3(A)～图3(C)绘示了根据本发明的电容检测装置利用外部电容的范例。3(A) to 3(C) illustrate an example of using an external capacitor in the capacitance detection device according to the present invention.

图4(A)～图4(C)绘示根据本发明的另一实施例中的电容检测装置其状态变化示意图。4(A) to 4(C) are schematic diagrams showing state changes of a capacitance detection device according to another embodiment of the present invention.

主要元件符号说明Description of main component symbols

100：电容检测电路 12：运算放大器100: capacitance detection circuit 12: operational amplifier

14、28：焊垫 Cfb：回授电容14, 28: Welding pad Cfb: Feedback capacitor

SW1～SW5：开关 Cx：待测电容SW1～SW5: switch Cx: capacitance to be tested

200：电容检测装置 22、42：运算放大器200: Capacitance detection device 22, 42: Operational amplifier

24、44：输入节点 26、46：判断模块24, 44: Input node 26, 46: Judgment module

29：控制模块 400：连接线29: Control module 400: Connecting line

500：芯片 600：感应面板500: chip 600: sensor panel

48：驱动节点 C1、C2、C1A、C1B：电容48: Drive node C1, C2, C1A, C1B: capacitor

具体实施方式 Detailed ways

根据本发明的一实施例为如图2(A)所示的电容检测装置200，其中包含两个电容C1～C2、五个开关SW1～SW5、运算放大器22、输入节点24及判断模块26。待测电容Cx透过输入节点24连接至电容检测装置200。若电容检测装置200和待测电容Cx位于不同封装芯片中，输入节点24可为一焊垫，但不以此为限。实务上，电容检测装置200可独立存在，亦可被整合于其他有检测电容量需求的系统中。An embodiment according to the present invention is a capacitance detection device 200 as shown in FIG. The capacitance Cx to be measured is connected to the capacitance detection device 200 through the input node 24 . If the capacitance detecting device 200 and the capacitance to be measured Cx are located in different packaged chips, the input node 24 may be a pad, but not limited thereto. In practice, the capacitance detection device 200 can exist independently, and can also be integrated into other systems that need to detect capacitance.

开关SW1～SW5的状态可由一控制模块(未显示)决定。在检测过程的第一阶段，开关SW1、SW3、SW4首先被设定为通路，而开关SW2、SW5被设定为断路；图2(A)中的电路等同于图2(B)所示的电路(暂忽略判断模块26)。在此设定下，运算放大器22的输出端(Vout)和正负输入端的电压都会等于参考电压VL。电容C2被放电至不存有电荷，电容C1被充电至存有电荷C1*VL，待测电容Cx则是被充电至存有电荷Cx*VL。The states of the switches SW1 - SW5 can be determined by a control module (not shown). In the first stage of the detection process, the switches SW1, SW3, SW4 are first set to open, and the switches SW2, SW5 are set to open; the circuit in Fig. 2(A) is equivalent to that shown in Fig. 2(B) circuit (ignoring the judging module 26 for now). Under this setting, the voltages of the output terminal (Vout) and the positive and negative input terminals of the operational amplifier 22 are equal to the reference voltage VL. Capacitor C2 is discharged to no charge, capacitor C1 is charged to charge C1*VL, and capacitor Cx to be tested is charged to charge Cx*VL.

随后，在检测过程的第二阶段，开关SW1、SW3、SW4被切换为断路，开关SW2、SW5被切换为通路；图2(A)中的电路等同于图2(C)所示的电路(暂忽略判断模块26)。在此设定下，运算放大器22的正负输入端的电压皆为参考电压VH，电容C1一侧的控制节点X被改接至控制电压VS。Subsequently, in the second stage of the detection process, the switches SW1, SW3, SW4 are switched to open circuit, and the switches SW2, SW5 are switched to open circuit; the circuit in Fig. 2(A) is equivalent to the circuit shown in Fig. 2(C) ( The judging module 26 is temporarily ignored). Under this setting, the voltages of the positive and negative input terminals of the operational amplifier 22 are both the reference voltage VH, and the control node X on the side of the capacitor C1 is reconnected to the control voltage VS.

上述两阶段间的开关切换会导致各电容的跨压改变，进而造成电荷在电容C1、C2、Cx间重新分配。对应于输入节点24的电荷平衡关系可被表示为：The switching between the above two stages will cause the voltage across the capacitors to change, and then cause the charges to be redistributed among the capacitors C1, C2, and Cx. The charge balance relationship corresponding to the input node 24 can be expressed as:

(VS+VL-VH)*C1+(Vout-VH)*C2＝(VH-VL)*Cx。(3)(VS+VL-VH)*C1+(Vout-VH)*C2=(VH-VL)*Cx. (3)

此实施例中的参考电压VH高于VL，且控制电压VS被设计为高于(VH-VL)。据此，由式(3)可看出，在第二阶段电流自输入节点24流入待测电容Cx以及由自电容C1流向输入节点24，换言之，自输入节点24流入待测电容Cx的正电荷至少有一部分是由自电容C1流向输入节点24的正电荷所贡献。至于自电容C2影响所及的部分，若Vout大于VH，电流是自自电容C2流向输入节点24，即由自电容C2流向输入节点24的是正电荷；若Vout小于VH，电流自输入节点24流向自电容C2，即由自电容C2流向输入节点24的是负电荷。不同于图1(C)中待测电容Cx的电荷改变完全由回授电容Cfb贡献的情况，在本实施例中，待测电容Cx的电荷改变是由电容C1、C2共同贡献。The reference voltage VH in this embodiment is higher than VL, and the control voltage VS is designed to be higher than (VH−VL). Accordingly, it can be seen from formula (3) that in the second stage, the current flows from the input node 24 into the capacitor Cx to be measured and flows from the self-capacitor C1 to the input node 24, in other words, the positive charge flowing from the input node 24 into the capacitor Cx to be measured At least a portion is contributed by positive charge flowing from capacitor C1 to input node 24 . As for the part affected by the self-capacitance C2, if Vout is greater than VH, the current flows from the self-capacitance C2 to the input node 24, that is, the positive charge flows from the self-capacitance C2 to the input node 24; if Vout is smaller than VH, the current flows from the input node 24 to the The self-capacitance C2, that is, the negative charges flowing from the self-capacitance C2 to the input node 24. Different from the situation in FIG. 1(C) where the charge change of the capacitor Cx under test is entirely contributed by the feedback capacitor Cfb, in this embodiment, the charge change of the capacitor Cx under test is jointly contributed by the capacitors C1 and C2.

式(3)可被进一步改写为：Equation (3) can be further rewritten as:

$Vout Vout = = VH VH + + ((VH VH - - VL VL)) * * \frac{Cx Cx}{C C 22} - - ((VS vs. + + VL VL - - VH VH)) * * \frac{C C 11}{C C 22} . . - - - - - - ((44))$

由于电压VL、VH、VS和电容C1、C2的数值皆为已知，根据输出电压Vout或者是电容C2两端的跨压变化(由零变为Vout-VH)，判断模块26即可推算出待测电容Cx的大小。若将待测电容Cx进一步拆解为未受使用者影响前即存在的背景电容Cbg及电容变化量Csig的总和，式(4)可被改写为：Since the values of the voltages VL, VH, VS and the capacitors C1 and C2 are all known, according to the output voltage Vout or the change in voltage across the capacitor C2 (from zero to Vout-VH), the judging module 26 can calculate the waiting time Measure the size of the capacitor Cx. If the capacitance Cx to be measured is further disassembled into the sum of the background capacitance Cbg and the capacitance change Csig that existed before being affected by the user, formula (4) can be rewritten as:

$Vout Vout = = VH VH + + ((VH VH - - VL VL)) * * \frac{Cbg Cbg}{C C 22} + + ((VH VH - - VL VL)) * * \frac{Csig Csig}{C C 22} - - ((VS vs. + + VL VL - - VH VH)) * * \frac{C C 11}{C C 22} . . - - - - - - ((55))$

由式(5)可看出，由于参考电压VH高于VL，且控制电压VS被设计为高于(VH-VL)，电容C1贡献的电荷可抵消背景电容Cbg贡献的电荷，使电压Vout较不易达到饱和状态。因此，即使选择较小的电容C2来提高电容变化量Csig的解析度，也不会使电压Vout很容易就因过高而饱和。易言之，只要选择大小适当的电容C1，电容检测装置200即可提供良好的测量解析度，并且不存在输出电压易饱和的问题。It can be seen from formula (5) that since the reference voltage VH is higher than VL, and the control voltage VS is designed to be higher than (VH-VL), the charge contributed by the capacitor C1 can offset the charge contributed by the background capacitor Cbg, so that the voltage Vout is relatively low Hard to reach saturation. Therefore, even if a smaller capacitor C2 is selected to increase the resolution of the capacitance variation Csig, the voltage Vout will not be easily saturated due to too high. In other words, as long as an appropriate capacitor C1 is selected, the capacitance detection device 200 can provide good measurement resolution, and there is no problem that the output voltage is easily saturated.

从电荷分配的观点来看，电容检测装置200的特征为利用自电容C1流向输入节点24的电荷做为自输入节点24流入背景电容Cbg的电荷，达到电荷抵销效果，使电压Vout较不易达到饱和状态。在参考电压VH高于VL的情况下，将控制电压VS设计为高于(VH-VL)可令自电容C1流向输入节点24的电荷为正电荷(等同于电流自自电容C1流向输入节点24)、自输入节点24流入背景电容Cbg的电荷也是正电荷(等同于电流自输入节点24流入背景电容Cbg)。在参考电压VH低于VL的情况下，将控制电压VS设计为低于(VH-VL)可令自电容C1流向输入节点24的电荷为负电荷(等同于电流自输入节点24流向自电容C1)、自输入节点24流入背景电容Cbg的电荷也是负电荷(等同于电流自背景电容Cbg流入输入节点24)，同样能达到前述电荷抵销效果。综上所述，只要藉由适当设计该等电容的跨压变化，使得自电容C1流向输入节点24的电荷与自输入节点24流入待测电容Cx的电荷正负相同，即可克服先前技术中难以兼顾测量解析度和避免输出电压饱和的问题。From the viewpoint of charge distribution, the characteristic of the capacitance detection device 200 is that the charge flowing from the capacitor C1 to the input node 24 is used as the charge flowing from the input node 24 into the background capacitor Cbg to achieve a charge offset effect, making the voltage Vout less likely to be achieved. saturation state. When the reference voltage VH is higher than VL, designing the control voltage VS to be higher than (VH-VL) can make the charge flowing from the self-capacitor C1 to the input node 24 to be a positive charge (equivalent to the current flowing from the self-capacitor C1 to the input node 24 ), the charges flowing from the input node 24 into the background capacitor Cbg are also positive charges (equal to the current flowing from the input node 24 into the background capacitor Cbg). When the reference voltage VH is lower than VL, designing the control voltage VS to be lower than (VH-VL) can make the charge flowing from the self-capacitor C1 to the input node 24 to be a negative charge (equivalent to the current flowing from the input node 24 to the self-capacitor C1 ), the charges flowing from the input node 24 into the background capacitor Cbg are also negative charges (equal to the current flowing from the background capacitor Cbg into the input node 24), which can also achieve the aforementioned charge offset effect. To sum up, as long as the cross-voltage changes of these capacitors are properly designed, the charge flowing from the capacitor C1 to the input node 24 is the same as the charge flowing from the input node 24 to the capacitor Cx to be measured, which can overcome the problems in the prior art. It is difficult to balance the measurement resolution and avoid the problem of output voltage saturation.

根据本发明的另一实施例为如图3(A)所示的电容检测装置。在此实施例中，电容C1被设置在运算放大器22所在的芯片500之外。事实上，无论电容C1是否与运算放大器22等元件被包含在同一个芯片内，都可以达到前述效果。值得注意的是，此实施例中的电容C1利用连接线400的寄生电容来实现。以电容式触控装置的情况为例，待测电容Cx通常是形成于一感应面板(例如图中绘示的区块600)上，并且透过软性电路板或印刷电路板上的连线线400与芯片500相连。Another embodiment according to the present invention is a capacitance detection device as shown in FIG. 3(A). In this embodiment, the capacitor C1 is disposed outside the chip 500 where the operational amplifier 22 is located. In fact, no matter whether the capacitor C1 is included in the same chip as the operational amplifier 22 or not, the aforementioned effect can be achieved. It should be noted that the capacitor C1 in this embodiment is realized by utilizing the parasitic capacitance of the connection line 400 . Taking the case of a capacitive touch device as an example, the capacitance Cx to be measured is usually formed on a sensing panel (such as the block 600 shown in the figure), and is connected through a flexible circuit board or a printed circuit board. Wire 400 is connected to chip 500 .

在此实施例中，连接线400所在的电路板具有一屏蔽(shielding)层，存在于连接线400与该屏蔽层间的寄生电容即作为电容C1。连接线400所在的电路板具有一可调整的接地端电位Vact，如图3(A)所示，该接地端透过焊垫28连接至芯片500中的开关SW4、SW5。藉由控制开关SW4、SW5的启闭，根据本发明的电容检测装置中的控制模块(未显示)即可达成改变电容C1的跨压的效果。换句话说，电容C1上的跨压变化可藉由控制该屏蔽层的接地端电位Vact实现。须说明的是，只要适当规划连接线400的形状、长度、厚度等特性，寄生电容(电容C1)的大小即为可精确估计、控制的。换言之，透过设计控制该连接线400与该屏蔽层，即可灵活调整接地端电位Vact及寄生电容(电容C1)，以实现控制电容C1上的跨压变化的效果。在另一实施例中，透过主动屏蔽(active shielding)或减耗(subtraction)等手段，亦可等效找出可藉由控制该屏蔽层的接地端电位Vact改变的电容C1。这种做法的好处在于可省去在芯片500中设置电容C1所占据的空间，同时有效利用原本被视为冗赘或负面因素的寄生电容。In this embodiment, the circuit board where the connection line 400 is located has a shielding layer, and the parasitic capacitance existing between the connection line 400 and the shielding layer is the capacitor C1. The circuit board where the connection line 400 is located has an adjustable ground potential Vact, as shown in FIG. By controlling the opening and closing of the switches SW4 and SW5, the control module (not shown) in the capacitance detection device according to the present invention can achieve the effect of changing the voltage across the capacitance C1. In other words, the change of the voltage across the capacitor C1 can be realized by controlling the potential Vact of the ground terminal of the shielding layer. It should be noted that as long as the shape, length, thickness and other characteristics of the connection line 400 are properly planned, the size of the parasitic capacitance (capacitance C1 ) can be accurately estimated and controlled. In other words, through design and control of the connection line 400 and the shielding layer, the ground potential Vact and the parasitic capacitance (capacitor C1 ) can be flexibly adjusted to achieve the effect of controlling the voltage across the capacitor C1. In another embodiment, through means such as active shielding or subtraction, the capacitance C1 that can be changed by controlling the potential Vact of the ground terminal of the shielding layer can also be equivalently found. The advantage of this method is that the space occupied by the capacitor C1 in the chip 500 can be saved, and at the same time, the parasitic capacitance which is considered redundant or negative factor can be effectively utilized.

如图3(B)所示，在另一实施例中，电容C1也可被拆解为两个部份：设置于芯片500外的电容C1A和设置于芯片500内的电容C1B。电容C1B可被设计为主要用以补偿因制程变异造成的电容C1A大小误差，因此不需要太大。举例而言，电容C1B的等级可在1～2微微法拉(pF)，但不以此为限。As shown in FIG. 3(B), in another embodiment, the capacitor C1 can also be disassembled into two parts: the capacitor C1A arranged outside the chip 500 and the capacitor C1B arranged inside the chip 500 . The capacitor C1B can be designed mainly to compensate the size error of the capacitor C1A caused by process variation, so it does not need to be too large. For example, the level of the capacitor C1B can be 1-2 picofarads (pF), but not limited thereto.

如图3(C)所示，在另一实施例中，电容C1A和电容C1B可以被设计为各自受不同的控制电压影响。在此范例中，当开关SW5为通路，电容C1B会被连接至提供控制电压VS的电压源，但电容C1A的电压变化受到控制模块29的控制。同样地，只要使得自电容C1A、C1B流向输入节点24的电荷与自输入节点24流入待测电容Cx的电荷正负相同，即可克服先前技术中难以兼顾测量解析度和避免输出电压饱和的问题。As shown in FIG. 3(C), in another embodiment, the capacitor C1A and the capacitor C1B can be designed to be affected by different control voltages respectively. In this example, when the switch SW5 is turned on, the capacitor C1B is connected to the voltage source providing the control voltage VS, but the voltage change of the capacitor C1A is controlled by the control module 29 . Similarly, as long as the charges flowing from the capacitances C1A and C1B to the input node 24 are the same positive and negative as the charges flowing from the input node 24 into the capacitor Cx to be measured, the problem of difficulty in both measurement resolution and avoiding output voltage saturation in the prior art can be overcome .

前述几个实施例都是以输入节点24的电压会变动的情况为例。实际上，输入节点24的电压亦可被设计为固定不变，例如图4(A)所示的实施例。请参阅图4(A)，开关SW1～SW5的状态可由一控制模块(未显示)决定，而待测电容Cx的两端分别透过输入节点44和驱动节点48连接至此电容检测装置。The aforementioned several embodiments are all taken as examples when the voltage of the input node 24 changes. In fact, the voltage of the input node 24 can also be designed to be constant, such as the embodiment shown in FIG. 4(A). Please refer to FIG. 4(A), the state of the switches SW1-SW5 can be determined by a control module (not shown), and the two ends of the capacitance Cx to be measured are respectively connected to the capacitance detection device through the input node 44 and the driving node 48 .

在检测过程的第一阶段，开关SW1、SW2、SW4首先被设定为通路，而开关SW3、SW5被设定为断路；图4(A)中的电路等同于图4(B)所示者(暂忽略判断模块46)。在这个情况下，运算放大器22的输出端(Vout)和正负输入端的电压都会等于参考电压Vref。电容C2被放电至不存有电荷，电容C1被充电至存有电荷C1*(VL-Vref)，待测电容Cx则是被充电至存有电荷Cx*(VH-Vref)。In the first stage of the detection process, the switches SW1, SW2, and SW4 are first set as open circuits, and the switches SW3, SW5 are set as open circuits; the circuit in Figure 4(A) is equivalent to that shown in Figure 4(B) (The judging module 46 is temporarily ignored). In this case, the voltages at the output terminal (Vout) and the positive and negative input terminals of the operational amplifier 22 are equal to the reference voltage Vref. Capacitor C2 is discharged to no charge, capacitor C1 is charged to charge C1*(VL-Vref), and capacitor Cx to be tested is charged to charge Cx*(VH-Vref).

随后，在检测过程的第二阶段，开关SW1、SW2、SW4首先被设定为断路，而开关SW3、SW5被设定为通路；图4(A)中的电路等同于图4(C)所示者(暂忽略判断模块46)。在这个情况下，运算放大器22的正负输入端的电压仍维持在等于参考电压Vref，电容C1一侧的控制节点被改接至提供控制电压VH的电源供应器，驱动节点48则是被转接至提供控制电压VL的电源供应器。Subsequently, in the second stage of the detection process, the switches SW1, SW2, SW4 are first set to open circuit, and the switches SW3, SW5 are set to open circuit; the circuit in Fig. 4(A) is equivalent to Fig. 4(C) displayer (ignoring the judging module 46 for now). In this case, the voltage of the positive and negative input ends of the operational amplifier 22 remains equal to the reference voltage Vref, the control node on the side of the capacitor C1 is reconnected to the power supply supplying the control voltage VH, and the driving node 48 is reconnected. To the power supply that provides the control voltage VL.

上述两阶段间的开关切换会导致各电容的跨压改变，进而造成电荷在电容C1、C2、Cx间重新分配。对应于输入节点44的电荷平衡关系可被表示为：The switching between the above two stages will cause the voltage across the capacitors to change, and then cause the charges to be redistributed among the capacitors C1, C2, and Cx. The charge balance relationship corresponding to the input node 44 can be expressed as:

(VH-VL)*C1+(Vout-Vref)*C2＝(VH-VL)*Cx。(6)(VH-VL)*C1+(Vout-Vref)*C2=(VH-VL)*Cx. (6)

此实施例中的参考电压VH高于VL。据此，由式(6)可看出，在第二阶段电流自输入节点44流入待测电容Cx以及由自电容C1流向输入节点44，换言之，自输入节点44流入待测电容Cx的正电荷至少有一部分是由自电容C1流向输入节点44的正电荷所贡献。至于自电容C2影响所及的部分，若Vout大于Vref，电流是自自电容C2流向输入节点44，即由自电容C2流向输入节点44的是正电荷；若Vout小于Vref，电流自输入节点44流向自电容C2，即由自电容C2流向输入节点44的是负电荷。待测电容Cx的电荷改变是由电容C1、C2共同贡献。The reference voltage VH in this embodiment is higher than VL. Accordingly, it can be seen from formula (6) that in the second stage, the current flows from the input node 44 into the capacitor Cx to be measured and flows from the self-capacitor C1 to the input node 44, in other words, the positive charge flowing from the input node 44 into the capacitor Cx to be measured At least some of this is contributed by positive charge flowing from capacitor C1 to input node 44 . As for the part affected by the self-capacitance C2, if Vout is greater than Vref, the current flows from the self-capacitance C2 to the input node 44, that is, the positive charge flows from the self-capacitance C2 to the input node 44; if Vout is smaller than Vref, the current flows from the input node 44 to the input node 44. The self-capacitance C2, that is, the negative charges flowing from the self-capacitance C2 to the input node 44. The charge change of the capacitor Cx to be measured is jointly contributed by the capacitors C1 and C2.

式(6)可被进一步改写为：Equation (6) can be further rewritten as:

$Vout Vout = = Vref Vref + + ((VH VH - - VL VL)) * * \frac{Cx Cx}{C C 22} - - ((VH VH - - VL VL)) * * \frac{C C 11}{C C 22} . . - - - - - - ((77))$

由于电压VL、VH、Vref和电容C1、C2的数值皆为已知，根据输出电压Vout或者是电容C2两端的跨压变化(由零变为Vout-Vref)，判断模块46即可推算出待测电容Cx的大小。若将待测电容Cx进一步拆解为未受使用者影响前即存在的背景电容Cbg及电容变化量Csig的总和，式(7)可被再改写为：Since the values of the voltages VL, VH, Vref and the capacitors C1 and C2 are all known, according to the output voltage Vout or the change in voltage across the capacitor C2 (from zero to Vout-Vref), the judging module 46 can calculate the waiting time Measure the size of the capacitor Cx. If the capacitance Cx to be measured is further disassembled into the sum of the background capacitance Cbg and the capacitance variation Csig that existed before being affected by the user, equation (7) can be rewritten as:

$Vout Vout = = Vref Vref + + ((VH VH - - VL VL)) * * \frac{Cbg Cbg}{C C 22} + + ((VH VH - - VL VL)) * * \frac{Csig Csig}{C C 22} - - ((VH VH - - VL VL)) * * \frac{C C 11}{C C 22} . . - - - - - - ((88))$

由式(8)可看出，电容C1贡献的电荷可抵消背景电容Cbg贡献的电荷，使电压Vout较不易达到饱和状态。因此，即使选择较小的电容C2来提高电容变化量Csig的解析度，也不会使电压Vout很容易就因过高而饱和。易言之，只要选择大小适当的电容C1，此电容检测装置即可提供良好的测量解析度，并且不存在输出电压易饱和的问题。It can be seen from formula (8) that the charge contributed by the capacitor C1 can offset the charge contributed by the background capacitor Cbg, making it difficult for the voltage Vout to reach a saturated state. Therefore, even if a smaller capacitor C2 is selected to increase the resolution of the capacitance variation Csig, the voltage Vout will not be easily saturated due to too high. In other words, as long as the capacitor C1 is selected with an appropriate size, the capacitance detection device can provide good measurement resolution, and there is no problem that the output voltage is easily saturated.

图4(A)所示的电容检测装置可用以配合例如互容式触控系统。更明确地说，输入节点44可被连接至互容式触控系统中的感应电极，驱动节点48可被连接至互容式触控系统中的驱动电极，而待测电容Cx就是该感应电极与该驱动电极间的互容(mutual capacitance)；切换提供给驱动节点48的电压即为供应驱动信号。此外，与前述几个实施例相同的是，图4(A)中的电容C1也可包含或完全是屏蔽层与连接线间的寄生电容。The capacitive detection device shown in FIG. 4(A) can be used in cooperation with, for example, a mutual capacitive touch system. More specifically, the input node 44 can be connected to the sensing electrode in the mutual capacitive touch system, the driving node 48 can be connected to the driving electrode in the mutual capacitive touch system, and the capacitance Cx to be measured is the sensing electrode Mutual capacitance with the driving electrode; switching the voltage provided to the driving node 48 is the supply driving signal. In addition, similar to the previous embodiments, the capacitor C1 in FIG. 4(A) may also include or completely be the parasitic capacitance between the shielding layer and the connecting wire.

综上所述，根据本发明的电容检测装置所运用的概念为：提供电容C1一第一跨压变化，并提供待测电容Cx一第二跨压变化，藉此使电容C2出现一第三跨压变化，再根据电容C1、C2的电容量及该等跨压变化来判断待测电容Cx的电容量。只要将第一跨压变化与第二跨压变化设计为使得自电容C1流向输入节点的电荷与自输入节点流入待测电容Cx的电荷正负相同，就可克服先前技术中难以兼顾测量解析度和避免输出电压饱和的问题。To sum up, the concept used by the capacitance detection device according to the present invention is: provide a first cross-voltage change of the capacitance C1, and provide a second cross-voltage change of the capacitance Cx to be measured, thereby causing a third cross-voltage change of the capacitance C2. The capacitance of the capacitor Cx to be tested is judged according to the capacitance of the capacitors C1 and C2 and the changes of the cross-voltage. As long as the first cross-voltage change and the second cross-voltage change are designed so that the charge flowing from the capacitor C1 to the input node is the same as the charge flowing from the input node to the capacitor Cx to be measured, it is possible to overcome the difficulty in balancing the measurement resolution in the prior art and avoid the problem of output voltage saturation.

根据本发明的另一实施例为一电容式触控系统，其中包含一显示器、多个感应电容及一个或多个如图2(A)、图3(A)、图3(B)、图3(C)或图4(A)所示的电容检测装置。该多个感应电容各自对应于该显示器上的一实体位置，其大小变化可受该一个或多个电容检测装置的检测。关于电容检测装置的运作方式可参考前述实施例的相关说明，不再赘述。Another embodiment according to the present invention is a capacitive touch system, which includes a display, a plurality of sensing capacitors and one or more 3(C) or the capacitance detection device shown in Figure 4(A). Each of the plurality of sensing capacitances corresponds to a physical position on the display, and its size change can be detected by the one or more capacitance detection devices. Regarding the operation mode of the capacitance detection device, reference may be made to the relevant descriptions of the foregoing embodiments, and details are not repeated here.

如上所述，本发明以上具体实施例提出一种新的电容检测装置及应用该电容检测装置的电容式触控系统。藉由在回授电容的外新增一个电容来适当供应待测电容在电荷重新分配过程中需要的电荷量，根据本发明以上具体实施例的电容检测装置可克服先前技术中难以兼顾测量解析度和避免输出电压饱和的问题。除了配合电容式触控系统之外，根据本发明以上具体实施例的电容检测装置也可广泛应用在其他各种需要测量电容值的场合。As mentioned above, the above specific embodiments of the present invention provide a new capacitance detection device and a capacitive touch system using the capacitance detection device. By adding a new capacitor outside the feedback capacitor to properly supply the amount of charge required by the capacitor to be measured during the charge redistribution process, the capacitance detection device according to the above specific embodiments of the present invention can overcome the difficulties in measuring resolution in the prior art and avoid the problem of output voltage saturation. In addition to cooperating with a capacitive touch system, the capacitance detection device according to the above specific embodiments of the present invention can also be widely used in various other occasions where capacitance needs to be measured.

藉由以上具体实施例的详述，希望能更加清楚描述本发明的特征与精神，而并非以上述所揭示的较佳具体实施例来对本发明的范畴加以限制。相反地，其目的是希望能涵盖各种改变及具相等性的安排于本发明所欲申请的专利范围的范畴内。Through the detailed description of the above specific embodiments, it is hoped that the characteristics and spirit of the present invention can be described more clearly, rather than the scope of the present invention is limited by the preferred specific embodiments disclosed above. On the contrary, the intention is to cover various changes and equivalent arrangements within the scope of the claimed patent scope of the present invention.

Claims

1. a capacitance detecting device is connected in a testing capacitance, and this capacitance detecting device comprises:

One first electric capacity and one second electric capacity see through an input node and are connected to this testing capacitance;

One control module, in order to provide this first electric capacity one first cross-pressure to change, and provide this testing capacitance one second cross-pressure to change, make by this this second electric capacity produce one the 3rd cross-pressure and change, wherein this first cross-pressure variation makes the electric charge that flows to the electric charge of this input node and flow into this testing capacitance from this input node from this first electric capacity positive and negative identical with this second cross-pressure variation; And

One judge module in order to change according to the electric capacity of this first electric capacity, electric capacity, this first cross-pressure variation, this second cross-pressure variation and the 3rd cross-pressure of this second electric capacity, is judged the electric capacity of this testing capacitance.

2. capacitance detecting device as claimed in claim 1, it is characterized in that, this capacitance detecting device and this testing capacitance see through a connecting line that is formed on the circuit board and join, this circuit board has a screen layer, wherein this first electric capacity comprises the stray capacitance between this connecting line and this screen layer, and this control module is controlled this screen layer to provide this first cross-pressure of this first electric capacity to change.

3. capacitance detecting device as claimed in claim 2 is characterized in that, this circuit board is a flexible circuit board or a printed circuit board (PCB).

4. capacitance detecting device as claimed in claim 1 is characterized in that, this first electric capacity is connected between this input node and a control node, and this second electric capacity is connected between this input node and an output node; This control module is controlled voltage in a very first time for inputting node and this output node one first input voltage and supplying control node one first; This control module is controlled voltage in one second time for inputting node one second input voltage and supplying control node one second; The difference of this first input voltage and this second input voltage is less than the difference of this first control voltage and this second control voltage.

5. capacitance detecting device as claimed in claim 4 is characterized in that, this control module comprises:

One operational amplifier has a first input end, the second input end and an output terminal, and this first input end is this input node, and this output terminal is this output node;

One first switch is connected between first input end and this output terminal, is path in this very first time, in this second time for opening circuit;

One second switch is connected between this second input end and one second input voltage supply, in this very first time for opening circuit, be path in this second time;

One the 3rd switch is connected between this second input end and one first input voltage supply, is path in this very first time, in this second time for opening circuit;

One the 4th switch is connected between this control node and an earth terminal, is path in this very first time, in this second time for opening circuit; And

One the 5th switch, be connected in this control node and one first control Voltage Supply Device between, in this very first time for opening circuit, be path in this second time.

6. capacitance detecting device as claimed in claim 1, it is characterized in that, this testing capacitance is connected in this input node and and drives between node, and this first electric capacity is connected between this input node and a control node, and this second electric capacity is connected between this input node and an output node; This control module should be inputted node and this output node one reference voltage, supplies control node one first voltage, supply drive node one second voltage in very first time confession; This control module should be inputted this reference voltage of node, supplies control this second voltage of node, supply drive this first voltage of node in the confession of one second time; This first voltage is different from this second voltage.

7. capacitance detecting device as claimed in claim 6 is characterized in that, this control module comprises:

One operational amplifier has a first input end, the second input end and an output terminal, and this first input end is this input node, and this output terminal is this output node, and this second input end is connected to a reference voltage supplies device;

One second switch is connected between this driving node and a second voltage supply, is path in this very first time, in this second time for opening circuit;

One the 3rd switch is connected between this driving node and one first Voltage Supply Device, in this very first time for opening circuit, be path in this second time;

One the 4th switch is connected between this control node and this first Voltage Supply Device, is path in this very first time, in this second time for opening circuit; And

One the 5th switch is connected between this control node and this second voltage supply, in this very first time for opening circuit, be path in this second time.

8. capacitance touch control system comprises:

One display;

A plurality of inductance capacitances are separately corresponding to the provider location on this display;

One first electric capacity and one second electric capacity, see through an input node be connected to these a plurality of inductance capacitances one of them as a testing capacitance;

9. capacitance touch control system as claimed in claim 8, it is characterized in that, this capacitance detecting device and this testing capacitance see through a connecting line that is formed on the circuit board and join, this circuit board has a screen layer, wherein this first electric capacity comprises the stray capacitance between this connecting line and this screen layer, and this control module is controlled this screen layer to provide this first cross-pressure of this first electric capacity to change.

10. capacitance touch control system as claimed in claim 9 is characterized in that, this circuit board is a flexible circuit board or a printed circuit board (PCB).

11. capacitance touch control system as claimed in claim 8 is characterized in that, this first electric capacity is connected between this input node and a control node, and this second electric capacity is connected between this input node and an output node; This control module is controlled voltage in a very first time for inputting node and this output node one first input voltage and supplying control node one first; This control module is controlled voltage in one second time for inputting node one second input voltage and supplying control node one second; The difference of this first input voltage and this second input voltage is less than the difference of this first control voltage and this second control voltage.

12. capacitance touch control system as claimed in claim 11 is characterized in that, this control module comprises:

13. capacitance touch control system as claimed in claim 8, it is characterized in that, this testing capacitance is connected in this input node and and drives between node, and this first electric capacity is connected between this input node and a control node, and this second electric capacity is connected between this input node and an output node; This control module should be inputted node and this output node one reference voltage, supplies control node one first voltage, supply drive node one second voltage in very first time confession; This control module should be inputted this reference voltage of node, supplies control this second voltage of node, supply drive this first voltage of node in the confession of one second time; This first voltage is different from this second voltage.

14. capacitance touch control system as claimed in claim 13 is characterized in that, this control module comprises:

One the 3rd switch is connected between this driving node and one first Voltage Supply Device, is path in this very first time, is short circuit in this second time;