TW201642097A - Touch panel and touch detection circuit - Google Patents

Abstract

Aspects of the disclosure provide a touch panel having an electrode array. The electrode array includes first electrodes arranged on a first layer, each first electrode patterned to include a plurality of sequentially connected first electrode elements that are generally shaped as elongated polygons, and second electrodes arranged on a second layer, each second electrode patterned to include a plurality of sequentially connected second electrode elements that are generally shaped as elongated polygons, wherein the first electrodes on the first layer and the second electrodes on the second layer are arranged over one another so as to form an interlocking pattern.

Description

Touch panel and touch detection circuit [related application]

The present application claims the benefit of U.S. Provisional Application Serial No. 62/005,509, entitled "Capacitive Touch Screen", filed on May 30, 2014, the entire contents of which is incorporated herein by reference.

The background description provided herein is for the purpose of general description of the disclosure. The work of the inventor of the presently-referenced name, as well as the aspects of the present specification that may not be prior art at the time of filing the application, whether explicitly or implicitly, should not be considered as being directed to the present disclosure. current technology.

In computer systems, the touch screen includes an array of addressable electrodes. When a finger or conductive pen approaches the electrode, it will disturb the electric field and change the capacitance of the electrode. Capacitance changes can be measured via a touch detection circuit and subsequently converted to coordinates provided to the computer system.

It is an object of the present invention to provide a touch panel having an electrode array. The electrode array includes a plurality of first electrodes disposed on the first layer, each of the first electrodes being patterned to include a plurality of sequentially connected first electrode elements and formed into an elongated polygon, and disposed on the second layer a plurality of second electrodes, each of the second electrodes being patterned to include a plurality of sequentially connected second electrode elements and shaped into an elongated polygon, wherein the first electrode on the first layer and the second electrode on the second layer They are arranged to be arranged to cross each other to form an interlocking pattern.

In an embodiment, the first electrode element on the first layer and the second electrode element on the second layer are hexagonal. In another embodiment, the first electrode element on the first layer and the second electrode element on the second layer are hollow hexagons. In an exemplary embodiment, the first hollow region located within the hollow hexagon of the first and second electrode members and the second hollow region between the adjacent hollow hexagons of the first and second electrode members includes A plurality of floating blocks. In another example, the floating block in each of the first hollow zone and the second hollow zone includes a plurality of floating blocks. In other examples, the floating block is coplanar with the first or second layer.

In an embodiment, at least one of the electrodes includes an additional branch located in a middle portion of the electrode. In another embodiment, the first electrode on the first layer and the second electrode on the second layer are coplanar with each other.

In an embodiment, the touch panel includes a display, wherein the electrode array is disposed in front of the display. In other embodiments, the touch panel includes a display in which the array of electrodes is integrated into the display.

It is an object of the present invention to provide a touch controller. The touch controller has a touch detection circuit for receiving a touch signal on the touch panel and determining a touch coordinate. The touch detection circuit includes an analog front end for converting a touch signal on the touch panel into a digital signal. The analog front end includes a hybrid sensing circuit for generating a voltage signal according to the received touch signal on the touch panel. The hybrid sensing circuit operates as a self-capacitance sensing circuit in at least one first mode, and the hybrid sensing circuit operates as a mutual capacitance sensing circuit in the second mode. The touch detection circuit further includes a digital signal processor for determining a touch coordinate based on the digital signal received from the analog front end.

In an embodiment, the hybrid sensing circuit has a set of switches for changing the sense of mixing The operation of the circuit between the first mode and the second mode is measured.

In another embodiment, when the hybrid sensing circuit operates in the first mode, the self-capacitance hybrid sensing circuit includes a voltage dividing circuit, and the voltage dividing circuit includes a first capacitor having a fixed capacitance and a touch A self-capacitor capacitor on the panel and connected to the first capacitor in series. In an example, when the hybrid sensing circuit operates in the first mode, the self-capacitance sensing circuit further includes an operational amplifier having a feedback capacitor and a feedback resistor, and the feedback capacitor and the feedback resistor are coupled to the operation. One of the amplifiers converts between the input end and the output end; in addition, the self-capacitance sensing circuit includes a resistor having a first end and a second end, the first end being coupled to the first capacitor and the self-capacitor capacitor A voltage dividing circuit is coupled between the second end and the conversion input of the operational amplifier. In one embodiment, the resistor has a first end coupled to the voltage dividing circuit, and the resistor is configured to have a large resistance value such that the voltage dividing circuit can ignore the current from the voltage dividing circuit under normal operation.

It is an object of the present invention to provide a method of operating a touch panel in two modes of operation with a hybrid sensing circuit. The method includes: sensing a touch on the touch panel by setting the hybrid sensing circuit operating in the first operating mode, switching the hybrid sensing circuit to the second operating mode, and operating in the second operating mode The measurement circuit senses the touch on the touch panel.

The method embodiment includes operating the touch panel in two operation modes by using a hybrid sensing circuit, wherein the first operation mode is one of sensing a self-capacitance change or sensing a mutual capacitance change, and the second operation mode is a sense Measured from capacitance change or sensing another change in mutual capacitance.

100‧‧‧ computer system

101‧‧‧ touch controller

102‧‧‧Detection circuit

103‧‧‧ analog front end

104‧‧‧Digital Signal Processor

105‧‧‧TX signal generator

106‧‧‧Touch panel

107‧‧‧electrode array

110‧‧‧Touch sensing device

120‧‧‧ processor

130‧‧‧Display device

140‧‧‧ storage module

150‧‧‧Input/output devices

210‧‧‧ Cover

220‧‧‧electrode

230‧‧‧ Grounding

250‧‧‧ fingers

260, 265‧‧‧ electric field lines

270‧‧‧ cover

280‧‧‧ drive electrodes

290‧‧‧ receiving electrode

300A, 300B, 300C, 300D‧‧‧ electrode array

301‧‧‧ first floor

302‧‧‧ second floor

310, 311, 312, 313‧‧‧ electrode components

320‧‧‧ Bridge

330‧‧‧ intersection

340‧‧‧ Touch point

350, 351‧‧‧ suspended blocks

360, 361‧‧ hollow area

370, 371‧‧ ‧ gap

380‧‧‧Extra branch

381‧‧‧ side trace

400‧‧‧ touch panel

401, 402‧‧‧ electrodes

403‧‧‧Shield

410‧‧‧ cover

421, 422‧‧ ‧ optical adhesive

430‧‧‧ dielectric layer

440‧‧‧Substrate layer

450‧‧‧ Air gap

451‧‧‧ cushion

460‧‧‧ display

500A, 500B‧‧‧electrode array

501, 502, 503‧‧ ‧ intersection

600A‧‧‧Self-capacitance sensing circuit

600B‧‧‧ mutual capacitance sensing circuit

610‧‧‧Input circuit

620‧‧‧Amplification circuit

700A, 700B‧‧‧Detection Circuit

701‧‧‧Transformer

702‧‧‧ low pass filter

703‧‧‧ Analog Digital Converter

704‧‧‧Digital Demodulator

705‧‧‧low-pass digital filter

706‧‧‧ calculus module

710‧‧‧ analog front end

715‧‧‧Digital Signal Processor

720‧‧‧Mixed sensing circuit

721‧‧‧Operational Amplifier

730‧‧‧Self-capacitance sensing circuit

740‧‧‧ mutual capacitance sensing circuit

C1-C4, R1-R4, X1-XN, Y1-YN‧‧‧ electrodes

The various embodiments of the present invention are intended to be illustrative only, and the same reference 1 is a schematic diagram of a computer system including a touch sensing device according to an embodiment of the invention; FIG. 2A and FIG. 2B are diagrams illustrating detecting a self-capacitance change of an electrode of a touch panel according to an embodiment of the invention; FIG. 2C and FIG. 2D are schematic diagrams showing mutual capacitance sensing methods for detecting mutual capacitance changes of two electrodes of a touch panel according to an embodiment of the invention; FIG. 3A-3D are diagrams according to FIG. FIG. 4 is a cross-sectional view showing an example of a layer structure of a touch panel according to an embodiment of the present invention; FIG. 5A and FIG. 5B are diagrams according to the present invention; FIG. 6A and FIG. 6B are schematic diagrams showing examples of two sensing circuits according to an embodiment of the invention; FIG. 7A is a diagram showing an example of mixing according to an embodiment of the invention; FIG. 7B is a schematic diagram showing two examples of a hybrid sensing circuit and a hybrid sensing circuit.

FIG. 1 is a schematic diagram of a computer system 100 including a touch sensing device 110 in accordance with an embodiment of the invention. In some embodiments, computer system 100 can be equivalent to a personal computer system Systems such as mobile phones, desktop computers, notebook computers, tablets, and the like. In an alternate embodiment, computer system 100 may be equivalent to a public computer system, such as an automated teller machine (ATM), a vending machine, a point of sale (POS) device, a kiosk, and the like. As shown, the computer system 100 includes a processor 120 coupled to the touch sensing device 110, the display device 130, the storage module 140, and an input/output (I/O) device 150.

The touch sensing device 110 is configured to detect a touch of a finger or a conductive pen and transmit a detection message to the processor 120, such as a touch location on the touch sensing device 110. The processor 120 interprets the touch message according to the program executed by the processor 120 and then performs the corresponding operation. In one embodiment, the touch sensing device 110 includes a touch panel 106 and a touch controller 101.

The touch panel 106 can be based on resistance, capacitance, surface acoustic waves, and infrared light. In an embodiment, the touch panel 106 is based on a capacitor and includes an electrode array 107. In various embodiments, the electrodes in the electrode array can have various shapes and be disposed at different locations to form various electrode patterns. In an embodiment, the electrode array 107 comprises a strip of two-layer electrodes. One layer of electrodes is arranged in rows while the other layer of electrodes is arranged in columns. The column electrodes and the row electrodes cross each other to form a matrix pattern. In another embodiment, the electrode array 107 includes two layers of electrodes, and each electrode includes a plurality of electrode elements (or cells) that are sequentially connected and have a diamond shape. Similar to the matrix pattern, one layer of electrodes is arranged in rows while the other layer of electrodes is arranged in columns. The column electrodes and the row electrodes are arranged to cross each other to form an interlocking diamond pattern.

In accordance with an aspect of the present invention, in one embodiment, the electrode array 107 is arranged in a hollow hexagonal pattern, whereby the touch sensing sensitivity of the touch panel 106 can be improved.

The electrodes in electrode array 107 are typically fabricated from any suitable electrically conductive material. In an embodiment, the touch panel 106 is a transparent capacitive touch panel and is placed in the display device. Set to the front, for example, display device 130. In this type of application, the electrodes can be made of a transparent conductive material such as indium tin oxide, metal film, carbon nanotubes, and the like. In another embodiment, the touch panel 106 is a non-transparent capacitive touch panel and is used as a touch pad, such as a touch pad in a notebook computer. In this type of application, the electrodes can be made of a non-transparent conductive material, such as a copper wire.

In operation, when a finger or a conductive pen approaches the touch panel 106, the capacitance between different electrodes (mutual capacitance) or between the electrode and the ground (self-capacitance) will change, and such capacitance change can be touched. The controller 101 measures the amount. Therefore, the touch on the touch panel 106 can be detected.

Touch controller 101 is typically used to continuously monitor changes in capacitance at different locations of the electrode array. In particular, the touch controller generates a drive signal, referred to as a transmit (TX) signal, and applies a voltage to the electrodes in the electrode array 107 to measure capacitance values in different drive electrodes, and the reception represents electricity in the different drive electrodes. The signal of the capacity. According to the received signal, the touch controller 101 can detect the capacitance change of the electrode array, and detect the touch and touch position on the panel 106 correspondingly, and then transmit the detection message to the processor 120.

In an embodiment, the touch controller 101 includes a TX signal generator 105. The TX signal generator 105 is used to generate a TX signal, such as a pulse wave, which is then sequentially added to the different electrodes.

In an embodiment, the touch controller 101 further includes a detection circuit 102. The touch controller 101 includes an analog front end 103 and a digital signal processor (DSP) 104. The analog front end 103 is for continuously receiving signals representing capacitances in different electrodes on the touch panel 106 from different electrodes (on which TX signals are applied) and converting the signals into signals that can be processed by subsequent DSPs. . In one embodiment, the TX signal generator 105 is used to generate a pulse, and the analog front end can be output via the power. Another pulse in which the capacitance in the different electrodes of the pole array is modulated. When the capacitance changes, the above modulation signal will change to indicate the capacitance change.

In accordance with an aspect of the present invention, in an embodiment, the analog front end 103 includes a hybrid sensing circuit that operates as a self-capacitance sensing circuit when operating in the first mode and operates in the second mode when operating in the first mode The hybrid sensing circuit is used as a mutual capacitance sensing circuit. It may be necessary to measure the mutual capacitance and the self capacitance with two independent analog front ends. Due to the hybrid architecture, the hybrid analog front end 103 reduces space utilization on the wafer and reduces hardware costs.

The DSP 104 is configured to process the output signal of the analog front end 103 and generate touch coordinate information that is executed on the touch panel 106. In addition, the DSP 104 can perform various software algorithms to achieve touch detection or control functions. For example, the DSP 104 can perform algorithms for eliminating charging noise, detecting glove touches, distinguishing between intentional touches (fingers) and unintentional touches (palms), and the like.

In various embodiments, when the size of the touch panel 106 is large, the capacity of one touch controller 101 is insufficient to monitor all capacitance changes of the touch panel 106, so that multiple touch controllers 101 can be used for monitoring. Different areas of the touch panel 106.

In various embodiments, touch controller 101 can be implemented in one or more integrated circuits (ICs) or can be implemented using separate components. In some embodiments, the touch controller 101 includes a memory module for storing the software code and the data used by the touch controller 101. In some embodiments, the touch controller 101 connects the touch panel 106 via a flexible circuit board (FPC) connector that includes a plurality of wires.

The processor 120 typically executes software code, such as operating system software, application software, and the like, to process data and control the operation of the computer system 100. The processor 120 can It can be a single-chip processor or can be implemented with multiple components. The storage module 130 typically stores software code and data used by the computer system 100. The storage module 130 can include read only memory (ROM), random access memory (RAM), hard disk drive, CD-ROM, cache memory, and the like. The I/O device 150 can receive input data from the computer system 100 or provide output data to the outside of the computer system 100. I/O devices can include keyboards, mice, speakers, microphones, cameras, network interfaces, and the like.

Display device 130 is for displaying a graphical user interface (GGUI) to present an output message of computer system 100. In an embodiment, display device 130 is a separate component, such as a monitor. In another embodiment, display device 130 is integrated with other components in computer system 100 to form a stand-alone device, such as a tablet or mobile phone. In various embodiments, the display device can be a liquid crystal display (LCD), a cathode ray tube (CRT), a plasma display, and the like.

FIG. 2A and FIG. 2B are schematic diagrams showing a self-capacitance sensing method for detecting a change in self-capacitance of an electrode of the touch panel 106 according to an embodiment of the invention. In FIG. 2A, it shows a situation in which no finger is touched, and the electrode 220 is disposed on the back surface of the cover lens 210 of the touch panel 106. The self-capacitance C _S between the electrode 220 and the ground 230 is equivalent to C _S0 . To measure the self capacitance C _S , a TX signal is added to the electrode 220. In FIG. 2B, when the finger 250 touches the cover, the capacitance C _F is added between the electrode 220 and the ground 230 via the human body whose potential is approximately at the ground potential. Now, the self-capacitance C _S between the electrode 220 and the ground 230 will increase from C _S0 to C _S0 + C _F . The self-capacitance change associated with the electrode 220 can be detected by the touch detection circuit 102, thereby detecting a finger touch.

FIG. 2C and FIG. 2D are schematic diagrams showing a mutual capacitance sensing method for detecting mutual capacitance changes of two electrodes of the touch panel 106 according to an embodiment of the invention. In FIG. 2C, it shows that there is no finger touch, and both the drive electrode 280 and the receiving electrode 290 are disposed on the back surface of the cover 270. The mutual capacitance C _M between the drive electrode 280 and the reception electrode 290 is equivalent to C _M0 . To measure the mutual capacitance C _M , a TX signal is added to the drive electrode 280 , and a received signal (RX) from the receive electrode 290 is transmitted to the touch detection circuit 102 . As shown, a plurality of electric field lines are distributed between the two electrodes 280 and 290. The first portion of the electric field line 265 is referred to as the near electric field line, which is adjacent to the two electrodes 280 and 290, and the second portion of the electric field line 260 is referred to as the fringe electric field line, which is projected from away from the two edge electrodes 280 and 290.

In FIG. 2D, when the finger 250 touches the cover plate 270, a portion of the fringe electric field lines 260 are terminated by the finger 250 due to the potential difference between the drive electrode 280 and the finger 250. Therefore, the electric field lines between the two electrodes 280 and 290 are reduced, causing the mutual capacitance C _{M to} decrease from C _M0 to C _M1 . The mutual capacitance change between the driving electrode 280 and the receiving electrode 290 can be detected by the touch detection circuit 102 to detect a finger touch.

It should be noted that in the above mutual capacitance change detection process, when the finger touches the cover plate 270, the near electric field line 265 is substantially unaffected, and the fringe electric field line 260 is substantially affected. Therefore, the change in the fringe electric field line 260 is a major factor causing the change in the mutual capacitance C _M .

In addition, according to the disclosed point of view, the touch sensitivity of the touch panel is indeed related to the mutual capacitance change rate. The mutual capacitance change rate is defined as the ratio of the mutual capacitance change to the original mutual capacitance before the change occurs. Therefore, in order to increase the mutual capacitance change rate, the strength of the near electric field can be reduced to reduce the original mutual capacitance, and the strength of the fringe electric field can be increased to increase the possible mutual capacitance change. Therefore, the touch sensitivity of the touch panel can be improved.

In addition, fingers with thick gloves do not affect the mutual capacitance C _M . Because thick gloves are not electrically conductive, the change in the fringing electric field caused by the gloves is very small, so that this change cannot be detected. On the other hand, a finger with a thick glove can still significantly cause a change in the self-capacitance C _S via the addition of a capacitor C _F , as shown in FIG. 2B . Therefore, a touch panel based on mutual capacitance sensing cannot detect a finger touch with a thick glove, and a touch panel based on self-capacitance sensing can.

3A-3D are schematic diagrams showing four electrode arrays having different electrode patterns in accordance with various embodiments of the present invention. In FIG. 3, the conventional electrode array 300A includes electrodes C1-C4 in which the first layer 301 is uniformly separated and arranged in a row, and electrodes R1-R4 in which the second layer 302 is uniformly separated and arranged in a column. Each of the electrodes C1-C4 or R1-R4 includes a sequentially connected rhombic electrode element 310 and is connected via a bridge 320. The column electrodes R1-R4 and the row electrodes C1-C4 are arranged on each other to form an interlocking pattern. In various embodiments, the first layer 301 and the second layer 302 can be coplanar, and each intersection 330 of the bridge between the row and column electrodes is filled with an insulator such that the row electrodes are insulated from the column electrodes. In an alternate embodiment, the first layer 301 and the second layer 302 can be disposed in two different planes with a thin dielectric layer sandwiched between the two layers 301 and 302. Since the electrode array 300A includes a rhombic electrode element, the arrangement of the electrode elements in the above electrode array 300A may be referred to as a diamond pattern.

One advantage of the above-described diamond pattern is that self-capacitance changes caused by finger touches are easily detected because each of the diamond-shaped electrode elements 310 has a large area for forming a large self-capacitance between the electrodes and the fingers. It is helpful. However, when using the mutual capacitance detection method, a large area of the electrode element may make it difficult to detect a finger touch. For example, as shown in FIG. 3A, a finger touch occurs at the center of the electrode element 311, and the touch point 340 is smaller than the area of the electrode element 311. Since the fringe electric field near the center of the electrode element 311 is too weak, the variation of the fringe electric field of this portion has little effect on the mutual capacitance. Therefore, the mutual capacitance change rate caused by the touch (defined as the ratio of the mutual capacitance change to the original mutual capacitance) cannot be detected. In addition, by large electrode components Large self-capacitance caused by the region may disturb the detection of mutual capacitance between the two electrodes. For example, when two finger touches occur simultaneously on two electrodes, when the human body is disconnected from the earth, the self-capacitance of the two electrodes may be connected in series between the two electrodes, thereby interfering with the mutual capacitance between the two electrodes.

FIG. 3B is a schematic diagram showing a conventional electrode array 300B having a hollow diamond pattern. The structure and conductive material of the electrode array 300B are similar to the electrode array 300A shown in FIG. 3A except that the electrode member 312 is a hollow diamond shape, and the hollow region of the electrode member 312 is filled with the floating block 350. The suspension block 350 is made of a conductive material and may be the same or different from the conductive material of the electrode. In one embodiment, the electrode array 300B is made of a transparent material, such as ITO, and the floating block may be made of the same transparent material so that the light transmittance is uniform throughout the electrode array 300B. In an alternate embodiment, the floating blocks 350 are all disposed on the top layer of the electrode array.

In the above hollow diamond pattern, the floating block 350 can help to shunt the fringing electric field emitted from the driving electrode to the receiving electrode, thereby enhancing the fringe electric field. When a finger touch occurs, the edge electric field change will be greater than the diamond pattern occurring in Figure 3A, resulting in a higher mutual capacitance change rate. A higher mutual capacitance change rate can increase the mutual capacitance sensitivity of the electrode array 300B. However, the hollow diamond pattern causes an increase in the parasitic resistance of the electrode, which is defined as the resistance of the electrode such as the electrode C1 or R1. The increased parasitic resistance can increase the current through the electrode, thereby increasing the charging time of the capacitor in the detection circuit, such as the detection circuit 102 of FIG. 1, thereby reducing the speed of the detection operation. For a large touch panel, a smaller electrode parasitic resistance is preferred.

FIG. 3C is a schematic diagram showing an electrode array 300C having a hollow hexagonal pattern. The structure and conductive material of the electrode and suspension block of the electrode array 300C are similar to the electrode array 300B shown in FIG. 3B. However, the electrode element 313 is now a hollow hexagon rather than a hollow diamond, electricity The hollow region 360 in the pole member 313 and the hollow region 361 interposed between the electrode members 313 are filled with a floating block including a plurality of separated floating blocks 351. In an alternate embodiment, the suspended blocks within hollow regions 360 and 361 are comprised of a single piece of suspended mass. In other alternative embodiments, electrode element 313 is generally shaped as an elongated polygon with or without an electrode having an inner region that is hollow.

According to the present disclosure, the mutual capacitance change rate in the hollow hexagon pattern shown in FIG. 3C is larger than the hollow diamond pattern shown in FIG. 3B. 3C, compared to the length L ₀ of FIG. 3B is equal to the length of a gap interposed between two adjacent hollow rhombus, interposed between adjacent hexagonal gap length L ₁ is relatively small. In an embodiment, the length L ₁ is half or less of the length L ₀ . The mutual capacitance between the column electrode and the row electrode is mainly determined by the near electric field in the vicinity of the gap between the edges of the electrode elements. Therefore, if the gap length is reduced, the mutual capacitance between adjacent electrodes is decreased. Therefore, in accordance with the present disclosure, when a finger touch occurs, similar to the hollow diamond pattern of FIG. 3B, the average amount of mutual capacitance change of FIG. 3C changes with the hollow hexagon pattern. Therefore, the mutual capacitance change rate of the hollow hexagonal pattern is increased as compared with the hollow diamond pattern.

In one embodiment, the hollow region 360 within the electrode member 313 and the interposed electrode member The hollow zone 361 between 313 is filled with a floating block comprising a plurality of separate floating blocks 351. It will be appreciated that the more gaps between the separated floating blocks 351, the more fringing the electric field lines exiting the gap. Therefore, the gap 371 between the plurality of separated floating blocks 351 enhances the fringe electric field in the hollow regions 360 and 361, thereby increasing the uniformity of the electric field distribution at the edge of the electrode array 300C and improving the sensitivity of the electrode array 300C.

Further, since the side length of the hexagonal electrode member of Fig. 3C is shorter than that of the rhombic electrode member of Fig. 3B, the electric resistance of each of the hollow hexagonal patterns as shown in Fig. 3C is reduced. In addition, as shown in FIG. 2B, when the touch occurs beyond the original self-capacitance C _S0 , it is defined as an additional self-capacitance C _F , and the self-capacitance change rate may be the same as the two patterns of FIG. 2C and FIG. 2B because the self-capacitance changes. It is mainly determined by the electrode size of the electrode array, and the electrode size is similar to the two patterns shown in FIG. 3B and FIG. 3C.

In one embodiment, the size of the hexagonal electrode member 313 of FIG. 3C is maintained above a certain level. When the size of the hexagonal electrode member 313 of FIG. 3C is too small, the electric field at the edge of the hollow region 361 between adjacent electrode members is weakened, so that the mutual capacitance change rate caused by the touch point A will be small. Therefore, the uniformity of the fringe electric field cannot be maintained.

3D is a schematic diagram of an electrode array 300D in which each electrode has an additional branch 380 therebetween, in accordance with an embodiment of the present invention. The electrode array 300D is the same as the electrode 300C shown in FIG. 3C, however, the extra branch 380 is strip-shaped and included in the middle of each electrode, and passes through all the electrode elements of each electrode, thereby reducing the parasitic resistance of each electrode. .

Traditionally, the extra branch 380 is made of a conductive material like the rest of each electrode. In an alternate embodiment, the additional branches 380 can be made of a conductive material that is different from the other portions of each electrode. In various embodiments, the width of the additional branches 380 may be the same or different than the width of the side traces 381 of the electrode elements, and the width of the additional branches 380 does not significantly affect the rate of change in mutual capacitance.

4 is a cross-sectional view showing an example of a layer structure of a touch panel 400 according to an embodiment of the invention. As shown, the touch panel 400 includes an array of electrodes having a first electrode 401 on a first layer and a second electrode 402 on a second layer. The two electrodes 401 and 402 are isolated by a dielectric layer 430, such as polyester (PET). The electrode array is covered by a cover plate 410 and the electrode array is bonded to the cover plate 410 using a layer of optical adhesive (OCA) 421. The cover may be made of glass or plastic. Below the electrode array is a substrate layer 440 that passes through a layer of OCA 422 and an electrode array Bonding. Substrate layer 440 can be made of glass or PET to provide a shielding layer 403 that shields interference signals from display 460. Shield layer 403 is typically made of a transparent conductive material such as ITO. The air gap 450 is disposed between the shield layer 403 provided by the gasket 451 and the display 460. Air gap 450 can reduce noise interference from display 460 to the electrode array. The display can be a liquid crystal display (LCD), a light emitting diode (LED) display, or other type of display.

In various embodiments, there may be a variety of different layer configurations. For example, in an embodiment, in order to make the touch panel 400 thinner, the first layer electrode and the second layer electrode of FIG. 4 may be coplanar, wherein an insulating layer is used for the intersection between the two layers. . In an alternate embodiment, the noise from display 460 can be ignored, so shield layer 403 and substrate layer 440 can be removed. In other embodiments, the electrode array can be integrated into the structure of display 460 to make the touch panel thinner. For example, the electrode array can be disposed between the top polarity layer and the color filter glass layer of the display module, such as display 460, to form an "on cell" stack structure. In another example, an array of electrodes can be placed under the color filter glass layer of the display module to form an "in cell" stack structure.

FIG. 5A is a schematic diagram of an electrode array 500A according to an embodiment of the invention. It shows a scanning process that determines the touch location based on self-capacitance measurements. In FIG. 5A, the electrode array 500A includes first layer electrodes X1-XN arranged in rows and second layer electrodes Y1-YN arranged in columns. The column electrodes and the row electrodes intersect each other to form a matrix pattern. Each intersection of the column and row electrodes can be mapped to a point of the Cartesian coordinate system and corresponds to a unique coordinate pair, such as the x and y coordinates.

In one embodiment, in order to detect a finger touch, a touch controller such as the touch controller 101 continuously scans the electrodes in the electrode array 500 one by one, and measures the magnitude of the self-capacitance C _S of each electrode. When a finger touch occurs at the touch point A as shown in FIG. 5A, the self-capacitance of the electrodes X1 and Y1 will change. For example, the self-capacitance of electrodes X1 and Y1 will increase by ΔC _Y1 and ΔC _{X1 , respectively} . The touch controller detects this change and determines the two electrodes X1 and Y1 associated with the change accordingly.

The above self-capacitance detection method is generally not capable of detecting multiple touches occurring at the same time. For example, in Figure 5A, two finger touches occur simultaneously at touch points A and B. The touch controller detects the self-capacitance changes of the electrodes Y1, Y3, X1 and X3, and correspondingly obtains four intersections at the touch points A, B, C and D, wherein the touch points C and D are false and scaled For "ghost points."

FIG. 5B is a schematic diagram of an electrode array 500B according to an embodiment of the invention. The electrode array 500B is the same as the electrode array 500A shown in FIG. 5A, however, FIG. 5B shows a scanning process for determining the touch position based on the mutual capacitance measurement.

In one embodiment, in order to detect a finger touch, a touch controller such as the touch controller 101 continuously scans the electrodes in the electrode array 500 to measure the magnitude of the mutual capacitance Cm between the column electrodes and the row electrodes. Unlike the scanning process of Figure 5A, which measures the self-capacitance of each electrode, Figure 5B measures the mutual capacitance of each of the intersections between the two electrodes. As shown in FIG. 5B, when a plurality of finger touches occur at the touch points E, F, and G, mutual capacitance changes of the intersections 501, 502, and 503 can be detected. Therefore, the coordinates of the intersections 501, 502, and 503 can be definitely determined.

In the above examples of Figures 5A and 5B, the mutual capacitance scanning process consumes more scanning time than the self capacitance scanning process. For example, the magnitude of the self-capacitance CS measuring the example of FIG. 5A is M+N, and the magnitude of the mutual capacitance CS of the example of FIG. 5B is measured as M x N.

6A and 6B are schematic diagrams showing examples of two sensing circuits in accordance with an embodiment of the present invention. The two circuits respectively sense self-capacitance changes or mutual capacitance changes, and output representations The signal of the change in capacitance.

FIG. 6A shows an example schematic diagram of a self-capacitance sensing circuit 600A including an input circuit 610 and an amplification circuit 620. In the input circuit 610, a driving signal V _TX such as a pulse wave signal from a touch controller such as the touch controller 101 is added to an end point of the capacitor C _T . Capacitor C _T preconfigured to have a certain capacitance value and coupled to the capacitor C _S, C _S represents the capacitor when the self-capacitance of one of the electrodes of the electrode array of electrodes in the touch occurs change. In addition, the resistor R _{IN is} coupled to the input circuit 610 to the amplifying circuit 620. The resistor R _{IN is} set to have a large resistance value so that the current flowing through the resistor R _IN can be ignored. As a result, the two capacitors C _T and C _S form a voltage divider and are being charged by the drive signal V _TX . Therefore, the peak voltage V _S ' of the output signal V _S of the input circuit can be determined as follows: Here, V _TX ' represents the peak voltage of the pulse wave drive signal V _TX , and C _T and C _S represent the capacitances of the respective capacitors. Therefore, the output signal V _S is a delayed pulse wave whose peak voltage V _S ' is modulated by a self-capacitance change.

In amplifier circuit 620, feedback capacitor C _F is coupled in parallel with feedback resistor R _F and is coupled between the inverting input and output of the operational amplifier (op amp). The resistor R _{IN is} connected to the inverting input of the operational amplifier, while the non-inverting input of the operational amplifier is biased by the voltage V _COM . When the peak voltage V _S ' of the output signal V _S of the input circuit 610 is added to one end of the resistor R _IN , the feedback capacitor C _F is charged, and the voltage drop of the capacitor C _T (also to the resistor R _F ) increased until the current through resistor R _iN is derived from all through the feedback resistor R _F. As a result, the resistor R _IN and the feedback resistor R _F become a voltage divider. Therefore, the peak voltage V _OUT ' of the output signal V _OUT in the output of the operational amplifier can be determined as follows: Therefore, the output signal V _OUT is a delayed pulse wave whose peak voltage V _S ' is amplified by the gain -R _F /R _IN .

Obviously, in the example of FIG. 6A, the change of the self-capacitance C _S causes the output signal V _{OUT of the} self-capacitance sensing circuit 600A to change, thereby causing a “modulation” effect, wherein the input signal V _TX is modulated by the self-capacitance change. An output signal V _OUT is formed.

FIG. 6B shows an example schematic diagram of a mutual capacitance sensing circuit 600B. As shown, a driving signal V _TX from a touch controller such as the touch controller 101, such as a pulse wave signal, is added to one end of the capacitor C _M , which represents the mutual interaction between the two electrodes in the touch panel. capacitance. A receive signal V _RX is received at the other end of the capacitor C _M and a receive signal V _RX is added to the conversion input of the operational amplifier. R _F C _F in parallel to the feedback capacitor and a feedback resistor, and is connected to the operational amplifier (op amp) and the inverting input terminal of the output terminal. In addition, the non-converting input of the operational amplifier is biased by voltage V _COM . When the pulse wave drive signal V _TX increases from the maximum voltage to its peak voltage, the capacitor C _M and the feedback capacitor C _F are charged. Since the feedback resistor R _F is set to have a large resistance value, the current flowing through the resistor R _IN can be ignored, and therefore, the capacitor C _M and the feedback capacitor C _F form a voltage divider. Therefore, the peak voltage V _OUT ' of the output signal V _OUT in the output of the operational amplifier can be determined as follows: Here, V _TX ' represents the peak voltage of the pulse wave drive signal V _TX , and C _M and C _F represent the capacitances of the respective capacitors. Therefore, the output signal V _OUT is a delayed pulse wave whose peak voltage V _TX ' of the input signal V _TX is amplified by the gain C _M /C _F .

Obviously, in the example of FIG. 6B, the change of the mutual capacitance C _M causes the output signal V _{OUT of the} self-capacitance sensing circuit 600A to change, thereby causing a “modulation” effect, wherein the input signal V _TX is modulated by the self-capacitance change. An output signal V _OUT is formed.

As described above, a touch panel using a self-capacitance sensing method can consume a short scan time (resulting in less power consumption) and can sense a thick glove finger touch, but does not support sensing multiple simultaneous touches. The touch panel using the mutual capacitance sensing method may take a long time (causing more power consumption), and can sense multiple touches occurring at the same time, but does not support thick glove touch. Therefore, the ideal touch panel and touch controller can simultaneously support self-capacitance sensing and mutual capacitance sensing.

FIG. 7A is a schematic diagram of an example of a detection circuit 700A including a hybrid sensing circuit 720 capable of simultaneously performing self-capacitance sensing and mutual capacitance sensing, in accordance with an embodiment of the invention.

The detection circuit 700A is similar to the detection circuit 102 of FIG. 1, but the display is more detailed. As shown, in one embodiment, detection circuit 700A includes an analog front end 710 and a digital signal processor (DSP) 715. The analog front end 710 is configured to convert the touch signal V _T representing a change in self capacitance or mutual capacitance into a digital signal and transmit it to the DSP 715. The DSP 715 determines the coordinates of the finger touch point on the touch panel based on the digital signal received from the analog front end, and then provides the coordinate information to the computer system, such as the computer system 100.

In an embodiment, the analog front end 710 includes a hybrid sensing circuit 720, a low pass filter 702, and an analog digital converter (ADC) 703. The DSP 715 includes a digital demodulator 704, a low pass digital filter 705, and a calculus module. 706. In operation, a signal representative of a change in capacitance will sequentially pass through elements 720, 702, and 706 described above. Specifically, the hybrid circuit 720 performs the function of the modulator 701, wherein the pulse wave drive signal V _TX is modulated by the touch signal V _T indicating a change in capacitance, and generates a modulated pulse wave signal. Then, the modulated pulse signal passes through the low pass filter 702 to remove high frequency noise. The filtered signal is then converted by the ADC 703 into a digital signal and transmitted to the DSP 715. In digital demodulator 704, the digitized signal described above is demodulated and passed to low pass digital filter 705. The low pass digital filter 705 then restores the touch signal V _T and passes it to the calculation module 706 where the touch signal V _T is processed and the associated algorithm is used to determine the coordinates corresponding to the finger touch.

FIG. 7B is a schematic diagram showing two examples of the hybrid sensing circuit 720 and the two converting circuits 730 and 740 of the hybrid sensing circuit 720 according to an embodiment of the invention. In an embodiment, the hybrid sensing circuit 720 is operable in the first mode and is a self-capacitance sensing circuit, and the hybrid sensing circuit 720 is operable in the second mode and is a mutual capacitance sensing circuit . In addition, hybrid sensing circuit 720 has a set of switches for changing the operation of the hybrid sensing circuit between the first mode and the second mode.

In the example of FIG. 7B, the hybrid sensing circuit 720 includes a first set of switches S1 as labeled S1 in FIG. 7B and a second set of switches S2 as referenced S2 in FIG. 7B. When the first group of switches S1 and the second group of switches S2 change their on/off states, the hybrid sensing circuit 720 can switch between the first mode of operation and the second mode of operation. Specifically, when the first group of switches S1 is on and the second group of switches S2 is off (this state is S1=ON, S2=OFF as shown in FIG. 7B), the hybrid sensing circuit 720 converts to the first The mode in which the hybrid sensing circuit 720 is implemented as a self-capacitance sensing circuit 730. Similarly, when the first group of switches S1 is off and the second group of switches S2 is on (this situation is as shown in Figure 7B, S1 = OFF, S2 = ON), the hybrid sensing circuit 720 is converted to the second mode. The hybrid sensing circuit 720 is implemented as a mutual capacitance sensing circuit 740. Thus, by varying the on/off states of the two sets of switches S1 and S2, the hybrid sensing circuit 720 can be used to sense self-capacitance changes and mutual capacitance changes.

As shown in FIG. 7B, in the hybrid sensing circuit 720, a driving signal V _TXS for self-capacitance detection is added to one end of the capacitor C _T in series with the resistor R _IN . The resistor R _{IN is} connected to the inverting terminal of the operational amplifier 721. The operational amplifier 721 has a feedback capacitor C _F and two feedback resistors R _F1 and R _F2 connected in series. The feedback capacitor C _F and the two feedback resistors R _F1 and R _F2 are disposed between the conversion input and the output of the operational amplifier 721. In addition, the non-inverting input of the operational amplifier 721 is biased by the voltage V _COM , and the output signal V _{OUT of the} hybrid sensing circuit 720 is transmitted from the output of the operational amplifier 721. In addition, the first S1 switch (the switch belonging to the first group of switches S1) is connected in parallel with R _F2 , and the first and second S2 switches are connected in parallel with R _IN . The third S2 switch is coupled between one of the terminals of the capacitor C _T and the output of the operational amplifier 721. Furthermore, the second S1 switch is connected to the self-capacitance capacitor C _S to the hybrid sensing circuit 720 between the capacitor C _T and the resistor R _IN , and one end of the self-capacitance capacitor C _S is grounded. Similarly, the fourth S2 switch connects the mutual capacitance capacitor C _M to the hybrid sensing circuit 720 between the capacitor C _T and the resistor R _IN . A drive signal V _TXM for mutual capacitance detection is added to the mutual capacitance capacitor C _M .

The self-capacitance sensing circuit 730 and the mutual capacitance sensing circuit 740 are the same as the self-capacitance sensing circuit 600A of FIG. 6A and the mutual capacitance sensing circuit 600B of FIG. 6B, respectively. Therefore, the description of the two sensing circuits 730 and 740 will not be described again.

In various embodiments, hybrid sensing circuit 720, along with other components, including analog front end 710 and DSP 715 in detection circuit 700A, may be implemented as a single integrated circuit (ICs) or multiple separate ICs. The two sets of switches S1 and S2 can be implemented using a transistor such as a bipolar transistor or a metal oxide half field effect transistor (MOSFET) or other suitable technique.

300C‧‧‧electrode array

313‧‧‧Electrode components

351‧‧‧suspension block

360, 361‧‧ hollow area

370, 371‧‧ ‧ gap

Claims (20)

A touch panel having an electrode array, the electrode array comprising: a plurality of first electrodes disposed on a first layer, each of the first electrodes being patterned to include a plurality of sequentially connected first electrode elements and Forming into an elongated polygon; and a plurality of second electrodes disposed on a second layer, each second electrode being patterned to include a plurality of sequentially connected second electrode elements and shaped into elongated polygons; wherein The first electrodes on one layer and the second electrodes on the second layer are arranged to cross each other to form an interlocking pattern. The touch panel of claim 1, wherein the first electrode elements on the first layer and the second electrode elements on the second layer are hexagonal. The touch panel of claim 2, wherein the first electrode elements on the first layer and the second electrode elements on the second layer are hollow hexagons. The touch panel of claim 3, wherein a first hollow region located in the hollow hexagon of the first and second electrode members and between the first and second electrode members A second hollow region between adjacent hollow hexagons includes a plurality of floating blocks. The touch panel of claim 4, wherein the floating blocks in each of the first hollow region and the second hollow region comprise a plurality of floating blocks. The touch panel of claim 4, wherein the floating blocks are coplanar with the first layer or the second layer. The touch panel of claim 1, wherein at least one of the electrodes comprises an additional branch located in an intermediate portion of the electrode. The touch panel of claim 1, wherein the first electrodes on the first layer The second electrodes on the second layer are coplanar with each other. The touch panel of claim 1, further comprising a display, wherein the electrode array is disposed in front of the display. The touch panel of claim 1, further comprising a display, wherein the electrode array is integrated into the display. A touch controller includes: a touch detection circuit for receiving a touch signal on a touch panel and determining a touch coordinate, the touch detection circuit comprising: an analog front end for using the touch panel The analog signal is converted into a digital signal, and the analog front end includes a hybrid sensing circuit, and the hybrid sensing circuit is configured to generate a voltage signal according to the received touch signal on the touch panel, and the hybrid sensing circuit operates In at least one first mode, as a self-capacitance sensing circuit, the hybrid sensing circuit operates as a mutual capacitance sensing circuit in a second mode; and a digital signal processor for The digital coordinates received from the analog front end determine the touch coordinates. The touch controller of claim 11, wherein the hybrid sensing circuit has a set of switches for changing an operation of the hybrid sensing circuit between the first mode and the second mode. The touch controller of claim 11, wherein when the hybrid sensing circuit operates in the first mode, the self-capacitance hybrid sensing circuit comprises: a voltage dividing circuit, including a setting having a One of the first capacitors of the fixed capacitor and one of the self-capacitor capacitors on the touch panel and one of the electrodes in series with the first capacitor. The touch controller of claim 13, wherein the self-capacitance sensing circuit further comprises: an operational amplifier having a feedback capacitor and a feedback resistor, the feedback capacitor and the feedback resistor being coupled to One of the operational amplifiers is coupled between the input and the output; and a resistor having a first end and a second end, the first end being coupled between the first capacitor and the self-capacitor The voltage dividing circuit is coupled to the conversion input of the operational amplifier. The touch controller of claim 13, wherein the resistor has a first end coupled to the voltage dividing circuit, and the resistor is configured to have a large resistance value, so that the voltage dividing circuit is The current from the voltage divider circuit can be ignored under normal operation. A method for operating a touch panel in a two operation mode by using a hybrid sensing circuit, comprising: sensing a touch on the touch panel by the hybrid sensing circuit configured to operate in a first operating mode; Switching the hybrid sensing circuit to a second mode of operation; and sensing the touch on the touch panel with the hybrid sensing circuit operating in the second mode of operation. A method of operating a touch panel in two modes of operation by a hybrid sensing circuit, wherein the first mode of operation is one of sensing a self-capacitance change or sensing a mutual capacitance change, and the second mode of operation is It is another one that senses self-capacitance change or senses mutual capacitance change. The method of claim 17, wherein when the hybrid sensing circuit is in a mode of sensing a self-capacitance change, the hybrid sensing circuit comprises: A voltage dividing circuit includes a first capacitor having a fixed capacitance and a self-capacitance capacitor on the touch panel and one of the electrodes connected in series with the first capacitor. The method of claim 18, wherein when the hybrid sensing circuit is in a mode of sensing self-capacitance change, the hybrid sensing circuit further comprises: an operational amplifier having a feedback capacitor and a feedback a resistor, the feedback capacitor and the feedback resistor are coupled between the conversion input end and an output end of the operational amplifier; and a resistor having a first end and a second end, the first end coupling Connected to the voltage dividing circuit between the first capacitor and the self-capacitor capacitor, the second end is coupled to the conversion input end of the operational amplifier, the resistor is set to have a large resistance value, so that the voltage divider The circuit can ignore the current from the voltage divider circuit under normal operation. The method of claim 16, wherein the hybrid sensing circuit has a first set of switches and a second set of switches, the first set of switches having a first on/off state, the second set of switches Having a second on/off state, the first on/off state and the second on/off state being different from each other, and switching the hybrid sensing circuit to the second mode of operation includes changing the first set of switches and the The on/off state of the two sets of switches to switch the hybrid sensing circuit between the first mode and the second mode.