CN103748540B - Active integrator for capacitive sensing array - Google Patents

Abstract

Disclose the active integrator of a kind of electric capacity for sensing touch sensor array.Described active integrator is configured to receive the response signal with positive part and negative part from described touch sensor array.Described response signal represents that electric conductor exists or is not present on described touch sensor array.Described active integrator is configured to continuously integrate the response signal.

Description

Active integrator for capacitive sensing array

Related application

This application claims on April 5th, 2011 submit to U.S. Provisional Patent Application No.61/472, the priority of 161, Its entire disclosure entirely it is incorporated to herein by quoting.

Technical field

The present invention relates generally to capacitance touch induction arrays, and more particularly, relate to connecing of touch sensor array Receive the active integrator of circuit.

Background technology

Calculating equipment, such as notebook computer, personal digital assistant (PDA), self-service terminal and cell phone, have User interface facilities, it is also referred to as human interface device (HID).The user interface facilities having become more common is tactile Touch sensor board (also commonly referred to as touch pad).The touch sensor plate of basic notebook computer simulates personal computer (PC) The function of mouse.Touch sensor plate is typically embedded in PC notebook for built-in portability.Touch sensor plate is by making Replicating mouse X/Y with two definition axles to move, the two definition axle comprises the one or more electric conductors of detection (such as finger) The a collection of sensor element of position.The click of mouse left/right key button, can by be positioned at two machineries near touch pad by Button, or by touch sensor plate percussion order above itself, be replicated.Touch sensor plate provides user interface facilities For performing these functions: the project in positioning pointer or selection display.These touch sensor plates can include multidimensional Sensor array is for detecting the motion on multiple axle.Sensor array can include one-dimensional sensor array, detects an axle On motion.Sensor array can also be two dimension, detects the motion on two axles.

Another user interface facilities having become more common is touch screen.Touch screen, also referred to as touches screen, touches window Mouthful, touch panel or kind of touch screen panels, be transparent display cover layer, its most pressure-sensitive (resistance or piezoelectricity), electrically susceptible Sense (condenser type), quick (surface acoustic wave (SAW)) of sound or photosensitive (infrared ray).The effect of such cover layer is to allow display quilt Use as input equipment, remove the keyboard as the primary input device mutual with the content of display and/or mouse.These Display may be coupled to computer, or is connected to network as terminal.Touch screen in retail settings, in point of sale In system, on ATM, on the mobile handset, on self-service terminal, in game console and on PDA, become the ripest Knowing, wherein, stylus is used for manipulating graphics user interface (GUI) and input data sometimes.User can touch touch screen or touch Touch sensor board to handle data.Such as, user can apply single touch from dish by using finger to touch touch screen surface List selects project.

A certain class touch sensor array includes first group of wire electrode separated and lines up right angle and separated by dielectric layer Second group of electrode.The two-dimensional array intersecting to form capacitor of gained, referred to as sensing element.If touch sensor array can be used Dry kind of a mode is scanned, and one of them (mutual capacitance sensing) allows single capacitive element measured.Other method (self-capacitance Sensing) whole sensor strip, or the most whole sensor array can be measured, the information about particular location is less, but It is carried out a read operation.

When the capacitor of two-dimensional array is in time placing, it is provided that for sensing the device of touch.Electric conductor (such as finger or Stylus) near touch sensor array, cause the total capacitance of the sensing element near electric conductor to change.These electricity can be measured The change held occurs wherein to produce the touch on " X-Y scheme " instruction array.

A kind of mode measuring this capacitance variations is to form circuit, and it includes being applied to each level with multiplex mode Signal driver (such as AC curtage source (" launch (TX) signal)) in the conductor of alignment.Electricity at each vertical alignment At pole, with application current/voltage line lock sense and scan similarly on the cross part of each electric capacity accumulate electric charge. Then, generally using the form of charge voltage transducer (that is, reception or " RX signal ") to measure this electric charge, it is sampled and protects Hold, be converted to be input to the digital form of processor for A/D converter.Processor is described capacitance map successively and determines touch Position.

Conventional capacitive sensing receives circuit and has many not enough.The capacitance variations caused due to electric conductor touch is usual The least.As a result, occur in a lot of voltages at ADC and represent the base line capacitance of sensing element array, so produce large-scale DC assembly. The capacitance variations caused by touch only accounts for the 1% of base line capacitance.Additionally, source circuit is the most noisy, and then make accurate Capacitance variations is measured complicated, and produces low signal-to-noise ratio (SNR).

Accompanying drawing is sketched

Embodiments of the present invention, according to the detailed description of the illustrative embodiments that combination accompanying drawing considered below proposes, Will be more readily understood, the most identical reference refers to identical element, wherein:

Fig. 1 shows the block diagram of an embodiment of electronic system, and this embodiment includes processing equipment, and it can be by It is configured to measure the power being applied to flexible touch sensitive surface from the electric capacity of flexible touch sensitive surface and calculating or detection Size.

Fig. 2 show capacitive touch sensors array and the electric capacity of measurement is converted into coordinate capacitance sensor one The block diagram of individual embodiment.

Fig. 3 shows the electric block diagram of an embodiment of active integrating circuit, this active integrating circuit be configured to from Receive electrode and receive RX signal to measure the electric capacity of the touch sensor array of Fig. 2.

Fig. 4 be the Fig. 3 according to embodiment active integrating circuit in use active integrator, bias control circuit with And the block diagram of the assembly of sampling-holding (S/H) circuit.

Fig. 5 is the schematic diagram of an embodiment of the assembly of the S/H circuit used in the active integrating circuit of Fig. 3 and 4.

Fig. 6 A and 6B is the various switches that are associated of the S/H circuit of the active integrator and Fig. 5 that are described separately Fig. 4 and signal Operation and the embodiment schematic diagram of relative time of existence.

Fig. 7 is the frequency spectrum of the responsive channels of the capacitance sensor of the touch sensor array of the Fig. 1 of the assembly using Figure 4 and 5 The curve chart of one embodiment of response.

Fig. 8 is to carry out operating active integrator and the S/H of active integrating circuit to measure the electric capacity of touch sensor array The flow chart of one embodiment of the method for circuit.

Fig. 9 is the flow chart of the step of the response signal illustrating in greater detail integrogram 8 continuously.

Figure 10 is another embodiment of Fig. 2, and the capacitance sensor of display Fig. 2 is configured to supply alignment unit, this school Quasi-unit is configured to supply the self calibration of capacitance sensor.

Detailed description of the invention

Embodiments of the present invention provide active integrator, and it is configured to measure touch sensor array or a part of array The electric capacity of (such as single bar).Active integrator is configured from touch sensor array to receive expression electric conductor and is present or not present in Response signal on touch sensor array.Response signal is generally assumed to be the touch sensible driven by alternating current/voltage source Array provides.As a result, response signal includes positive part and negative part.Embodiments described herein use active integrator and Support circuit and respond signal with continuous integral.This continuous integral characteristic is mainly the knot of the character of the switching capacity of active integrator Really.One possible advantage of employing switching capacity active integrator can be the SNR of the improvement surpassing traditional design.At one In embodiment, when switching frequency is matched with fundamental frequency and the phase place of response signal, output signal has with this response signal Narrow passband centered by fundamental frequency, causes the SNR substantially improved.This method is referred to as all-wave demodulation.

In one embodiment, active integrator includes the operational amplifier being coupled to a pair feedback condenser (opamp).One feedback condenser is configured to store the electric charge of the positive part in response to response signal, and the second feedback capacity Device is configured to store the electric charge of the negative part in response to response signal.First feedback condenser and the second feedback condenser can quilts It is configured to the variable sensitivity calibration to allow touch sensible receptor.In one embodiment, active integrator is by coupling Closing sample-hold (S/H) circuit, it is configured to the output by means of one or more switch all-waves demodulation active integrator Signal.In the presence of the positive part of response signal, the first capacitor is just being configured to hold on the outfan of active integrator Signal, and in the presence of the negative part of response signal, the second capacitor is configured to hold on the outfan of active integrator Negative signal.

Fig. 1 shows the block diagram of an embodiment of electronic system 100, and this embodiment includes processing equipment 110, its Can be configured to measure and be applied to flexible touch sensitive surface from the electric capacity of flexible touch sensitive surface and calculating or detection The size of power.Electronic system 100 includes touch sensible surface 116 (such as touch screen, or touch pad), and it is coupled to process and sets Standby 110 and main frame 150.In one embodiment, touch sensible surface 116 is two dimension user interface, and it uses sensor array Row 121 detect the touch on surface 116.

In one embodiment, sensor array 121 includes the biography being set to the matrix (also referred to as XY matrix) of two dimension Sensor component 121 (1)-121 (N) (wherein N is positive integer).Sensor array 121 is via one or many of transmission multiple signals Individual emulation bus 115 is coupled to the pin 113 (1)-113 (N) of processing equipment 110.In this embodiment, each sensor unit Part 121 (1)-121 (N) is represented as capacitor.In sensor array 121, the self-capacitance of each sensor is by processing equipment Capacitance sensor 101 in 110 measures.

In one embodiment, capacitance sensor 101 can include relaxation oscillator or for electric capacity is converted into measurement Other device of value.Capacitance sensor 101 can also include that enumerator or timer are to measure agitator output.Capacitance sensor 101 can also include that count value (such as capacitance) is converted to sensor element detection decision-making and (also referred to as switchs by component software Detection decision-making) or relative amplitude.In another embodiment, what capacitance sensor 101 included being described below is active long-pending Parallel circuit 300.

It should be noted that, it is known that the method for various measurement electric capacity, such as current vs voltage phase-shift measurement, resistor-capacitor circuit During chargometer, the transfer of capacitive bridge potentiometer, electric charge, Approach by inchmeal, sigma-delta modulator, electric charge summation circuit, field effect, mutually Electric capacity, frequency displacement, or other capacitance measurement algorithm.It should be noted, however, that replace the assessment original count relative to threshold value, electric capacity Sensor 101 can assess other measurement result to determine that user is mutual.Such as, there is the capacitance sensing of sigma-delta modulator In device 101, the ratio of the pulse width of capacitance sensor 101 assessment output, replace the original count above or below certain threshold value.

In one embodiment, processing equipment 110 also includes processing logic 102.The operation processing logic 102 can be Firmware realizes, or, it can also be in hardware or software to realize.Process logic 102 can receive from capacitance sensing The signal of device 101, and determine the state of sensor array 121, such as object (such as, finger) is detected is at sensor On array 121, also it is close to sensor array 121 (e.g., determine the existence of object), when detecting on an array of sensors , follow the tracks of the motion of object during object (e.g., determine the position of object), or relevant to the object detected on a touch sensor Out of Memory.

In another embodiment, execution in processing equipment 110 is replaced to process the operation of logic 102, processing equipment 110 Initial data can be sent or part processes data to main frame 150.As it is shown in figure 1, main frame 150 can include decision logic 151, should Decision logic 151 execution processes the part or all of operation of logic 102.The operation of decision logic 151 can be at firmware, hardware, soft Part or a combination thereof realize.Main frame 150 can include the advanced application DLL (API) applied in 152, and it is to reception The data arrived perform routine, as compensated sensitivity differences, other backoff algorithm, baseline renewal routine, starting and/or initialize example Journey, interpolation operation, or zoom operations.Can be in the decision-making outside processing equipment 110 about the operation processed described by logic 102 Logic 151, application 152 or realization in other hardware, software and/or firmware.In some other embodiments, process sets Standby 110 is main frame 150.

In another embodiment, processing equipment 110 can also include non-inductive movable block 103.This block 103 can by with In processing and/or receiving/send data to and from main frame 150.Such as, add-on assemble (such as, keyboard, keypad, mouse, with Track ball, LED, display, or other external equipment) can be implemented to together with processing equipment 110 along with sensor array 121 Operation.

In one embodiment, electronic system 100 is implemented in and includes that touch sensible surface 116 is as user interface In equipment, such as hand-hold electronic equipments, portable phone, cell phone, notebook computer, personal computer, personal data help Reason (PDA), self-service terminal, keyboard, television set, remote controller, monitor, handheld multimedia devices, handheld video player, The control panel of game station, family or commercial Application, or other computer is outside or input equipment.Or, electronic system 100 can be used in other type of equipment.It should be noted that, the assembly of electronic system 1000 can include above-mentioned all component. Or, electronic system 100 can only include some above-mentioned parts, or includes the most unlisted add-on assemble.

Fig. 2 shows capacitive touch sensors array 121 and the electric capacity of measurement is converted into the capacitance sensor of coordinate The block diagram of one embodiment of 101.Coordinate is calculated based on the capacitance meter measured.In one embodiment, sensor array 121 and capacitance sensor 101 be implemented in the system of such as electronic system 100.Sensor array 121 includes N × M electrode Matrix 225 (N number of reception electrode and M emission electrode), these electrodes also include launching (TX) electrode 222 and receiving (RX) electricity Pole 223.Each electrode in matrix 225 is connected to capacitive sensing electricity by demultiplexer 212 and multiplexer 213 Road 201.

Capacitance sensor 101 includes that multiplexer controls 211, demultiplexer 212 and multiplexer 213, clock Generator 214, signal generator 215, demodulator circuit 216 and analog-digital converter (ADC) 217.ADC217 also sits with touching Mark transducer 218 couples.Touch coordinate transducer 218 outputs a signal to process logic 102.

In one embodiment, processing logic 102 can be to process core 102.Process core to may reside within jointly Carrier substrates on, such as, as integrated circuit (" IC ") die substrate, multi-chip module substrate etc..Or, process core 102 Assembly can be one or more single integrated circuit and/or discrete component.In an illustrative embodiments, process Core 102 is configured to supply Based Intelligent Control programmable system on sheetOn this sheet programmable system by This semiconductor company of pula (Cypress Semiconductor Corporation, the San of San Jose match Jose, California) manufacture.Or, processing core 102 can be one or many well known to the skilled artisan in the art Other processing equipment individual, such as microprocessor or CPU, controller, application specific processor, digital signal processor (" DSP "), special IC (" ASIC ") and field programmable gate array (" FPGA ") etc..In one embodiment, place Other assembly of reason core 102 and processing equipment 110 is integrated in same integrated circuit.

It should be noted that, embodiment as herein described is not limited to so that process core 102 is coupled to main frame 150 Configuration, but can include measuring the electric capacity on touch sensor array 121 and sending the system of initial data to master computer, Wherein, in master computer, initial data is employed to be analyzed.It practice, the process completed by processing core 102 also may be used To complete in main frame.Main frame can be microprocessor, such as, can also be benefited from the common skill of this area of the disclosure The other type of processing equipment that art personnel understand.

In electronic system 100, the assembly in addition to touch sensor array 121 can be integrated into the IC processing core 102, Or, in single IC.Or, the description of electronic system 100 can be generated and be compiled to be incorporated to other integrated circuit In.Such as, the behavioral scaling code or its part that describe electronic system 100 can use hardware descriptive language to generate, such as VHDL or Verilog, and store machine-accessible medium (such as CD-ROM, hard disk, floppy disk etc.).Additionally, behavioral scaling code Method at Register Transfer Level (" RTL ") code, netlist, or even circuit layout can be compiled as, and store machineaccessible In medium.Behavioral scaling code, RTL code, netlist and circuit layout all represent the various abstraction level describing electronic system 100.

It should be noted that, the assembly of electronic system 100 can include above-mentioned all component.Or, electronic system 100 can be only Including some said modules.

In one embodiment, electronic system 100 is used for notebook computer.Or, electronic equipment may be used for it In its application, such as cell phone, personal digital assistant (" PDA "), keyboard, television set, remote controllers, monitor, hand-held Multimedia equipment, handheld video player, portable game equipment or control panel.

Electrode matrix 225 is launched and receives electrode and can be arranged so that each emission electrode is overlapping and passes each Reception electrode, to form crossed array, remains electrically isolated from one another simultaneously.Therefore, each emission electrode can connect so that Capacitance Coupled is each Receive electrode.Such as, emission electrode 222 at emission electrode 222 and receives Capacitance Coupled reception electrode 223 at the overlapping point of electrode 223.

Clock signal is provided to signal generator 215 by clock generator 214, and signal generator 215 generates TX signal 224 It is supplied to the emission electrode of touch sensor array 121.In one embodiment, signal generator 215 includes one group according to coming The switch operated is carried out from the clock signal of clock generator 214.By periodically the output of signal generator 215 being connected To the first voltage, being then attached to the second voltage, switch can produce TX signal 224, wherein said first voltage and the second electricity Pressure is different.In another embodiment, will be described below active integrating circuit 300 and be coupled to signal generator 215. Those of ordinary skill in the art it being understood that signal generator 215 can provide the TX signal 224, TX signal 224 to be There is any periodic signal of positive part and negative part, including, such as, sine wave, square wave, triangular wave etc..

The output of signal generator 215 connects has demultiplexer 212, demultiplexer 212 to allow TX signal 224 to be answered Any one of M electrode for touch sensor array 121.In one embodiment, multiplexer controls 211 controls Demultiplexer 212, in order to make TX signal 224 be applied to each emission electrode 222 with controlled sequence.Demultiplexer 212 Can be used for making TX signal 224 currently without other emission electrode ground connection being applied to, floating or be connected by other signal To it.

Because launching and receiving Capacitance Coupled between electrode, the TX signal 224 being applied to each emission electrode induces Electric current in each reception electrode.Such as, it is applied on emission electrode 222 by demultiplexer 212 when TX signal 224 Time, TX signal 224 induces RX signal 227 on the reception electrode of matrix 225.By using multiplexer 213, receive electricity Then RX signal 227 in each of pole can be measured sequentially, in order to N number of each of reception electrode be sequentially connected to Demodulator circuit 216.

By using demultiplexer 212 and multiplexer 213 to select each of TX electrode and RX electrode can use Combination, the mutual capacitance that each cross part between TX electrode and RX electrode is associated can be sensed.In order to improve performance, Multiplexer 213 is likely to be segmented to allow the more than one reception electrode in matrix 225 to be routed to the demodulation added Circuit 216.In the configuration optimized, wherein there is the example of 1 couple 1 correspondence of demodulator circuit 216 and reception electrode, multiplexing Device 213 may be not present in system.

When object (such as finger) is near electrode matrix 225, this object makes the mutual capacitance between only some electrode reduce. Such as, if finger is placed near the cross part of emission electrode 222 and reception electrode 223, the existence of finger will reduce electrode Mutual capacitance between 222 and 223.Therefore, it is possible to by measurement on one or more reception electrodes to the mutual capacitance reduced Time identify the emission electrode that is applied to of TX signal 224, and identify one or more receptions of the mutual capacitance with reduction Electrode, determines the position of finger on touch pad.

The mutual capacitance relevant by determining each cross part of electrode in matrix 225, it may be determined that one or more Touch the position of contact.This determines it can is continuous print, concurrently, or can more frequently being occur at the electricity commonly used In extremely.

In alternative embodiments, it is likely to be used for for detecting other method of finger or electric conductor existence, finger Or electric conductor may with one or more electrodes that grid or other pattern arrange at promote the increase of electric capacity.Such as, it is set to Finger near the electrode of capacitance sensor, may introduce extra ground capacity, which increase between electrode and ground connection Total capacitance.The position of finger can be determined according in the position one or more electrodes increasing electric capacity being detected.

Sensor current signal 227 carries out rectification by demodulator circuit 216.Exported by the electric current of demodulator circuit 216 rectification May then pass through ADC217 to carry out filtering and being converted into digital code.In one embodiment, demodulator circuit potentially includes The active integrating circuit 300 that will be described below.

Digital code is converted to expression input on touch sensor array 121 by touch coordinate transducer 218 The touch coordinate of position.This touch coordinate is sent to process logic 102 as input signal.In one embodiment, defeated Enter signal to be received at the input processing logic 102.In one embodiment, this input may be configured to receive Indicate multiple row-coordinate and the capacitance measurement of multiple row coordinate.Alternatively, this input may be configured to receive row-coordinate and Row coordinate.

In one embodiment, the system of a kind of contact position for following the tracks of on touch sensible surface can be based on root The capacitance measurement carried out according to capacitance sensor array determines the size of the power of contact every time.In one embodiment, additionally it is possible to Determine the capacitance touch sensing system of dynamics in each contact in multiple contacts of the touch sensible surface applications, Ke Yishi By flexible material, such as PMMA, and may not cover between capacitance sensor array and LCD display panel.? In this embodiment, the electric capacity change of sensor element is probably the sensing closer by the VCOM plane of LCD display panel The displacement of device element causes.

Fig. 3 represents the electric block diagram of an embodiment of active integrating circuit 300, and this active integrating circuit 300 is configured To receive from the RX signal 227 receiving electrode, (e.g., single to measure the touch sensor array 121 in Fig. 2 or partial array Band) electric capacity.Active integrating circuit 300 includes: alignment unit 321, active integrator 326, sample-hold (S/H) circuit 340 With sequential device circuit 345.The multiplexer 213 of Fig. 2 is coupled to the first input 324 of active integrator 326.Bias control Circuit 328 is coupled to the first input 324 of active integrator 326 by one or more switches 330.Virtual-ground connection VY quilt It is coupled to the second input 338 of active integrator 326.The output 339 of active integrator 326 is coupled to sample-hold (S/H) Circuit 340.S/H circuit 340 is differentially coupled to ADC217 by the first and second outputs 342,344.Hereinafter referred to as The central control circuit of sequential device circuit 345, controls (as represented) by reference marker " A " generally at whole touch screen subsystem (TSS) all switches in and activity, including the active integrating circuit hereafter will being described in conjunction with Fig. 3,6A, 6B and 8 300.Alignment unit 321 provides the self calibration of capacitance sensor 101, and is both coupled to by one or more switches 331 RX signal 227 is coupled to again multiplexer 213, and hereafter will be opened by one or more in conjunction with what Figure 10 was described Close (not shown) and be coupled to TX signal 227 and Demultiplexor 212.

Fig. 4 is active integrator 326, the bias control circuit 328 and S/H used in the active integrating circuit 300 of Fig. 3 The block diagram of the assembly of circuit 340.In one embodiment, active integrator 326 can be switched capacitor integrator, should Switched capacitor integrator includes the operational amplifier 446 with negative input end 450, positive input terminal 452 and outfan 454.The One integrating condenser 456 (is also indicated as C_INTP), via switch 458a-458d between outfan 454 and negative input end 450 Couple.Second integral capacitor 460 (is also indicated as C_INTN), via multiple switch 462a-462d outfan 454 He Couple between negative input end 450.

Fig. 5 is the assembly of an embodiment of the S/H circuit 340 used in the active integrating circuit 300 of Fig. 3 and 4 Schematic diagram.In one embodiment, S/H circuit 340 includes that a S/H capacitor 466a (is also indicated as C_SHP), first S/H capacitor 466a via switch 468a (being also indicated as " shp ") at the input of S/H buffer 467a and operational amplifier Couple or decouple between the outfan 454 of 446.S/H circuit 340 also includes that the 2nd S/H capacitor 466b (is also indicated as C_SHN), the 2nd S/H capacitor 466b via switch 468b (being also indicated as " shn ") S/H buffer 467b input and Couple or decouple between the outfan 454 of operational amplifier 46.The outfan of S/H buffer 467a, 467B and S/H buffer are originally Body is via being labeled as " adc_；" switch 469a-469d coupling or the decoupling positive input 342 of difference ADC217 and negative input 344. Be labeled as " shpp ", " shnn ", "！shp&&！Adc_ samples " and "！shn&&！Adc_ sample " multiple switch 470a-470d general S/H buffer is configured to the purpose that will be described below.For the purpose that will be described below, it is separately input to S/H buffering Input 471a, 471b of being labeled as " bufp_pdb " and " bufn_pdb " of device 467a, 467B is used for energising or power-off is each S/H buffer 467a, 467B.

With reference to Fig. 3-5, sequential device 345 controls all switches in whole touch screen subsystem (TSS) the most completely And activity.This includes activating TX signal, and TX signal is applied to touch sensor array 121 (such as, uprise or step-down), active Switch (such as, p1, p2, p1p, p2p), control line switch pwc1/pwc2, IDAC value and S/H circuit in integrator 326 340 etc..Using sequential device 345, all activities in RX and TX circuit occur in the way of Complete Synchronization, below with reference to Fig. 7 is described.Sequential device circuit 345 conductThe part of processing equipment realizes, and this processing equipment is logical by customize Forming with digital block (UDB), it is active long-pending that this customization general digital block (UDB) is arranged to the sequential chart according to Fig. 6 a and 6b All switches in device 326 are divided to provide timing.As used herein, UDB is to be optimized to produce all common embeddings The free logic (PLD) of the customization function of formula peripheral hardware and concrete application or design and the set of architecture logic (data path).UDB Can be used for realizing various general and concrete digital logic device, include but not limited to, field programmable gate array (FPGA), programmable logic array (PAL) and CPLD (CPLD) etc..

In the embodiment that Fig. 4 describes, bias control circuit 328 include being coupling in ground connection and gain module 474 it Between electric current output digital analog converter (IDAC) 472.Gain module 474 is by being also respectively labeled as the one of pwc1 and pwc2 Switch 476a-476b is coupled to the input negative input end 450 of operational amplifier 446.Switch 476a (pwc1) is configured to By negative current I_DACNIt is applied to the negative input end 450 of operational amplifier 446, in order to offset by the operation of pwc1 and stem from appearance The normal base line electric charge of the response signal in the output of touch sensor array 121.Equally, switch 476b (pwc2) be configured to by I_DACPIt is applied to the negative input end 450 of operational amplifier 446, in order to stemmed from by the operation counteracting of pwc2 and there is touch sensible The negative baseline electric charge of the response signal in the output of array 121.

In one embodiment, bias control circuit 328 is used for minimizing appearance at the Differential Input of ADC217 The baseline offset of response signal, in order to maximize and represent the defeated of the capacitance variations that causes close to touch sensor array 121 of electric conductor Go out the number of position.As a result, the dynamic range of capacitance sensor 101 can be improved.

The tolerance that design with sensor panel and manufacture are associated can make the base line capacitance of some sensing elements produce Significant change, even in single touch sensor array 121.This can reduce the dynamic range of ADC217 further, because of For the most not carrying the baseline electric charge of the information about touch event from the fixed charge of any sense wire.Therefore, no Being to use single, fixed value in bias control circuit (that is, IDAC472), this value can be with real-time programming to compensate current inspection The actual baseline electric charge of the sense wire measured.Most preferably arrange can or at the manufacturing time of whole touch system, or In the power-up procedures of final products, it is determined in " self-correcting " routine.

It is various that the S/H circuit 340 of the active integrator 326 and Fig. 5 that Fig. 6 A and 6B illustrates Fig. 4 respectively is associated One embodiment of the relative time of switch and the operation of signal and existence.It is coupled to the switch 458a-of active integrator 326 458d, 462a-462d and be coupled to the equal timing of switch 468a, 468b, 469a-469d and 470a-470d of S/H circuit 340 with Constantly essentially without positive part and the negative part of " dead time " continuous integral response signal.Once respond the negative portion of signal Dividing and be integrated, the positive part at response signal can be at capacitor C_INTPBefore upper integral, actually it is being switched to electricity Container C_INTPIn not do not postpone.Additionally, once plus or minus signal has been integrated, integrated signal can be respectively by being coupled to Switch 468a, 468b, 469a-469d and 470a-470d of S/H circuit 340 are applied to C_SHPOn, followed by C_SHN.S/H circuit Therefore " difference " output of 340 be configured to the integration response signal of all wave rectification input so that the identical polar of input signal Always present to the Differential Input 342,344 of ADC217.

Fig. 7 illustrates the response of the capacitance sensor 101 of the touch sensor array 121 of the Fig. 1 of the assembly using Figure 4 and 5 One embodiment of the spectral response of channel.Owing to active integrator 326 can be substantially synchronized driving while integration One in S/H circuit 340, and capacitor 456,460 can keep or reset, and another is essentially without when stagnating Between continuous integral, compared with the channel of integration using single capacitor and non-temporal/polarity to coordinate S/H circuit 340, obtain Channel has narrow-band frequency response 780, and its response 782 displays that in the figure 7.Narrow-band frequency response has corresponding to input signal The peak value 784 of the fundamental frequency of (that is, TX signal 224).As a result, SNR has obtained significant raising compared to conventional design.

Fig. 8 is that the active integrator 326 and S/H circuit 340 operating active integrating circuit 300 is for measuring touch sensible battle array The flow chart 800 of one embodiment of the method for the electric capacity of row 121.At block 802, active integrator 326 is from touch sensible battle array Row 121 receive to be had the response signal of positive part and negative part (such as, periodically response signal has negative part and (is just followed by Part), such as sine wave, square wave, triangular wave etc.).Response signal represents that electric conductor exists or is not present in touch sensible On array 121.At block 804, active integrator 326 integration response signal continuously (with way of full-wave rectification, sees following figure 8).As long as response signal exists, block 802 and 804 so ad infinitum repeats down in the cycle of each response signal.

Fig. 9 is the flow chart of the block 804 of the signal of integration response continuously illustrating in greater detail Fig. 8.Referring now to Fig. 4,5 With 9, at block 902, the electric charge in response to the positive part of response signal is accumulated in first integral capacitor 456, C_INTPOn.Particularly It is, when TX signal 227 is activated from high to low, active integrator 326 to switch 458a, 458b (p1/p1p) accordingly then It is closed, and switchs 462a, 462b (p2/p2p) and be disconnected.Input charge then can be at capacitor 456 (C_INTP) upper integral, The voltage (that is, node 454) at the output of integrator making capacitor 456 two ends produces the voltage increased.Integrating condenser Input 450 be constantly maintained at Vx, it is identical with Vy (that is, node 452), and Vy does not changes.

At block 904, the electric charge in response to the negative part of response signal is added to second integral capacitor 460, C_INTNOn.More Particularly, after all of signal has been stablized, TX signal 227 is guided to apply low to high transformation by sequential device 345, simultaneously Switch 458a, 458b (p1/p1p) is disconnected, and switchs 462a, 462b (P2/P2P) and be closed.This is by capacitor 460 (C_INTN) It is connected to active integrator 326, simultaneously capacitor 456 (C_INTP) it is in quick condition, the most temporarily keep its electric charge (capacitor Electric charge on 456 can not leak).It addition, after the electric charge entered has been integrated, at block 906, the cycle starts again at, by electric capacity Device 456 (C_INTP) switch back into active integrator 326 to collect next charge packet, and the like.Therefore, positive charge wraps in electricity Container 456 (C_INTP) upper accumulation, and negative charge wraps in capacitor 460 (C_INTN) upper accumulation.

At block 908, at 910, when positive and negative charge is respectively at capacitor 456 (C_INTP) and capacitor 460 (C_INTN) two ends produce When giving birth to the corresponding generating positive and negative voltage relative to node 450 (Vy), export sampling capacitor 466a (C_SHP) and 466b (C_SHN) Distinguish via the corresponding non-overlapped Guan Bi/disconnection of pair of switches 468a-468b (shp) and pair of switches 470a-470b (shn) It is connected to integrator output 454/ remove from integrator output 454.As a result, output sampling capacitor 466a (C_SHP) and 466b (C_SHN) carry identical voltage with corresponding integrating condenser 456,460 respectively at its two ends.

After the circulation N of predetermined quantity, at block 912, the downstream ADC217 of Fig. 2 is guided to measure electric capacity by sequential device 345 Device 466a (C_SHP) and 466b (C_SHNDifferential voltage (referred to as " secondary integration ") between), during this time, at block 914, capacitor 456,460,466a and 466b resets, and whole process restarts.Differential voltage represents capacitor 456 (C respectively_INTP) and 460(C_INTNPositive charge on) and the difference of negative charge.As a result, two half periods of any TX pulse are added together, and this is suitable In all wave rectification.Although two half periods are at discrete step integration, but have therebetween and have the shortest interruption to adapt to amass Dividing the switching of capacitor, this operation is substantially referred to as " continuously " integration.

More particularly, S/H circuit 340 is operable to produce differential voltage to ADC217 at three phases.These three Stage includes sampling from integrator circuit 326, keeping sampling electric charge and drive ADC217 on S/H circuit 340.Below step Relevant signal is described.

Each exporting the integrator of a upper Tx clock cycle of S/H buffer 467a, 467b carries out 454 samplings.Just S/H buffer 467a samples positive integrating condenser 456 (C_INTP) (generally, Tx has its last high rim when), negative The negative integrating condenser 460 (C of S/H buffer 467a sampling_INTP) (Tx has its last low edge when).Change The first signal be buffer power on signal 471a, 471b (bufp_pdb and bufn_pdb).S/H buffer 467a, 467b quilt Dynamic driving, therefore they only consume electric current in sampling phase (shp) period and driving ADC phase place (adc_ sampling) period. In sampling configuration, operation switch 470a (shpp) makes S/H buffer 467a enter unit gain pattern and at sampling capacitance Device 466a (C_SHP) and 466b (C_SHN) right side V is set_Y.Operation switch 468a (shp) is with at sampling/holding capacitor device 466a (C_SHP) up-sampling positive input (from active integrator 326).When the two signal returns to 0, S/H buffer 467a, 467b warp By input 471a, 471b (bufp_pdb and bufn_pdb) power-off, sampling/holding capacitor device 468a (C_SHP) a node warp By switch 470b (！shp&&！Adc_ samples) it is connected to V_Y, and secondary nodal point be float.This allows at C_SHPUpper " holding " The positive integrator voltage of sampling.Similar operation is at sampling/holding capacitor device 466b (C_SHN) up-sample and keep negative integrator electricity Pressure.Just before adc_ sample conversion, S/H buffer 467a, 467b are again powered up (bufp_pdb and bufn_pdb), C_SHP And C_SHNIt is placed in the feedback of the buffer of each of which, and the SAR capacitor C in ADC217_ADCPAnd C_ADCNFill Electricity reaches C_SHPAnd C_SHNThe value of upper storage.

The continuous integral of the time-interleaving at the input and output of active integrator 326 causes the panel scan time more Hurry up, this can also reduce operating current.Operating current reduces can reduce battery consumption, and this has the electricity of touch sensor array Pond operating system is particular importance.

In another embodiment of active integrating circuit 300, single input, dual output S/H circuit can be removed 340, and ADC217 can replace with sufficiently fast single input ADC.Having sufficiently fast AC, ADC can be directly in output 454 The positively and negatively signal that upper quick sampling sends from integrator circuit 326, and then process core 102 can be digitally by this Two signal subtractions.

Figure 10 is that in another embodiment of the Fig. 2 illustrating capacitance sensor 101, this capacitance sensor is configured to supply Alignment unit 321, this alignment unit 321 is configured to supply the self calibration of capacitance sensor 101 and via selection circuit 1092 and demultiplexer 212 input TX signal 227 couple between touch sensor array 121.Alignment unit 321 includes One capacitor 1094 (being also indicated as CFM), the second capacitor 1096 (being also labeled as CM), and connect with the second capacitor 1096 Switch 1098.Alignment unit 321 is configured to by making not existing and existing of electricity container 1094,1096 simulation electric conductor So that calibration capacitance sensor 101.Alignment unit 321 can be used to calibrate mutual capacitance sensing and self-capacitance sensing.Such as, Respectively, the switch 1098 of disconnection can with simulated touch event, the switch 1098 of Guan Bi can simulate no touch event (that is, by Value in mutual capacitance is actually and reduces during touching).Using the capacitor on these chips, touching class signal can be given birth to Become, it is allowed to measure the gain from front to back of (and proofreading subsequently) each channel.After calibration is completed, all channels performance Going out same overall gain to actual touch signal, this significantly improves the computational accuracy of finger touch position.For gain The method of calibration can include the programming of the actual capacitance value (or digital value 1004) of each integrating condenser.

In self-calibration mode, each channel 1000a-1000n of touch sensor array 121 can also be via DeMux Device 212, multiplexer 213, active integrator 326, sample-hold circuit 340 and ADC217 are by scanning channel 1000a- 1000n mono-calibrates next further, and wherein, ADC217 then digitized is connected to process core 102.An enforcement In mode, according to the method shown in Fig. 8, one of channel 1000a-1000n of selection is by active integrator 326, sampling-protect Hold circuit 340 and ADC217 and carry out continuous integral.Processing in core 102 with software analog selection circuit 802 and two or Multiple gain correcting value 804, for digital calibration factory or during the operation of capacitance sensor 101 operates identical or not With touch sensor array 121 in and between the channel variance that causes of component variations.Some or all of assembly 1002,1004 The those of ordinary skill in the art benefiting from the disclosure other technology intelligible can be used to realize.

Again returning to Figure 10, the calibration value 1004 obtained can store in memory and can be as " digital gain Calibration " factor is applied to each output of channel 1000a-1000n.Digital gain calibration allows touch location precision to less than near Like about 0.2mm.

Returning to Fig. 4, in one embodiment, first integral capacitor 456 and second integral capacitor 460 can be Variable/programmable capacitor, to allow the correction of the second gain degree, is used for eliminating channel gain variance.

The embodiment of invention as described herein includes various operation.These operation can pass through nextport hardware component NextPort, software, Firmware or a combination thereof perform.As used herein, term " couple " direct-coupling can be represented or by one or Multiple intermediate module INDIRECT COUPLING.Any signal being provided on different bus described herein can be with other signal timesharing Multiplexing is also provided on one or more common bus.It addition, the interconnection between circuit unit or block can be shown as bus or Single signal line.Each bus can be optionally one or more single-signal-line, and every single-signal-line can be alternatively For bus.

Some embodiment can be implemented as a kind of computer program, and it can include on a computer-readable medium The instruction stored.These instructions can be used for being programmed to carry out assigned operation to universal or special processor.Computer-readable Medium includes for storing or transmit appointing of information with machine (such as, computer) readable form (such as, software, process application) What mechanism.Computer-readable recording medium can include, but not limited to magnetic storage medium (such as, floppy disk)；Optical storage media (such as, CD-ROM)；Magnetic-optical storage medium；Read only memory (ROM)；Random access memory (RAM)；Erasable programmable stores Device (such as, EPROM and EEPROM)；Flash memory, or be suitable to store the other kinds of medium of e-command.Computer-readable passes Defeated medium includes but not limited to, electricity, light, sound or other form transmitting signal (such as, carrier wave, infrared signal, numeral Signal etc.), or be suitable to send the other kinds of medium of e-command.

It addition, some embodiment can be implemented in a distributed computing environment, wherein computer-readable medium is by one Individual above computer system storage and/or perform.Additionally, the information transmitted between computer systems can or be drawn or Person is pushed over the transmission medium connecting computer system.

Although operational approach herein is shown and described in a particular order, but the operation of every kind of method order can With change so that some operation can perform in a reverse order, or make some operate can at least partly and other Operation performs simultaneously.In another embodiment, instruction or the child-operation of different operating can be according to interval and/or side alternately Formula.

In explanation previously, describe the present invention by reference to specific illustrative embodiments.But, very Obviously, in without departing from such as the wider array of spirit and scope of appended claims claimed invention, the present invention can be entered Row various modifications and variations.Therefore, the specification and drawings is considered have illustrative sense and non-limiting sense.

Claims (20)

1. a circuit, including:

Active integrator, is configured to measure the electric capacity of touch sensor array, and wherein, described active integrator is configured to from institute Stating touch sensor array and receive the response signal with positive part and negative part, wherein, described response signal represents described tactile Touching the presence or absence of electric conductor on induction arrays, and wherein, described active integrator is configured to continuously described in integration Responding signal, the described positive part and the use second integral capacitor that respond signal described in use first integral capacitor integration amass Divide the described negative part of described response signal.

Circuit the most according to claim 1, wherein, described active integrator includes switched capacitor integrator.

Circuit the most according to claim 1, wherein, described active integrator is configured to have with described response signal Passband centered by fundamental frequency.

Circuit the most according to claim 1, wherein:

It is first defeated that described first integral capacitor is coupled to the outfan of described active integrator and described active integrator Enter end；And

Described second integral capacitor is coupled to the described outfan of described active integrator and the institute of described active integrator State first input end.

Circuit the most according to claim 4, also includes:

First switch, is configured to connect or disconnect described first integral electricity between described outfan and described first input end Container, and

Second switch, is connected as connecting or disconnect described second integral electric capacity between described outfan and described first input end Device.

Circuit the most according to claim 5,

Wherein, described first switch closes in response to described positive part, and disconnects in response to described negative part, and

Wherein, described second switch closes in response to described negative part, and disconnects in response to described positive part.

Circuit the most according to claim 1, also includes that bias control circuit, described bias control circuit are coupled to described The first input end of active integrator, and it is configured to minimize direct current (DC) component of described response signal.

Circuit the most according to claim 7, wherein, described bias control circuit includes:

Digital simulation D/A converter,

Gain circuitry, it is coupled to described D/A converter；And

First switch and second switch, each described first input being coupled to described gain circuitry and described active integrator End,

Wherein, described first switch is configured in the presence of described positive part be applied to negative signal described active integrator Described first input end, and wherein, described second switch is configured in the presence of described negative part positive signal is applied to institute State the first input end of active integrator.

Circuit the most according to claim 1, also includes that sample-hold circuit, described sample-hold circuit are coupled to institute Stating the outfan of active integrator, the output signal of wherein said active integrator is applied on described sample-hold circuit.

Circuit the most according to claim 9, wherein, described sample-hold circuit includes:

It is connected in series and is coupled in the first defeated of the described outfan of described active integrator and analog-digital converter ADC Enter the first capacitor between end and the first switch；And,

It is connected in series and is coupled between the described outfan of described active integrator and second input of described ADC Second capacitor and second switch,

Wherein, described first switch promotes described first capacitor to keep described active in the presence of being configured as described positive part Positive signal on the described outfan of integrator, and wherein, in the presence of described second switch is configured as described negative part Described second capacitor is promoted to keep the negative signal on the described outfan of described active integrator.

11. circuit according to claim 1, are additionally included between input signal source and described touch sensor array coupling Self-calibration circuit.

12. circuit according to claim 11, wherein, described self-calibration circuit includes:

First capacitor, it is coupling between described input signal source and described touch sensor array；

Second capacitor, it is coupling between described input signal source and described touch sensor array；And

Switching, it is connected with described second capacitor,

Wherein, described switch is configured to insert or remove described first capacitor with the existence of simulated touch object or do not deposit ?.

13. circuit according to claim 1, also include that mode selection circuit, described mode selection circuit are coupled to institute State active integrator and be configured to permit described active integrator and carry out with self-capacitance inductive mode and mutual capacitance inductive mode Integration.

14. 1 kinds are used for the method measuring the electric capacity of touch sensor array, including:

Receiving the response signal from described touch sensor array at active integrator, described response signal has positive part and bears Part；And

Use response signal described in described active integrator continuous integral to measure capacitance variations, use first integral capacitor to amass The described negative part of signal is responded described in the described positive part of point described response signal and use second integral capacitor integration, its In, described capacitance variations represents the presence or absence of electric conductor.

15. methods according to claim 14, wherein, respond signal and also include described in continuous integral:

A () uses the described first integral capacitor accumulation between the input and the outfan that are coupling in described active integrator to ring The electric charge of positive part described in Ying Yu；

B () uses the described second integral electric capacity being coupling between the described input of described active integrator and described outfan Device accumulation is in response to the electric charge of described negative part；And

C () repetition step (a) and (b) reaches predetermined cycle-index.

16. methods according to claim 15, wherein, described step (a) and (b) also include:

The 3rd coupled between the described outfan and the first input end of analog-digital converter ADC of described active integrator Capacitor up-sampling-keep the described electric charge in response to described positive part；And

Adopt on 4th capacitor of coupling between the described outfan and second input of described ADC of described active integrator Sample-holding is in response to the described electric charge of described negative part.

17. methods according to claim 16, wherein, described step (a) and (b) also include:

D () measures the differential voltage between described 3rd capacitor and the combination of described 4th capacitor；

E () discharges described first integral capacitor, described second integral capacitor, described 3rd capacitor and described 4th electric capacity Electric charge on each capacitor in device；And

F () repeats step (a)-(e).

18. methods according to claim 14, also include:

Bias control is applied to the first input end of described active integrator, and wherein said application includes:

In the presence of described positive part, negative signal is applied to described first input end；And

In the presence of described negative part, positive signal is applied to described first input end.

19. 1 kinds of devices being used for measuring the electric capacity of touch sensor array, including:

Processing equipment, it is configured to detect electric conductor existence on described touch sensor array, wherein, described processing equipment Including capacitive sensing circuit, described capacitive sensing circuit includes that the active of electric capacity being configured to measure described touch sensor array amasss Point device, wherein said active integrator is configured to receive and has positive part and negative part from described touch sensor array Response signal, wherein, described response signal represents described electric conductor presence or absence on described touch sensor array, and And wherein, described active integrator is configured to respond described in integration continuously signal, uses first integral capacitor integration institute State the described negative part responding signal described in the response described positive part of signal and use second integral capacitor integration.

20. devices according to claim 19, wherein:

It is first defeated that described first integral capacitor is coupled to the outfan of described active integrator and described active integrator Enter end；And

Described second integral capacitor is coupled to the described outfan of described active integrator and the institute of described active integrator State first input end.