CN102750060B - Projection-type capacitive touch screen system time domain noise reduction method by space differentiation - Google Patents
Projection-type capacitive touch screen system time domain noise reduction method by space differentiation Download PDFInfo
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Abstract
The invention discloses a projection-type capacitive touch screen system time domain noise reduction method by space differentiation. The method includes the steps that (1), a plurality of identical artificial circuit processing elements and relevant selection controllers are arranged inside a touch screen control chip; (2), a reference inducing line set of any target touch screen inducing line set to be processed in a touch screen inducing line array is selected according to space distribution; (3), identical imitation processors are used for driving and reading a target sensor and a reference sensor simultanously; (4), information of the target sensor and the reference sensor is judged; (5), the steps of (2), (3) and (4) are repeated until all target inducing lines of the touch screen are processed to finish one frame; (6) according to the distribution of status values of the inducing lines of the frame, finger touch points are calculated and judged, and time or space misinformation touch points are eliminated according to former frame information; and (7), according to the state of a current frame, the step (2) is returned or other operation is performed. According to the projection-type capacitive touch screen system time domain noise reduction method by the space differentiation, the system performance can be effectively improved, and the power consumption is reduced.
Description
Technical field
The invention belongs to projection-type capacitive touch screen and touch screen control system field, be specifically related to a kind of time domain noise reduction method utilizing Spatial Difference, for the impact of accurate stress release treatment on touch-control system, improve capacitance plate antijamming capability.
Background technology
Projection-type capacitive touch screen system, shields (hereinafter referred to as " capacitance plate ") by projecting type capacitor and touch screen controller (hereinafter referred to as " touch-control circuit ") forms.Capacitance plate is made up of base material and sensor array.Substrate material has glass, PET etc., comprises opaque base material.Sensor array is many has the line of induction of given shape to arrange regularly the array formed, and the line of induction uses indium stannum alloy (ITO) or carbon or other conductive materials to make.In electrical connection, the line of induction of sensor array is directly connected with the port of touch-control circuit.Touch-control circuit is by circuit board, and electronic devices and components are formed.Circuit board can be ordinary circuit board (PCB) or flexible PCB (FPC), for connecting electronic devices and components.Electronic devices and components comprise Passive components, as Resistor-Capacitor Unit and function element, as special touch-control integrated circuit (IC) chip.Function element contains analog circuitry processes device, for the line of induction of driving sensor array, or reads signal from the line of induction of sensor array.Microprocessor (MCU) or digital signal processor (DSP) is also comprised, for realizing specific calculation process (related algorithm), to determine the duty obtaining sensor array in function element.Also storer is comprised in touch-control circuit, for storage program (Firmware), status data and operation result.Touch-control circuit also comprises clock generator, produces high accurate clock signal for synchronous between touch-control circuit each functional module, and with the sequential control of host information interactive process, the clock period does not change with the change of temperature and voltage substantially.Touch-control circuit and outside connection, be the line of induction of sensor array, another side is power lead and other signals of communication of host (host).Host refers to cell phone mainboard, computer main board or other application systems.
The basic functional principle of projection-type capacitive touch screen system is, touch-control circuit is according to pre-determined Time and place order, the line of induction of driving sensor array a group by a group, and read signal from the line of induction of driving sensor array, then carry out algorithm process.In certain particular moment, the line of induction that this group analog circuitry processes device drives or reads or line of induction group, be called " the target line of induction ".Control the circuit of this time and space order, be called selection control circuit.When the line of induction inside all sensors array has been processed as the target line of induction, be called a frame (Frame).The action forever repeating every frame of projection-type capacitive touch screen system, unless host order projection-type capacitive touch screen system stops action.
In projection-type capacitive touch screen system, main exist two kinds of electronic signal noise disturbing effects, is called for short noise.The first is electromagnetic interference (EMI), and English is Electro Magnetic Interference, and be called for short EMI, this noise mainly comes from the interference of periphery electron device for the sensor of capacitive touch screen.The second noise be finger close to or bring when touching capacitive touch screen sensor.Noise drastically influence degree of stability and the handling of touch-control system.Therefore, for the deviser of capacitive touch screen system, how setting up a stable touch-control system effectively reliably in actual application environment, is a challenge.
EMI noise, such as be coupled to the switching noise of touch-control system from LCDs, or come from the noise of mobile phone radio frequency electron device, also have the noise etc. from application processor feed-in, these noises significantly reduce the effect with useful signal in projection-type capacitive touch screen system, both signal to noise ratio (S/N ratio)s.No matter point whether close to or touch the sensor of touch-screen, these EMI noises all can be coupled in the middle of sensor signal path.Noise size is relevant with the capacitance of sensor in projection-type capacitive touch screen system.Fig. 1 shows the sensor signal being subject to the impact of LCDs switching noise.The transverse axis of Fig. 1 is clock periodicity, is equivalent to the time, and the longitudinal axis represents the signal of 21 lines of induction, and Fig. 1 is overall close to black, represents that EMI interference is extensively distributed in time and touch-screen spatially.
Some noises are had to disturb in addition, such as power supply noise, or the specific noise of device, they are with characteristic noise frequency, these interference also can be coupled on the sensor of projection-type capacitive touch screen system by equal proportion, its proportionate relationship is that the finger capacitance (Cf) of touch is than touch-control system intrinsic capacity (Cs). Fig. 2 depicts under such interference, the signal sensed in touch-screen system.The transverse axis of Fig. 2 is clock number, is equivalent to the time, and the longitudinal axis illustrates the signal of 2 lines of induction, by the interference obviously can seeing the external noise that finger is introduced in figure.
Current most of projection-type self-capacitance (self projective capacitance, be called for short self-PROCAP) have employed induction arranged side by side (parallel sensing) method in system or projection-type mutual capacitance (mutual projective capacitance is called for short mutual-PROCAP) system.Such method needs complicated front end sensor circuit and loaded down with trivial details follow-up signal process.In consumption processing power, need the complexity of circuit, and all need above the power consumption that consumes of practical function to improve.
In correlative technology field, Maxim Integrated Products Inc. of the U.S. is in China and have submitted patented claim " for using the noise cancellation technique of the capacitance touch screen controller of differential sensing " abroad, and its Chinese Patent Application No. is 201110108199.6.Although this technology uses the concept of adjacent differential, due to the restriction of the analog processor number that it uses, and there is the restriction etc. that the adjacent line of induction effectively can not eliminate finger introducing noise, the effect of its stress release treatment needs to improve further.
Summary of the invention
Technology of the present invention is dealt with problems: overcome the deficiencies in the prior art, provides a kind of projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference, is applied to projection-type capacitive touch screen system, can effectively improves system performance and reduce power consumption.
The technology of the present invention solution: the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference, its feature is: described projection-type capacitive touch screen system comprises projecting type capacitor screen and touch screen controller, described projecting type capacitor screen comprises base material and is attached to the sensor array that base material arranges, and described sensor array is that many lines of induction are arranged the array formed regularly; Described touch screen controller comprises multiple identical analog circuitry processes device, selection control, digital processing unit and storer; Described multiple analog processor is divided into two classes by application target, and a class is used for driving and reading the target line of induction, i.e. target simulation processor, another kind of for driving and read with reference to the line of induction, namely with reference to analog processor; Described selection control circuit comprises target selection control circuit part and with reference to selecting control circuit part, connects described two analoglike processors respectively; The described target line of induction refers at current time, according to the order preset, or random order, or the order of the digital processing unit instruction received is by the line of induction selecting control circuit to select from sensor array many lines of induction; The described reference line of induction refers to calculate the action that capacitance plate is pointed more accurately, get rid of ambient noise interference impact, by the line of induction selecting control circuit to choose, by carrying out computing to the target line of induction and with reference to the state of the line of induction simultaneously, obtain the state of the target line of induction, reduce noise effect; Described digital processing unit instruction order, can produce according to institute's working procedure digital processing unit is inner, or digital processing unit receives, and the instruction of host passs on.The described various line of induction, independent of one another between each line of induction, there is no interaction relation, be independently subject to the control of selection control;
Described method realizes as follows:
The first step, the select target line of induction and the reference line of induction
The order that target selection control circuit provides by the order preset or randomizer or the order of digital processing unit instruction received, control the switch arrays in it, target simulation processor be dynamically connected to the target line of induction;
Selection with reference to the line of induction is identical with the selection course of the target line of induction, namely with reference to the order selecting control circuit to provide by the order preset or randomizer or the order of digital processing unit instruction received, control the switch arrays in it, be dynamically connected to reference on the line of induction with reference to analog processor; But be not that any line of induction of sensor array can be selected as with reference to the line of induction, along with the difference of noise source needing stress release treatment, choose these alternative conditions with reference to the line of induction different, wherein it is crucial that different from the minimum space distance of the target line of induction or the restrictive condition of maximum space distance with reference to the line of induction.For eliminating EMI noise impact, need 2, the chosen distance target line of induction interval line of induction apart from the above line of induction as the reference line of induction, can determine with further reference to the relative position of the current goal line of induction in induction arrays in the selection put with reference to the line of induction before this, such as when system EMI noise source mainly display screen switching noise time, select the line of induction in the centre of line of induction array as with reference to line as far as possible, and in order to be coupled into the noise of induction system when eliminating finger touching capacitance plate, then need 2, the chosen distance target line of induction interval line of induction apart from the following line of induction as the reference line of induction, can determine with further reference to the relative position of the current goal line of induction in induction arrays in the selection put with reference to the line of induction before this, such as when sensor of interest is positioned near sensors edges but there are 2 lines of induction at range sensor edge apart from time above, select the line of induction away from the side of sensor array column border as with reference to line, because near the line of induction of this column border of sensor, the i.e. line of induction at touch-screen edge, easily be subject to wire or other accidental factor interference.Selecting with reference to the process of the line of induction is be priority orders with the select target line of induction, namely first the selected target line of induction is then selected with reference to the line of induction according to conditions such as target line of induction positions, at synchronization, the target line of induction, can not become the reference line of induction of himself;
Second step, drive the target line of induction and the reference line of induction, and read back the target line of induction and the status information with reference to the line of induction, whole process is identical for the target line of induction with reference to the line of induction, and driving any time in reading process, analog controller is identical with the Electric signal processing action with reference to the line of induction to the target line of induction.First analog processor uses the line of induction of the constant pressure source of timesharing adjustable voltage and the constant current source driving sensor array of timesharing adjustable current, analog processor reads the signal of this line of induction from the line of induction simultaneously, by the target line of induction with reference to the analog voltage signal digitizing on the line of induction, obtain the current goal line of induction and the state with reference to the line of induction; Then, digital processing unit reads the current goal line of induction and the state with reference to the line of induction in time from target simulation processor with reference to analog processor, by deposit data in the storer of position corresponding to the line of induction;
3rd step, the state of data processor according to the current target line of induction, the align mode with reference to the state of the line of induction, the historic state of the target line of induction and the target line of induction, calculate the current goal line of induction and whether have finger movement, and record finger movement departure, upgrade historic state; By the difference between the signal to the target line of induction and the reference line of induction, and the change of value itself, judge on the target line of induction with or without finger touching; When the historic state of the described target line of induction refers to the last identical line of induction as the target line of induction, read and be stored in the line of induction state value of the information memory location in storage space preset of this target line of induction; Described target line of induction align mode is line of induction calibration in sensor array, the line of induction state value namely obtained during non-inductive state;
4th step, according to predetermined line of induction choosing method, choose the next target line of induction in sensor array and the reference line of induction thereof, step is identical with the first step, then the process of second step to the 3rd step is carried out, and repeat until each article of line of induction of the sensor array line of induction all completes above-mentioned 3rd as the target line of induction, be referred to as a frame (Frame) in the present invention;
5th step, often complete a frame process after, digital processing unit, according to the total data of sensor array existing in storer, judges finger touch situation; And digital processing unit and host communication, to host report finger coordinate, track and gesture; Then according to the disposal route of the present situation determination next frame.Described judgement finger situation, comprises the position having one or more finger touch that digital processing unit calculates, is called position, touch point; The touch point of the wrong report spatially caused due to special noise condition deleted by digital processing unit, such as space distribution and the irrational touch point of intensity distributions; Digital processing unit according to the result of this frame and the some frames of history, comprehensive descision, the upper irrational touch point of erasing time distribution; Digital processing unit according to the result of this frame and the some frames of history, comprehensive descision finger touch track.Describedly determine next frame disposal route, comprise and normally return the first step, or system hibernates, system speed-raising runs, or system down runs, or other special preset procedures.Perform special preset procedures and refer to that digital processing unit distributes similarity higher than predetermined threshold value according to the touch point distribution of this frame with the touch point of presetting, namely touch screen controller can contrast existing touch point situation and judges, and according to preset touch mode, redirect performs preset function; Special preset function can comprise calibration touch-screen reference value etc., possible preset in advance.
Described each line of induction electrical structure, principle of work, workflow is all identical.
Independent of one another between described every bar line of induction or line of induction group, there is no interaction relation, be independently subject to the control of selection control.
At any time, are inverse lines of induction except the described target line of induction with reference to other lines of induction except the line of induction, namely these line of induction states can not be used to the computing carried out the target line of induction or judgement.
At any time, the described target line of induction is the different lines of induction from the reference line of induction; But the target line of induction of current time originally can use the line of induction for referencial use in another time or space, also can use as the target line of induction in another time or space with reference to the line of induction itself.
It is relevant that the minimal number of the described reference line of induction and touch-screen system differentiate the finger number processed, and the finger number of process is more, and the number of the required reference line of induction is more.
The number of described analog processor is more than or equal to 2, and the structure of analog circuitry processes device is identical.
Calculate in described 4th step and judge whether the current goal line of induction has finger movement, and the method recording finger movement departure adopts multiple weighting subtraction, and these weighting subtraction results contrast, then select the effective information of certain result of storage to be stored in designated space position as the departure of finger movement.
In described 5th step, other initialization process are that digital processing unit distributes similarity higher than predetermined threshold value according to the touch point distribution of this frame with the touch point of presetting, perform preset procedures, namely touch screen controller can contrast existing touch point situation, judge and foundation preset touch mode, redirect performs preset function; Described preset function comprises calibration touch-screen reference value.
The described first step, the 3rd step, the 4th step and the 5th step can be cured to special IC (ASIC), or as the firmware (Firmware) of application system DSP/MCU, or be implemented in existing host system in the mode of software-driven (Driver).
In described second step, analog processor uses the line of induction of the constant pressure source of timesharing adjustable voltage and the constant current source driving sensor array of timesharing adjustable current.
The present invention's advantage is compared with prior art:
(1) the present invention is realized jointly by hardware and algorithm, rely on new construction and the new algorithm of touch-control circuit, coordinate the simple sensor array structure of capacitance plate, eliminate the noise effect that projection-type capacitive touch screen system is subject to, effectively improve touch-screen system performance and reduce power consumption.
(2), compared with the inducing method arranged side by side of the present invention and other projection-type self-capacitance systems or projection-type mutual capacitance systems, provide equal or better signal quality, and required for the power consumption that expends lower because do not need to use complicated front end induction treatment circuit.Meanwhile, compared with the capacitance touch control system responded to use order, even if these order induction systems employ complicated signal processing circuit, the present invention still can provide the higher system stability under complex work environment.
(3) the present invention is while providing better signal quality, maintains simple and convenient follow-up signal treatment scheme.
(4) with existing correlation technique, Maxim Integrated Products Inc. of the U.S. compares at the file that China and the overseas application number submitted to are 201110108199.6 " for using the noise cancellation technique of the capacitance touch screen controller of differential sensing ", the present invention due to employ multiple analog processor and utilize space region every characteristic, really can eliminate noise effect in the same time; And targetedly noise reduction being carried out to EMI and finger introducing noise, noise reduction is more accurate, more thoroughly; Present invention utilizes the discrimination technology between frame, eliminate other finger touchings that specific factor does not cause further and judge by accident.
(5) digital processing algorithm or the side's of calculating algorithm that use in the projection-type capacitive touch screen system time domain noise reduction method of Spatial Difference is utilized, integrated circuit (ASIC) can be cured to, or as the firmware (Firmware) of application system DSP/MCU, or be implemented in existing host system in the mode of software-driven (Driver).
In a word, the projection-type capacitive touch screen system time domain noise reduction method of Spatial Difference of the present invention is utilized in projection-type capacitive touch screen system, provide high-quality signal, maintain the feature of simple process circuit, and then achieve Low Power High Performance solution.
Accompanying drawing explanation
Fig. 1 is the touch screen induction signal being subject to the interference of LCDs switching noise;
Fig. 2 is the sensor signal being subject to noise;
Fig. 3 is hardware circuit framed structure schematic diagram of the present invention;
Fig. 4 is that the line of induction of specific embodiment of the invention drives reading decision flow chart;
Fig. 5 is the result of Fig. 1 signal after the inventive method noise reduction process;
Fig. 6 is the result of Fig. 2 signal after the inventive method noise reduction process.
Embodiment
Method of the present invention make use of the following characteristic of projection-type capacitive touch screen system: no matter whether (1) pointed near to or in contact with the Sensor section to touch-screen system, and EMI noise all can be coupled to all sensors.(2) because finger touches the characteristic noise introduced simultaneously, its noise contributions scope is near the line of induction of finger touching.(3) projection-type capacitive touch screen system under normal operation, and finger can not touch the line of induction of all sensors.(4) if use palm or miscellaneous equipment, touch all lines of induction by force, so this state does not belong to touch-screen and normally manipulates state, and this operator scheme can be detected the speed of (5) touch screen controller process line of induction simply, touch touch-screen faster than people or other mechanical test equipments far away or change the speed of touch condition.
The projection-type capacitive touch screen system that the present invention adopts, shields (hereinafter referred to as " capacitance plate ") by projecting type capacitor and touch screen controller (hereinafter referred to as " touch-control circuit ") forms.Capacitance plate is made up of base material and sensor array, and touch-control circuit is by circuit board, and electronic devices and components are formed.In electrical connection, the line of induction of sensor array is directly connected with the port of touch-control circuit.
As shown in Figure 3, the present invention is implemented as follows:
The first step, the sensor array manufactured and designed in capacitance plate.
Capacitance plate is made up of base material and sensor array.Substrate material has glass, PET etc., comprises opaque base material.Sensor array is many has the line of induction of given shape to arrange regularly the array formed, and the line of induction uses indium stannum alloy (ITO) or carbon or other conductive materials to make.In the termination of the line of induction, conductive connecting is had the line of induction to be connected the object boundary place of the capacitance plate extended on capacitance plate base material, so that capacitance plate is connected with touch control circuit.Sensor and the line of induction, the mode usually being etched by plated film or print, is attached on base material.
In electrical connection, the line of induction of sensor array is directly connected with the port of touch-control circuit; In production method, the general method adopting hot pressing, links together the flexible circuit board of capacitance plate and touch-control circuit.
Feature of the present invention is that every bar line of induction of requirement capacitance plate or line of induction group are independent of one another, does not have interaction relation, independently can be subject to the control of touch-control circuit.
Second step, the touch-control circuit manufactured and designed in capacitance plate.
One of assembly of touch-control circuit is circuit board, comprise ordinary circuit board (PCB) or flexible PCB (FPC), for the electrical and physical connection between electronic devices and components, and as the electrical and physical connection between the touch-control circuit above as described in the first step and capacitance plate.
Outside dividing circuit plate, touch-control circuit also comprises electronic devices and components.The kind of electronic devices and components comprises connector, passive device and function element.Connector be for physics and or electrically upper touch-control circuit and outside to be coupled together; Passive device is resistance, electric capacity and magnetic bead etc. mainly; Function element has been the main devices of touch-control circuit function, and such as special touch-control integrated circuit (IC) chip or protection circuit be not by the ESD protective device etc. of electrostatic damage.
Touch-control circuit and outside connection, be the line of induction of sensor array, another side is power lead and other signals of communication of host (host).Host refers to cell phone mainboard, computer main board, or other application systems.
Function element in touch-control circuit realizes the drived control to the sensor of capacitance plate, and carries out analyzing and processing to the signal read back from sensor.The important functional module of function element has four:
(2.1) analog circuitry processes device, for the line of induction of driving sensor array, or reads signal from the line of induction.The important component part of analog circuitry processes device comprises the charging circuit that timesharing adjustable current constant-current charging circuit and timesharing adjustable voltage constant voltage charging circuit are combined to form, and signal conversion multidigit analog to digital converter (ADC) for reading line of induction state.The number of analog circuitry processes device in the present invention, is far smaller than the number of the line of induction in sensor array, such as actual can choice for use 3 analog processors when using, the sensor array that alignment processing is made up of 32 lines of induction.For driving or the reading of every bar line of induction, be realize analog processor and sensor-interconnect by multi-path choice control circuit, and then complete.Sometimes the line of induction in capacitance plate is divided into some groups by multi-path choice control circuit, and duty is all identical at any time often to organize the inner line of induction, and the present invention calls line of induction group the line of induction of such a group.Arrange multiple analog processor in the present invention, namely the number of analog processor is more than or equal to 2.Multiple analog processor is divided into two classes, and a class is used for driving and reading the target line of induction, another kind of for driving and reading with reference to the line of induction.
(2.2) multi-path choice control circuit (MUX, hereinafter referred to as " selection control circuit "), the order that it provides by the order preset or randomizer or the order of the instruction of digital processing unit received, gauge tap array, is dynamically connected to the target line of induction and the reference line of induction of capacitance plate by analog processor.Select the inside of control circuit, comprise the electrical connection of switch arrays for analog processor and the line of induction or line of induction group; Comprise one or more randomizers, the scope of the value of its random number is identical with line of induction number or line of induction number group; Comprise internal clocking or the interface circuit from external reception clock signal; Comprise the digital interface circuit with microprocessor (MCU) or digital signal processor (DSP), receive or inform the line of induction or the line of induction group coding of process at present.
(2.3) digital processing unit comprises microprocessor (MCU) or digital signal processor (DSP), for realizing computation process (algorithm), to determine the duty obtaining sensor array; Also can be used for the instruction to selecting control circuit to provide the process line of induction, this instruction can be the permanent order according to being programmed in advance in the middle of program simultaneously, or to be submitted to according to using software to produce pseudo random number and to select control circuit.Algorithm is by the difference between the signal to the target line of induction and the reference line of induction, and the change of value itself, judges on capacitance plate with or without finger touching; There are how many fingers to touch simultaneously; Touch points where; Analysis meter calculates the track of many fingers, the relation namely between this line of induction action and line of induction action last time.Digital processing unit signal wiring comprises host interface, includes but not limited to I2C, SPI, PS2, USB standard interface; Select control circuit interface, be used to indicate or receive current line of induction coding; Analog processor interface, refers to for the state reading the line of induction; Clock and reset signal interface.
(2.4) storer, includes but not limited to static memory (SRAM), dynamic storage (DRAM), non-volatility memorizer (NVM).These storeies are used for storage program (Firmware), status data and operation result.
These hardware systems, after loading externally fed, enter the 3rd step below automatically.
3rd step, the selected target line of induction and the reference line of induction.In the present invention, the first select target line of induction, then determines with reference to the line of induction.The object of the select target line of induction is whether this target line of induction of observation is subject to pointing the impact of touching; The object with reference to the line of induction is selected to be utilize to offset noise to the impact of the target line of induction with reference to the line of induction; The target line of induction and the reference line of induction are all the existing lines of induction on capacitance plate; The target line of induction is all the different lines of induction from the reference line of induction at any time.After capacitance plate system is loaded power supply, automatically enter this step.
(3.1) the select target line of induction.The target line of induction refers at current time, according to the order preset, or random order, or the order of digital processing unit instruction, by a line of induction in the capacitance plate induction arrays selecting control circuit to choose or line of induction group.Whether touch-screen system wishes to differentiate on this target line of induction, have finger movement to occur, if or judge have finger movement to occur, then record and the side-play amount without same line of induction during finger movement or the state compared with line of induction group simultaneously.If the line of induction inside sensor array or line of induction group nonnegative integer are numbered 0,1,2 ..., n, default order can be sequentially 0,1,2..n, and first time selects 0; Or decreasing order n, n-1 ... 0; Or odd number even number 1,3,5 ... 2k+1,0,2,4 ..2m, first time selects 1; Or inside and outside alternately n, 0, n-1,1, n-2,2..., first time selects n.The concrete electrical action of the select target line of induction is that analog processor is connected to the target line of induction by electronic switch by control circuit.The target line of induction can be a line of induction or one group of line of induction, and at this moment required analog processor may be one or more.As time goes on, second time will be selected in subsequent step, for the third time ..., n-th time, so far all sweep traces are all set to the target line of induction each 1 time, also referred to as completing a frame (Frame).
(3.2) select with reference to the line of induction.After touch-control circuit have selected the target line of induction, next for the target line of induction is selected with reference to the line of induction.Refer to calculate the action that capacitance plate is pointed more accurately with reference to the line of induction, get rid of ambient noise interference impact, and the one or more lines of induction chosen, these lines of induction are lines of induction existing on touch-screen, and the state with reference to the line of induction is used for the state computation of the target line of induction.The number of the reference line of induction that the present invention uses, different along with the finger number difference of capacitance plate system needs detecting process, capacitance plate system needs the finger number detecting process more, and the number of the reference line of induction of needs is more.Such as detect the capacitance plate system of 2 fingers, the reference line of induction number of needs, be less than reference line of induction number required in the capacitance plate system of detecting 5 finger.To select with reference to the method for the line of induction can be random or according to prior setting order.Can be random with reference to the line of induction, but be not that any line of induction of sensor array can be selected as with reference to the line of induction.Along with the difference of noise source needing stress release treatment, choose these alternative conditions with reference to the lines of induction different, namely with reference to the line of induction and the target line of induction minimum space apart from or the restrictive condition of maximum space distance different.For eliminating EMI noise impact, need 2, the chosen distance target line of induction interval line of induction apart from the above line of induction as with reference to the line of induction, can determine with further reference to the relative position of the current goal line of induction in induction arrays in the selection put with reference to the line of induction before this; In order to be coupled into the noise of induction system when eliminating finger touching capacitance plate, then need 2, the chosen distance target line of induction interval line of induction apart from the following line of induction as the reference line of induction; Can determine with further reference to the relative position of the current goal line of induction in induction arrays in the selection put with reference to the line of induction before this, such as, select the line of induction near touch screen center portion as the reference line of induction of elimination EMI noise as far as possible.Notice and select process and the select target line of induction with reference to the line of induction to have priority orders, be i.e. the first select target line of induction, then select the reference line of induction according to the target line of induction.At any time, the target line of induction, can not become the reference line of induction of himself.Identical with the target line of induction, the concrete electrical action with reference to the line of induction is selected to be that analog processor is connected to reference to the line of induction by electronic switch by control circuit, this electronic switch switches connection procedure, with following 4th step touch screen controller drive read the line of induction process compared with and of short duration, expend time in hardly.
4th step, reads flow process according to predetermined driving, obtains the target line of induction and the state with reference to the line of induction.This process mainly divides 3 parts.Whole process is identical for the target line of induction with reference to the line of induction.
(4.1) process (Driving) is driven.Driving process is the charge and discharge process of analog processor for the line of induction, and this process may need several clock period to complete.Clock can produce in capacitance plate internal system, also can from host (host).Discharge and recharge has combinationally used the constant current source of timesharing adjustable current, and the constant pressure source of timesharing adjustable voltage.
(4.2) induction process (Sensing).Multidigit analog to digital converter (ADC) in analog processor by the analog voltage signal digitizing on the line of induction, then through calibration process etc., is transformed to digital quantity.Only comprise a small amount of storage space in analog processor, not as the use of the multiple line of induction state of long storage time, can power consumption be saved like this and save cost.
(4.3) data read process (Reading).According to algorithm requirement, digital processing unit (comprising MCU or DSP) reads the current goal line of induction and the state with reference to the line of induction in time from analog processor, by deposit data in the storage space deserved, for the 5th step process below.Notice that reading process relates to multiple analog processor, and in each analog processor, store the limited storage space of line of induction state, so the reading handling process of data needs to complete in time before analog processor internal storage unit is refreshed.The reading transfer process of data, can use the normal W method of memory of digital processing unit, also can use direct memory reading/writing method (DMA).
5th step, digital processing unit is according to the state from the current target line of induction, with reference to the state of the line of induction, the historic state of the target line of induction, the align mode of the target line of induction, calculating judges whether the current goal line of induction has finger movement, and records finger movement departure, upgrades historic state.In the middle of this step, key content comprises:
(5.1) historic state of the target line of induction, when referring to the last identical line of induction as the target line of induction, reads and is stored in the line of induction state value deserving position.
(5.2) target line of induction align mode is that capacitance plate calibrates the parameter obtained, specifically see the description in (8.1) of the 8th step.
(5.3) whether the current goal line of induction has finger movement and finger movement departure, main calculation methods is multiple weighting subtractions, and these weighting subtraction results contrast, be then select the effective information of certain result of storage to be stored in designated space position as the departure of finger movement.Notice that departure has extracted the effective information of weighting subtraction in order to reduce computational complexity and to reduce storage space.
For 2 finger projection-type capacitive touch screen systems, to host, touch-control circuit reports that 2 are independently pointed coordinate, system is subject to the impact of EMI interference, and uses this patent to eliminate this impact.In exemplary systems of this 2 finger, with T(t) represent the state of working sensor t, when applying this patent, use the reference sensor of 3 spaced apart preset, its state D1(t), D2(t), D3(t) represent.
(5.3.1) the time domain noise reduction method in order to ensure Spatial Difference effectively can provide reference signal, space region every reference sensor between relative position must keep 2 sensor distance or more.
(5.3.2), when being located at time t, label is the signal that the working sensor of n receives is SIGT(t
n), simultaneously space region every the signal of 3 reference sensors be respectively SIG
d1(t
n), SIG
d2(t
n), SIG
d3(t
n).So can set up one group of difference formula by these data, based on the output signal sampled, derive following absolute difference score value:
DI FF
TD1（t
n）=ABS（SIG
T（t
n）-SIG
D1（t
n））；
DI FF
TD2（t
n）=ABS（SIG
T（t
n）-SIG
D2（t
n））；
DI FF
TD3（t
n）=ABS（SIG
T（t
n）-SIG
D3（t
n））；
In Fig. 4 of the present invention, because length and font size reason, use symbol Sdt1(), Sdt2(), Sdt3() and, represent DI FF
tD1(), DI FF
tD2(), DI FF
tD3(); Use ST() represent SIG
t(), uses SD1(), SD2(), SD3() and represent SIG
d1(), SIG
d2(), SIG
d3().
To DIFF
tD1(t
n), DIFF
tD2(t
n) and DIFF
tD3(t
n) do following analysis.In following analysis table, " FU_th " indicates the threshold value without finger signal; " FD_th " represents the thresholding detecting finger signal, and " Ref " is effective reference signal; " Odt " is the useful signal output valve after analyzing; O1, O2, O3 are aforementioned DIFF
tD1(), DIFF
tD2(), DIFF
tD3() is own, or gets its significance bit, or it is according to the result after specific formulation amplification, and its amplification method can be Linear Amplifer or Image magnify.Gauge outfit, namely front 2 row of form illustrate working sensor and space region every reference sensor between associate.Such as the mark of T & D1 is the relation of working sensor T and reference sensor D1, below analogizes.
Due to SIG
t(t
n), SIG
d1(t
n), SIG
d2(t
n), SIG
d3(t
n) in the identical time with identical Space Coupling to identical noise, so DIFF
tD1(t
n), DIFF
tD2(t
n) and DIFF
tD3(t
n) result of signal differential eliminates noise figure.
For 2 finger touch systems, 3 reference sensors can be used; System also can only arrange 2 reference sensors by optimizing.
Above-mentioned exemplary method, its algorithm and framework can be in use to many finger projection-type capacitive touch screen systems.Many microgrippers can report more than 3 or 3 coordinates pointed of same time to host.In order to obtain the accurate judgement to EMI noise, need the restriction of observing minimum transducer spacing, on the other hand, for obtaining the impact of finger feed-in noise, also need to observe the restriction of maximum sensor distance, linear with reference sensor number in the complexity putting process before this.
6th step, according to the content in the 3rd step, be exactly according to set line of induction choosing method, choose the next target line of induction in sensor matrices and with reference to the line of induction.Method step is identical with the 3rd step, then carries out the process of the 4th step the 5th step; Repeat the three the 4 5th steps, until each article of line of induction of capacitance plate all completes the process of the 345 step as the target line of induction, be referred to as a frame (Frame).
Fig. 4 illustrates above-mentioned 5th step and the 6th step and drives the process flow diagram reading and judge, example shown in figure is that sensor array shows 32 lines of induction, and the select target line of induction is according to 1,2 ... the label order of 32 is carried out.
7th step, often complete a frame process after, digital processing unit is according to the total data of existing sensor array between the particular memory storing pocket, and judge the situation of finger touch, main process comprises:
(7.1) finger touch situations is calculated and record according to current array.This process mainly picks out a few line of induction information, and there is a big difference for the status information that they retain in storage space and other most lines of induction, and the absolute value of such as signal exceedes certain threshold value preset.
(7.2) in order to reduce touch-screen system wrong report, algorithm removes isolated " pseudo-touching " point, such as: " finger touch " that happen suddenly over time and space, should be removed simultaneously.Temporal " burst finger touch event " is that finger signal is flashed in frame history, and it is stable occurs that frame number is less than preset value, such as, only in 1 frame, occur finger signal, and the interval of frame is 1/10000 second; Such signal demand is excluded." burst finger signal " spatially, refer in specific locus, finger only can not touch the only a few line of induction in sensor array, such as near the tip of sensor, as long as there is finger, only can not touch a tip, necessarily also touch other sensors near tip; Therefore, this touch signal spatially " flashed " is that the noise factor of some the unknown produces, should be deleted.
(7.3) calculate finger coordinate points with interpolation or spline method, or claim touch point; And judge the track distribution of many fingers, calculate gesture or gesture trend.This part mainly comprises the method using specific numerical evaluation, and interpolation goes out coordinate points accurately, because when finger touches touch-screen, its scope is not limited to a sensor, may between several sensing station, and interpolation method can be linear, or secondary, or batten.Another main processes is the track calculating out finger operation according to frame history, or anticipation finger runs possible track trend.
(7.4) when host requires, to host report finger coordinate, track, gesture.
8th step, result according to the 7th step, judge disposal route and the time interval of next frame, mainly contain five kinds of situations:
(8.1) during the 7th step, receive host's order or perceive default special touch manner, such as receive the instruction directly stopping the subsequent operation of this frame and return, or the preset mode that all lines of induction are all touched on touch screen, then complete the corresponding operation of process, then return aforementioned 3rd step.
(8.2) the 7th steps do not detect that any finger is touched, and several frame does not detect finger signal above.Now, judge that capacitance plate is in operatorless pattern, at this moment relieving system processing speed, such as, reduce system clock frequency, then returns aforementioned 3rd step.
(8.3) in the 7th step, detect finger touch, have and judge it is not noise signal from space distribution, and the data not having finger touch completely of former frame.Now, judgement is that finger starts to touch capacitance plate, at this moment accelerates system processing speed, such as, improve system clock frequency and then return aforementioned 3rd step.Or the situation near the line of induction taking a sample test finger signal, namely when system operating frequency is constant, next frame is made up of half or less line of induction, repeat the three to the seven step, result is in identical time range, complete 2 times or more frame processing speeds doubly, because the line of induction sum processing every frame reduces by half or less.
(8.4) normal operating conditions, returns the 3rd step.
(8.5) enter battery saving mode according to host's instruction, stop all work or some work, enter the 9th step.
9th step, the order of wait host, enter the 3rd step, or again powered after power-off, automatically enter the 3rd step.
Facts have proved, the inventive method effectively can reduce noise effect.Fig. 5 and Fig. 6 represent respectively Fig. 1 and Fig. 2 remove noise after result, can find out at a glance and to be removed in the noise effect of Fig. 1 and Fig. 2.Fig. 1 and Fig. 5 is many objectives line of induction of sensor array, with clock periodicity, i.e. and the time, the change of line of induction state value, in Fig. 1, line of induction state is subject to the impact of EMI noise, almost cannot identification, in Fig. 5, noise effect is eliminated, can be clear that the change of finger signal.Shown in Fig. 2 and Fig. 6 is 2 specific lines of induction, and the transverse axis of drawing is clock periodicity, and the longitudinal axis is state value, in Fig. 2, signal is subject to pointing the impact introducing noise, amplitude cannot accurately judge, Fig. 6 is that 2 lines of induction are eliminated the effects of the act later state, accurately can obtain state value.
The present invention is owing to effectively eliminating common mode voltage transient noise, the wave noise of power supply, the radiated noise of external environment of LCD self, save system resource overhead, improve the yield rate of product, the finger trace improving capacitance touch control screen detects degree of accuracy.
In this description, the present invention is described with reference to its particular instance.But still can make various amendment and conversion obviously, and not deviate from scope of the present invention, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (10)
1. utilize the projection-type capacitive touch screen system time domain noise reduction method of Spatial Difference, it is characterized in that: described projection-type capacitive touch screen system comprises projecting type capacitor screen and touch screen controller, described projecting type capacitor screen comprises base material and is attached to base material arranged regularly by many lines of induction and forms sensor array; Described touch screen controller comprises multiple identical analog circuitry processes device, selection control, digital processing unit and storer; Described multiple analog processor purposes is divided into two classes, and a class is used for driving and reading the target line of induction, i.e. target simulation processor, another kind of for driving and read with reference to the line of induction, namely with reference to analog processor; Described selection control circuit comprises the target line of induction and selects control circuit and select control circuit with reference to the line of induction, connects the analog processor of described every class and the corresponding line of induction respectively; The described target line of induction refers at current time, one that is selected from the whole line of induction of sensor array by target selection control circuit or one group of line of induction or multiple line of induction group; The described reference line of induction refers to get rid of ambient noise interference impact, judge more accurately to calculate the action that capacitance plate is touched, by being different from the line of induction of the target line of induction or one group of line of induction or multiple line of induction group with reference to the locus selecting control circuit to choose; Independent of one another between described every bar line of induction or line of induction group, there is no interaction relation, be independently subject to the control of selection control;
Described method realizes as follows:
The first step, the select target line of induction and the reference line of induction
The order that target selection control circuit provides by the order preset or randomizer or the order of digital processing unit instruction received, control the switch arrays opening and closing in it, target simulation processor be dynamically connected to the target line of induction;
Selection with reference to the line of induction is identical with the selection course of the target line of induction, namely with reference to the order selecting control circuit to provide by the order preset or randomizer or the order of digital processing unit instruction received, control the switch arrays opening and closing in it, be dynamically connected to reference on the line of induction with reference to analog processor, any line of induction not in sensor array all can be selected as with reference to the line of induction, along with the difference of noise source needing stress release treatment, choose these alternative conditions with reference to the line of induction different, namely different from the minimum space distance of the target line of induction or the restrictive condition of maximum space distance with reference to the line of induction, described restrictive condition is for eliminating EMI noise impact, need 2, the chosen distance target line of induction interval line of induction apart from the above line of induction as the reference line of induction, can determine with further reference to the relative position of the current goal line of induction in induction arrays in the selection put with reference to the line of induction before this, in order to be coupled into the noise of induction system when eliminating finger touching capacitance plate, then need 2, the chosen distance target line of induction interval line of induction apart from the following line of induction as with reference to the line of induction, can determine with further reference to the relative position of the current goal line of induction in induction arrays in the selection put with reference to the line of induction before this, select the process with reference to the line of induction to be have priority orders with the select target line of induction, namely the first selected target line of induction is then selected with reference to the line of induction according to conditions such as target line of induction positions, at synchronization, the target line of induction, can not become the reference line of induction of himself,
Second step, drive the target line of induction and the reference line of induction, and their status information of reading back, whole process is identical for the target line of induction with reference to the line of induction, and driving any time in reading process, analog controller is identical with the Electric signal processing action with reference to the line of induction to the target line of induction; The line of induction of analog processor first driving sensor array, analog processor reads the signal of this line of induction from the line of induction simultaneously, by the target line of induction with reference to the analog voltage signal digitizing on the line of induction, obtain the current goal line of induction and the state with reference to the line of induction, then, digital processing unit reads the current goal line of induction and the state with reference to the line of induction in time from target simulation processor with reference to analog processor, by deposit data in the storer of position corresponding to the line of induction;
3rd step, the state of digital processing unit according to the current target line of induction, the align mode with reference to the state of the line of induction, the historic state of the target line of induction and the target line of induction, calculate the current goal line of induction and whether have finger movement, and record finger movement departure, upgrade historic state; When the historic state of the described target line of induction refers to the last identical line of induction as the target line of induction, read and be stored in the line of induction state value of storage space position preset corresponding to this target line of induction; Described target line of induction align mode is line of induction reference value in sensor array, namely without this target line of induction state value obtained during finger touch screen;
4th step, according to predetermined line of induction choosing method, choose the next target line of induction in sensor array and with reference to the line of induction, step is identical with the first step; Then carry out the process of above-mentioned second step and the 3rd step, and repeat until each article of line of induction of the sensor array line of induction all completes above-mentioned 3rd step as the target line of induction, be referred to as a frame (Frame);
5th step, often complete a frame process after, digital processing unit, according to the total data of sensor array existing in storer, judges finger touch situation; And digital processing unit and host communication, to host report finger coordinate, track and gesture; Then according to the disposal route of the present situation determination next frame; Described judgement finger situation, comprises the position having one or more finger touch calculated, is called position, touch point; The touch point of the wrong report spatially due to noise condition initiation deleted by digital processing unit; According to the result of this frame and the some frames of history, comprehensive descision, the upper irrational touch point of erasing time distribution; According to the result of this frame and the some frames of history, comprehensive descision finger touch track; Describedly determine next frame disposal route, comprise and normally return the first step, or system hibernates, system speed-raising runs, or system down runs, or other preset procedures;
At any time, the described target line of induction is the different lines of induction from the reference line of induction; But the target line of induction of current time originally can use the line of induction for referencial use in another time or space, also can use as the target line of induction in another time or space with reference to the line of induction itself.
2. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, is characterized in that: described each line of induction electrical structure, principle of work, workflow is all identical.
3. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, is characterized in that: independent of one another between described every bar line of induction or line of induction group, does not have interaction relation, is independently subject to the control of selection control.
4. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, it is characterized in that: at any time, are inverse lines of induction except the described target line of induction with reference to other lines of induction except the line of induction, namely these line of induction states can not be used to the computing carried out the target line of induction or judgement.
5. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, it is characterized in that: it is relevant that described minimal number with reference to the line of induction and touch-screen system differentiate the finger number processed, the finger number of process is more, and the required number with reference to the line of induction is more.
6. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, it is characterized in that: the number of described analog processor is more than or equal to 2, and the structure of analog circuitry processes device is identical.
7. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, it is characterized in that: calculate in described 3rd step and judge whether the current goal line of induction has finger movement, and the method recording finger movement departure adopts multiple weighting subtraction, and these weighting subtraction results contrast, then select the effective information of certain result of storage to be stored in designated space position as the departure of finger movement.
8. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, it is characterized in that: in described 5th step, other initialization process are that digital processing unit distributes similarity higher than predetermined threshold value according to the touch point distribution of this frame with the touch point of presetting, perform preset procedures, namely touch screen controller can contrast existing touch point situation, judge and foundation preset touch mode, redirect performs preset function; Described preset function comprises calibration touch-screen reference value.
9. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, it is characterized in that: the described first step, 3rd step, 4th step and the 5th step can be cured to special IC (ASIC), or as the firmware (Firmware) of application system DSP/MCU, or be implemented in existing host system in the mode of software-driven (Driver).
10. the projection-type capacitive touch screen system time domain noise reduction method utilizing Spatial Difference according to claim 1, it is characterized in that: in described second step, analog processor uses the line of induction of the constant pressure source of timesharing adjustable voltage and the constant current source driving sensor array of timesharing adjustable current.
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| CN103064571B (en) * | 2012-12-31 | 2016-01-27 | 深圳市汇顶科技股份有限公司 | Capacitive screen touch detection system |
| KR102127861B1 (en) * | 2013-03-05 | 2020-06-30 | 삼성전자주식회사 | Capacitive touch system with improved touch sensing precision and coordinates extracting method therefore |
| CN104714704B (en) * | 2013-12-12 | 2017-09-29 | 奇景光电股份有限公司 | Touch-control sensing display device and the method for reducing described device wrong report touch point |
| US9405389B2 (en) * | 2014-08-29 | 2016-08-02 | Microsoft Technology Licensing, Llc | Noise reduction through democratic alpha smoothing |
| CN105786271B (en) * | 2014-12-26 | 2019-06-28 | 宸鸿科技(厦门)有限公司 | Touch-control system and its method for detecting |
| KR102382999B1 (en) | 2015-01-08 | 2022-04-05 | 삼성디스플레이 주식회사 | Display device including touch sensor |
| TWI566139B (en) * | 2015-02-26 | 2017-01-11 | 宏碁股份有限公司 | Touch apparatus and signal processing method thereof |
| CN110199247B (en) * | 2017-12-27 | 2022-07-29 | 深圳市汇顶科技股份有限公司 | Noise detection method and device, electronic equipment and computer readable storage medium |
| CN109739385B (en) * | 2019-01-08 | 2022-05-24 | 合肥京东方光电科技有限公司 | Method and device for touch finger identification based on capacitance signal and touch screen |
| CN111459346B (en) * | 2020-03-31 | 2021-09-07 | 深圳市汇顶科技股份有限公司 | Capacitive touch device and gesture recognition method, chip and storage medium thereof |
| CN115373543A (en) * | 2022-09-16 | 2022-11-22 | 铂睿特(深圳)触控显示技术有限公司 | Method for recognizing touch signal by capacitive touch screen |
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