CN203376701U - Touch screen control system and signal processing circuit thereof - Google Patents
Touch screen control system and signal processing circuit thereof Download PDFInfo
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- CN203376701U CN203376701U CN201320259365.7U CN201320259365U CN203376701U CN 203376701 U CN203376701 U CN 203376701U CN 201320259365 U CN201320259365 U CN 201320259365U CN 203376701 U CN203376701 U CN 203376701U
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Abstract
The utility model discloses the signal processing circuit of a touch screen control system, which comprises a detecting unit and a calculating unit coupled to the detecting unit. Whether a first signal received by the detecting unit is a touch signal or a noise signal is judged by means of the detecting unit according to a threshold value, and then the detecting unit outputs the signal as an output signal. The calculating unit carries out a smoothing treatment on the noise signal to generate a second signal and transmit the second signal to the detecting unit. When the first signal is judged as a touch signal by means of the detecting unit, the detecting unit outputs the touch signal as an output signal. When the first signal is judged as a noise signal by means of the detecting unit, the detecting unit outputs the second signal as an output signal. The utility model also provides a touch screen control system. By means of the touch screen control system, the signal to noise ratio is increased, so that the detecting accuracy of contact points is improved.
Description
Technical field
The utility model relates to the touching technique field, relates in particular to a kind of touch screen control system and its signal processing circuit.
Background technology
In the market of various consumption electronic products now, that the movable electronic products such as PDA(Personal Digital Assistant), mobile phone (mobile phone), notebook (notebook), flat computer (tablet) all be take is light, thin, function is intrepid is Orientation of design, so the movable electronic product interface tool that uses widely touch-screen (touch panel) to link up as its data.Touch-screen is a kind of hommization input media, it is except meeting the requirement that can do multi-level menu design, the mode of operation that also can simultaneously have the hommizations such as the functions such as keyboard, mouse and handwriting input, especially will input with output and be incorporated into the speciality of same interface (as screen), especially other traditional input media part can't be obtained.
In general touch screen control system, judge that the mode that on touch-screen, whether certain point occurs to touch is, when touch is arranged, can make voltage or current signal change, judge on touch-screen that by the change amplitude of detecting this type of signal this point is as touching or not touching.But if noise is too large, can makes the signal level of touch too approaching with the signal level do not touched, and make signal to noise ratio (S/N ratio) (Signal-to-noise ratio, SNR) too low, and then affect the detecting degree of accuracy of system for touch point.
The utility model content
In view of this, for the signal to noise ratio (S/N ratio) that improves touch-screen to increase the detecting degree of accuracy of touch point, the utility model provides a kind of touch screen control system and its signal processing circuit, by widening the signal level gap between Yu Wei touch point, touch point, improve the signal to noise ratio (S/N ratio) of touch-screen to promote the detecting degree of accuracy of touch point.
The utility model discloses a kind of signal processing circuit of touch screen control system, includes a detecting unit, and the first signal received according to a threshold decision is a touch signal or a noise signal and then is exported as an output signal; And an arithmetic element, be coupled to this detecting unit, receive this noise signal that this detecting unit is exported, this noise signal is carried out to a smoothing processing to produce a secondary signal to this detecting unit; Wherein, it is this touch signal that this detecting unit is judged this first signal, exports this touch signal for this output signal; It is noise signal that this detecting unit is judged this first signal, and exporting this secondary signal is this output signal.
The utility model also discloses a kind of touch screen control system, includes a touch panel device, has a plurality of detecting points, is used for producing a signal; One mimic channel, be coupled to this touch panel device, is used for carrying out analog signal processing according to the signal corresponding on this touch panel device, each detecting point produces, to produce an analog output signal; One analog digital converting unit, be coupled to this mimic channel, is used for this analog output signal is converted to a first signal, and exports this first signal; One signal processing circuit, be coupled to this analog digital converting unit; And a digital circuit, be coupled to this signal processing circuit, be used for receiving the signal of this signal processing circuit output, and the signal of this signal processing circuit output is carried out to digital signal processing.This signal processing circuit includes a detecting unit, and this first signal received according to a threshold decision is a touch signal or a noise signal and then is exported as an output signal; And an arithmetic element, be coupled to this detecting unit, receive this noise signal that this detecting unit is exported, this noise signal is carried out to a smoothing processing to produce a secondary signal to this detecting unit; Wherein, it is this touch signal that this detecting unit is judged this first signal, exports this first signal for this output signal; This detecting unit judges that this first signal is noise signal, and exporting this secondary signal is this output signal.
The touch screen control system that the utility model provides and its signal processing circuit, passing threshold judges that a first signal is touch signal or noise signal, touch signal is directly exported, noise signal is carried out exporting after smoothing processing again, to widen the signal level gap between Yu Wei touch point, touch point, improve whereby signal to noise ratio (S/N ratio) to promote the detecting degree of accuracy of touch point.
The accompanying drawing explanation
The schematic diagram that Fig. 1 is the utility model embodiment mono-touch screen control system.
Fig. 2 A is that a first signal is subject to noise to produce the schematic diagram that height fluctuates.
To be the utility model embodiment signal processing circuit carry out the schematic diagram of the output signal that smoothing processing produces by first signal shown in Fig. 2 A to Fig. 2 B.
The schematic diagram that Fig. 3 A is another first signal of the utility model embodiment.
Fig. 3 B, 3C and 3D are respectively all signals in the first signal of Fig. 3 A and carry out 4,8 and 16 signal schematic representations that smoothing processing produces.
The schematic diagram of another output signal that Fig. 3 E is the utility model embodiment signal processing circuit of first signal shown in Fig. 3 A being carried out to smoothing processing.
The schematic diagram that Fig. 4 is another touch screen control system of the utility model embodiment.
The schematic diagram of the embodiment that Fig. 5 is signal processing circuit.
Fig. 6 is another touch signal of the utility model embodiment at the waveform schematic diagram of the output terminal of the output terminal of the input end of analog-digital converter, analog-digital converter and signal processing circuit.
The schematic diagram that Fig. 7 is the utility model embodiment mono-signal processing flow.
Wherein, description of reference numerals is as follows:
10 touch screen control systems
102 touch panel devices
104 mimic channels
106 analog-digital converters
108 digital circuits
20 touch screen control systems
200 signal processing circuits
202 detecting units
204 arithmetic elements
206 threshold adjustment unit
ST1, ST3, ST5 first signal
ST2, ST4 secondary signal
OUT1, OUT2 output signal
A1～A3 discrete value
502 circuit for detecting
504 multiplexers
510 buffer units
512 subtrators
514 adder units
516 dividers
REG_1～REG_X, REG_IN, register
REG_OUT
70 flow processs
700～708 steps
Embodiment
Please refer to Fig. 1, the schematic diagram that Fig. 1 is the utility model embodiment mono-touch screen control system 20.As shown in Figure 1, touch screen control system 20 roughly comprises a touch panel device 102, a mimic channel 104, an analog-digital converter (analog-to-digital converter) 106, one signal processing circuit 200 and a digital circuit 108.Mimic channel 104 is coupled to touch panel device 102, and analog-digital converter 106 is coupled to mimic channel 104, and signal processing circuit 200 is coupled between analog-digital converter 106 and digital circuit 108.
Judging first signal ST1 when detecting unit 202 is touch signal, export the output signal OUT1 of this first signal ST1 as signal processing circuit 200, judging first signal ST1 when detecting unit 202 is noise signal, exports the output signal OUT1 of this secondary signal ST2 as signal processing circuit 200.Can judge that when first signal ST1 is positioned at a touch scope this first signal ST1 is touch signal, when first signal ST1 is not positioned at this touch scope, can not judge that this first signal ST1 is noise signal.The touch scope can be set with reference to the output valve (being the numerical value of first signal ST1) of analog-digital converter 106.In general, analog-digital converter 106 can have different discrete values according to the difference of its output figure place.For instance, for the analog-digital converter of 10, each output has 2
10=1024 kinds of possible discrete values.Can be in 0～1023 discrete value, the definitional part discrete value is positioned at the touch scope, and other discrete value is not positioned at the touch scope.For example, when threshold value TH is 600, definable is greater than 600 discrete value and is positioned at the touch scope, is less than 600 discrete value and is not positioned at the touch scope; Perhaps definable is less than 600 discrete value and is positioned at the touch scope, is greater than 600 discrete value and is not positioned at the touch scope.Specifically, if the signal that a specific detecting o'clock is sensed at a special time is judged as while being positioned at the touch scope, mean that this specific detecting point position receives touch at this special time; Otherwise, if the signal that a specific detecting o'clock is sensed at a special time is judged as while not being positioned in the touch scope, mean that this specific detecting point position does not receive touch at this special time.The noise be subject in various degree due to first signal ST1 produces the fluctuation that height rises and falls, and after smoothing processing, can reduce the amplitude of noise signal fluctuation, and then improves signal to noise ratio (S/N ratio) to promote the detecting degree of accuracy of touch point.
Please refer to Fig. 2 A, the longitudinal axis means the discrete value that analog-digital converter 106 is exported, the digital value of the concrete longitudinal axis correspondence that to be voltage signal obtain after analog-digital converter 106 is processed, transverse axis means the difference detecting point position of touch panel device 102, it is corresponding with the scanning detecting time, therefore transverse axis also can mean the time, and its per unit can be considered each signal in first signal ST1.Above-mentioned first signal ST1 is subject to noise to produce the fluctuation just risen and fallen can be with reference to figure 2A.During actual operation, induction electrode in touch panel device 102 is sequentially obtained the induced signal of each detecting point position with scan mode, its can be by row one column scan mode (for instance, swept to last row of touch panel device 102 by the first row of touch panel device 102), or scan by any possible order, therefore, the signal that different detecting point location sensitives arrive, can be orderly sent in signal processing circuit 200 and carry out subsequent treatment, after all detecting points have all scanned once, then restart scanning by first detecting point.The signal that different detecting points are sensed at different time may comprise noise in various degree, and these noises in various degree make first signal ST1 present the state that height rises and falls, as shown in Figure 2 A.It should be noted that, the output signal that the first signal ST1 illustrated in Fig. 2 A is analog-digital converter 106, in other embodiments, first signal ST1 can be any signal that is subject to noise in touch screen control system 20, thus signal processing circuit 200 configurable in the signal transmission path of touch screen control system 20 any position that may be subject to noise.
With reference to figure 1 and Fig. 2 A, as aforementioned, learn, threshold value TH can be used to judge according to first signal ST1 the foundation that no touch is arranged simultaneously.In Fig. 2 A, when the discrete value of first signal ST1, during lower than threshold value TH, in detecting unit 202 judgement touch panel devices 102, specific detecting point receives touch, and now first signal ST1 is touch signal; During higher than threshold value TH, in detecting unit 202 judgement touch panel devices 102, specific detecting point is not received to touch when the discrete value of first signal ST1, now first signal ST1 is noise signal.In other embodiments, in the time of also basis for estimation can being designed to discrete value as first signal ST1 higher than threshold value TH, in detecting unit 202 judgement touch panel devices 102, specific detecting point receives touch; When the discrete value of first signal ST1, during lower than threshold value TH, in detecting unit 202 judgement touch panel devices 102, specific detecting point does not receive touch, and received first signal is noise signal, but design is not limited to this.
Refer again to Fig. 2 A, first signal ST1 obviously has low discrete value between 113rd～142 units, specifically, the maximum discrete value between 113rd～142 units is A1(approximately 350), and be A2(approximately 500 in the smallest discrete value of other unit (below 112 and more than 143)).Thus, threshold value TH can be set between discrete value A1～A2 to arbitrary numerical value of (approximately 350～500), threshold value for the fixed value between discrete value A1～A2 to obtain correct touch judgement.
The utility model can carry out smoothing processing by the above-mentioned first signal ST1 that is judged to be noise signal, makes in first signal ST1, and the height caused due to noise fluctuates and significantly reduces.Please refer to Fig. 2 B, to be the utility model embodiment signal processing circuit 200 carry out the schematic diagram of the output signal OUT1 that smoothing processing produces by first signal ST1 shown in Fig. 2 A to Fig. 2 B.As shown in Fig. 2 B, in output signal OUT1, the height that noise causes fluctuates and reduces manyly, therefore when the maximum discrete value between 113rd～142 units still is A1, in the smallest discrete value of other unit (reaching more than 143 below 112), brings up to A3(approximately 700).Therefore, there is the touch screen control system 20 of signal processing circuit 200 applicable to more diversified, even worse environment.
Yet, when all first signal ST1 are used for carrying out smoothing processing, not only noise significantly reduces, corresponding to the signal that receives touch, reach and also can reduce because of the moving average computing corresponding to the discrete value gap between the signal that does not receive touch.Please refer to the 3A～3D figure, the schematic diagram that Fig. 3 A is another first signal ST3, all carry out 4,8 and 16 signals that smoothing processing produces and Fig. 3 B, 3C and 3D illustrate respectively all signals (being touch signal and noise signal) in the first signal ST3 of Fig. 3 A.Relatively the 3A～3D figure can find, when the signal stroke count that carries out smoothing processing, heals when large, and noise signal is eliminated more smoothly, but touch signal is also significantly eliminated.Therefore, for avoiding reducing because of moving average corresponding to the discrete value gap between the signal that touches and do not touch, carrying out before smoothing processing, must first judging in first signal ST3, whether each signal is touch signal.In other words, utilize detecting unit 202 to judge according to threshold value TH in first signal ST3, whether each signal is positioned at the touch scope, and determine whether this signal is carried out to smoothing processing according to this judged result.When detecting unit 202 judgement first signal ST3 are touch signal, for avoiding smoothing processing to make corresponding to the discrete value gap between the signal that touches and do not touch, reduce, the output signal that can directly to export the first signal ST3 that is judged as touch signal be signal processing circuit 200, and do not carry out smoothing processing.When detecting unit 202 judgement first signal ST3 are noise signal, the first signal ST3 that is judged as noise signal can be sent to arithmetic element 204, carry out smoothing processing to produce a secondary signal ST4 by arithmetic element 204.First signal ST3 is in conjunction with an output signal OUT2 of secondary signal ST4 and then generation signal processing circuit 200.Please refer to Fig. 3 E, Fig. 3 E is the schematic diagram of output signal OUT2 that carries out the signal processing circuit 200 of smoothing processing.As shown in Fig. 3 E, in output signal OUT2, the suffered noise of the output signal OUT2 of signal processing circuit 200 can reduce because of smoothing processing, make signal just rise and fall to flatten slow, but corresponding to the still complete reservation of signal waveform touched occurs.Thus, can optionally to first signal ST3, carry out smoothing processing according to threshold value TH and improve signal to noise ratio (S/N ratio), also can prevent that touch signal is eliminated because of smoothing processing.
From the above, threshold value TH plays the part of epochmaking role in judging whether to carry out the process of smoothing processing.Therefore, be necessary the optimization of design of threshold value TH, to avoid the erroneous judgement between touch signal and noise signal.Threshold value TH can be designed to a discrete value in the discrete value of analog-digital converter 106 output, and preferably, the discrete value of threshold value TH in the middle of can being designed to, make threshold value TH between the signal that touches and do not touch.In part embodiment, threshold value TH also can be adjusted by a threshold adjustment unit.Please refer to Fig. 4, the schematic diagram that Fig. 4 is another touch screen control system 250 of the utility model embodiment.Framework and the touch screen control system shown in Fig. 1 20 of touch screen control system 250 are similar, and therefore intimate assembly or signal mean with same-sign.As shown in Figure 4, touch screen control system 250 is with the Main Differences of touch screen control system 20, touch screen control system 250 also comprises a threshold adjustment unit 206, and threshold adjustment unit 206 is coupled to detecting unit 202, is used for adjusting threshold value TH to adapt to various environment.Before touch screen control system 20 or 250 is brought into use, can design by the test of varying environment best threshold value TH.After the touch screen control system 250 with threshold adjustment unit 206 is brought into use, but passing threshold adjustment unit 206 is adjusted threshold value TH according in one or more detecting point is in the past between a given period, being detected a N obtained N first signal.This N first signal may comprise corresponding to the touch signal touched and corresponding to the noise signal do not touched or only comprise touch signal or only comprise noise signal, signal processing circuit 200 again for N the touch signal of obtaining between this given period and not touch signal obtain respectively maximal value and minimum value (being maximal value and the minimum value that noise causes the first signal fluctuation), and adjust according to this threshold value TH.Thus, threshold value TH can automatically be adjusted to optimum value when external environment change, and then makes touch screen control system 250 adapt to various environment.In addition, threshold value TH also can be designed to a fixed value, and now threshold adjustment unit 206 only must be exported fixed value as threshold value TH, or threshold value TH is included in detecting unit 202 and does not need to use threshold adjustment unit 206.
Specifically, according to the difference of the scope of touch, can carry out the threshold value TH design of different modes and adjust.In part embodiment, when the first signal discrete value received, during lower than threshold value TH, the corresponding detecting point of detecting unit 202 judgement receives touch (being that signal is positioned at the touch scope); And when the first signal discrete value received during higher than threshold value TH, the corresponding detecting point of detecting unit 202 judgement does not receive touch (being that signal is not positioned at the touch scope).But in other embodiments, also can design system to when the first signal discrete value received during higher than threshold value TH, the corresponding detecting point of detecting unit 202 judgement receives touch (being that signal is positioned at the touch scope); And when the first signal discrete value received during lower than threshold value TH, the corresponding detecting point of detecting unit 202 judgement does not receive touch (being that signal is not positioned at the touch scope).Thus, the design of threshold value TH and adjustment must be carried out according to different touch scope definitions.In part embodiment, detecting unit 202 can carry out mark in the first signal of judging, and makes threshold adjustment unit 206 adjust threshold value TH according to the first signal that between a given period, interior detecting unit 202 receives.
For instance, when the touch scope is positioned at the scope that is less than threshold value TH, threshold value TH must be greater than all touch signals, and must be less than all noise signals.All can carry out the adjustment of threshold value TH before touch screen control system 250 is brought into use or after bringing into use.If adjust threshold value TH according to noise signal, threshold value TH must be designed to be less than or equal to the minimum value of all noise signals; If adjust threshold value TH with touch signal, threshold value TH must be designed to be more than or equal to the maximal value of all touch signals.Wherein, preferably embodiment is, threshold value TH is designed to the intermediate value between the maximal value of the minimum value of all noise signals and all touch signals, and retaining buffer area to this minimum value and threshold value TH at threshold value TH between this maximal value, the erroneous judgement probability that makes touch reach between touching reaches minimum.
Otherwise when the touch scope is positioned at the scope that is greater than threshold value TH, threshold value TH must be greater than all noise signals, and must be less than all touch signals.If adjust threshold value TH by noise signal, threshold value TH must be designed to be more than or equal to the maximal value of all noise signals; If adjust threshold value TH with touch signal, threshold value TH must be designed to be less than or equal to the minimum value of all touch signals.Wherein, preferably embodiment is, threshold value TH is designed to the intermediate value between the minimum value of the maximal value of all noise signals and all touch signals, and retaining buffer area to this maximal value and threshold value TH at threshold value TH between this minimum value, the erroneous judgement probability that makes touch reach between touching reaches minimum.
In part embodiment, can when touch panel device 102 dormancy, be considered as between above-mentioned given period adjusting threshold value TH, or within a set time the signal of lasting cumulative amount be all to be considered as between given period time of touch signal, or within a set time lasting accumulating signal be all to be considered as between given period time of noise signal, but be not limited to this.In general, can be considered during touch panel device 102 dormancy without any touch and occur, any signal fluctuation therefore occurred when dormancy is all produced by noise.Specifically, touch screen control system 250 can be according in 102 past of touch panel device, one section dormancy time, one or more detecting point is detected M time, the all M obtained signals are all the noise signal touched corresponding to not, therefore, when the touch scope is positioned at the scope that is less than threshold value TH, must find out M the minimum value in newspaper point signal, and passing threshold adjustment unit 206 adjustment threshold value TH, make threshold value TH be less than this minimum value.When the touch scope is positioned at the scope that is greater than threshold value TH, must find out M the maximal value in newspaper point signal, and passing threshold adjustment unit 206 adjustment threshold value TH, make threshold value TH be greater than this maximal value.
Please refer to Fig. 5, the schematic diagram of the embodiment that Fig. 5 is signal processing circuit 200.As shown in Figure 5, detecting unit 202 comprises a circuit for detecting 502 and a multiplexer 504.Circuit for detecting 502 receives first signal ST1 and threshold value TH, according to threshold value TH, judges that first signal ST1 is touch signal or noise signal.Multiplexer 504 is coupled to circuit for detecting 502, and multiplexer 504 receives first signal ST1, secondary signal ST2, according to the judged result of circuit for detecting 502, selects output first signal ST1 or the secondary signal ST2 output signal OUT1 as signal processing circuit 200.
Please continue to refer to Fig. 5, arithmetic element 204 comprises a buffer unit 510, a subtrator 512, an adder unit 514 and a divider 516, first signal ST1 alleged in arithmetic element 204 is the noise signal for the treatment of smoothing processing, therefore with noise signal, is referred to as it.Arithmetic element 204 also comprises register REG_IN and register REG_OUT, wherein, register REG_IN stores the noise signal of a up-to-date reception, register REG_OUT stores the cumulative total value of noise signal of at every turn wanting to carry out smoothing processing, for example every 10 noise signals are carried out to smoothing processing, buffer unit 510 can be kept in 10 noise signal values, the noise signal that wherein enters the earliest buffer unit 510 is defined as 1, the storage content of register REG_OUT is followed successively by the totalling signal value of noise signal 1～10, the totalling signal value of noise signal 2～11, the totalling signal value of noise signal 3～12, the like.Buffer unit 510 is coupled to circuit for detecting 502, can be used to temporary noise signal of wanting to carry out smoothing processing, when arithmetic element 204 need be carried out the smoothing processing of X signal, buffer unit 510 can comprise X register REG_1～REG_X, and storage is used for wanting to carry out X signal value of smoothing processing respectively.
Adder unit 514 is coupled to divider 516, and the output terminal of adder unit 514 can be coupled to the input end of subtrator 512, adder unit 514 can receive removing operation result and exporting divider 516 to as one first cumulative signal value of subtrator 512, with this example explanation, the storage content that is about to register REG_OUT exports divider 516 to.In addition, adder unit 514 also can by one second cumulative signal value again feedback export subtrator 512 to, this the second cumulative signal value can be the overall result that adds that operation result adds the up-to-date noise signal that enters buffer unit 510 that removes of last subtrator 512, with this example explanation, be that the mobile cumulative signal value of storing in register REG_OUT adds the fresh signal value of storing in register REG_IN, the signal of wherein storing in register REG_IN is a noise signal up-to-date in the first signal ST1 from detecting unit 202, this up-to-date noise signal also is stored in register REG_1, therefore, in part embodiment, also can not use register REG_IN, directly the signal of storing in register REG_1 is sent to adder unit 514, with with register REG_OUT in the signal stored carry out additive operation.Similarly, register REG_OUT storage be the cumulative total value of signal removed after the noise signal that enters the earliest buffer unit 510, with this example explanation, be the register REG_IN that last register REG_OUT adds this and deduct again register REG_X, therefore, in part embodiment, also can not use register REG_OUT, directly allow the input end of adder unit 514 be coupled to the output terminal of subtrator 512, and mobile operation result obtained in subtrator 512 directly is sent to adder unit 514.
Specifically, when signal processing circuit 200 receives a first signal ST1 from analog-digital converter 106, circuit for detecting 502 first judges according to threshold value TH whether first signal ST1 is touch signal.When circuit for detecting 502 judgement first signal ST1 are touch signal, mean that first signal ST1 does not need to carry out smoothing processing.Now, multiplexer 504, according to the judged result of circuit for detecting 502, directly will be judged to be the first signal ST1 output of touch signal, as the output signal OUT1 of signal processing circuit 200.When circuit for detecting 502 judgement first signal ST1 are noise signal, mean that first signal ST1 need carry out smoothing processing, now, the first signal ST1 that circuit for detecting 502 will be judged to be noise signal is sent to register REG_1 and the register REG_IN in the buffer unit 510 in arithmetic element 204.In buffer unit 510, each signal originally be stored in register REG_1～REG_X is transferred into previous register, for instance, originally the signal in register REG_1 is transferred into register REG_2, originally the signal in register REG_2 is transferred into register REG_3, and the signal in register REG_ (X-1) is transferred into register REG_X originally.Signal in register REG_X is transferred into subtrator 512, to carry out subtraction.Subtrator 512 receives from the additive operation result of adder unit 514 and from the signal of register REG_X, subtrator 512 can deduct the former the latter to remove the noise signal that enters the earliest buffer unit 510, then this is removed to operation result sends and be stored in register REG_OUT.Then, adder unit 514 receives from the signal value of register REG_OUT and exports the first cumulative signal value to divider 516.In addition, adder unit 514 will carry out phase from the signal value of register REG_OUT and signal value from register REG_IN again and be exported the second cumulative signal value to subtrator 512, as the subtraction of next stage.Then, divider 516 again by the operation result of adder unit 514 divided by X, process with finishing smooth, and produce secondary signal ST2 to export multiplexer 504 to.Finally, multiplexer 504 according to the judged result of circuit for detecting 502, is exported secondary signal ST2, as the output signal OUT1 of signal processing circuit 200 again.
Wherein, in the operation workflow of above-mentioned arithmetic element 204, the noise signal that the secondary signal ST2 of each output is nearest X pen input arithmetic element 204 adds up the operation result obtained divided by X again.
Please refer to Fig. 6, Fig. 6 is another signal of the utility model embodiment ST5 at the waveform schematic diagram of the output terminal of the output terminal of the input end of analog-digital converter 106, analog-digital converter 106 and signal processing circuit 200.Wherein, transverse axis means the time, and the longitudinal axis of the input end waveform of analog-digital converter 106 means voltage, and the longitudinal axis of the output terminal waveform of the output terminal of analog-digital converter 106 and signal processing circuit 200 means the discrete value that voltage is corresponding.As shown in Figure 6, the signal ST5 of the input end of analog-digital converter 106 is subject to noise, produces the fluctuation that height rises and falls.After by analog-digital converter 106, being converted to the signal of digital form, signal ST5 presents more discrete waveform, but still is subject to the impact of noise and presents height and rise and fall.Now, if can suitably adjust threshold value TH, make threshold value TH higher than corresponding to touch signal maximum lower than the noise signal minimum value, and noise signal is carried out to smoothing processing, for example moving average computing, the signal fluctuation that noise causes can also can be retained corresponding to the signal touched by filtering, and this signal processing results is presented at the waveform of the output terminal of signal processing circuit 200 in Fig. 6.
It should be noted that, main spirits of the present utility model is by touch signal is directly exported, noise signal is carried out exporting after smoothing processing again, to widen the accurate gap in position between touch signal and noise signal, improve whereby signal to noise ratio (S/N ratio) to promote the degree of accuracy of touch point detecting.Those skilled in the art works as and can modify according to this or change, and is not limited to this.For instance, above-mentioned signal processing circuit 200 is configured between analog-digital converter 106 and digital circuit 108, but in other embodiments, signal processing circuit 200 can be configured in to other position in touch screen control system 20 or 250.Clearer and more definite, because signal processing circuit 200 is the signals that are subject to noise for processing, therefore, as long as have noise in environment and signal quality is subject to noise effect, the mode that all can optionally to signal, carry out smoothing processing with the utility model reduces the signal fluctuation that noise causes.Thus, signal processing circuit 200 configurable on the signal transmission path of touch screen control system 20 or 250 any position that may be subject to noise.For instance, signal processing circuit 200 is configurable before analog-digital converter 106, and now signal processing circuit 200 can realize smoothing processing by mimic channel.In addition, the circuit framework in Fig. 5 and smoothing processing flow process also can be carried out various variation or modification.For instance, above-mentioned computing flow process is first carried out subtraction by subtrator 512, then carries out additive operation by the operation result of 514 pairs of subtrators 512 of adder unit.In other embodiments, also can first by adder unit 514, carry out additive operation, then carry out subtraction by the operation result of 512 pairs of adder units 514 of subtrator.No matter by which kind of compute mode, increase to reach the effect that noise when reduces the degree of difficulty of touch point detecting as long as noise can be carried out to smoothing processing, in the scope of all protecting at the utility model.
The running of above-mentioned signal processing circuit 200, can be summarized as a signal processing flow 70.As shown in Figure 7, signal processing flow 70 comprises the following steps:
Step 700: start.
Step 702: according to threshold value TH, judge whether first signal ST1 is a touch signal.If perform step 704; If not, perform step 706.
Step 704: directly export first signal ST1, as the output signal OUT1 of signal processing circuit 200.
Step 706: first signal ST1 is carried out to smoothing processing, and to produce secondary signal ST2, and output secondary signal ST2 is as the output signal OUT1 of signal processing circuit 200.
Step 708: finish.
Detailed operation about signal processing flow 70 can, with reference to above-mentioned explanation, not repeat them here.Wherein noise signal being carried out to smoothing processing comprises noise signal is carried out to simple moving average computing or weight moving average computing to produce a secondary signal with the step that produces a secondary signal.
In one embodiment, when first signal ST1 is less than threshold value TH, judgement first signal ST1 is touch signal, and, when first signal ST1 is greater than threshold value TH, judgement first signal ST1 is noise signal.Perhaps also can set when first signal ST1 is greater than threshold value TH, judgement first signal ST1 is touch signal, and, when first signal ST1 is less than threshold value TH, judgement first signal ST1 is noise signal.Threshold value TH is the fixed value between touch signal maximum and noise signal minimum value, or threshold value TH is the fixed value between touch signal minimum value and noise signal maximal value.
In one embodiment, the signal processing method that the utility model provides also comprises according to first signal ST1 interior between a given period adjusts threshold value TH.Particularly, when the first signal ST1 that is less than threshold value TH in first signal ST1 is judged as touch signal, the step of adjusting threshold value TH according to first signal ST1 interior between this given period includes: the minimum signal value in those noise signals in being adjusted between this given period by threshold value TH, or under the minimum signal value in all noise signals in being adjusted between this given period by threshold value TH; Or the maximum signal level in all touch signals in threshold value TH is adjusted between this given period, or in being adjusted between this given period by threshold value TH on the maximum signal level in all touch signals; Or threshold value TH is adjusted to the maximum signal level of interior all touch signals between this given period and the intermediate value between all those noise signal minimum signal value.When the first signal ST1 that is greater than threshold value TH in first signal ST1 is judged as touch signal, the step of wherein according to the first signal ST1 between this given period, adjusting this threshold value includes: the maximum signal level in the noise signal in being adjusted between this given period by threshold value TH, or on the maximum signal level in the noise signal in being adjusted between this given period by threshold value TH; Or the minimum signal value in the noise signal in being adjusted between this given period by threshold value TH, or under the minimum signal value in the noise signal in being adjusted between this given period by threshold value TH; Or threshold value TH is adjusted to the minimum signal value of interior all touch signals between this given period and the intermediate value between all those noise signal maximum signal levels.
The touch screen control system that the utility model embodiment provides and its signal processing circuit, optionally signal is carried out to smoothing processing, that is passing threshold judgement first signal is touch signal or noise signal, touch signal is directly exported, noise signal is carried out exporting after smoothing processing again, to widen the gap between touch signal position standard and noise signal position standard, improve whereby signal to noise ratio (S/N ratio) to promote the degree of accuracy of touch point detecting.
The foregoing is only preferred embodiment of the present utility model, be not limited to the utility model, for a person skilled in the art, the utility model can have various modifications and variations.All within spirit of the present utility model and principle, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection domain of the present utility model.
Claims (7)
1. the signal processing circuit of a touch screen control system, is characterized in that, includes:
One detecting unit, the first signal received according to a threshold decision is a touch signal or a noise signal and then is exported as an output signal; And
One arithmetic element, be coupled to this detecting unit, receives this noise signal that this detecting unit is exported, and this noise signal is carried out to a smoothing processing to produce a secondary signal to this detecting unit;
Wherein, it is this touch signal that this detecting unit is judged this first signal, exports this first signal for this output signal, and this detecting unit is judged this first signal for this noise signal, and exporting this secondary signal is this output signal.
2. signal processing circuit as claimed in claim 1, it is characterized in that, this signal processing circuit also comprises a threshold adjustment unit, and this threshold adjustment unit is coupled to this detecting unit, according to those first signals that between a given period, interior this detecting unit receives, adjusts this threshold value.
3. signal processing circuit as claimed in claim 1, it is characterized in that, this signal processing circuit also comprises a threshold adjustment unit, this threshold adjustment unit is coupled to this detecting unit, when the first signal that is less than this threshold value in those first signals is judged as touch signal, the mode that this threshold adjustment unit is adjusted this threshold value includes:
This threshold adjustment unit is adjusted into the minimum signal value in those noise signals interior between this given period by this threshold value, maybe this threshold value is adjusted under the minimum signal value in those noise signals interior between this given period; Or
This threshold adjustment unit is adjusted into the maximum signal level in those touch signals interior between this given period by this threshold value, maybe this threshold value is adjusted on the maximum signal level in those touch signals interior between this given period; Or
Intermediate value in this threshold adjustment unit is adjusted to this threshold value between this given period between the minimum signal value of the maximum signal level of all those touch signals and all those noise signals.
4. signal processing circuit as claimed in claim 1, it is characterized in that, this signal processing circuit also comprises a threshold adjustment unit, this threshold adjustment unit is coupled to this detecting unit, when the first signal that is greater than this threshold value in those first signals is judged as touch signal, the mode that this threshold adjustment unit is adjusted this threshold value according to those first signals between this given period includes: the maximum in this threshold adjustment unit those noise signals in being adjusted between this given period by this threshold value
Signal value, maybe be adjusted to this threshold value on the maximum signal level in those touch signals interior between this given period; Or
This threshold adjustment unit is adjusted into the minimum signal value in those touch signals interior between this given period by this threshold value, maybe this threshold value is adjusted under the minimum signal value in those touch signals interior between this given period; Or
Intermediate value in this threshold adjustment unit is adjusted to this threshold value between this given period between the maximum signal level of the minimum signal value of all those touch signals and all those noise signals.
5. signal processing circuit as claimed in claim 1, is characterized in that, this detecting unit includes:
One circuit for detecting, being used for according to this first signal of this threshold decision is this touch signal or this noise signal; And
One multiplexer, be coupled to this circuit for detecting, receives this secondary signal that this first signal and this arithmetic element are exported, and, according to the judged result of this circuit for detecting, select this first signal of output or this secondary signal.
6. signal processing circuit as claimed in claim 1, is characterized in that, this arithmetic element includes:
One buffer unit, be coupled to this circuit for detecting, is used for keeping in a plurality of these noise signals of wanting to carry out the moving average computing;
One subtrator, be coupled to this buffer unit, and the noise signal that enters the earliest this buffer unit in the plurality of noise signal is carried out to subtraction, to remove this noise signal that enters the earliest this buffer unit;
One divider, according to this subtrator remove operation result as dividend, and using in this buffer unit can keep in noise signal quantity as divisor, carry out division arithmetic to produce this secondary signal; And
One adder unit, be coupled to this subtrator and this divider, receive removing operation result and exporting this divider to as one first cumulative signal value of this subtrator, also export one second cumulative signal value to this subtrator, wherein this second cumulative signal value is by the overall result that adds that operation result adds the noise signal that finally enters this buffer unit in the plurality of noise signal that removes of this subtrator.
7. a touch screen control system, is characterized in that, this touch screen control system also includes:
One touch panel device, have a plurality of detecting points, is used for touch sensible produce a signal;
One mimic channel, be coupled to this touch panel device, is used for basis corresponding to every on this touch panel device
The signal that 1 detecting point produces carries out analog signal processing, to produce an analog output signal;
One analog digital converting unit, be coupled to this mimic channel, is used for this analog output signal is converted to a first signal, and exports this first signal;
One signal processing circuit, be coupled to this analog digital converting unit, includes:
One detecting unit, this first signal received according to a threshold decision is a touch signal or a noise signal and then is exported as an output signal; And
One arithmetic element, be coupled to this detecting unit, receives this noise signal that this detecting unit is exported,
This noise signal is carried out to a smoothing processing to produce a secondary signal to this detecting unit;
Wherein, it is this touch signal that this detecting unit is judged this first signal, exports this first signal for this output signal, and it is noise signal that this detecting unit is judged this first signal, and exporting this secondary signal is this output signal; And
One digital circuit, be coupled to this signal processing circuit, is used for receiving this first signal and secondary signal, and this first signal and this secondary signal are carried out to digital signal processing.
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