CN104199581A - Capacitive detection circuit and capacitive detection device based on large C<TP> and small C<TP> - Google Patents
Capacitive detection circuit and capacitive detection device based on large C<TP> and small C<TP> Download PDFInfo
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- CN104199581A CN104199581A CN201410437122.7A CN201410437122A CN104199581A CN 104199581 A CN104199581 A CN 104199581A CN 201410437122 A CN201410437122 A CN 201410437122A CN 104199581 A CN104199581 A CN 104199581A
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Abstract
The invention relates to the field of electronics, and discloses a capacitive detection circuit and a capacitive detection device based on a large C<TP> and a small C<TP>. The circuit comprises the on-screen capacitors C<TP>, a feedback capacitor C<f> and an operational amplifier and further comprises a programmable capacitor array C<s>, a first charging switch, a second charging switch, a first change-over switch and a second change-over switch, one end of each C<TP> is connected with first bias voltage through the first charging switch and connected with the negative input end of the operational amplifier through the first change-over switch, and the other end of each C<TP> is grounded; one end of the C<s> is connected with second bias voltage through the second charging switch and connected with the negative input end of the operational amplifier through the second change-over switch, and the other end of the C<s> is grounded; the first bias voltage is lower than the second bias voltage. The output common mode level of the operational amplifier is adjusted through the newly added C<s>, the oscillation amplitude of the output common mode level is enlarged, and capacitive detection sensitivity is improved.
Description
Technical field
The present invention relates to electronic applications, particularly based on large C
tPcapacitive detection circuit, based on little C
tPcapacitive detection circuit and capacitance detecting device.
Background technology
In recent years, capacitive touch screen, due to advantages such as it are simple to operation, and transmittance is high, wear-resisting, finds broad application in the design of intelligent terminal, as single-point touches, multiple point touching etc.The variation that capacitive touch screen mainly shields electric capacity by detection detects the generation that whether has touch.Along with the development of capacitance technology, its sensitivity and precision all to be had higher requirement, position how to judge accurately slight touch point becomes the current problem that needs solution.
In prior art, as shown in Figure 1, testing circuit mainly comprises capacitor C on a screen
tP, feedback capacity C
fand an operational amplifier 101, capacitance detecting process is mainly divided into charging and two kinds of patterns of conversion, utilizes charge switch 104, switch 105 and charge switch 106 to control.Specifically, in charge mode, charge switch 104 and charge switch 106 closures, switch 105 is opened, and its circuit connects as shown in Figure 2, in this pattern, built-in bias voltage V
tPto shielding upper capacitor C
tPcharge, and feedback capacity C
fin cleared condition; And in translative mode, charge switch 104 and charge switch 106 are opened, switch 105 closures, circuit structure as shown in Figure 3, utilizes law of conservation of charge can obtain amplifier and is output as:
If now shield upper capacitance variations △ C
tP, the exporting change of amplifier is:
Due in actual design application, consider the finished product of chip, C
tPcapital is much larger than C
fso,
value just larger, again due to V
oUTvariation range be (0, V to the maximum
dD), according to above formula (1), can obtain, for guaranteeing V
oUTdo not exceed amplifier output area, (V
tP-V
cM) need be very little, then according to △ Q=(V
cM-V
tP) △ C
tPcan obtain, the variation range of △ Q can be due to (V
tP-V
cM) restriction and become very little, the input signal-to-noise ratio while touch detecting is reduced, antijamming capability declines, and causes the sensitvity constraint of capacitance detecting.
Summary of the invention
The object of the present invention is to provide a kind of based on large C
tP, little C
tPcapacitive detection circuit and capacitance detecting device, make capacitive detection circuit can expand the output common mode level amplitude of oscillation, improve capacitance detecting sensitivity.
For solving the problems of the technologies described above, it is a kind of based on large C that embodiments of the present invention provide
tPcapacitive detection circuit, comprise: capacitor C on screen
tP, feedback capacity Cf and an operational amplifier; Described based on large C
tPcapacitive detection circuit also comprise: programmable capacitor array Cs, the first charge switch, the second charge switch, the first switch and the second switch;
Described C
tPone end by described the first charge switch, be connected with the first bias voltage, and by described the first switch, be connected described C with the negative input end of described operational amplifier
tPother end ground connection;
One end of described Cs is connected with the second bias voltage by described the second charge switch, and is connected with the negative input end of described operational amplifier by described the second switch, the other end ground connection of described Cs;
Wherein, described the first bias voltage is less than described the second bias voltage.
It is a kind of based on little C that embodiments of the present invention also provide
tPcapacitive detection circuit, comprise: capacitor C on screen
tP, feedback capacity Cf and an operational amplifier; Described based on little C
tPcapacitive detection circuit also comprise: programmable capacitor array Cs, the first charge switch, the second charge switch, the first switch and the second switch;
Described C
tPone end by described the first charge switch, be connected with the second bias voltage, and by described the first switch, be connected described C with the negative input end of described operational amplifier
tPother end ground connection;
One end of described Cs is connected with the first bias voltage by described the second charge switch, and is connected with the negative input end of described operational amplifier by described the second switch, the other end ground connection of described Cs;
Wherein, described the first bias voltage is less than described the second bias voltage.
Embodiments of the present invention also provide a kind of capacitance detecting device, comprise: described above based on large C
tPcapacitive detection circuit and described above based on little C
tPcapacitive detection circuit, also comprise a selector switch;
Capacitor C on screen
tPvalue while being greater than the value of programmable capacitor array Cs, described selector switch is communicated with described based on large C
tPcapacitive detection circuit;
Capacitor C on screen
tPvalue while being less than the value of programmable capacitor array Cs, described selector switch is communicated with described based on little C
tPcapacitive detection circuit.
Embodiment of the present invention in terms of existing technologies, has increased programmable capacitor array Cs, in the charging stage of capacitance detecting, utilizes different bias voltages to C
tPcharge respectively with Cs, at the translate phase of capacitance detecting, can utilize capacitor C on Cs absorbing screen
tPpartial charge, with this, regulate the output common mode level of amplifier, expand the output common mode level amplitude of oscillation, improve capacitance detecting sensitivity.
As further improvement, described based on large C
tPcapacitive detection circuit also comprise: the 3rd charge switch, the 4th charge switch and the 3rd switch; Described the 3rd charge switch ground connection is passed through in one end of described Cf, and is connected with the negative input end of described operational amplifier by described the 3rd switch, and the other end of described Cf is connected with the negative input end of described operational amplifier by described the 4th charge switch.
Utilize charge switch and switch to regulate the connection of Cf, make in the charging stage, the output voltage that utilizes amplifier charges for Cf, and Cf is reversed the certain electric weight of preliminary filling, can further expand the variation range of output common mode level.
As further improvement, described based on large C
tPcapacitive detection circuit also comprise: the 5th charge switch, the 6th charge switch, the 7th charge switch, the 4th switch and the 5th switch; Described the 5th charge switch ground connection is passed through in one end of described Cf, and is connected with the negative input end of described operational amplifier by described the 4th switch; The other end of described Cf connects the 3rd bias voltage Vs by described the 6th charge switch, and is connected with the output terminal of described operational amplifier by described the 5th switch; Between the negative input end of described operational amplifier and output terminal, by described the 7th charge switch, connect.
Utilize charge switch and switch to regulate the connection of Cf, make in the charging stage, utilize a controlled bias voltage Vs to charge for Cf, Cf is reversed the certain electric weight of preliminary filling, when further expanding the variation range of output common mode level, make variation range more controlled.
Accompanying drawing explanation
Fig. 1 is according to the capacitive detection circuit structural drawing in background technology;
Fig. 2 is the charged state structural drawing according to the capacitive detection circuit in background technology;
Fig. 3 is the transition status structural drawing according to the capacitive detection circuit in background technology;
Fig. 4 be according in the first embodiment based on large C
tPcapacitive detection circuit structural drawing;
Fig. 5 be according in the first embodiment based on large C
tPcapacitive detection circuit charged state structural drawing;
Fig. 6 be according in the first embodiment based on large C
tPcapacitive detection circuit transition status structural drawing;
Fig. 7 be according in the second embodiment based on large C
tPcapacitive detection circuit structural drawing;
Fig. 8 be according in the 3rd embodiment based on large C
tPcapacitive detection circuit structural drawing;
Fig. 9 be according in the 4th embodiment based on little C
tPcapacitive detection circuit structural drawing;
Figure 10 be according in the 5th embodiment based on little C
tPcapacitive detection circuit structural drawing;
Figure 11 be according in the 6th embodiment based on little C
tPcapacitive detection circuit structural drawing;
Figure 12 is according to the capacitance detecting device structured flowchart in the 7th embodiment;
Figure 13 is according to the capacitance detecting device circuit structure diagram in the 7th embodiment.
Embodiment
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, the embodiments of the present invention are explained in detail.Yet, persons of ordinary skill in the art may appreciate that in each embodiment of the present invention, in order to make reader understand the application better, many ins and outs have been proposed.But, even without these ins and outs and the many variations based on following embodiment and modification, also can realize each claim of the application technical scheme required for protection.
The present inventor's discovery, in existing capacitive detection circuit application, the capacitor C that different touch screens is corresponding
tPvariation larger, for making the wider range of application that has of the present invention.Can make full use of C
tPthe adjusting of charging level, makes the capacitance range maximum detecting.In addition, because the upper electric capacity of screen is large or hour, the variation range of its output common mode level may be different, if design is for the capacitive detection circuit of the upper capacitance of difference screen, can fully amplify the out-put dynamic range of operational amplifier, due to tester, can rule of thumb to know on the screen of capacitance plate of application that capacitance is roughly large or little again, so according to electric capacity capacitance on different screens, design different capacitive detection circuits, can effectively expand the variation range of output common mode level.
The first embodiment of the present invention relates to a kind of based on large C
tPcapacitive detection circuit, its circuit structure as shown in Figure 4, specifically comprises: capacitor C on screen
tP, feedback capacity Cf, operational amplifier 101, resistance 102, electric capacity 103, programmable capacitor array Cs, the first charge switch 201, the second charge switch 203, charge switch 205, the first switch 202 and the second switch 204.
In present embodiment based on large C
tPcapacitive detection circuit concrete connect as follows: resistance 102 is connected to operational amplifier 101 positive input terminals and bias voltage V
cMbetween, electric capacity 103 is connected between operational amplifier 101 positive input terminals and earth terminal; Cf is connected between the negative input end and output terminal of operational amplifier 101, charge switch 205 is connected in parallel on to the two ends of Cf simultaneously; C
tPone end by the first charge switch 201, be connected with the first bias voltage V1, and by the first switch 202, be connected C with the negative input end of operational amplifier 101
tPother end ground connection; One end of Cs is connected with the second bias voltage V2 by the second charge switch 203, and is connected with the negative input end of operational amplifier 101 by the second switch 204, the other end ground connection of Cs.It should be noted that, the first bias voltage V1 in present embodiment is less than the second bias voltage V2.
In actual applications, in the charging stage, by the first charge switch 201, the second charge switch 203 and charge switch 205 closures, the first switch 202 and the second switch 204 are opened respectively, and circuit construction variations is for as shown in Figure 5; Now, C
tPbe connected between the first bias voltage V1 and earth terminal, Cf two terminal shortcircuits connect, and the first bias voltage V1 is C
tPcharging, the second bias voltage V2 is Cs charging, simultaneously Cf zero clearing.At translate phase, respectively the first charge switch 201, the second charge switch 203 and charge switch 205 are opened, the first switch 202 and the second switch 204 closures, circuit construction variations is for as shown in Figure 6; C
tPbe connected between the negative input end and earth terminal of operational amplifier 101, Cs is connected between the negative input end and earth terminal of operational amplifier 101, and Cf is directly connected between the negative input end and output terminal of operational amplifier 101, C
tPelectric charge be passed to respectively Cf and Cs.
Specifically, in present embodiment based on large C
tPcapacitive detection circuit at translate phase, according to the short characteristic of the void of charge conservation and amplifier, can obtain the output of final amplifier as shown in the formula (3):
If electric capacity is changed to C on screen
tP+ △ C
tP, the exporting change of amplifier is following formula (4)
From above formula (3) formula, can find out capacitor C on screen
tPa part of electric charge will be by capacitor array C
sabsorb, thereby the output common mode level of amplifier can simply regulate, namely by regulating C
sthe size restriction of DC operation state to output common mode level that carry out bucking circuit.Therefore, when circuit carries out testing, need to be to programmable capacitor array C
scarry out initialized " frequency modulation " process, its object is exactly in order to make amplifier be output as common mode electrical level V
cM, namely make the V in formula (3)
oUT=V
cM.Now, above formula (4) can be changed to following formula (5):
(V wherein
cM-V
1) can be unrestricted and increase, that is to say, the variation of output common mode level will not be subject to the DC operation state restriction of circuit and expand, and also just improve the sensitivity of capacitive detection circuit.
In addition, due to V
oUT=V
cM, can obtain following formula (6):
In the present embodiment, general large C
tPbe interpreted as that its capacitance meets C
tP>C
s, its dynamic output area is from V
cMto V
dD, can be by reducing common mode electrical level V
cMregulate the direct-current working volts of amplifier.
For instance, suppose now C
tP=80
pf (capacitance is larger), meanwhile, can arrange V
1=0, V
2=V
dD, V
cM=V
dD/ 3, C
s=40
pf makes amplifier output V
oUT=V
cM.After this when having finger touch, on screen, electric capacity increases △ C
tP, amplifier output increases
due to common mode electrical level V now
cM=V
dD/ 3, the dynamic detection range of its output is from V
dD/ 3 to V
dD, maximum can have 2*V
dD/ 3 variable quantity, thereby can be by regulating C
fstrengthen the sensitivity of detection, known according to above formula (5), its size is:
Wherein, △ C
tP, maxfor shielding the amplitude of variation of upper electric capacity maximum.
Can obtain final electric capacity to the conversion gain of voltage is
Present embodiment in terms of existing technologies, has increased programmable capacitor array Cs, in the charging stage of capacitance detecting, utilizes different bias voltages to C
tPcharge respectively with Cs, at the translate phase of capacitance detecting, can utilize capacitor C on Cs absorbing screen
tPpartial charge, with this, eliminate the impact of circuit DC operation state on the out-put dynamic range of capacitive detection circuit, regulate the output common mode level of amplifier, expand the output common mode level amplitude of oscillation, improve detection sensitivity.
The second embodiment of the present invention relates to a kind of based on large C
tPcapacitive detection circuit.The second embodiment is on the basis of the first embodiment, to have done further improvement, and main improvements are: in the charging stage of the first embodiment, Cf two terminal shortcircuits connect, and make Cf zero clearing.And in second embodiment of the invention, utilize charge switch and switch to regulate the connection of Cf, make in the charging stage, the output voltage that utilizes amplifier charges for Cf, Cf is reversed the certain electric weight of preliminary filling, can further expand the variation range of output common mode level.
Specifically, in present embodiment based on large C
tPcapacitive detection circuit as shown in Figure 7, also comprise: the 3rd charge switch 206, the 4th charge switch 208 and the 3rd switch 207; The 3rd charge switch 206 ground connection are passed through in one end of Cf, and are connected with the negative input end of operational amplifier 101 by the 3rd switch 207, and the other end of Cf is connected with the negative input end of operational amplifier 101 by the 4th charge switch 208.
Because Cf is connected in the charging stage between the output and ground of amplifier, namely in the charging stage, Cf by preliminary filling reverse electric charge, according to the short characteristic of the void of charge conservation and amplifier, can obtain equally V
oUTvariation lower limit will be lower, its variation range is also just larger, in present embodiment based on large C
tPthe sensitivity of capacitive detection circuit will be higher.
The 3rd embodiment of the present invention relates to a kind of based on large C equally
tPcapacitive detection circuit.The 3rd embodiment is on the basis of the first embodiment, to have done further improvement, and main improvements are: in the first embodiment, charging stage Cf two terminal shortcircuits connect, and make Cf zero clearing.And in third embodiment of the invention, utilizing controlled bias voltage Vs to charge for Cf, Cf is reversed the certain electric weight of preliminary filling, when further expanding the variation range of output common mode level, makes variation range more controlled.
The present inventor finds, in the second embodiment, although the output of amplifier is adjusted to (V
cM～V
dD), its amplitude of oscillation still leaves certain allowance, can be by making full use of C
fthe quantity of electric charge of pre-punching, so that the further amplitude of oscillation that increases output.
Specifically, in present embodiment based on large C
tPcapacitive detection circuit as shown in Figure 8, also comprise: the 5th charge switch 212, the 6th charge switch 210, the 7th charge switch 213, the 4th switch 209 and the 5th switch 211.Wherein, the 5th charge switch 212 ground connection are passed through in one end of Cf, and are connected with the negative input end of operational amplifier 101 by the 4th switch 209; The other end of Cf connects the 3rd bias voltage Vs by the 6th charge switch 210, and is connected with the output terminal of operational amplifier 101 by the 5th switch 211; Between the negative input end of operational amplifier 101 and output terminal, by the 7th charge switch 213, connect.
Similar to the second embodiment, because Cf is connected between the output and ground of amplifier in the charging stage, namely in the charging stage, Cf by preliminary filling reverse electric charge, according to the short characteristic of the void of charge conservation and amplifier, above formula (3) can be changed to equally:
Visible, the output of amplifier becomes (V
cM-V
s～V
dD), V
oUTlower limit will be lower, its variation range is also just larger, sensitivity further improves.
For instance, if now establish V
cM=V
s=V
dD/ 2, the amplitude of oscillation of amplifier can reach (0～V
dD).
The 4th embodiment of the present invention relates to a kind of based on little C
tPcapacitive detection circuit, its circuit structure as shown in Figure 9, specifically comprises: capacitor C on screen
tP, feedback capacity Cf, operational amplifier 101, resistance 102, electric capacity 103, programmable capacitor array Cs, the first charge switch 201, the second charge switch 203, charge switch 205, the first switch 202 and the second switch 204.
Because capacitive detection circuit in present embodiment is based on little C
tPcapacitive detection circuit, its syndeton is compared with the first embodiment, difference be only that be C in the charging stage by the second bias voltage V2
tPcharging, is that Cs charges by the first bias voltage V1, due at little C
tPdetection prerequisite under, for guaranteeing the normal work of amplifier, need to make as C
tPthe bias voltage of charging is greater than the bias voltage into Cs charging.Other syndetons and design concept are all similar with the first embodiment, do not repeat them here.
The 5th embodiment of the present invention relates to a kind of based on little C
tPcapacitive detection circuit.The 5th embodiment is on the basis of the 4th embodiment, to have done further improvement, and main improvements are: in the 4th embodiment, charging stage Cf two terminal shortcircuits connect, and make Cf zero clearing.And in fifth embodiment of the invention, utilize charge switch and switch to regulate the connection of Cf, make in the charging stage, the output voltage that utilizes amplifier charges for Cf, Cf is reversed the certain electric weight of preliminary filling, can further expand the variation range of output common mode level.
Specifically, in present embodiment based on little C
tPcapacitive detection circuit circuit as shown in figure 10, the Fig. 7 in its syndeton and the second embodiment is roughly the same, the key distinction is, in present embodiment, based on little C
tPcapacitive detection circuit also comprise: the 3rd charge switch 206, the 4th charge switch 208 and the 3rd switch 207; The 3rd charge switch ground connection is passed through in one end of Cf, and is connected with the negative input end of operational amplifier by the 3rd switch, and the other end of Cf is connected with the negative input end of operational amplifier by the 4th charge switch.In charging stage, be C
tPthe bias voltage of charging is greater than the bias voltage into Cs charging.That is to say, in the charging stage, the output voltage that utilizes amplifier charges for Cf, and Cf is reversed the certain electric weight of preliminary filling; At translate phase, its connection is identical with the Fig. 6 in the first embodiment, can obtain final amplifier be output as according to the short characteristic of the void of charge conservation and amplifier:
Now, if the upper electric capacity of screen is changed to C
tP+ △ C
tP, the exporting change of amplifier is:
Now, for regulating amplifier output common mode level, need to make C
smeet:
For instance, suppose that needing the capacitance size detecting is C
tP=20
pf, now can arrange V
1=0, V
2=V
dD, V
cM=V
dD/ 3, C
s=40
pf makes amplifier output V
oUT=2*V
cM.From (8) formula, can find out, if now the upper electric capacity of screen increases △ C
tP, amplifier output will reduce
due to amplifier now, exporting DC level is 2*V
dD/ 3, its output still has 2*V
dD/ 3 dynamic detection range, feedback capacity C now
fsize can be set to:
△ C wherein
tP, maxfor now shielding the amplitude of variation of upper electric capacity maximum.
If establish V
cM=V
dD/ 2, the output voltage swing of amplifier can reach from V
dDmaximum magnitude to 0.
The 6th embodiment of the present invention relates to a kind of based on little C equally
tPcapacitive detection circuit.The 6th embodiment is on the basis of the 4th embodiment, to have done further improvement, and main improvements are: in the charging stage of the 4th embodiment, Cf two terminal shortcircuits connect, and make Cf zero clearing.And in charging stage in sixth embodiment of the invention, utilizing controlled bias voltage Vs to charge for Cf, Cf is reversed the certain electric weight of preliminary filling, when further expanding the variation range of output common mode level, makes variation range more controlled.
Specifically, in present embodiment based on little C
tPcapacitive detection circuit as shown in figure 11, the Fig. 8 in its syndeton and the 3rd embodiment is roughly the same, the key distinction is, in present embodiment based on little C
tPcapacitive detection circuit also comprise: the 5th charge switch 212, the 6th charge switch 210, the 7th charge switch 213, the 4th switch 209 and the 5th switch 211.Wherein, the 5th charge switch 212 ground connection are passed through in one end of Cf, and are connected with the negative input end of operational amplifier 101 by the 4th switch 209; The other end of Cf connects the 3rd bias voltage Vs by the 6th charge switch 210, and is connected with the output terminal of operational amplifier 101 by the 5th switch 211; Between the negative input end of operational amplifier 101 and output terminal, by the 7th charge switch 213, connect.In charging stage, be C
tPthe bias voltage of charging is greater than the bias voltage into Cs charging.
That is to say, in the charging stage, utilize controlled a 3rd bias voltage Vs to charge for Cf; At translate phase, its connection is identical with the Fig. 6 in the first embodiment, can obtain V according to the short characteristic of the void of charge conservation and amplifier
oUTvariation lower limit in lower by controlled, its variation range is also just larger, sensitivity further improves.
The 7th embodiment of the present invention relates to a kind of capacitance detecting device.Its structured flowchart as shown in figure 12, specifically comprises: as in the first embodiment to the three embodiments any one based on large C
tPcapacitive detection circuit and as the 4th embodiment to the six embodiments in any one based on little C
tPcapacitive detection circuit, also comprise a selector switch.Utilize selector switch to integrate based on large C
tPcapacitive detection circuit and based on little C
tPcapacitive detection circuit, make capacitance detecting chip when producing, components and parts wherein can be multiplexing in a large number, meanwhile, also can be according to different C
tPvalue, changes capacitive detection circuit flexibly, expands its application scenarios.
Specifically, capacitor C on screen
tPvalue while being greater than the value of programmable capacitor array Cs, selector switch is communicated with based on large C
tPcapacitive detection circuit; Capacitor C on screen
tPvalue while being less than the value of programmable capacitor array Cs, selector switch is communicated with based on little C
tPcapacitive detection circuit.
It should be noted that, because capacitance detecting technician can rule of thumb be known C
tPvalue approximate range, also can utilize analog switch to realize the function of selector switch in present embodiment, in present embodiment, with utilize in the first embodiment based on large C
tPcapacitive detection circuit and the 4th embodiment in based on little C
tPcapacitive detection circuit be example, as shown in figure 13, specifically, the selector switch 30 in present embodiment can comprise its structure: the first switch 301, second switch 302, the 3rd switch 303 and the 4th switch 304; Wherein, the second bias voltage V2 is connected with the first charge switch 201 by the first switch 301, and the second bias voltage V2 is connected with the second charge switch 203 by second switch 302; The first bias voltage V1 is connected with the first charge switch 201 by the 3rd switch 303, and the second bias voltage V2 is connected with the second charge switch 203 by the 4th switch 304.
In actual applications, in second switch 302 and the 3rd switch 303 closures, when the first switch 301 and the 4th switch 304 are opened, be communicated with the first capacitive detection circuit; At second switch 302 and the 3rd switch 303, open, when the first switch 301 and the 4th switch 304 are closed, be communicated with the second capacitive detection circuit.
It is worth mentioning that, the selector switch in present embodiment can also utilize digital control scheme to realize, first to C
tPvalue detect, judge its size, then be communicated with different capacitive detection circuits.
Persons of ordinary skill in the art may appreciate that the respective embodiments described above are to realize specific embodiments of the invention, and in actual applications, can to it, do various changes in the form and details, and without departing from the spirit and scope of the present invention.
Claims (8)
1. one kind based on large C
tPcapacitive detection circuit, comprise: capacitor C on screen
tP, feedback capacity Cf and an operational amplifier; It is characterized in that, described based on large C
tPcapacitive detection circuit also comprise: programmable capacitor array Cs, the first charge switch, the second charge switch, the first switch and the second switch;
Described C
tPone end by described the first charge switch, be connected with the first bias voltage, and by described the first switch, be connected described C with the negative input end of described operational amplifier
tPother end ground connection;
One end of described Cs is connected with the second bias voltage by described the second charge switch, and is connected with the negative input end of described operational amplifier by described the second switch, the other end ground connection of described Cs;
Wherein, described the first bias voltage is less than described the second bias voltage.
2. according to claim 1 based on large C
tPcapacitive detection circuit, it is characterized in that, described based on large C
tPcapacitive detection circuit also comprise: the 3rd charge switch, the 4th charge switch and the 3rd switch;
Described the 3rd charge switch ground connection is passed through in one end of described Cf, and is connected with the negative input end of described operational amplifier by described the 3rd switch, and the other end of described Cf is connected with the negative input end of described operational amplifier by described the 4th charge switch.
3. according to claim 1 based on large C
tPcapacitive detection circuit, it is characterized in that, described based on large C
tPcapacitive detection circuit also comprise: the 5th charge switch, the 6th charge switch, the 7th charge switch, the 4th switch and the 5th switch;
Described the 5th charge switch ground connection is passed through in one end of described Cf, and is connected with the negative input end of described operational amplifier by described the 4th switch;
The other end of described Cf connects the 3rd bias voltage Vs by described the 6th charge switch, and is connected with the output terminal of described operational amplifier by described the 5th switch;
Between the negative input end of described operational amplifier and output terminal, by described the 7th charge switch, connect.
4. one kind based on little C
tPcapacitive detection circuit, comprise: capacitor C on screen
tP, feedback capacity Cf and an operational amplifier; It is characterized in that, described based on little C
tPcapacitive detection circuit also comprise: programmable capacitor array Cs, the first charge switch, the second charge switch, the first switch and the second switch;
Described C
tPone end by described the first charge switch, be connected with the second bias voltage, and by described the first switch, be connected described C with the negative input end of described operational amplifier
tPother end ground connection;
One end of described Cs is connected with the first bias voltage by described the second charge switch, and is connected with the negative input end of described operational amplifier by described the second switch, the other end ground connection of described Cs;
Wherein, described the first bias voltage is less than described the second bias voltage.
5. according to claim 4 based on little C
tPcapacitive detection circuit, it is characterized in that, described based on little C
tPcapacitive detection circuit also comprise: the 3rd charge switch, the 4th charge switch and the 3rd switch;
Described the 3rd charge switch ground connection is passed through in one end of described Cf, and is connected with the negative input end of described operational amplifier by described the 3rd switch, and the other end of described Cf is connected with the negative input end of described operational amplifier by described the 4th charge switch.
6. according to claim 4 based on little C
tPcapacitive detection circuit, it is characterized in that, described based on little C
tPcapacitive detection circuit also comprise: the 5th charge switch, the 6th charge switch, the 7th charge switch, the 4th switch and the 5th switch;
Described the 5th charge switch ground connection is passed through in one end of described Cf, and is connected with the negative input end of described operational amplifier by described the 4th switch;
The other end of described Cf connects the 3rd bias voltage Vs by described the 6th charge switch, and is connected with the output terminal of described operational amplifier by described the 5th switch;
Between the negative input end of described operational amplifier and output terminal, by described the 7th charge switch, connect.
7. a capacitance detecting device, is characterized in that, comprises: as described in any one in claims 1 to 3 based on large C
tPcapacitive detection circuit and as described in any one in claim 4 to 6 based on little C
tPcapacitive detection circuit, also comprise a selector switch;
Capacitor C on screen
tPvalue while being greater than the value of programmable capacitor array Cs, described selector switch is communicated with described based on large C
tPcapacitive detection circuit;
Capacitor C on screen
tPvalue while being less than the value of programmable capacitor array Cs, described selector switch is communicated with described based on little C
tPcapacitive detection circuit.
8. capacitive detection circuit according to claim 7, is characterized in that, described selector switch comprises: the first switch, second switch, the 3rd switch and the 4th switch;
Described the second bias voltage is connected with described the first charge switch by described the first switch, and described the second bias voltage is connected with described the second charge switch by described second switch;
Described the first bias voltage is connected with described the first charge switch by described the 3rd switch, and described the second bias voltage is connected with described the second charge switch by described the 4th switch.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106553431A (en) * | 2016-10-25 | 2017-04-05 | 广州市爱司凯科技股份有限公司 | The plate adjustment of the printing plate of CTP platemaking machine detects circuit and detection method in place |
| WO2019183922A1 (en) * | 2018-03-30 | 2019-10-03 | 深圳市为通博科技有限责任公司 | Capacitive detection circuit, touch detection apparatus, and terminal device |
| TWI714007B (en) * | 2018-04-06 | 2020-12-21 | 美商高通公司 | Self capacitance drive offset cancellation in touch controller integrated circuits |
| TWI727558B (en) * | 2018-12-26 | 2021-05-11 | 南韓商樂金顯示科技股份有限公司 | Touch circuit, touch display device and driving method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080191714A1 (en) * | 2007-02-08 | 2008-08-14 | Denso Corporation | Capacitive physical quantity detection device |
| CN101556297A (en) * | 2008-04-08 | 2009-10-14 | 瑞鼎科技股份有限公司 | Capacitance value measuring circuit and measuring method thereof |
| TW201118387A (en) * | 2009-11-19 | 2011-06-01 | Raydium Semiconductor Corp | Capacitance measurement circuit and method therefor |
| JP2013088382A (en) * | 2011-10-21 | 2013-05-13 | Asahi Kasei Electronics Co Ltd | Electrostatic capacitance detection circuit and signal processing circuit for touch sensor |
| TW201337279A (en) * | 2012-03-05 | 2013-09-16 | Mstar Semiconductor Inc | Device for detecting capacitance and capacitive-type touch control system utilizing the same |
-
2014
- 2014-08-29 CN CN201410437122.7A patent/CN104199581B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080191714A1 (en) * | 2007-02-08 | 2008-08-14 | Denso Corporation | Capacitive physical quantity detection device |
| CN101556297A (en) * | 2008-04-08 | 2009-10-14 | 瑞鼎科技股份有限公司 | Capacitance value measuring circuit and measuring method thereof |
| TW201118387A (en) * | 2009-11-19 | 2011-06-01 | Raydium Semiconductor Corp | Capacitance measurement circuit and method therefor |
| JP2013088382A (en) * | 2011-10-21 | 2013-05-13 | Asahi Kasei Electronics Co Ltd | Electrostatic capacitance detection circuit and signal processing circuit for touch sensor |
| TW201337279A (en) * | 2012-03-05 | 2013-09-16 | Mstar Semiconductor Inc | Device for detecting capacitance and capacitive-type touch control system utilizing the same |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106553431A (en) * | 2016-10-25 | 2017-04-05 | 广州市爱司凯科技股份有限公司 | The plate adjustment of the printing plate of CTP platemaking machine detects circuit and detection method in place |
| WO2019183922A1 (en) * | 2018-03-30 | 2019-10-03 | 深圳市为通博科技有限责任公司 | Capacitive detection circuit, touch detection apparatus, and terminal device |
| US10698550B2 (en) | 2018-03-30 | 2020-06-30 | Shenzhen Weitongbo Technology Co., Ltd. | Capacitance detection circuit, touch detection device and terminal device |
| TWI714007B (en) * | 2018-04-06 | 2020-12-21 | 美商高通公司 | Self capacitance drive offset cancellation in touch controller integrated circuits |
| TWI727558B (en) * | 2018-12-26 | 2021-05-11 | 南韓商樂金顯示科技股份有限公司 | Touch circuit, touch display device and driving method thereof |
| US11221700B2 (en) | 2018-12-26 | 2022-01-11 | Lg Display Co., Ltd. | Touch circuit, touch display device and driving method thereof |
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