CN213987461U - Basic capacitance compensation circuit, chip, touch display and information processing device - Google Patents
Basic capacitance compensation circuit, chip, touch display and information processing device Download PDFInfo
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- CN213987461U CN213987461U CN202023049691.4U CN202023049691U CN213987461U CN 213987461 U CN213987461 U CN 213987461U CN 202023049691 U CN202023049691 U CN 202023049691U CN 213987461 U CN213987461 U CN 213987461U
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Abstract
A basic capacitance compensation circuit, a chip, a touch display screen and an information processing device comprise a current power supply conversion circuit, a pull-up circuit and a pull-down circuit, wherein the current power supply conversion circuit is provided with a current input end, an excitation signal input end and a voltage output end; the current input end is respectively connected with one end of the pull-up circuit and one end of the pull-down circuit and is connected to the basic capacitor of the touch screen; the excitation signal input end is connected with an excitation signal; the other end of the pull-up circuit is connected with the positive electrode of the power supply; the other end of the pull-down circuit is connected with the negative electrode of the power supply. The basic capacitance compensation circuit of the invention adopts the polysilicon resistor or the MOS resistor and the corresponding switch time sequence as the compensation circuit to compensate the basic capacitance, thereby reducing the area of the chip and the cost of the chip.
Description
Technical Field
The invention relates to the technical field of integrated circuit design, in particular to a control circuit of a capacitive touch screen.
Background
Because the capacitance to ground of the capacitive touch screen is very large, the inherent basic capacitance of the touch screen is eliminated in a self-capacitance type touch screen controller in a compensation mode at present so as to achieve the purpose of detecting the capacitance of a finger or other conductors.
Most of the existing compensation technologies adopt an MIM (metal insulator metal) capacitor or an MOM (metal oxide metal) capacitor to compensate the basic capacitor of the touch screen, but the MIM capacitor and the MOM capacitor have the problem of small capacitance value per unit area, and if the touch screen with a large basic capacitor is encountered, a large number of MIM capacitors or MOM capacitors are required, which occupies a large chip area and greatly increases the chip cost.
Disclosure of Invention
In order to solve the defects of the prior art, an object of the present invention is to provide a basic capacitor compensation circuit, which uses a polysilicon resistor or a MOS (metal oxide semiconductor) resistor and a corresponding switch timing sequence as a compensation circuit to compensate a basic capacitor, thereby reducing the chip area and the chip cost.
To achieve the above object, the present invention provides a basic capacitance compensation circuit, including a current power conversion circuit, a pull-up circuit, and a pull-down circuit, wherein,
the current power supply conversion circuit is provided with a current input end, an excitation signal input end and a voltage output end;
the current input end is respectively connected with one end of the pull-up circuit and one end of the pull-down circuit and is connected to the basic capacitor of the touch screen;
the excitation signal input end is connected with an excitation signal;
the other end of the pull-up circuit is connected with the positive electrode of the power supply; the other end of the pull-down circuit is connected with the negative electrode of the power supply.
Furthermore, the current power supply switching circuit also comprises an amplifier, a feedback capacitor, a first switch and a second switch, wherein,
the feedback capacitor and the second switch are connected in parallel between the negative input end and the voltage output end of the amplifier;
the negative input end of the amplifier is connected with one end of the first switch;
the other end of the first switch is respectively connected with one end of the pull-up circuit and one end of the pull-down circuit and is connected to a basic capacitor of the touch screen;
the positive input end of the amplifier is connected with an excitation signal.
Further, the pull-up circuit comprises a pull-up resistor and a pull-up switch; the pull-down circuit comprises a pull-down resistor and a pull-down switch, wherein,
one end of the pull-up resistor and one end of the pull-down resistor are connected and connected to the other end of the first switch;
the other end of the pull-up resistor is connected with the positive electrode of a power supply through the pull-up connector;
the other end of the pull-down resistor is connected with the negative electrode of the power supply through the pull-down switch.
Further, the pull-up resistor and the pull-down resistor are polysilicon resistors.
Further, the pull-up resistor and the pull-down resistor are MOS resistors.
Further, the pull-up circuit includes a pull-up transistor; the pull-down circuit includes a pull-down transistor, wherein,
the drain electrode of the pull-up transistor, the source electrode of the pull-down transistor and the other end of the first switch are connected and connected to a basic capacitor of the touch screen;
the source electrode of the pull-up transistor is connected with the positive electrode of the power supply; the drain electrode of the pull-down transistor is connected with the negative electrode of the power supply;
the grid electrode of the pull-up transistor and the grid electrode of the pull-down transistor are respectively connected with a control signal.
In order to achieve the above object, the present invention further provides a capacitance compensation chip, which includes a capacitance compensation circuit and a control unit, wherein,
the control unit controls the capacitance compensation circuit to compensate the basic capacitance of the touch screen;
the capacitance compensation circuit is the basic capacitance compensation circuit.
In order to achieve the above object, the present invention further provides a touch display, which includes a capacitance compensation chip and a capacitive touch screen,
the capacitance compensation chip adopts the capacitance compensation chip, and when the capacitive touch screen is touched, the basic capacitance of the capacitive touch screen is compensated.
In order to achieve the above object, the present invention further provides an information processing apparatus, comprising a touch display and a central processing unit, wherein,
the touch display adopts the touch display;
and the central processing unit and the touch display perform information interaction.
The basic capacitance compensation circuit has the following beneficial effects:
the basic capacitance compensation circuit adopts a polysilicon resistor or an MOS resistor and a corresponding switch time sequence as a compensation circuit to compensate the basic capacitance, and the compensation principle is to compensate the basic capacitance by utilizing the current flowing through the polysilicon resistor or the MOS resistor. Since the current is inversely proportional to the resistance value, the larger the basic capacitance to be compensated, the smaller the required resistance is, and thus, for the capacitive panel requiring more compensation, the smaller chip area is required, which greatly reduces the chip cost.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic block diagram of one embodiment of a basic capacitance compensation circuit according to the present invention;
FIG. 2 is a timing diagram of a basic capacitance compensation circuit according to the present invention;
FIG. 3 is a schematic block diagram of yet another embodiment of a basic capacitance compensation circuit according to the present invention;
FIG. 4 is a schematic block diagram of a touch chip according to the present invention;
FIG. 5 is a schematic block diagram of a touch display according to the present invention;
fig. 6 is a schematic block diagram of an information processing apparatus according to the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
Example 1
Fig. 1 is a schematic block diagram of an embodiment of a basic capacitance compensation circuit according to the present invention, as shown in fig. 1, the basic capacitance compensation circuit of the present invention includes an amplifier OP, a feedback capacitor Cfb, a first switch s1, a second switch s2, a pull-up resistor R1, a pull-up switch Su, a pull-down resistor R2, and a pull-down switch Sd, wherein,
the feedback capacitor Cfb and the second switch s2 are connected in parallel between the negative input terminal of the amplifier OP and the output terminal Vout.
The negative input terminal of the amplifier OP is connected to one terminal of the first switch s 1.
The other end of the first switch s1 is connected to one end of a pull-up resistor R1 and one end of a pull-down resistor R2, and is connected to a base capacitor Cbase of the touch screen.
In fig. 1, Δ C is a change capacitance generated when the screen is touched.
The other end of the pull-up resistor R1 is connected with one end of a pull-up switch Su; the other end of the pull-up switch Su is connected to the positive electrode VDD of the power supply.
The other end of the pull-down resistor R2 is connected with one end of a pull-down switch Sd; the other end of the pull-down switch Sd is connected to a negative electrode VSS of the power supply.
The positive input of the amplifier OP is the input of the pump signal.
In the embodiment of the present invention, the first switch s1, the second switch s2, the feedback capacitor Cfb and the current source converting circuit,
the positive input end of the amplifier OP is the excitation signal input end of the current power supply conversion circuit;
the output end of the amplifier OP is the power output end Vout of the current power supply conversion circuit;
the other end of the first switch s1 (connected to one end of the pull-up resistor R1 and one end of the pull-down resistor R2) is a current input end of the current power conversion circuit.
The pull-up resistor R1 and the pull-up switch Su form a pull-up circuit of the invention; the pull-down resistor R2 and the pull-down switch Sd constitute the pull-down circuit of the present invention.
In the embodiment of the present invention, the pull-up resistor R1 and the pull-down resistor R2 may be polysilicon resistors or MOS resistors. Since the MOS resistor occupies a smaller chip area, the pull-up resistor R1 and the pull-down resistor R2 preferably use MOS resistors.
Fig. 2 is a timing diagram of the basic capacitance compensation circuit according to the present invention, and the operation of the basic capacitance compensation circuit according to the present invention will be described in detail with reference to fig. 2.
At the rising edge of the stimulus signal (stimulus signal):
the first switch s1 and the second switch s2 are connected with a high level, the pull-up switch Su and the pull-down switch Sd are connected with a low level, the amplifier OP is a buffer amplifier with a gain, and the basic capacitor Cbase is reset;
the first switch s1 and the second switch s2 are connected with a low level, the pull-up switch Su is connected with a high level, the pull-down switch is connected with a low level, the basic capacitor Cbase is simultaneously connected to the negative input end of the amplifier OP, and the pull-up resistor R1 is connected between the basic capacitor Cbase and the positive power supply VDD.
At the falling edge of the excitation signal:
the first switch s1 and the second switch s2 are connected with a high level, the pull-up switch Su and the pull-down switch Sd are connected with a low level, the amplifier OP is a buffer amplifier with a gain, and the basic capacitor Cbase is reset;
the first switch s1 and the second switch s2 are connected with a low level, the pull-up switch Su is connected with a low level, the pull-down switch Sd is connected with a high level, the basic capacitor Cbase is simultaneously connected to the negative input end of the amplifier OP, and the pull-down resistor R2 is connected between the basic capacitor Cbase and the negative power supply VSS.
In the embodiment of the present invention, since the base capacitance Cbase of the touch screen is generally very large as tens of pF or even tens of pF, if there is no compensation circuit, the output of the amplifier OP is saturated, and the variable capacitance Δ C when touching the touch screen cannot be distinguished. With the compensation circuit, the base capacitance can be cancelled out and only the current over the varying capacitance Δ C is transferred to the feedback capacitance Cfb.
In the embodiment of the present invention, since the excitation signal does not reach the target voltage from 0 instantaneously, taking the rising edge of the excitation signal as an example, assuming that the rising slope of the excitation signal is k, the current flowing through R1 at time t is:
then if at time t1 the supply voltage VDD is raised, then the charge flowing through R is:
assuming that R1 is 100Kohm and the excitation signal rises to 5.5V at the supply voltage VDD in 1us, the charge provided via R1 is:
Q＝2.75×10-11C
the relationship between the capacitance and the charge is as follows:
in the case where U is 5.5V:
i.e. this charge can raise the potential of the 5.5pF capacitor from 0 to 5.5V.
Example 2
Fig. 3 is a schematic block diagram of another embodiment of the basic capacitance compensation circuit according to the present invention, as shown in fig. 3, the basic capacitance compensation circuit of the present invention, an amplifier OP, a feedback capacitor Cfb, a first switch s1, a second switch s2, a pull-up transistor Q1, and a pull-down transistor Q2, wherein,
the feedback capacitor Cfb and the second switch s2 are connected in parallel between the negative input terminal of the amplifier OP and the output terminal Vout.
The negative input terminal of the amplifier OP is connected to one terminal of the first switch s 1.
The other end of the first switch s1 is connected to the drain of the pull-up transistor Q1, the source of the pull-down transistor Q2, and connected to the base capacitance Cbase of the touch screen.
In fig. 2, Δ C is a change capacitance generated when the screen is touched.
The gate of pull-up transistor Q1 is connected to the control signal and its source is connected to the positive VDD of the power supply.
The pull-down transistor Q2 has a gate connected to the control signal and a drain connected to the negative terminal VSS of the power supply.
The positive input of the amplifier OP is the input of the pump signal.
In the embodiment of the present invention, the first switch s1, the second switch s2, the feedback capacitor Cfb and the current source converting circuit,
the positive input end of the amplifier OP is the excitation signal input end of the current power supply conversion circuit;
the output end of the amplifier OP is the power output end Vout of the current power supply conversion circuit;
the other end of the first switch s1 connected to the drain of the pull-up transistor Q1 and the source of the pull-down transistor Q2 is a current input terminal of the current power conversion circuit.
In this embodiment, pull-up transistor Q1 is a pull-up circuit of the present invention; the pull-down transistor Q2 is a pull-down circuit of the present invention.
Example 3
The invention also provides a capacitance compensation chip. Fig. 4 is a schematic block diagram of a capacitance compensation chip 40 according to the present invention, as shown in fig. 4, which includes a capacitance compensation circuit 41 and a control unit 42, wherein,
the capacitance compensation circuit 41 has at least one basic capacitance compensation circuit in the above-described embodiment.
And the control unit 42 is used for controlling the capacitance compensation circuit 41 to compensate the basic capacitance Cbase of the touch screen.
Example 4
The invention also provides a touch display. Fig. 5 is a schematic block diagram of a touch display according to the present invention, and as shown in fig. 5, the touch display 50 of the present invention includes a capacitance compensation chip 51 and a capacitive touch screen 52, wherein,
and a capacitance compensation chip 51 which employs the capacitance compensation chip 40 in the above-described embodiment.
When the capacitive touch screen 52 is touched, a basic capacitance compensation circuit inside the capacitance compensation chip 51 is started to compensate the basic capacitance Cbase of the touch screen.
In the embodiment of the present invention, the capacitive touch screen 52 is a liquid crystal display, an OLED display, a QLED display, a Mini LED display, or a Micro LED display.
Example 5
The invention also provides an information processing device. Fig. 6 is a schematic block diagram of an information processing apparatus 60 according to the present invention, as shown in fig. 6, the information processing apparatus 60 includes a touch display 61 and a central processing unit 62, wherein,
a touch display 61, which adopts the touch display 50 in the above embodiments.
The central processor 62 and the touch display 61 perform information interaction.
In the embodiment of the present invention, the information processing apparatus 60 may be a mobile terminal, a desktop terminal, or other terminal devices.
Those of ordinary skill in the art will understand that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A basic capacitance compensation circuit, comprising a current source conversion circuit, a pull-up circuit, and a pull-down circuit, wherein,
the current power supply conversion circuit is provided with a current input end, an excitation signal input end and a voltage output end;
the current input end is respectively connected with one end of the pull-up circuit and one end of the pull-down circuit and is connected to the basic capacitor of the touch screen;
the excitation signal input end is connected with an excitation signal;
the other end of the pull-up circuit is connected with the positive electrode of the power supply; the other end of the pull-down circuit is connected with the negative electrode of the power supply.
2. The fundamental capacitance compensation circuit of claim 1, wherein the current source conversion circuit further comprises an amplifier, a feedback capacitor, a first switch, and a second switch, wherein,
the feedback capacitor and the second switch are connected in parallel between the negative input end and the voltage output end of the amplifier;
the negative input end of the amplifier is connected with one end of the first switch;
the other end of the first switch is respectively connected with one end of the pull-up circuit and one end of the pull-down circuit and is connected to a basic capacitor of the touch screen;
the positive input end of the amplifier is connected with an excitation signal.
3. The fundamental capacitance compensation circuit of claim 2,
the pull-up circuit comprises a pull-up resistor and a pull-up switch; the pull-down circuit comprises a pull-down resistor and a pull-down switch, wherein,
one end of the pull-up resistor and one end of the pull-down resistor are connected and connected to the other end of the first switch;
the other end of the pull-up resistor is connected with the positive electrode of a power supply through the pull-up connector;
the other end of the pull-down resistor is connected with the negative electrode of the power supply through the pull-down switch.
4. The fundamental capacitance compensation circuit of claim 3, wherein the pull-up resistor and the pull-down resistor are polysilicon resistors.
5. The fundamental capacitance compensation circuit of claim 3, wherein the pull-up resistor and the pull-down resistor are MOS resistors.
6. The fundamental capacitance compensation circuit of claim 2, wherein the pull-up circuit comprises a pull-up transistor; the pull-down circuit includes a pull-down transistor, wherein,
the drain electrode of the pull-up transistor, the source electrode of the pull-down transistor and the other end of the first switch are connected and connected to a basic capacitor of the touch screen;
the source electrode of the pull-up transistor is connected with the positive electrode of the power supply; the drain electrode of the pull-down transistor is connected with the negative electrode of the power supply;
the grid electrode of the pull-up transistor and the grid electrode of the pull-down transistor are respectively connected with a control signal.
7. A capacitance compensation chip is characterized by comprising a capacitance compensation circuit and a control unit, wherein,
the control unit controls the capacitance compensation circuit to compensate the basic capacitance of the touch screen;
the capacitance compensation circuit is the basic capacitance compensation circuit of any one of claims 1-6.
8. A touch display comprises a capacitance compensation chip and a capacitive touch screen, wherein,
the capacitance compensation chip of claim 7 is used for compensating the basic capacitance of the capacitive touch screen when the capacitive touch screen is touched.
9. An information processing device, comprising a touch display and a central processing unit, wherein,
the touch display which adopts the touch display of claim 8;
and the central processing unit and the touch display perform information interaction.
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| CN202023049691.4U CN213987461U (en) | 2020-12-17 | 2020-12-17 | Basic capacitance compensation circuit, chip, touch display and information processing device |
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| CN202023049691.4U CN213987461U (en) | 2020-12-17 | 2020-12-17 | Basic capacitance compensation circuit, chip, touch display and information processing device |
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| CN213987461U true CN213987461U (en) | 2021-08-17 |
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