CN212693886U - Capacitance detection circuit, chip, circuit board, module and electronic equipment - Google Patents
Capacitance detection circuit, chip, circuit board, module and electronic equipment Download PDFInfo
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- CN212693886U CN212693886U CN202020489815.1U CN202020489815U CN212693886U CN 212693886 U CN212693886 U CN 212693886U CN 202020489815 U CN202020489815 U CN 202020489815U CN 212693886 U CN212693886 U CN 212693886U
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Abstract
An embodiment of the utility model provides an electric capacity detection circuitry, chip, circuit board, module and electronic equipment, electric capacity detection circuitry is applied to electric capacity detection chip, wherein electric capacity detection chip includes at least one detection pin, electric capacity detection circuitry includes: and the input end of the buffer circuit is connected with the detection pin, and the output end of the buffer circuit is also used for connecting an external shielding wire. The embodiment of the utility model provides a capacitance detection circuit can restrain the parasitic capacitance who detects the pin, improves the precision that electric capacity detected.
Description
Technical Field
The utility model relates to a touch detection technology field, concretely relates to electric capacity detection circuitry, chip, circuit board, module and electronic equipment.
Background
Through technical evolution and mass production inspection for many years, the touch key technology is mature day by day. Due to the advantages of convenience, fashion, low cost, and the like, more and more electronic products are turning from traditional mechanical keys to touch keys. The touch key judges the occurrence of a touch event by detecting the capacitance change on the key through the capacitance detection chip, and the capacitance change on the detection pin of the capacitance detection chip can be caused by the capacitance change of the key, so that the touch event is detected.
In fact, the capacitance detection chip often needs to detect very small capacitance changes, so the accuracy of capacitance detection is very important. The detection pins on the capacitance detection chip are connected to the sensor through PCB traces, and usually, a ground wire is laid around the PCB traces in order to shield the PCB traces from external interference. Laying the ground wire can shield the parasitic capacitance between the PCB wires, but increases the capacitance to ground of the PCB wires, thereby influencing the capacitance change of the detection pins and reducing the precision of capacitance detection.
SUMMERY OF THE UTILITY MODEL
In view of the above problems, the present invention provides a capacitance detection circuit, a chip, a circuit board, a module and an electronic device, to solve the above technical problems.
The embodiment of the utility model provides an adopt following technical scheme to realize:
a capacitance detection circuit is applied to a chip, wherein the chip comprises at least one detection pin, and the capacitance detection circuit comprises: and the input end of the buffer circuit is connected with the detection pin, and the output end of the buffer circuit is also used for connecting an external shielding wire.
Further, the buffer circuit is a linear regulator.
Furthermore, the capacitance detection circuit also comprises a switch unit, wherein one end of the switch unit is respectively connected with each detection pin, and the other end of the switch unit is connected with the input end of the buffer circuit.
Furthermore, the switch unit comprises at least one switch corresponding to the detection pin, one end of each switch is connected with the input end of the buffer circuit, and the other end of each switch is connected with the corresponding detection pin.
Further, the switch is any one or combination of a triode, a field effect transistor and a silicon controlled rectifier.
The embodiment of the utility model provides a chip is still provided, including at least one electric capacity detection circuitry who detects pin and above-mentioned arbitrary one, electric capacity detection circuitry connects in detecting the pin, and at least one detects the pin and is used for connecting outside electric capacity sensing element.
Furthermore, the chip also comprises a shielding pin, and the buffer circuit is connected with an external shielding wire through the shielding pin.
The embodiment of the utility model provides a still provide a circuit board, including shielded wire and the chip of above-mentioned arbitrary, the chip is connected in the shielded wire.
The embodiment of the utility model provides a still provide a capacitance detection module, include foretell circuit board and locate the electric capacity sensing element of circuit board.
The embodiment of the utility model provides an electronic equipment is still provided, including the equipment main part and locate foretell electric capacity detection module in the equipment main part.
Compared with the prior art, the embodiment of the utility model provides an electric capacity detection circuitry is applied to the chip including at least one detection pin, and this electric capacity detection circuitry is provided with buffer circuit, and buffer circuit's input is connected and is detected the pin, and the output is used for connecting outside shielded wire for detect the pressure differential between pin and the shielded wire and keep unchangeable basically, thereby restrain the parasitic capacitance who detects the pin, improve the precision that electric capacity detected.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 shows a schematic diagram of a capacitance detection system according to an embodiment of the present invention.
Fig. 2 shows a schematic diagram of a capacitance detection circuit provided by an embodiment of the present invention.
Fig. 3 shows a schematic diagram of another capacitance detection circuit provided by an embodiment of the present invention.
Fig. 4 shows a schematic diagram of the structure of the switching unit in fig. 3.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.
Through technical evolution and mass production inspection for many years, the touch key technology is mature day by day. Due to the advantages of convenience, fashion, low cost, and the like, more and more electronic products are turning from traditional mechanical keys to touch keys. The touch key judges the occurrence of a touch event by detecting the capacitance change on the key through the capacitance detection chip, and the capacitance change on the detection pin of the capacitance detection chip can be caused by the capacitance change of the key, so that the touch event is detected.
In fact, the capacitance detection chip often needs to detect very small capacitance changes, so the capacitance detection accuracy is very important. Detection pins on the capacitance detection chip are usually connected with the sensor through PCB wiring, however, parasitic capacitance can be generated between the PCB wiring, the parasitic capacitance of the PCB wiring is obviously changed along with the surrounding environment, and capacitance change caused by the detection pins during detection of the sensor can be submerged, so that an error capacitance detection result is caused. The conventional approach is to lay ground wires around the PCB traces to shield the PCB traces from interference and external electromagnetic interference. However, although the parasitic capacitance of the PCB trace can be eliminated by laying the ground wire, the parasitic capacitance to ground is generated between the PCB trace and the ground wire, so that the capacitance change on the detection pin is still affected, and the precision of capacitance detection is reduced.
In order to solve the above problem, the inventor has carried out long-term research, has proposed electric capacity detection circuitry, chip, circuit board, module and electronic equipment in the embodiment of the utility model provides an in which electric capacity detection circuitry is including being applied to the chip that includes at least one detection pin, and be provided with buffer circuit, buffer circuit's input is connected and is detected the pin, and the output is used for connecting outside shielded wire for detect the pressure differential between pin and the shielded wire and remain unchanged basically, thereby restrain the parasitic capacitance who detects the pin, improve the precision that electric capacity detected.
In order to make the technical field person understand the scheme of the present invention better, the following will combine the drawings in the embodiments of the present invention to perform clear and complete description on the technical scheme in the embodiments of the present invention. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by the skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1, fig. 1 illustrates a capacitance detection system 10 according to an embodiment of the present invention. The capacitive detection system 10 includes a sensor 11 and a chip 12. The chip 12 may be a capacitance detection chip, wherein the chip 12 includes at least one detection pin TK, the detection pin TK is connected to the sensor 11 outside the chip through a PCB trace, when the sensor 11 detects operations such as pressing or touching by a user, an output signal thereof changes, which may cause a capacitance change on the detection pin TK of the chip 12, and the chip 12 determines a magnitude of the output signal of the sensor by detecting the capacitance change on the detection pin TK.
As shown in fig. 2, fig. 2 shows a capacitance detection circuit 100 according to an embodiment of the present invention, where the capacitance detection circuit 100 is applied to the capacitance detection system 10, and particularly, to the chip 12.
The capacitance detection circuit 100 comprises a buffer circuit 110, wherein an input end of the buffer circuit 110 is connected with the detection pin TK, and an output end of the buffer circuit 110 is used for connecting with an external shielding wire 13. It should be noted that the shield wire 13 in the embodiment of the present invention may not be used as a ground wire, and is a shield wire independent from the ground wire. For example, the shield line 13 may be a shield line disposed at the periphery of a specific trace, made of a conductive medium and not grounded. As another example, the shield line 13 may be disposed at the periphery of the trace between the detection pin TK and the sensor 11.
The embodiment of the utility model provides a set up buffer circuit 110 through setting up between shielded wire 13 and detection pin TK, because the voltage between buffer circuit 110's input and the output remains unchanged basically for detect the pressure differential between pin TK and the shielded wire 13 and also remain unchanged basically, thereby restrain the parasitic capacitance who detects pin TK, so that parasitic capacitance causes the interference to the actual detection electric capacity that detects pin TK, thereby improve the precision that electric capacity detected. Additionally, the embodiment of the utility model provides an in can set up shielded wire 13 and walk line around replacing the ground wire at PCB, reach the effect of shielding external disturbance, and because shielded wire 13 is being connected to buffer circuit 110's output for connect the PCB of detecting pin TK and walk the line and do not have parasitic capacitance between the shielded wire 13, consequently, the utility model discloses implementation provides an electric capacity detection circuitry 100 when reaching the same shielding effect with prior art, can not increase the parasitic capacitance on detecting pin TK, can cut the precision that improves electric capacity detection really.
In some embodiments, the buffer circuit 110 may be a linear regulator, such as a low dropout regulator (LDO). Specifically, the input end of the low dropout regulator is connected with the detection pin TK, and the output end of the low dropout regulator is used for connecting with the external shielding wire 13. Because the output voltage and the input voltage of the low dropout regulator are basically kept stable, the voltage difference between the TK and the shielding wire 13 is basically zero, and the parasitic capacitance of the TK can be effectively inhibited.
The linear voltage regulator can adopt the original LDO in the power management module of the chip, and does not need to be additionally provided with new circuit elements so as to save the circuit cost.
The embodiment of the utility model provides a capacitance detection circuit is through setting up linear voltage stabilizer between the shielded wire that detects pin and outside for the pressure differential between detection pin and the shielded wire remains unchanged basically, thereby suppresses the parasitic capacitance who detects the pin, improves the precision that electric capacity detected.
As shown in fig. 3, the embodiment of the present invention further provides a capacitance detection circuit 200, which is applied to the chip 12 in the capacitance detection system 10. And the capacitance detection circuit 200 includes a buffer circuit 210 that is the same as the buffer circuit 110 in the capacitance detection circuit 100 described above. In addition, the capacitance detection circuit 200 is different from the capacitance detection circuit 100 described above in that the capacitance detection circuit 200 further includes a switching unit 220.
One end of the switch unit 220 is connected to each of the detection pins, and the other end is connected to the input end of the buffer circuit 210. In this embodiment, when there is only one detection pin, the switch unit 220 is used to conduct the connection between the detection pin and the buffer circuit 210 when the detection pin is working. In some embodiments, when there is only one detection pin, the switch unit 220 may not be needed, and the detection pin may be connected to the buffer circuit 210.
In this embodiment, when there are more than two detection pins, the switch unit 220 is used to conduct the connection between one of the detection pins and the buffer circuit 210 when the detection pin works. Specifically, when the chip has a plurality of detection pins, each time the capacitance detection can keep one of the detection pins working. Therefore, when any detection pin works, the switch unit 220 switches on the connection between the detection pin and the buffer circuit 210, so that the detection pin does not generate parasitic capacitance during working, the precision of capacitance detection is ensured, and energy loss can be reduced. In addition, the switch unit 220 switches the connection between any one of the detection pins and the buffer circuit 210, and there is no need to set one buffer circuit 210 for each detection pin, and in this embodiment, one buffer circuit 210 is adopted, so that all the detection pins do not generate parasitic capacitance during operation, thereby saving cost.
As shown in fig. 4, the switch unit 220 includes at least one switch corresponding to the detection pin, wherein one end of each switch is connected to the output terminal of the buffer circuit 210, and the other end is connected to the corresponding detection pin. By controlling the on/off of the switch corresponding to the detection pin, when any detection pin works, the detection pin is connected to the buffer circuit 210. In this embodiment, the switch may be any one or more of a triode, a field effect transistor, and a thyristor. It should be noted that the on-off of switch can be controlled by the outside clock signal of electric capacity detection circuit, and clock signal's production relies on the clock generation circuit among the prior art, promptly the embodiment of the utility model provides an on-off control accessible prior art realizes, is the implementation mode based on hardware circuit.
The embodiment of the utility model provides a capacitance detection circuit, through setting up buffer circuit and switch unit, not only can be when shielding external disturbance, restrain the parasitic capacitance who detects the pin, improve the precision that electric capacity detected. And all detection pins can not generate parasitic capacitance during working, so that the cost is saved.
An embodiment of the utility model provides a still provides a chip, this chip include at least one detect pin and locate the chip inside as above-mentioned electric capacity detection circuitry. The capacitance detection circuit is connected with the detection pins, and at least one detection pin is used for being connected with an external capacitance sensing element.
Further, the chip also includes a shield pin. The buffer circuit is connected with an external shielding wire through a shielding pin. Specifically, the input terminal of the buffer circuit is connected to each of the detection pins, and the output terminal thereof is connected to the shield pin. It should be noted that the shielding pin is not a detection pin, and is only used for connecting the output end of the buffer circuit and an external shielding wire, so as to provide a certain potential for the shielding wire, so that the voltage difference between the detection pin TK and the shielding wire 13 is kept substantially unchanged.
The embodiment of the utility model provides a chip through setting up buffer circuit and switch unit, not only can be when shielding external disturbance, restraines the parasitic capacitance who detects the pin, improves the precision that electric capacity detected. And all detection pins can not generate parasitic capacitance during working, so that the cost is saved.
An embodiment of the utility model provides a still provides a circuit board, and this circuit board includes shielded wire and foretell chip, and wherein, the chip is connected in the shielded wire.
The circuit board may be a printed circuit board or a flexible circuit board.
In this embodiment, the shielding line is disposed around the circuit board trace to replace the ground line to shield the external interference.
The embodiment of the utility model provides a circuit board through setting up buffer circuit and switch unit, not only can be when shielding external disturbance, restraines the parasitic capacitance who detects the pin, improves the precision that electric capacity detected. And all detection pins can not generate parasitic capacitance during working, so that the cost is saved.
The embodiment of the utility model provides a still provide a capacitance detection module, this capacitance detection module includes above-mentioned arbitrary embodiment the circuit board and locate the electric capacity sensing element of circuit board.
In this embodiment, the capacitive sensing element may be a capacitive touch sensor, a capacitive pressure sensor, or any other sensing element capable of causing a change in a capacitance value.
The embodiment of the utility model provides a capacitance detection module through setting up buffer circuit and switch unit, not only can be when shielding external disturbance, restraines the parasitic capacitance who detects the pin, improves the precision that electric capacity detected. And all detection pins can not generate parasitic capacitance during working, so that the cost is saved.
The embodiment of the utility model provides an electronic equipment is still provided, including the equipment main part and locate in the equipment main part like above-mentioned electric capacity detection module.
In this embodiment, the electronic device may be, but is not limited to, a smart phone, a tablet computer, a smart watch, an electronic book reader, and the like.
The embodiment of the utility model provides an electronic equipment, through setting up buffer circuit and switch unit, not only can be when shielding external disturbance, restrain the parasitic capacitance who detects the pin, improve the precision that electric capacity detected. And all detection pins can not generate parasitic capacitance during working, so that the cost is saved.
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above description, and although the present invention has been disclosed by the preferred embodiment, it is not limited to the present invention, and any person skilled in the art can make modifications or changes equivalent to the equivalent embodiments by utilizing the above disclosed technical contents without departing from the technical scope of the present invention, but all the modifications, changes and changes of the technical spirit of the present invention made to the above embodiments are also within the scope of the technical solution of the present invention.
Claims (10)
1. A capacitance detection circuit applied to a chip, wherein the chip comprises at least one detection pin, the capacitance detection circuit comprising: and the input end of the buffer circuit is connected with the detection pin, and the output end of the buffer circuit is also used for connecting an external shielding wire.
2. The capacitance detection circuit of claim 1, wherein the buffer circuit is a linear regulator.
3. The capacitance detection circuit according to claim 1 or 2, further comprising a switch unit, wherein one end of the switch unit is connected to each of the detection pins, and the other end of the switch unit is connected to the input end of the buffer circuit.
4. The capacitance detection circuit according to claim 3, wherein the switch unit comprises at least one switch corresponding to the detection pin, and one end of each switch is connected to the input end of the buffer circuit, and the other end of each switch is connected to the corresponding detection pin.
5. The capacitance detection circuit of claim 4, wherein the switch is any one or more of a triode, a field effect transistor, and a thyristor.
6. A chip, comprising at least one detection pin and the capacitance detection circuit according to any one of claims 1 to 5, wherein the capacitance detection circuit is connected to the detection pin, and at least one detection pin is used for connecting an external capacitance sensing element.
7. The chip of claim 6, further comprising a shield pin through which the buffer circuit is connected to an external shield line.
8. A circuit board comprising a shield wire and the chip of claim 6 or 7, said chip being connected to said shield wire.
9. A capacitance detection module comprising the circuit board of claim 8 and a capacitance sensing element disposed on the circuit board.
10. An electronic device comprising a device body and the capacitance detection module of claim 9 disposed within the device body.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020489815.1U CN212693886U (en) | 2020-04-07 | 2020-04-07 | Capacitance detection circuit, chip, circuit board, module and electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020489815.1U CN212693886U (en) | 2020-04-07 | 2020-04-07 | Capacitance detection circuit, chip, circuit board, module and electronic equipment |
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| Publication Number | Publication Date |
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| CN212693886U true CN212693886U (en) | 2021-03-12 |
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| CN202020489815.1U Active CN212693886U (en) | 2020-04-07 | 2020-04-07 | Capacitance detection circuit, chip, circuit board, module and electronic equipment |
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