CN114577377B - Embedded surface leadless touch sensor and electronic equipment - Google Patents
Embedded surface leadless touch sensor and electronic equipment Download PDFInfo
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- CN114577377B CN114577377B CN202210198395.5A CN202210198395A CN114577377B CN 114577377 B CN114577377 B CN 114577377B CN 202210198395 A CN202210198395 A CN 202210198395A CN 114577377 B CN114577377 B CN 114577377B
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- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
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Abstract
The invention belongs to the technical field of sensors, and provides an embedded surface leadless touch sensor and electronic equipment. The embedded surface leadless touch sensor is composed of a sensitive layer, an insulating layer and a coupling capacitance electrode layer which are sequentially overlapped, wherein the sensitive layer is used for sensing a pressure change signal and converting the pressure change signal into a resistance change signal, and the coupling capacitance electrode layer is used for sensing the resistance change signal and converting the resistance change signal into a voltage change signal based on a capacitive coupling resistance tomography principle when the coupling capacitance electrode layer is not in direct contact with the sensitive layer. The embedded surface leadless touch sensor has the characteristics of small wiring quantity, high wiring utilization rate, high durability and mechanical strength, and high spatial resolution and sensitivity. The coupling capacitance electrode layer is connected with a buffer circuit with bidirectional working capacity, and the buffer circuit has the characteristics of capability of actively compensating parasitic capacitance in a system, simple structure and low cost.
Description
Technical Field
The invention belongs to the technical field of sensors, and particularly relates to an embedded surface leadless touch sensor and electronic equipment.
Background
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Haptic sensations play an important role in human interaction with the environment. With the development of the intellectualization of robots and manipulators, the touch sensor also plays a more important role in the robot system. With the development of intelligent artificial limb technology, the touch sensor is also applied to the field of intelligent artificial limbs to a certain extent. The lack of tactile feedback in conventional prostheses, particularly upper prostheses, has caused certain inconveniences to the use of the prostheses. There have been studies attempting to install a force sensor based on a change in resistance in a fingertip of an upper prosthesis to collect mechanical information and feed it back to a user through a vibration ring installed on the arm of the user. Similarly, it has been investigated to attach other similar sensors to the prosthetic finger tip and squeeze the user's arm using a shape memory alloy actuator attached to the user's arm to achieve higher resolution. The application of the touch sensor in the intelligent artificial limb has great significance for improving the usability and the function of the intelligent artificial limb.
However, the following problems are generally encountered in the development and popularization of tactile sensors, particularly pressure sensors that directly measure pressure:
(1) The number of connections is large: in applications such as slip detection, material identification, and shape identification, it is often necessary to collect pressure information from multiple points at a time. A common solution today is to use an array structure, i.e. to divide the signal lines of the sensor into row and column lines, and to connect or make a single point pressure sensor at each intersection of the row and column lines. This approach has a high number of connections and a low utilization, for example, for a 16-point sensor with 8 connections, 4 rows and 4 columns, 1 row and 4 column lines for each scan, 3 rows being idle, and a connection utilization of 62.5%. Or a plurality of intelligent sensors with the MCU are connected by using a bus, and the cost of the mode is higher.
(2) Poor durability: besides that the zero point and the sensitivity of the sensor may change after a plurality of working cycles, scratches and cracks on sensitive materials and connecting wires can also have a great influence on the measurement during the use process. Moreover, stress concentration can be caused by the discontinuity of material mechanical properties caused by the threading holes when the wires are connected to the sensitive material. The current common mitigation method is to cover the sensor surface with a "synthetic skin". The addition of protective films or elements generally reduces the sensitivity and spatial resolution of the sensing system.
(3) The spatial resolution is low: the spatial resolution of the system is difficult to improve due to the cost of the system (e.g., smart sensor solutions) or the number of total connections (e.g., arrayed sensors), and the space occupied by the auxiliary components in the system (e.g., MCU and connections). In addition, there is also a problem that the effective sensing area does not completely cover the whole sensing plane, and there is a blind area on the sensor.
Disclosure of Invention
In order to solve the technical problems in the background art, the invention provides an embedded surface leadless touch sensor and an electronic device, which have the characteristics of less wiring quantity, high wiring utilization rate, high durability and mechanical strength, high spatial resolution and sensitivity and no blind area.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides an embedded surface leadless touch sensor which is formed by a sensitive layer, an insulating layer and a coupling capacitance electrode layer which are sequentially overlapped, wherein the sensitive layer is used for sensing a pressure change signal and converting the pressure change signal into a resistance change signal, and the coupling capacitance electrode layer is used for sensing the resistance change signal and converting the resistance change signal into a voltage change signal based on a capacitive coupling resistance tomography principle when the coupling capacitance electrode layer is not in direct contact with the sensitive layer.
As an embodiment, the sensitive layer is directly imaged based on the principle of capacitively coupled resistance tomography.
In one embodiment, the embedded surface leadless tactile sensor has a planar structure.
In one embodiment, the embedded surface leadless tactile sensor has a curved surface structure.
In one embodiment, the embedded surface leadless tactile sensor has a cylindrical surface structure.
As an implementation manner, a plurality of coupling capacitor electrode plates are arranged on the coupling capacitor electrode layer, and each coupling capacitor electrode plate is connected with the buffer circuit. In one embodiment, the buffer circuit includes an operational amplifier and four resistors, wherein one end of each of the first resistor and the second resistor is connected to the negative input terminal and the positive input terminal of the operational amplifier, and the other end of each of the first resistor and the second resistor is connected to the output terminal of the operational amplifier; one end of the third resistor and one end of the fourth resistor are respectively connected with the negative input end and the positive input end of the operational amplifier, and the other ends of the third resistor and the fourth resistor are both grounded.
In one embodiment, the impedance of the second resistor is greater than the impedance of the fourth resistor. This facilitates the compensation of the circuit to bring it into a negative feedback state, thereby allowing the circuit to operate normally.
In one embodiment, an active compensation capacitor is connected in parallel to the first resistor.
Wherein the buffer circuit is optional.
In one embodiment, the a/D conversion circuit is connected to the processor through a wireless transmission module.
The coupling capacitor electrode plate and the buffer circuit are manufactured on the same printed circuit board.
In one embodiment, the buffer circuit transmits the signals acquired by the buffer circuit to the processor through the signal conditioning circuit and the a/D conversion circuit in sequence, and the processor obtains the pressure distribution on the pressure-sensitive layer according to the received signals.
In one embodiment, the A/D conversion circuit is connected with the processor through a signal line.
A second aspect of the invention provides an electronic device comprising an embedded surface leadless tactile sensor as described above.
Compared with the prior art, the invention has the beneficial effects that:
(1) The embedded surface leadless touch sensor provided by the invention is composed of a sensitive layer, an insulating layer and a coupling capacitance electrode layer which are sequentially overlapped, wherein the sensitive layer senses a pressure change signal and converts the pressure change signal into a resistance change signal, and the coupling capacitance electrode layer senses the resistance change signal and converts the resistance change signal into a voltage change signal based on a capacitance coupling resistance tomography principle under the condition that the coupling capacitance electrode layer is not in direct contact with the sensitive layer. Moreover, no threading is arranged on the touch sensor, so that the stress concentration phenomenon at the connecting point of the lead and the sensitive material when a working load is applied is avoided, and the service life is prolonged; the surface of the sensor has no lead wire, so that the sensor is convenient to clean, maintain, disinfect, repair and recycle, the wiring quantity is small, the spatial resolution is high, and the sensing range does not have a sensing blind area caused by other components such as threading and the like; the insulating layer can be part of other equipment such as a mechanical gripper, so that the system volume can be reduced, and the rigidity of the sensor can be improved.
(2) The coupling capacitor electrode plate is also connected with a buffer circuit, wherein the buffer circuit is designed aiming at the area of a small electrode plate, and has the advantages of improving the system sensitivity, reducing a negative sensitivity area and reducing the system complexity; the buffer circuit has bidirectional working capability, and can zoom and compensate parasitic parameters of devices. Compared with the circuit which uses a switch to switch two circuits which only work in one direction as shown in the figure 8, the buffer circuit of the invention can reduce the cost and the complexity of the system.
Advantages of additional aspects of the invention will be set forth in part 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, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic diagram of one configuration of an embedded surface leadless tactile sensor of an embodiment of the present invention;
FIG. 2 is a schematic view of another embodiment of an embedded surface leadless tactile sensor of the present invention;
FIG. 3 is a schematic diagram of an embedded surface leadless tactile sensor application of an embodiment of the present invention;
FIG. 4 is a schematic diagram of a buffer circuit according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a performance simulation of a buffer circuit according to an embodiment of the present invention;
FIG. 6 is a simulation result of the performance of the buffer circuit according to the embodiment of the present invention;
FIG. 7 (a) is a pressure distribution measurement experiment result 1 for an embedded surface leadless tactile sensor of an embodiment of the present invention;
FIG. 7 (b) is a pressure distribution measurement experiment result 2 of an embedded surface leadless tactile sensor of an embodiment of the present invention;
fig. 8 is a schematic diagram of a circuit using switches to switch two circuits that can only operate in one direction.
Detailed Description
The invention is further described with reference to the following figures and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example one
The embodiment provides an embedded surface leadless touch sensor, which is formed by a sensitive layer 1, an insulating layer 2 and a coupling capacitance electrode layer 3 which are sequentially overlapped, wherein the sensitive layer 1 is used for sensing a pressure change signal and converting the pressure change signal into a resistance change signal, and the coupling capacitance electrode layer 3 is used for sensing the resistance change signal and converting the resistance change signal into a voltage change signal based on a capacitive coupling resistance tomography principle when the sensing layer is not in direct contact with the sensitive layer.
Wherein the sensitive layer is directly imaged based on the principle of capacitive coupling resistance tomography.
In this embodiment, the buried surface leadless tactile sensor has a planar structure.
It should be noted here that the embedded surface leadless tactile sensor may also be a cylindrical surface structure as shown in fig. 2, or a curved surface structure.
In the case of satisfying the signal transmission (for example, through wireless communication + wireless power transmission technology), the person skilled in the art can apply the invention to a closed curved surface such as a spherical surface without any gap. Therefore, the size and shape of the sensor should not be a limiting part.
In a specific implementation process, a plurality of coupling capacitor electrode plates are distributed on the coupling capacitor electrode layer 3, and each coupling capacitor electrode plate is connected with the buffer circuit.
Fig. 3 is a schematic diagram of an application of the embedded surface leadless tactile sensor of the embodiment, wherein the insulating layer 2 in the embedded surface leadless tactile sensor is a part of a gripper. The embedded surface leadless touch sensor is organically combined with the mechanical paw, so that the system volume can be reduced, and the rigidity of the sensor can be improved.
A specific structure of the buffer circuit is given as shown in fig. 4. The buffer circuit comprises an operational amplifier and four resistors, wherein one ends of a first resistor R1 and a second resistor R2 are respectively connected with a negative input end and a positive input end of the operational amplifier OPA, and the other ends of the first resistor R1 and the second resistor R2 are respectively connected with an output end of the operational amplifier OPA; one end of the third resistor R3 and one end of the fourth resistor R4 are respectively connected with the negative input end and the positive input end of the operational amplifier OPA, and the other ends of the third resistor R3 and the fourth resistor R4 are both grounded.
As can be seen from fig. 4:
V o ＝A ol (V + -V - )
wherein R is 1 、R 2 、R 3 And R 4 Are the resistance values of the first, second, third and fourth resistors, respectively, V o Is the output voltage of the operational amplifier, V + And V - Respectively, the positive and negative voltage inputs of the operational amplifier, I + And I - Respectively, the positive interface current and the negative interface current of the buffer circuit, A ol Is the amplification of the operational amplifier.
Setting:
R 1 ＝R 3
R 2 ＝R 4
mode 1 (current injection mode, operating direction 1):
I - R 1 ＝-V o +2V -
-I + R 2 ＝-V o +2V +
let A ol Infinity, having V + ＝V - ：
I - R 1 ＝-I + R 2
Mode 2 (voltage following mode, working direction 2):
i.e. V + The voltage on is always true at V - Is reflected in the above. V - Terminal-sourced current multiplied by a reduction factor (the reduction factor is reduced by V) - Parasitic parameter pair V of end circuit + End effects. ) Is always at V + And the end is reflected.
Here, it is to be noted that R 1 、R 2 、R 3 And R 4 May contain an imaginary part, e.g. replaced by a capacitance, an inductance, a resistance or a combination thereof having a corresponding impedance value.
Wherein the impedance of the second resistor of the buffer circuit is greater than the fourth resistor. This facilitates the compensation of the circuit to bring it into a negative feedback state, thereby allowing the circuit to operate normally.
Those skilled in the art can apply R to meet the appropriate impedance 1 、R 2 、R 3 And R 4 And replaced with a capacitor, an inductor, a resistor, or a combination thereof having a corresponding impedance value. Therefore, the types of devices included in the circuit should not be a limiting part.
The buffer circuit of this embodiment, V + Terminal voltage transmission to V - ，V - The terminal current is multiplied by a proportionality coefficient and then transmitted to V + And (4) an end. Due to the effect of the proportionality coefficient, the capacitive characteristic exposed by the system is greatly reduced, and then the current reduction effect is matched, so that: at V - Measuring by end (channel selector) to obtain V + Terminal voltage (connected with a coupling capacitor plate); at V - A current is input to the terminal (channel selector) and can be at V + The end (connected with the coupling capacitor plate) also obtains a current for exciting the sensitive layer; due to compensation and current scaling, V - Non-ideal characteristics of end devices vs. V + The terminals have little effect so that the buffer circuit exhibits a significant input impedance in mode 2.
Fig. 5 is a schematic diagram showing a simulation of the performance of the buffer circuit according to the embodiment. Wherein, C3 is an additional active compensation capacitor used for actively compensating the parasitic capacitance of the post-stage circuit; and C2 and R5 are operational amplifier loop compensation devices and are used for ensuring that the operational amplifier works in a negative feedback state and stabilizing a working point. C1 and C21 are coupling capacitors, R6 and R21 are Equivalent Series Resistance (ESR) of the coupling capacitors, C4 and C22 are parasitic capacitors of a subsequent stage circuit, C3 is a compensation capacitor, and R22 is used for determining a DC operating point. The current flowing through the coupling capacitors C1 and C21 is a non-ideal current injection into the circuit, which is ideally 0App. The voltages at the output node Out and the node OutCompare are output voltages using the buffer circuit described in this embodiment and output voltages without the buffer circuit described in the present invention, respectively, and the ideal value thereof is 2Vpp.
Fig. 6 shows a performance simulation result of the buffer circuit of the embodiment. Where the output voltage is 2Vpp and the current injection is 0 in the ideal case. As can be seen from fig. 6, the scheme without the buffer circuit of the present embodiment has the following problems: (1) more susceptible to coupling capacitance variations; (2) lower voltage gain; (3) greater current injection; (4) there is no plateau in voltage gain and current injection.
TABLE 1 sensitivity test results
The buffer circuit is applied to the sensor system, and sensitivity comparison experiments are carried out on the sensor system without the buffer circuit. The experimental result shows that the buffer circuit provided by the embodiment has a larger output signal size compared with the conventional scheme, and can improve the signal-to-noise ratio of the system. Meanwhile, the size of the output signal is less influenced by the distance between the polar plates.
In some embodiments, the a/D conversion circuit is connected to the processor through a wireless transmission module.
In other embodiments, the A/D conversion circuit and the processor may be connected by a signal line.
The buffer circuit transmits the acquired signals to the processor through the signal conditioning circuit and the A/D conversion circuit in sequence, and the processor obtains the pressure distribution on the pressure-sensitive layer according to the received signals. Fig. 7 (a) and 7 (b) show experimental results 1 and 2 for measuring the pressure distribution of the embedded surface leadless tactile sensor of the present embodiment.
It should be noted that the signal conditioning circuit, the a/D conversion circuit, and the signal preprocessing circuit are all conventional circuit structures, and are not described in detail here.
Example two
This embodiment provides an electronic device that includes an embedded surface leadless tactile sensor as described above.
It should be noted that, in the electronic device of the present embodiment, besides the embedded surface leadless tactile sensor, other structures can be implemented by using the prior art, and are not described in detail herein.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. 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. An embedded surface leadless touch sensor is characterized by comprising a sensitive layer, an insulating layer and a coupling capacitance electrode layer which are sequentially overlapped, wherein the sensitive layer is used for sensing a pressure change signal and converting the pressure change signal into a resistance change signal, and the coupling capacitance electrode layer is used for sensing the resistance change signal and converting the resistance change signal into a voltage change signal based on a capacitive coupling resistance tomography principle when the coupling capacitance electrode layer is not in direct contact with the sensitive layer;
a plurality of coupling capacitor electrode plates are distributed on the coupling capacitor electrode layer, and each coupling capacitor electrode plate is connected with the buffer circuit;
the buffer circuit comprises an operational amplifier and four resistors, wherein one ends of the first resistor and the second resistor are respectively connected with the negative input end and the positive input end of the operational amplifier, and the other ends of the first resistor and the second resistor are respectively connected with the output end of the operational amplifier; one end of the third resistor and one end of the fourth resistor are respectively connected with the negative input end and the positive input end of the operational amplifier, and the other ends of the third resistor and the fourth resistor are both grounded.
2. The embedded surface leadless tactile sensor of claim 1 wherein the sensitive layer is directly imaged based on capacitively coupled resistive tomography.
3. The embedded surface leadless tactile sensor of claim 1 wherein the embedded surface leadless tactile sensor is a planar structure.
4. The embedded surface leadless tactile sensor of claim 1 wherein the embedded surface leadless tactile sensor is a curved surface structure or a cylindrical surface structure.
5. The embedded surface leadless tactile sensor of claim 1 wherein the second resistance has a resistance greater than a fourth resistance.
6. The embedded surface leadless tactile sensor of claim 1 wherein the first resistor has an active compensation capacitor connected in parallel therewith.
7. The embedded surface leadless tactile sensor of claim 1, wherein the buffer circuit sequentially transmits the signals obtained by the buffer circuit to the processor via the signal conditioning circuit and the a/D conversion circuit, and the processor obtains the pressure distribution on the pressure-sensitive layer according to the received signals.
8. The embedded surface leadless tactile sensor of claim 7, wherein the a/D conversion circuit is connected to the processor via a wireless transmission module or signal line.
9. An electronic device comprising the embedded surface leadless tactile sensor of any of claims 1-8.
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| CN202210198395.5A CN114577377B (en) | 2022-03-01 | 2022-03-01 | Embedded surface leadless touch sensor and electronic equipment |
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| CN202210198395.5A CN114577377B (en) | 2022-03-01 | 2022-03-01 | Embedded surface leadless touch sensor and electronic equipment |
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| CN114577377B true CN114577377B (en) | 2023-01-17 |
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Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011209285A (en) * | 2010-03-30 | 2011-10-20 | Tk Holdings Inc | Force measurement system |
| TWI488099B (en) * | 2013-06-20 | 2015-06-11 | Ind Tech Res Inst | Touch device and sensing compensation method |
| US10401241B2 (en) * | 2016-06-08 | 2019-09-03 | The University Of British Columbia | Surface sensor arrays using ionically conducting material |
| CN106768518A (en) * | 2016-12-09 | 2017-05-31 | 中国科学院合肥物质科学研究院 | Flexible pressure-sensitive sensor based on EIT technologies |
| CN110207862B (en) * | 2019-05-28 | 2020-07-03 | 北京航空航天大学 | Tactile pressure sensor based on electrical impedance tomography and signal acquisition method |
| CN112067170A (en) * | 2020-09-14 | 2020-12-11 | 哈尔滨工业大学 | Flexible touch sensor based on transformer principle and flexible touch detection system thereof |
| CN113749661A (en) * | 2021-08-30 | 2021-12-07 | 西安交通大学 | Capacitive coupling PCB electrode structure for collecting human body bioelectricity signals |
| CN113970395B (en) * | 2021-11-16 | 2022-09-30 | 浙江大学 | Flexible sensor with contact and non-contact sensing functions and manufacturing method thereof |
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