CN107655498A - A kind of capacitance type touch sensor signal detection system - Google Patents
A kind of capacitance type touch sensor signal detection system Download PDFInfo
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- CN107655498A CN107655498A CN201610583294.4A CN201610583294A CN107655498A CN 107655498 A CN107655498 A CN 107655498A CN 201610583294 A CN201610583294 A CN 201610583294A CN 107655498 A CN107655498 A CN 107655498A
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- touch sensor
- capacitance type
- type touch
- signal detection
- detection system
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
- G01D5/241—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by relative movement of capacitor electrodes
- G01D5/2417—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by relative movement of capacitor electrodes by varying separation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
- G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Position Input By Displaying (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
Signal detection system all has a major impact to the resolving power of capacitance type touch sensor, stability and signal to noise ratio.A kind of capacitance type touch sensor signal detection system based on PCap01 electric capacity numeral conversion chips is invented, the haptic unit of capacitance type touch sensor is gated using FPGA control variable connectors and carries out array scanning, by transferring data to host computer by usb communication after SPI communication reading PCap01 measurement result, with D prism map and the stressing conditions on surface chart Dynamic Announce capacitance type touch sensor surface in host computer, the sampling rate of system is up to 1 frame/second.Test result indicates that the signal detection system of invention can meet the needs of capacitance type touch sensor, by the data of collection can obtain capacitance type touch sensor surface by force information.
Description
Art
The present invention relates to a kind of detecting system, more particularly to a kind of capacitance type touch sensor signal detection system.
Background technology
Tactile can obtain some geometric properties and physical characteristic of body surface, including hardness, pattern, roughness, bullet
Property, material etc..With bionic development, touch sensor is in robot bionic, medicine equipment, athletic training, ergonomic
Etc. field obtains a wide range of applications.Touch sensor mainly has a variety of shapes such as condenser type, resistance-type, piezoelectric type, optical fiber type
Formula, wherein capacitance type touch sensor are always the study hotspot in this field because the advantages that temperature drift is small, high sensitivity.From
Point of view of practicability is set out, and touch sensor should have the advantages that resolving power is high, range is big, stability is good, noise is small, except sensing
Device material in itself and structure, signal detection system are also the important guarantee of sensor performance.
Domestic and foreign scholars have done numerous studies to the signal detecting method of capacitance type touch sensor.Cheng etc. is using just
String encourages and the signal of the method for peak detection detection capacitance type touch sensor, sampling rate can reach 15 frames/second, still
Whole circuit is all made up of discrete component, and volume is larger.Le etc., Sergio etc., Surapaneni etc. use what is specially designed
Chip carries out the signal detection of capacitance type touch sensor, and experiment proves that this scheme sampling rate is fast, precision is higher, it is real to be easy to
The miniaturization of existing sensor, but production cost is higher and does not have good expansibility.Boie proposes one kind and utilizes phase
The method of quick demodulation principle detection capacitance type touch sensor signal, analyzes the noise of circuit and the source of stray capacitance, and
The tonogram picture of touch sensor is acquired by experiment.Peng etc. is set using business electric capacity conversion chip AD7147 and AD7746
The signal deteching circuit of capacitance type touch sensor has been counted, but because the electric capacity switching rate of both chips is relatively low, respectively
For 1.5kHz and 200Hz so that touch sensor dynamic range is narrower.
The content of the invention
The invention aims to improve resolving power, stability and the signal to noise ratio of capacitance type touch sensor, devise
A kind of signal detection system of the capacitance type touch sensor based on PCap01 electric capacity numeral conversion chips.
The technical solution adopted for the present invention to solve the technical problems is：
Capacitance type touch sensor signal detection system is by touch sensor, PCap01 electric capacity numerals conversion chip, FPGA, EZ-
A few part compositions such as USB single-chip microcomputers, host computer.
Described capacitance type touch sensor uses sandwich structure, is mainly made up of 4 parts:Upper electrode layer, lower electricity
Pole layer, Middle spacer layer and contact layer.Upper electrode layer and lower electrode layer are process by flexible PCB (FPCB) technique, often
8 strip electrodes are respectively embedded in layer.The electrode Orthogonally arrangement of upper electrode layer and lower electrode layer, 64 are formd altogether in its point of intersection
Individual electric capacity, each electric capacity are exactly a haptic unit, referred to as touch member.Middle spacer layer is made up of silica gel plate hollow out, hollow out
Place faces the position touched where member, can increase the deformation quantity of upper electrode by this design, increases the spirit of sensor
Sensitivity.The superiors are contact layers, and disk is made made of silica gel one by one, and each contact is affixed on tactile first position of upper electrode layer
The surface put.Contact can not only allow the extraneous power applied to be applied to just and touch in member, increase the sensitivity of sensor, and
Upper electrode layer can be protected not scratched by extraneous sharp object, improve the durability of sensor.
Described PCap01 is a electric capacity for the exclusively carrying out capacitance measurement numeral conversion with single-chip microcomputer processing unit
Single-chip, have the advantages that precision is high, conversion speed is fast, temperature drift is small, can compensate for parasitic capacitance.PCap01 chips electric capacity in theory
Measurement frequency is up to 500 kHz, but because the stability of the faster chip output valve of measurement frequency is poorer, system configuration PCap01
Measurement frequency be 1.04 kHz, the sampling rate of whole system is up to 15 frames/second.
Described EZ-USB is configured to slave-FIFO patterns, easily can carry out usb communication with host computer.
Described host computer is write as by LabVIEW, after the data that USB port inputs are read by VISA interfaces, passes through three
Block diagram and surface chart Dynamic Announce measurement result are tieed up, the stress on touch sensor surface can be learnt in real time according to these images
Situation.
The beneficial effects of the invention are as follows：
The stability of capacitance type touch sensor signal detection system can ensure within the 3% of initial capacitance value, pass through array
Formula scanning touch sensor touches the capacitance of member, obtains the stressing conditions on touch sensor surface.Test result indicates that design
Signal detection system can meet the detection demand of capacitance type touch sensor electric capacity.
Brief description of the drawings
The present invention is further described with reference to the accompanying drawings and examples.
Fig. 1 is signal detection system block diagram.
Fig. 2 is FPGA control flows.
Fig. 3 is PCap01 compensation parasitic capacitance circuit signals.
Fig. 4 is sensor construction signal.
Fig. 5 is Fundamentals of Sensors signal.
Fig. 6 is capacitance type touch sensor equivalent circuit simplified model.
Fig. 7 is the equivalent circuit of single tactile member.
Wherein, 1- electric shocks layer, 2- upper electrode layers, 3- Middle spacer layers, 4- lower electrode layers, 5- Top electrodes, 6- bottom electrodes.
Embodiment
As shown in figure 1, capacitance type touch sensor signal detection system is turned by touch sensor, PCap01 electric capacity numeral
Change a few part compositions such as chip, FPGA, EZ-USB single-chip microcomputer, host computer.Using FPGA control variable connector gating capacitive touch
Feel the haptic unit of sensor and carry out array scanning, led to after PCap01 measurement result is read by SPI communication by USB
Letter transfers data to host computer, with D prism map and surface chart Dynamic Announce capacitance type touch sensor table in host computer
The stressing conditions in face, the sampling rate of system is up to 15 frames/second.
As shown in Fig. 2 controllers of the FPGA as system, controls row selection variable connector and column selection variable connector pair
Touch sensor carries out array scanning according to some cycles.When a certain tactile first in choosing, after variable connector conducting is stable,
FPGA controls the corresponding capacitance for touching member of PCap01 chips measurement by SPI communication, passes measured value after reading its output signal
Be defeated by EZ-USB single-chip microcomputers, EZUSB is saved it in buffer, after continue to scan on next tactile member.EZ-USB by with
Slave-FIFO patterns are set to, easily can carry out usb communication with host computer.When all tactile members of touch sensor are all scanned
During completion, this frame data is transferred to host computer by FPGA control EZ-USB single-chip microcomputers by USB port.In view of PCap01 chips
Electric capacity switching rate, FPGA each seconds the data of 15 frame capacitance type touch sensors can be transmitted to host computer.Host computer by
LabVIEW is write as, aobvious by D prism map and surface chart dynamic after the data that USB port inputs are read by VISA interfaces
Show measurement result, the stressing conditions on touch sensor surface can be learnt in real time according to these images.
As shown in figure 3, measured capacitance and an optional reference capacitance are connected to same electric discharge electricity by PCap01 chips
Resistance, measured capacitance and reference capacitance discharge after being charged to supply voltage respectively, the split-second precision numeral conversion of chip internal
Device TDC will record both discharge times, and discharge time is directly proportional to the size of electric capacity.Measurement is tied in order to reduce temperature
The influence of fruit, chip is using the ratio of measured capacitance and reference capacitance as numeral output.By select chip operation pattern for
Floating ground, can set chip to carry out the internal compensation and external compensation of parasitic capacitance, as shown in Fig. 7.CxFor the electricity to be measured of chip
Hold, CpexFor the external parasitic capacitances of chip, CintFor the internal parasitic capacitances of chip.In one-shot measurement, chip controls conducting
The break-make for switching A0, A1, B0, B1 carries out 4 discharge and recharges to testing capacitance.1st charge and discharge electric connection A0, B1, disconnect A1, B0;
2nd charge and discharge electric connection A1, B0, disconnect A0, B1;3rd charge and discharge electric connection A0, A1, disconnect B0, B1.Chip passes through this 3 times
Discharge and recharge carries out external compensation, compensates CpexParasitic capacitance.The 4th charge and discharge electrically disconnected A0, A1, B0, B1, only to endophyte electricity
Hold CintDischarge and recharge, carry out internal compensation.Most of parasitic capacitance over the ground can be balanced out by the compensation of chip.
As shown in figure 4, sensor uses sandwich structure, mainly it is made up of 4 parts:Upper electrode layer, lower electrode layer,
Middle spacer layer and contact layer.Top electrode and lower electrode layer are process by flexible PCB (FPCB) technique, each in every layer
It embedded in 8 strip electrodes.The electrode Orthogonally arrangement of upper electrode layer and lower electrode layer, 64 electricity are formd altogether in its point of intersection
Hold, each electric capacity is exactly a haptic unit, referred to as touches member.Middle spacer layer is made up of silica gel plate hollow out, the place of hollow out
The position for touching member place is faced, the deformation quantity of upper electrode can be increased by this design, increases the sensitivity of sensor.
The superiors are contact layers, and disk is made made of silica gel one by one, and each contact is affixed on tactile first position of upper electrode layer
Surface.Contact can not only allow the extraneous power applied to be applied to just and touch in member, increase the sensitivity of sensor, and can be with
Protect upper electrode layer not scratched by extraneous sharp object, improve the durability of sensor.
Fundamentals of Sensors as shown in Figure 5 are as schemed, when contact is changed by the pressure in the external world, upper electrode layer contact institute
Position stress bending situation it is different, cause the distance between upper electrode layer electrode and lower electrode layer electrode to change, so as to touch
The capacitance of member changes, and the variable quantity can that first capacitance is touched by detecting extrapolates the size for touching pressure at member.Will
64 capacitances for touching member detect respectively according to certain rule, it is possible to learn the stressing conditions on touch sensor surface.
Strip shaped electric poles in upper electrode layer and lower electrode layer introduce same one end of sensor in FPCB by line, then by soft
Cable seat is introduced between in detection circuit, and so design can separate the non-sensitive part of sensor and signal detection system,
It is modular to design the compliance and practicality for having fully ensured that sensor.
The equivalent circuit of capacitance type touch sensor as shown in Figure 6 simplifies signal, and row electrode and each of row electrode have drawn 3
Bar.Row scanning and column scan control the gating of variable connector to be controlled by FPGA.Thicker lines are the row chosen in figure
Electrode and row electrode, after certain a line electrode and selected a certain row electrode, the position for the tactile member to be detected also is determined, choosing
In row electrode and row electrode through variable connector be connected to electric capacity conversion chip input carry out electric capacity detection.Remaining
The row electrode and row electrode not being selected are connected to ground by variable connector, to reduce noise.
The equivalent circuit diagram of single tactile member as shown in Figure 7, wherein Cij are the actual capacitance value of tactile member to be measured, and Rij is to treat
Survey the dielectric loss touched in member, Csi and Csj are respectively the parasitic capacitance of the row electrode and row electrode where tactile member to be measured, Rsi
Be respectively the conducting resistance for the variable connector for controlling row electrode and row electrode gating with Rsj, Cgi and Cgj be respectively row electrode and
The equivalent capacity of the parasitic capacitance such as the parasitic capacitance of wire and chip drain capacitance where row electrode, it can thus be appreciated that influenceing signal detection
The factor of circuit mainly has the factors such as the conducting resistance of dielectric loss, various parasitic capacitances and variable connector, its dielectric loss
Influence can ignore.The performance of detection circuit is so improved, on the one hand to select the less variable connector of conducting resistance,
On the other hand circuit board rational deployment is connected up and various parasitic capacitances is compensated, should try one's best selecting circuit noise in addition
Small chip.
Claims (5)
1. a kind of capacitance type touch sensor signal detection system by touch sensor, PCap01 electric capacity numerals conversion chip,
A few part compositions such as FPGA, EZ-USB single-chip microcomputer, host computer.
2. capacitance type touch sensor signal detection system according to claim 1, it is characterized in that described capacitive touch
Feel that sensor uses sandwich structure, be mainly made up of 4 parts:Upper electrode layer, lower electrode layer, Middle spacer layer and contact
Layer；Upper electrode layer and lower electrode layer are process by flexible PCB (FPCB) technique, and 8 bar shaped electricity are embedded in every layer
Pole；The electrode Orthogonally arrangement of upper electrode layer and lower electrode layer, 64 electric capacity is formd altogether in its point of intersection, each electric capacity is exactly one
Individual haptic unit, referred to as touch member；Middle spacer layer is made up of silica gel plate hollow out, and the place of hollow out faces the position touched where member
Put, the deformation quantity of upper electrode can be increased by this design, increase the sensitivity of sensor；The superiors are contact layers, by
Disk made of silica gel is made one by one, and each contact is affixed on the surface of tactile first position of upper electrode layer；Not only may be used contact
Touched with allowing the extraneous power applied to be applied to just in member, increase the sensitivity of sensor, and can protect upper electrode layer not by
Extraneous sharp object scratches, and improves the durability of sensor.
3. capacitance type touch sensor signal detection system according to claim 1, it is characterized in that described PCap01 is
A electric capacity for the exclusively carrying out capacitance measurement numeral conversion single-chip with single-chip microcomputer processing unit, has precision height, conversion
Speed is fast, temperature drift is small, can compensate for the advantages that parasitic capacitance；PCap01 chips in theory capacitance measurement frequency up to 500 kHz, but
Be due to the faster chip output valve of measurement frequency stability it is poorer, system configuration PCap01 measurement frequency is 1.04 kHz,
The sampling rate of whole system is up to 15 frames/second.
4. capacitance type touch sensor signal detection system according to claim 1, it is characterized in that described EZ-USB quilts
Slave-FIFO patterns are configured to, easily can carry out usb communication with host computer.
5. capacitance type touch sensor signal detection system according to claim 1, it is characterized in that described host computer by
LabVIEW is write as, aobvious by D prism map and surface chart dynamic after the data that USB port inputs are read by VISA interfaces
Show measurement result, the stressing conditions on touch sensor surface can be learnt in real time according to these images.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201610583294.4A CN107655498A (en) | 2016-07-24 | 2016-07-24 | A kind of capacitance type touch sensor signal detection system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610583294.4A CN107655498A (en) | 2016-07-24 | 2016-07-24 | A kind of capacitance type touch sensor signal detection system |
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| CN107655498A true CN107655498A (en) | 2018-02-02 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109708810A (en) * | 2019-02-21 | 2019-05-03 | 钛深科技(深圳)有限公司 | A kind of apparatus and system for film tactile sensing chip testing |
| CN111504521A (en) * | 2020-05-07 | 2020-08-07 | 腾讯科技（深圳）有限公司 | Flexible capacitor array, preparation method thereof and capacitor array detection system |
| CN111618912A (en) * | 2020-06-28 | 2020-09-04 | 威海华菱光电股份有限公司 | Tactile sensor |
| CN113575051A (en) * | 2021-08-23 | 2021-11-02 | 石河子大学 | Seed metering real-time monitoring system of air-aspiration type seed metering device based on capacitive sensor |
| CN113939722A (en) * | 2019-02-22 | 2022-01-14 | 触零有限公司 | Pressure sensing device and method |
-
2016
- 2016-07-24 CN CN201610583294.4A patent/CN107655498A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109708810A (en) * | 2019-02-21 | 2019-05-03 | 钛深科技(深圳)有限公司 | A kind of apparatus and system for film tactile sensing chip testing |
| CN113939722A (en) * | 2019-02-22 | 2022-01-14 | 触零有限公司 | Pressure sensing device and method |
| CN111504521A (en) * | 2020-05-07 | 2020-08-07 | 腾讯科技（深圳）有限公司 | Flexible capacitor array, preparation method thereof and capacitor array detection system |
| CN111504521B (en) * | 2020-05-07 | 2021-09-03 | 腾讯科技（深圳）有限公司 | Flexible capacitor array, preparation method thereof and capacitor array detection system |
| WO2021223581A1 (en) * | 2020-05-07 | 2021-11-11 | 腾讯科技（深圳）有限公司 | Flexible capacitor array and preparation method therefor, capacitor array detection system, and robot |
| CN111618912A (en) * | 2020-06-28 | 2020-09-04 | 威海华菱光电股份有限公司 | Tactile sensor |
| CN113575051A (en) * | 2021-08-23 | 2021-11-02 | 石河子大学 | Seed metering real-time monitoring system of air-aspiration type seed metering device based on capacitive sensor |
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Application publication date: 20180202 |