CN102707695A - Switching system for electrical impedance tomography - Google Patents
Switching system for electrical impedance tomography Download PDFInfo
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- CN102707695A CN102707695A CN2012101887865A CN201210188786A CN102707695A CN 102707695 A CN102707695 A CN 102707695A CN 2012101887865 A CN2012101887865 A CN 2012101887865A CN 201210188786 A CN201210188786 A CN 201210188786A CN 102707695 A CN102707695 A CN 102707695A
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Abstract
The invention discloses a switching system for electrical impedance tomography (EIT). The switching system comprises a flexible flat cable pin-shaped socket, a D-SUB connector, four shape memory alloy (SMA) connectors, four groups of decoding circuits, four groups of electric control switch circuits and a shielding driving circuit, wherein the shielding driving circuit is connected with the D-SUB connector through a shielding signal connecting wire; the input ends of the four groups of electric control switch circuits are connected with the D-SUB connector through an internal connecting bus respectively; the input end of each group of decoding circuit is connected with the output end of a group of electric control switch circuit respectively; the output ends of the four groups of decoding circuits are connected to the same flexible flat cable pin-shaped socket; and each SMA connector is connected to a group of electric control switch circuit. The switching system is ingenious in concept; the switching system of the conventional EIT system forms a subsystem independent from a data acquisition system, so that an electrode distribution parameter is reduced; and due to the adoption of novel switches and a shielding driving technology, the whole EIT system has the advantages of high imaging accuracy, high imaging speed, long service life, wide working frequency range and the like.
Description
Technical field
The present invention relates to a kind of switching system, specifically, relate to a kind of switching system that is used for electrical impedance tomography.
Background technology
(Electrical Impedance Tomography EIT) is the technology of a kind of noninvasive resistivity distribution with inside of human body rebuilding body inner tissue image that is target to electrical impedance tomography.Human body is a big bioelectricity conductor; Each tissue, organ all have certain impedance; When the local organs generation pathology of human body, the impedance of part is inevitable different with other positions, thereby can come through the measurement of impedance the pathology of human organ is diagnosed.With nuclear medicine compared with techniques such as CT, MRI, EIT have harmless harmless, cost is low, volume is little, safe, simple to operate, to advantages such as early carcinoma kitchen range sensitivities, doctor and patient are acceptant.But the imaging precision of EIT is not high relatively, because data acquisition and the image taking speed of EIT are higher, can be used for the patient is carried out real-time for a long time, dynamic monitoring, has medical application prospect widely.
The EIT imaging is the inverse problem solution procedure of a serious morbid state, reconstitutes picture and is broadly divided into three types: back projection, process of iteration, a step linear approach, above reconstruction algorithm is to all requirements to some extent of convergence.Therefore, no matter take which kind of data acquisition scheme, the picture quality of EIT imaging all depends on the data precision that is collected, and very high to the data accuracy requirement.According to the EIT basic functional principle, EIT system architecture basically identical is described as numerous data and patents (like CN03134598.0) about the EIT aspect, all is made up of data acquisition system (DAS), electrode, excitation system, data processing and imaging system.The performance of electrode, data acquisition system (DAS) directly influences the image data precision, thus image quality, and data acquisition system (DAS) comprises switching system, LNA, difference amplification, filtering, AD etc., wherein the design of switching system is a difficult point.
At present, also there are many difficulties in the EIT technology in clinical practice, and one of them is exactly that the image data precision is not high enough, image quality is impacted, and then influence EIT system accuracy of detection.The switching system performance is undesirable to be the key factor that causes data precision not high, particularly for working frequency range in the multifrequency EIT of 10KHz～1MHz system.The traditional E IT system has all adopted ESS Electronic Switching System commonly used, and has adopted cross bar switch and multiple-pole switch, attempts to reduce as much as possible the factor of paying no attention to that it brings.But because the physical arrangement of electronic switch commonly used restriction; Exist inevitably conducting resistance inconsistent, crosstalk, number of drawbacks such as distortion, leakage, noise; And ESS Electronic Switching System commonly used can produce relatively large electric capacity; Be generally 10～30pF, when using switch in parallel, electric capacity also can increase.And the capacity effect of electronic switch commonly used; Can influence system's input and output impedance greatly; Thereby cause acquired signal waveform gross distortion, expect that with system the signal that detects is different greatly, produce very serious data error; Especially be operated in 1MHz when following when system frequency, this influence of experimental verification is very outstanding.Electronic switch commonly used causes crosstalks, distortion, leakage, noise, capacity effect all can influence data precision and limit whole EIT system maximum operation frequency, is difficult to eliminate this defective from theoretical and technology at present.
Summary of the invention
The object of the present invention is to provide a kind of switching system that is used for electrical impedance tomography, solve the phenomenon of crosstalking of adopting at present that ESS Electronic Switching System commonly used exists, distortion, leakage, noise, capacity effect and cause the not high problem of EIT system data precision and maximum operation frequency.
To achieve these goals, the technical scheme of the present invention's employing is following:
A kind of switching system that is used for electrical impedance tomography comprises winding displacement aciculiform socket, D-SUB connector, 4 SMA connectors, 4 groups of decoding schemes, 4 groups of electric-controlled switch circuit, shielding driving circuit; Wherein, The shielding driving circuit is connected with the D-SUB connector through the shielded signal connecting line; Pin one end of 4 groups of electric-controlled switch circuit is connected with the D-SUB connector through interior connecting bus respectively; The output terminal of every group of decoding scheme is connected with one group of electric-controlled switch circuit control end respectively, and the input end of 4 groups of decoding schemes then is connected on the same winding displacement aciculiform socket, and each SMA connector is connected on the pin other end of one group of electric-controlled switch circuit.
Further, said electric-controlled switch circuit comprises multiselect one electric-controlled switch and switch driving circuit; Wherein, Many signal pins end of multiselect one electric-controlled switch is connected on the interior connecting bus; The mono signal leads ends is connected with the SMA connector, and its control end then is connected with the output terminal of switch driving circuit, and the input end of said switch driving circuit is connected with the output terminal of said decoding scheme.
Said decoding scheme comprises decoder chip and resistance; Wherein, the output terminal of decoder chip links to each other with the input end of switch driving circuit, and the input end of decoder chip then links to each other with winding displacement aciculiform socket through resistance.
Said shielding driving circuit comprises operational amplifier and resistance, and wherein, the output terminal of operational amplifier links to each other with the D-SUB connector; Resistance then is arranged between the inverting input and output terminal of operational amplifier.
Again further, said winding displacement aciculiform socket is 24 faller gill line aciculiform sockets; Said decoder chip is the 4-16 decoder chip; Said multiselect one electric-controlled switch is for to select 1 electric-controlled switch based on 16 of novel switched structure.
Compared with prior art, the present invention has following beneficial effect:
(1) the present invention constitutes switching system through adopting the new electronic control switch combination; Overcome electronic switch commonly used intrinsic crosstalk, problem such as distortion, leakage, noise, capacity effect; EIT system data precision and maximum operation frequency have been improved; Thereby improved the imaging precision of EIT system, expanded the band limits of multifrequency EIT system.
(2) electric-controlled switch of the present invention's employing has low delay, feature of long life; Make phase delay time and life-span of switching system near electronic switch commonly used; Satisfy system requirements, and do not have problems such as the crosstalking of electronic switch commonly used, distortion, leakage, noise, capacity effect.
(3) the present invention is independent from data acquisition system (DAS) with switching system, forms subsystem, greatly reduce the length of electrode, thus reduced electrode long cause crosstalk, problem such as distributed capacitance.
(4) the present invention realizes the shielding actuation techniques through the shielding driving circuit, has further reduced problems such as crosstalking of causing because of electrode is long, capacity effect.
(5) the present invention is skillfully constructed, and is simple in structure, cheap, is fit to apply.
Description of drawings
System chart when Fig. 1 is applied to the electrical impedance tomography system for the present invention.
Fig. 2 is a system principle diagram of the present invention.
Fig. 3 is the schematic block circuit diagram of shielding driving circuit among the present invention.
Fig. 4 is the schematic block circuit diagram of 4-16 decoding scheme among the present invention.
Fig. 5 among the present invention 16 select 1 electric-controlled switch circuit schematic block circuit diagram.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is described further, embodiment of the present invention includes but not limited to the following example.
Embodiment
As depicted in figs. 1 and 2, this switching system that is used for electrical impedance tomography is a sub-systems of EIT system, and the EIT system is mainly shown by master control, driving source, switching system, signal condition and acquisition system, Flame Image Process and master and 16 electrodes are formed.And this switching system comprises input interface, output interface, 4 groups of 4-16 decoding schemes, selects 1 electric-controlled switch circuit, shielding driving circuit for 4 group 16.Wherein, input interface comprises 24 faller gill line aciculiform sockets, D-SUB socket, 2 SMA connectors; 24 faller gill line aciculiform sockets are mainly used in the receiving key control signal, wherein have 16 pins to connect 4 groups of decoding schemes, 2 pins to connect+the 5V power supply, 2 pin ground connection, 2 pins connect-the 5V power supply, and all the other pin hoverings are reserved; The D-SUB socket is totally 40 pins, is divided into 20 pins and following 20 pins, and wherein, 16 pins in 20 pins are respectively applied for and connect 16 electrodes down, receive 16 electrode signals; 2 SMA connectors connect source+, source-signal respectively, and source+, source-are the difference pumping signal that the driving source of EIT system produces.Output interface comprises D-SUB connector, 2 SMA connectors; Wherein 2 SMA connectors are exported the signal condition and the acquisition system of signal+, signal-signal to EIT system respectively, and signal+, signal-are the channel signal after selecting through electrode and electric-controlled switch circuit; 16 pins in last 20 pins of D-SUB connector are used for the corresponding shielded signal of output electrode.The output terminal of 4 groups of 4-16 decoding schemes is connected with this 24 faller gill line aciculiform socket; The output terminal of every group of 4-16 decoding scheme then connects one group 16 respectively and selects 1 electric-controlled switch circuit; Select for every group 16 1 electric-controlled switch circuit to connect a SMA connector simultaneously; And the many signal pins end that selects 1 electric-controlled switch circuit for 4 group 16 all is connected on the interior connecting bus, and is connected with the D-SUB socket through interior connecting bus, electrode signal line.Said shielding driving circuit links to each other with the D-SUB connector through the shielded signal line.D-SUB socket and D-SUB connector complement one another, and are referred to as the D-SUB connector.
Select 1 electric-controlled switch circuit to be elaborated to shielding driving circuit, 4-16 decoder circuit and 16 respectively below.
As shown in Figure 3, above-mentioned shielding driving circuit is made up of operational amplifier and resistance, and wherein, the two ends of resistance are concatenation operation amplifier's inverting input and output terminal respectively, makes emitter follower of the common formation of resistance and operational amplifier.The input end of this emitter follower is the in-phase input end of operational amplifier, and output terminal is the output terminal of operational amplifier, with the input end and a path electrode signal communication of emitter follower, and the shielded signal of then corresponding this path electrode of output terminal output.The emitter follower that 16 route operational amplifiers and resistance are formed constitutes 16 tunnel shielding driving circuits altogether, i.e. 16 emitter followers, and they control an electrode signal respectively, exports a shielded signal, thus realization feeds back to electrode signal the function of screen layer.
As shown in Figure 4, above-mentioned 4-16 decoder circuit is made up of 4-16 decoder chip and resistance, and totally 4 groups of 4-16 decoder circuits among the present invention are used for respectively the digital control sign indicating number that master control is sent is deciphered, and produce and select 1 electric-controlled switch circuit control signal for 4 group 16.The input end of switch driving circuit directly links to each other with 16 output terminals of 4-16 code translator, and 4 digital input ends of 4-16 decoder chip then link to each other with 24 faller gill line aciculiform sockets after the resistance in series respectively.The master control of EIT system is sent digital control sign indicating number gets into decoder chip then and translates correct switch control code earlier through resistance, and exports 16 to and select 1 electric-controlled switch.When the digital high signal occurring, be generally 3.3V, because decoder chip input impedance is big, need electric current little, the voltage difference at resistance two ends is very little, and the code translator input voltage is similar to 3.3V, and increasing resistance does not have influence to normal decoding; If outside have very big surge voltage to arrive, though most voltage at the input end of code translator, but owing to the metering function of resistance, can not cause damage to code translator yet.Code translator is worked according to normal 4-16 decoded mode, shown in table one:
Table one
As shown in Figure 5; Above-mentioned 16 select 1 electric-controlled switch circuit to be made up of electric-controlled switch, triode and resistance; The present invention selects 1 electric-controlled switch circuit totally for 4 group 16, and each group connects a SMA connector, is used for importing source+, source-signal and output signal+, signal-signal.Interconnective triode and resistance constitute the driving circuit of electric-controlled switch; To drive electric-controlled switch; And electric-controlled switch have do not have crosstalk, undistorted, ultralow leakage, ultra-low noise, ultralow conducting resistance, lowly postpone, feature of long life; Its control end links to each other with switch driving circuit after 16 electric-controlled switch parallel connections, constitutes 16 and selects 1 electric-controlled switch circuit, and its many signal pins end is connected with the SMA connector with interior connecting bus respectively with the mono signal leads ends.Because the electric-controlled switch control end need consume very big electric current, and common digital device can't drive, therefore use triode to realize driving.Because to have only an output code is 1 to the 4-16 decoder circuit at every turn, so this 16 selects 1 electric-controlled switch circuit also to have only an electric-controlled switch to be in closure state at every turn.
When the EIT system works, its driving source circuit can provide pumping signal source+, source-, the electrode channel that needs switching system that pumping signal the is switched to appointment simultaneously output of getting on.Master control this moment provides the energizing switch control code earlier, and switching system of the present invention is after receiving the energizing switch control code, and electrode signal passage and source+, the source-with appointment connects respectively.Simultaneously; The EIT system is after sending pumping signal; Also will come the measurement target signal through electrode, so the master control meeting of EIT system sends potential electrode passage gating control code and give switching system, switching system is after receiving this control code; Electrode signal passage and signal+, signal-with appointment connects respectively, realizes specifying the measurement of electrode channel differential signal.
Framework of the present invention and design not only are directed against the EIT system of 16 electrodes; Can also only need the electric-controlled switch quantity of correspondence, the output terminal quantity of decoder chip and the joint quantity of D-SUB connector are adjusted into get final product identical with number of electrodes to the EIT system of other quantity electrodes.The routine that above-mentioned variation belongs to the industry changes, and need not pay creative work, and therefore, above-mentioned variation also belongs within protection scope of the present invention.
According to the foregoing description, just can realize the present invention well.
Claims (7)
1. a switching system that is used for electrical impedance tomography is characterized in that, comprises winding displacement aciculiform socket, D-SUB connector, 4 SMA connectors, 4 groups of decoding schemes, 4 groups of electric-controlled switch circuit, shielding driving circuit; Wherein, The shielding driving circuit is connected with the D-SUB connector through the shielded signal connecting line; Pin one end of 4 groups of electric-controlled switch circuit is connected with the D-SUB connector through interior connecting bus respectively; The output terminal of every group of decoding scheme is connected with one group of electric-controlled switch circuit control end respectively, and the input end of 4 groups of decoding schemes then is connected on the same winding displacement aciculiform socket, and each SMA connector is connected on the pin other end of one group of electric-controlled switch circuit.
2. a kind of switching system that is used for electrical impedance tomography according to claim 1 is characterized in that said electric-controlled switch circuit comprises multiselect one electric-controlled switch and switch driving circuit; Wherein, Many signal pins end of multiselect one electric-controlled switch is connected on the interior connecting bus; The mono signal leads ends is connected with the SMA connector, and its control end then is connected with the output terminal of switch driving circuit, and the input end of said switch driving circuit is connected with the output terminal of said decoding scheme.
3. a kind of switching system that is used for electrical impedance tomography according to claim 2 is characterized in that said decoding scheme comprises decoder chip and resistance; Wherein, the output terminal of decoder chip links to each other with the input end of switch driving circuit, and the input end of decoder chip then links to each other with winding displacement aciculiform socket through resistance.
4. a kind of switching system that is used for electrical impedance tomography according to claim 3 is characterized in that said shielding driving circuit comprises operational amplifier and resistance, and wherein, the output terminal of operational amplifier links to each other with the D-SUB connector; Resistance then is arranged between the inverting input and output terminal of operational amplifier.
5. a kind of switching system that is used for electrical impedance tomography according to claim 4 is characterized in that, said winding displacement aciculiform socket is 24 faller gill line aciculiform sockets.
6. a kind of switching system that is used for electrical impedance tomography according to claim 5 is characterized in that said decoder chip is the 4-16 decoder chip.
7. a kind of switching system that is used for electrical impedance tomography according to claim 6 is characterized in that, said multiselect one electric-controlled switch is 16 to select 1 electric-controlled switch, and this electric-controlled switch is novel switched.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210188786.5A CN102707695B (en) | 2012-06-08 | 2012-06-08 | Switching system for electrical impedance tomography |
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| CN201210188786.5A CN102707695B (en) | 2012-06-08 | 2012-06-08 | Switching system for electrical impedance tomography |
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| CN102707695B CN102707695B (en) | 2014-05-07 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103054578A (en) * | 2013-01-24 | 2013-04-24 | 四川大学 | Meridian point search tester |
| CN103228104A (en) * | 2013-02-27 | 2013-07-31 | 思澜科技（成都）有限公司 | Single-out-multiple switching circuit PCB (printed circuit board) of electrical impedance tomography serial data acquisition system |
| CN105982671A (en) * | 2015-03-03 | 2016-10-05 | 思澜科技（成都）有限公司 | Optimized bioelectric-impedance test circuit |
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| CN101125080A (en) * | 2007-09-25 | 2008-02-20 | 重庆大学 | Increment magnifying type signal measuring device using for impedance imaging |
| GB2449275A (en) * | 2007-05-15 | 2008-11-19 | Thomas William Bach | Driving a sensor pad for electrical impedance tomography (EIT) |
| WO2011113169A1 (en) * | 2010-03-16 | 2011-09-22 | Swisstom Ag | Electrode for a scanning electrical impedance tomography device and a scanning electrical impedance tomography device |
| CN102274025A (en) * | 2011-05-30 | 2011-12-14 | 郑州大学 | Multi-electrode electrical impedance tomography data acquisition system |
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Patent Citations (4)
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|---|---|---|---|---|
| GB2449275A (en) * | 2007-05-15 | 2008-11-19 | Thomas William Bach | Driving a sensor pad for electrical impedance tomography (EIT) |
| CN101125080A (en) * | 2007-09-25 | 2008-02-20 | 重庆大学 | Increment magnifying type signal measuring device using for impedance imaging |
| WO2011113169A1 (en) * | 2010-03-16 | 2011-09-22 | Swisstom Ag | Electrode for a scanning electrical impedance tomography device and a scanning electrical impedance tomography device |
| CN102274025A (en) * | 2011-05-30 | 2011-12-14 | 郑州大学 | Multi-electrode electrical impedance tomography data acquisition system |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103054578A (en) * | 2013-01-24 | 2013-04-24 | 四川大学 | Meridian point search tester |
| CN103228104A (en) * | 2013-02-27 | 2013-07-31 | 思澜科技（成都）有限公司 | Single-out-multiple switching circuit PCB (printed circuit board) of electrical impedance tomography serial data acquisition system |
| CN103228104B (en) * | 2013-02-27 | 2018-01-09 | 思澜科技（成都）有限公司 | The on-off circuit PCB of electrical impedance tomography serial data collection system multiselect 1 |
| CN105982671A (en) * | 2015-03-03 | 2016-10-05 | 思澜科技（成都）有限公司 | Optimized bioelectric-impedance test circuit |
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