CN103142225B - Electroencephalograph for determining contact status between electrode and scalp and method for determining same - Google Patents
Electroencephalograph for determining contact status between electrode and scalp and method for determining same Download PDFInfo
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Abstract
The invention relates to an electroencephalograph for determining the contact status between an electrode and a scalp and a method for determining the contact status between the electrode and the scalp. The electroencephalograph comprises an electroencephalogram signal detecting circuit and a scalp impedance detecting circuit, wherein the electroencephalogram signal detecting circuit is provided with at least one set of interfaces connected with a reference electrode and a plurality of electrodes to be detected, which are contacted with scalp, through lead wires; and the scalp impedance detecting circuit is independent from the electroencephalogram signal detecting circuit to be connected with the interfaces of the electrodes to be detected and the reference electrode. According to the invention, the electroencephalogram signal detecting circuit and the scalp impedance detecting circuit are respectively detected, the contact status is determined by a threshold value determining method, and the method is simple in circuit, high in circuit anti-interference performance and quick in speed; not only can the detection precision of the scalp impedance be improved, but also the acquiring and the process of the electroencephalogram signal can not be influenced; and the large information content electroencephalogram signal can be most accurately processed, and the scalp impedance information can be most timely processed, so that a product is better in performance.
Description
Technical field
The invention belongs to medical Instrument field, particularly a kind of electroencephalograph and determination methods thereof that electrode and scalp contact condition are judged.
Background technology
Along with scientific and technical progress and development, improving constantly of living standards of the people, also more and more higher to the requirement of medical detection level.Brain electric system plays an important role in clinical diagnosis as a kind of important medical apparatus and instruments that detects brain diseases.But current brain electricity product memory capacity is little, gather lead number less, poor anti jamming capability, stability be also poor, some brain electro-detection equipment does not possess the function of detecting electrode connection, and what possess this function can not measure the impedance between brain electricity and electrode and scalp simultaneously.Along with biocybernetics method research brain function becomes the importance that brain is studied, the importance of Processig of EEG information is also more and more obvious.Aspect preclinical medicine, because brain electricity has synthetically reflected neural activity, thereby its research contributes to the further investigated of neuromechanism in physiology and pathology activity.Aspect clinical medicine, Processig of EEG information not only provides objective basis for the diagnosis of some disease of brain, and provides effective treatment means for some disease of brain.In the research of psychology, psychiatry, Cognitive Science, Processig of EEG information has important learning value and wide application prospect.Therefore, advance brain electro-detection class armarium to develop in depth and breadth to high point, could meet the demand of forward position medical applications.
Because EEG signals itself is very faint, in measuring process, can be subject to various impacts, produce artifact, and then affect the quality of EEG signals.And the principal element that affects EEG signals quality has: the noise that the interference that AC power frequency interference, electrode and scalp loose contact are introduced and amplification channel are introduced etc.
Publication number is the Chinese patent of CN2610843, a kind of " brain scalp impedance detector " disclosed, a kind of impedance detection circuit of brain electricity is proposed in patent, the detection signal of the brain electricity of this circuit and the test signal of scalp impedance are mixed in together, amplify by common brain electricity amplifying circuit, then by after high pass and low-pass filtering, two kinds of signals being extracted respectively, obtain corresponding brain electric information and impedance information.EEG signals is the low frequency signal of 0-30Hz, and traditional brain electricity amplifying circuit designs for low frequency signal, and the decay meeting of the high-frequency signal to modulation impedance information is more serious, thereby makes the impedance information that draws not accurate enough.Publication number is the Chinese patent of CN101199418, a kind of " brain impedance detection circuitry and EEG checking device " disclosed, a kind of impedance detection circuit of brain electricity is proposed in patent, this circuit passes through constant-current source, scalp, earth resistance forms loop, this circuit is provided with separately an earth resistance for measuring the exciting circuit of scalp impedance and test circuit altogether, in use, requiring to contact with scalp as the electrode of earth resistance must be good, its reaction be not the EEG type impedance between real measurement electrode and reference electrode, complexity and the inaccuracy of test are increased.
Above-mentioned two open files have all adopted the driving source of traditional simple alternating current constant-current source as human-body biological impedance measurement, what frequency adopted is all lower than 50KHz, calculate its impedance by its virtual value, and in circuit, simple alternating current constant current excitation signal and EEG signals all can be input in EEG signals testing circuit simultaneously, sine wave signal is easy to the measurement of pcs signal to produce and disturb, and the circuit of its processing is wanted to complicated with respect to other circuit.And resistance and the signal wave phase error measured lower than the simple alternating current constant current excitation signal of 50KHz are large, in the time requiring EEG signals to synchronize with scalp impedance signal, will produce error in official hour, and good, the bad and three kinds of states that come off that only need contact with scalp electrode in actual application judge, and undesired accurately resistance, the simple alternating current constant-current source therefore adopting is too complicated as the circuit of the driving source of human-body biological impedance measurement.
Summary of the invention
The object of the invention is to propose a kind of electroencephalograph and determination methods thereof that electrode and scalp contact condition are judged, for the high frequency feature of modulation signal, adopt human body impedance close to the frequency of pure resistance characteristic as excitation, select the long-pending amplifier of high gain-bandwidth, impedance information is distinguished over to EEG signals to be processed, thereby improve the accuracy of impedance information, and adopt square wave as driving source, the energy size that electrode is obtained with the contact resistance of scalp compares to judge with setting value contact good with bad.
To achieve these goals, technical scheme of the present invention is:
The electroencephalograph that electrode and scalp contact condition are judged: comprise EEG signals testing circuit and scalp impedance detection circuit, described EEG signals testing circuit is provided with at least one group and connects the tested electrode of multiple contact scalps and the EEG signals interface of a reference electrode by conducting wire; Wherein, described scalp impedance detection circuit comprises high frequency pumping loop and scalp impedance acquisition cuicuit; Described high frequency pumping loop comprises that dutycycle is square-wave generator and the multichannel capacitance-resistance charge-discharge circuit of 1:1, described capacitance-resistance charge-discharge circuit is made up of the first resistance and the first capacitances in series, described square-wave generator output connects a phase inverter, the output of phase inverter connects a roadlock and holds charge-discharge circuit resistance terminal, after all the other capacitance-resistance charge-discharge circuit resistance terminal parallel connections, be connected with square-wave generator output, the capacitance-resistance series circuit capacitance terminal of described parallel connection is connected with tested electrode interface respectively, and a described roadlock holds charge-discharge circuit capacitance terminal and is connected with reference electrode interface; Tested electrode interface and reference electrode interface are connected the input of scalp impedance acquisition cuicuit simultaneously, and scalp electrical impedance signal is passed to microprocessor by the output of scalp impedance acquisition cuicuit.
Further, described square-wave generator is that dutycycle is that the frequency of 1:1 is 60KHz to 70KHz square-wave generator to scheme.
Further, described square-wave generator is that dutycycle is that the frequency of 1:1 is 64KHz square-wave generator to scheme.
Further, described the first resistance is 1 megohm to scheme, and described the first electric capacity is 4.7 nano farads.
Further, described impedance acquisition cuicuit is linked in sequence and comprises frequency selection circuit, differential amplifier circuit, demodulation amplifying circuit and A/D convertor circuit scheme, described frequency selection circuit comprises multichannel resistance-capacitance circuit, described resistance-capacitance circuit is made up of second capacitance series the second resistance, one end connecting analog power cathode of the second resistance, described reference electrode is connected in series with a roadlock capacitive circuit, described multiple tested electrode is connected in series with remaining resistance-capacitance circuit respectively, the junction point of described the second electric capacity and the second resistance is connected a follow circuit as output, multiple follow circuits that described and multiple tested electrodes are connected connect a multichannel and select an analog switch, multichannel selects the output of an analog switch to connect the difference input of differential amplifier circuit together with the follow circuit output being connected with reference electrode.
Further, described the second electric capacity is 4.7 nano farads to scheme, and described the second resistance is 20 kilohms.
Further, described demodulation amplifying circuit comprises demodulator circuit and signal amplification circuit to scheme, and described demodulator circuit comprises the 3rd resistance, the 3rd electric capacity, the 4th resistance, the 5th resistance, the 4th electric capacity; Described the 3rd resistance is connected with the 3rd electric capacity one end, the 3rd electric capacity other end connects respectively the 4th resistance and the 5th resistance one end, the 5th resistance other end connects the 4th electric capacity one end, the 4th resistance and the 4th electric capacity other end connecting analog power cathode, the 5th resistance is connected the input of signal amplification circuit with the link of the 4th electric capacity.
Further, described the 3rd resistance is 1 kilohm to scheme, and described the 3rd electric capacity is 100 picofarads, and the 4th resistance is 249 kilohms, and the 5th resistance is 10 kilohms, and the 4th electric capacity is 62 picofarads.
The electrode contact state judging method of the electroencephalograph based on electrode and scalp contact condition are judged: comprise EEG signals testing circuit and scalp impedance detection circuit, described EEG signals testing circuit has at least a group interface to connect tested electrode and a reference electrode of multiple contact scalps by conducting wire; Described scalp impedance detection circuit comprises high frequency pumping loop and scalp impedance acquisition cuicuit; Described high frequency pumping loop comprises that dutycycle is 60KHz to 70KHz square-wave generator and the multichannel capacitance-resistance charge-discharge circuit of 1:1, described capacitance-resistance charge-discharge circuit is made up of the first resistance and the first capacitances in series, described square-wave generator output connects a phase inverter, the output of phase inverter connects a roadlock and holds charge-discharge circuit resistance terminal, after all the other capacitance-resistance charge-discharge circuit resistance terminal parallel connections, be connected with square-wave generator output, the capacitance-resistance series circuit capacitance terminal of described parallel connection is connected with tested electrode respectively, and a described roadlock holds charge-discharge circuit capacitance terminal and is connected with reference electrode; Tested electrode and reference electrode are connected the input of scalp impedance acquisition cuicuit simultaneously, and scalp electrical impedance signal is passed to microprocessor by the output of scalp impedance acquisition cuicuit; It is characterized in that, described impedance measurement method comprises: have a scalp impedance magnitude decision threshold table, obtain scalp impedance value between tested electrode and reference electrode by scalp impedance detection circuit, impedance value and threshold value table are compared to judgement, when impedance value meets contact while coming off threshold value, export the electrode contact signal that comes off, in the time that impedance value meets loose contact threshold value, export an electrode loose contact signal, in the time that impedance value meets contact good threshold, export an electrode contact good signal.
Scheme is further, described method is further: also have a scalp impedance detection circuit to connect the multiple tested electrode corresponding table one by one of multiple tested electrodes and the connection of EEG signals testing circuit, by described scalp impedance detection circuit to the result of determination of tested electrode contact impedance with EEG signals testing circuit to the EEG signals of the tested electrode collection corresponding external equipment that outputs to one by one.
The present invention compared with prior art tool has the following advantages: the testing circuit of the testing circuit of EEG signals and scalp impedance is divided into two-way and measures, not only improved the precision of scalp impedance detection, also can not affect the acquisition process of EEG signals simultaneously; The present invention adopts the method for qualitative judgement to judge contact condition, and circuit is simple, and circuit anti-interference is strong, and speed is fast; EEG signals adopts the sigma-delta ADC of high accuracy low speed, the successive approximation type a/d C that scalp impedance detection is used the low precision of high speed, the EEG signals of large information capacity can be obtained the most accurately, scalp impedance information obtains processing the most timely, makes the performance of product more excellent; Host computer adopts FIR digital filtering network technology that the digital brain electrical signal of collection and digital scalp impedance information are optimized to processing, shows, thereby provide stronger basis for estimation for pathological analysis with different identification means.
Like this, measuring the contact impedance state that obtains in time electrode in EEG signals, just can provide the most effectively for removing brain electricity artifact, foundation the most timely.
Below in conjunction with drawings and Examples, the present invention is described in detail.
Brief description of the drawings
Fig. 1 is electrical block diagram of the present invention;
Fig. 2 is high frequency pumping equivalent circuit of the present invention;
Fig. 3 is Fig. 2 each point oscillogram;
Fig. 4 is frequency selection circuit, differential amplifier circuit schematic diagram;
Fig. 5 is demodulation amplifying circuit schematic diagram of the present invention.
Detailed description of the invention
Embodiment 1:
A kind of electroencephalograph embodiment with impedance detection function: referring to Fig. 1, described electroencephalograph comprises EEG signals testing circuit 1 and scalp impedance detection circuit 2, described EEG signals testing circuit is provided with at least one group and connects the tested electrode 3 of multiple contact scalps and the EEG signals interface of a reference electrode 4 by conducting wire, can arrange according to the actual needs two to three groups or many groups, the present embodiment is two groups; Wherein, described scalp impedance detection circuit is independent of EEG signals testing circuit and is connected with tested electrode interface and reference electrode interface, be being separated from each other in analog with EEG signals testing circuit in analog of scalp impedance detection circuit, the scalp impedance signal input of described scalp impedance detection circuit is connected with tested electrode interface and the reference electrode interface of EEG signals testing circuit respectively.EEG signals testing circuit is the universal circuit of known use, this circuit is changed through the A/D of prime filter circuit 1-1, amplifying circuit 1-2, low-speed highly precise the EEG signals gathering after ADC 1-3, after the signal processing of microprocessor 5, be uploaded to host computer and carry out display analysis again.
In embodiment, as shown in Figure 1, described scalp impedance detection circuit comprises high frequency pumping loop 2-1 and impedance acquisition cuicuit 2-2, as shown in Figure 2, described high frequency pumping loop comprises that dutycycle is that the frequency of 1:1 is 60KHz to 70KHz square-wave generator 2-1-1 and multichannel capacitance-resistance charge-discharge circuit 2-1-2, described capacitance-resistance charge-discharge circuit is composed in series by the first resistance R 1 and the first capacitor C 1, described square-wave generator output connects a phase inverter 2-1-3, the output of phase inverter connects a roadlock and holds charge-discharge circuit resistance terminal, after all the other capacitance-resistance charge-discharge circuit resistance terminal parallel connections, be connected with square-wave generator output, the capacitance-resistance series circuit capacitance terminal of described parallel connection is connected with tested electrode respectively, a described roadlock holds charge-discharge circuit capacitance terminal and is connected with reference electrode, tested electrode and reference electrode are connected the input of impedance acquisition cuicuit simultaneously, and scalp electrical impedance signal is passed to microprocessor by the output of impedance acquisition cuicuit.Fig. 2 is an equivalent circuit, and as shown in Figure 1, square wave is to be produced by high frequency pumping square-wave pulse generator to actual circuit, and current-limiting resistance, integrating circuit and block isolating circuit have formed capacitance-resistance charge-discharge circuit.
In the research report of " observation and control technology " 2012 the 32nd volume the 4th interim " multi-frequency and multi-segment human biological electricity impedance measurement system ", show, the impedance of human body driving frequency during at 50KHz to 100KHz phase error less, approaching is the characteristic of pure resistance, in embodiment, due near 64KHz frequency band, human body impedance is approximate pure resistance characteristic, about 1-10K Ω magnitude, therefore square-wave generator parameter preferably, described square-wave generator is that dutycycle is that the frequency of 1:1 is 64KHz square-wave generator.
In embodiment, again due near 64KHz frequency band, human body impedance is approximate pure resistance characteristic, about 1-10K Ω magnitude, and therefore will access interelectrode equivalent impedance is pure resistance r.In each cycle of square wave, two C1 are that r and two R1 fixed resistances discharge and recharge by scalp termination.Getting R1 is that 1M Ω, two C1 are respectively 4.7nF.The time constant of circuit is approximately 4700 μ s like this, and the cycle T of square wave is 16 μ s, Gu discharge and recharge all incomplete at every turn, on electric capacity, voltage waveform is the shape of approximate triangular wave, therefore, parameter preferably, described the first resistance is 1 megohm, described the first electric capacity is 4.7 nano farads, and as shown in Figure 3, the amplitude that the information of scalp impedance has been included in B1 and B2 electric potential waveform has suffered the waveform of each point.
In embodiment, referring to Fig. 4, described impedance acquisition cuicuit is linked in sequence and comprises frequency selection circuit, differential amplifier circuit 2-2-2, demodulation amplifying circuit 2-2-4 and A/D convertor circuit 2-2-5, described frequency selection circuit comprises multichannel resistance-capacitance circuit, resistance-capacitance circuit is connected in series the second resistance R 2 by the second capacitor C 2 and forms, one end connecting analog power cathode of the second resistance, described reference electrode is connected in series with a roadlock capacitive circuit, described multiple tested electrode is connected in series with remaining resistance-capacitance circuit respectively, in order to reduce the impact on EEG signals testing circuit, improve the input impedance of differential amplifier circuit, the junction point of the second electric capacity and the second resistance is connected a follow circuit 2-2-1 who is formed by operational amplifier as output, the follow circuit output that tested electrode is connected with reference electrode connects the difference input of differential amplifier circuit, in embodiment, the amplification of differential amplifier circuit is 30 times.
In embodiment, frequency selection circuit is 64Khz frequency selection circuit, and wherein C2 is 4.7 nano farads (nF), and R2 is 20 kilohms (K Ω).
In embodiment, referring to Fig. 4, multiple follow circuits that described and multiple tested electrodes are connected connect a multichannel and select an analog switch 2-2-3, multichannel selects the output of an analog switch to connect the difference input of differential amplifier circuit together with the follow circuit output being connected with reference electrode, and multichannel selects the control end of an analog switch to connect microprocessor.
In embodiment, described demodulation amplifying circuit comprises demodulator circuit and signal amplification circuit (secondary amplification), and described demodulator circuit comprises the 3rd resistance R 3, the 3rd capacitor C 3, the 4th resistance R 4, the 5th resistance R 5, the 4th capacitor C 4; Described the 3rd resistance is connected with the 3rd electric capacity one end, the 3rd electric capacity other end connects respectively the 4th resistance and the 5th resistance one end, the 5th resistance other end connects the 4th electric capacity one end, the 4th resistance and the 4th electric capacity other end connecting analog power cathode, the 5th resistance is connected the input of signal amplification circuit with the link of the 4th electric capacity.
In embodiment, demodulator circuit is the demodulation to 64Khz signal, and wherein, R3 is 1 kilohm (K Ω), and C3 is 100 picofarads (PF), and R4 is 249 kilohms (K Ω), and R5 is 10 kilohms (K Ω), and C4 is 62 picofarads (PF).
In above-described embodiment, the testing circuit of scalp impedance signal is added in forward and high-frequency carrier signal negative anode and the negative terminal of brain wave acquisition signal, EEG signals with scalp impedance information is just added on high-frequency carrier signal, access the long-pending difference amplifier of high gain-bandwidth with the high-frequency signal of impedance information after by integrating circuit and high-pass filtering network, after the filtering of intergrade, enter two-level operating amplifier, signal after amplification passes through the successive approximation type a/d C of the low precision of high speed again, according to different energy threshold scopes, judge the contact impedance of electrode, thereby provide the state of electrode access, contact is good, loose contact, three kinds of states come off, on brain electricity box, control display lamp goes out, dodge or bright come three kinds of states of indicating electrode access, be that lamp goes out expression contact well, lamp dodges and represents loose contact, the bright expression of lamp comes off.
The Treatment Analysis of EEG signals and scalp impedance information, comprises the Treatment Analysis of EEG signals, for the EEG signals of continuous acquisition is carried out to digital filtering, then filtered data is carried out to figure conversion, finally waveform is shown; The Treatment Analysis of scalp impedance information, for timing acquiring scalp impedance information, by timing acquiring scalp impedance signal, judges termination value according to different sampled values, and shows.In the time gathering, identify, identify with different colors or flag event mode, with red waveform and the printed words labelling state that comes off that comes off, with yellow waveform and loose contact printed words labelling loose contact state, with normal color labelling contact kilter, such mark mode is checking while looking back waveform as pathological analysis provides stronger basis for estimation.
In embodiment, it is the feature of the present embodiment that a point two-way for the testing circuit of EEG signals and scalp impedance detection circuit is processed; And the successive approximation type a/d C that adopts the high-precision A/D conversion adc circuit of low speed, scalp impedance signal to adopt the low essence of high speed for EEG signals.
Embodiment 2:
The electrode contact state judging method embodiment of electroencephalograph electrode and scalp contact condition being judged based on embodiment 1: comprise EEG signals testing circuit and scalp impedance detection circuit, at least one group interface of described EEG signals testing circuit connects tested electrode and a reference electrode of multiple contact scalps by conducting wire, described scalp impedance detection circuit comprises high frequency pumping loop and scalp impedance acquisition cuicuit, described high frequency pumping loop comprises that dutycycle is 60KHz to 70KHz square-wave generator and the multichannel capacitance-resistance charge-discharge circuit of 1:1, described capacitance-resistance charge-discharge circuit is made up of the first resistance and the first capacitances in series, described square-wave generator output connects a phase inverter, the output of phase inverter connects a roadlock and holds charge-discharge circuit resistance terminal, after all the other capacitance-resistance charge-discharge circuit resistance terminal parallel connections, be connected with square-wave generator output, the capacitance-resistance series circuit capacitance terminal of described parallel connection is connected with tested electrode interface respectively, a described roadlock holds charge-discharge circuit capacitance terminal and is connected with reference electrode, tested electrode and reference electrode are connected the input of scalp impedance acquisition cuicuit simultaneously, and scalp electrical impedance signal is passed to microprocessor by the output of scalp impedance acquisition cuicuit, wherein, described impedance measurement method comprises: have a scalp impedance magnitude decision threshold table, obtain scalp impedance value between tested electrode and reference electrode by scalp impedance detection circuit, impedance value and threshold value table are compared to judgement, when impedance value meets contact while coming off threshold value, export the electrode contact signal that comes off, in the time that impedance value meets loose contact threshold value, export an electrode loose contact signal, in the time that impedance value meets contact good threshold, export an electrode contact good signal.Described scalp electrical impedance signal is actually the electric potential signal at scalp equivalent resistance r resistance two ends in Fig. 2.In the time that electrode and scalp do not connect completely, electrode is in the state of coming off, that is to say r resistance infinity in Fig. 2, equivalent circuit belongs to and opens circuit, two waveforms that are added in so the single spin-echo at difference amplifier two ends do difference and obtain maximum and minima later, can be judged to be to lead to come off according to threshold value.When electrode and scalp contact when good completely, electrode does not come off, and in Fig. 2, r resistance is very little, and B1 and B2 can regard isoelectric level as, obtain so with reference to zero potential value after differential amplifier circuit.Now can being judged to be to lead, it is good to connect.Marginal situation can be judged to be the situation of leading and not contacted completely.The value of three kinds of above-mentioned situations is stored in memorizer as judgment threshold.
In embodiment, described method is further: have a scalp impedance detection circuit to connect multiple tested electrodes and the EEG signals testing circuit multiple tested electrodes of connection corresponding table one by one, by described scalp impedance detection circuit to the result of determination of tested electrode contact impedance with EEG signals testing circuit to the EEG signals of the tested electrode collection corresponding external equipment that outputs to one by one.
In above-described embodiment, the detection of scalp impedance signal is added in positive and high-frequency carrier signal negative anode and the negative terminal of brain wave acquisition signal, EEG signals with scalp impedance information is just added on high-frequency carrier signal, access the long-pending difference amplifier of high gain-bandwidth with the high-frequency signal of impedance information after by integrating circuit and high-pass filtering network, after the filtering of intergrade, enter two-level operating amplifier, signal after amplification passes through the successive approximation type a/d C(A/D change-over circuit of the low precision of high speed again) circuit, according to different energy threshold scopes (because be not constant-current source form, do not know the size of electric current, therefore use energy value analog electrical resistance instead of real resistance value).Judge the contact impedance state of electrode, thereby provide the state of electrode access, i.e. contact is good, loose contact, three kinds of states come off, on brain electricity box, control that display lamp goes out, sudden strain of a muscle or bright come three kinds of states of indicating electrode access, be that lamp goes out expression contact well, lamp dodges and represents loose contact, and the bright expression of lamp comes off.
The Treatment Analysis of EEG signals and scalp impedance information, comprises the Treatment Analysis of EEG signals, for the EEG signals of continuous acquisition is carried out to digital filtering, then filtered data is carried out to figure conversion, finally waveform is shown; The Treatment Analysis of scalp impedance information, for timing acquiring scalp impedance information, by timing acquiring scalp impedance signal, judges termination value according to different sampled values, and shows.In the time gathering, identify, identify with different colors or flag event mode, with red waveform and the printed words labelling state that comes off that comes off, with yellow waveform and loose contact printed words labelling loose contact state, with normal color labelling contact kilter, such mark mode is checking while looking back waveform as pathological analysis provides stronger basis for estimation.
Claims (8)
1. the electroencephalograph that pair electrode and scalp contact condition judge: comprise EEG signals testing circuit and scalp impedance detection circuit, described EEG signals testing circuit is provided with at least one group and connects the tested electrode of multiple contact scalps and the EEG signals interface of a reference electrode by conducting wire, it is characterized in that, described scalp impedance detection circuit comprises high frequency pumping loop and scalp impedance acquisition cuicuit, described high frequency pumping loop comprises that dutycycle is square-wave generator and the multichannel capacitance-resistance charge-discharge circuit of 1:1, described capacitance-resistance charge-discharge circuit is made up of the first resistance and the first capacitances in series, described square-wave generator output connects a phase inverter, the roadlock that the output of phase inverter connects in multichannel capacitance-resistance charge-discharge circuit holds charge-discharge circuit resistance terminal, after all the other capacitance-resistance charge-discharge circuit resistance terminal parallel connections, be connected with square-wave generator output, the capacitance-resistance charge-discharge circuit capacitance terminal of described parallel connection is connected with tested electrode interface respectively, a described roadlock holds charge-discharge circuit capacitance terminal and is connected with reference electrode interface, tested electrode interface and reference electrode interface are connected the input of scalp impedance acquisition cuicuit simultaneously, and scalp electrical impedance signal is passed to microprocessor by the output of scalp impedance acquisition cuicuit,
Described square-wave generator is that dutycycle is that the frequency of 1:1 is 60KHz to 70KHz square-wave generator;
Described impedance acquisition cuicuit comprises the frequency selection circuit, differential amplifier circuit, demodulation amplifying circuit and the A/D convertor circuit that are linked in sequence, described frequency selection circuit comprises multichannel resistance-capacitance circuit, described resistance-capacitance circuit is made up of second capacitance series the second resistance, one end connecting analog power cathode of the second resistance, described reference electrode is connected in series with a roadlock capacitive circuit, described multiple tested electrode is connected in series with remaining resistance-capacitance circuit respectively, the junction point of described the second electric capacity and the second resistance is connected a follow circuit as output, multiple follow circuits that described and multiple tested electrodes are connected connect a multichannel and select an analog switch, multichannel selects the output of an analog switch to connect the difference input of differential amplifier circuit together with the follow circuit output being connected with reference electrode.
2. the electroencephalograph that electrode and scalp contact condition are judged according to claim 1, is characterized in that, described square-wave generator is that dutycycle is that the frequency of 1:1 is 64KHz square-wave generator.
3. the electroencephalograph that electrode and scalp contact condition are judged according to claim 1, is characterized in that, described the first resistance is 1 megohm, and described the first electric capacity is 4.7 nano farads.
4. the electroencephalograph that electrode and scalp contact condition are judged according to claim 1, is characterized in that, described the second electric capacity is 4.7 nano farads, and described the second resistance is 20 kilohms.
5. the electroencephalograph that electrode and scalp contact condition are judged according to claim 1, it is characterized in that, described demodulation amplifying circuit comprises demodulator circuit and signal amplification circuit, and described demodulator circuit comprises the 3rd resistance, the 3rd electric capacity, the 4th resistance, the 5th resistance, the 4th electric capacity; Described the 3rd resistance is connected with the 3rd electric capacity one end, the 3rd electric capacity other end connects respectively the 4th resistance and the 5th resistance one end, the 5th resistance other end connects the 4th electric capacity one end, the 4th resistance and the 4th electric capacity other end connecting analog power cathode, the 5th resistance is connected the input of signal amplification circuit with the link of the 4th electric capacity.
6. the electroencephalograph that electrode and scalp contact condition are judged according to claim 5, is characterized in that, described the 3rd resistance is 1 kilohm, described the 3rd electric capacity is 100 picofarads, the 4th resistance is 249 kilohms, and the 5th resistance is 10 kilohms, and the 4th electric capacity is 62 picofarads.
7. the electrode contact state judging method of the electroencephalograph based on electrode and scalp contact condition are judged: comprise EEG signals testing circuit and scalp impedance detection circuit, described EEG signals testing circuit has at least a group interface to connect tested electrode and a reference electrode of multiple contact scalps by conducting wire, described scalp impedance detection circuit comprises high frequency pumping loop and scalp impedance acquisition cuicuit, described high frequency pumping loop comprises that dutycycle is 60KHz to 70KHz square-wave generator and the multichannel capacitance-resistance charge-discharge circuit of 1:1, described capacitance-resistance charge-discharge circuit is made up of the first resistance and the first capacitances in series, described square-wave generator output connects a phase inverter, the roadlock that the output of phase inverter connects in multichannel capacitance-resistance charge-discharge circuit holds charge-discharge circuit resistance terminal, after all the other capacitance-resistance charge-discharge circuit resistance terminal parallel connections, be connected with square-wave generator output, the capacitance-resistance charge-discharge circuit capacitance terminal of described parallel connection is connected with tested electrode respectively, a described roadlock holds charge-discharge circuit capacitance terminal and is connected with reference electrode, tested electrode and reference electrode are connected the input of scalp impedance acquisition cuicuit simultaneously, and scalp electrical impedance signal is passed to microprocessor by the output of scalp impedance acquisition cuicuit, described impedance acquisition cuicuit comprises the frequency selection circuit, differential amplifier circuit, demodulation amplifying circuit and the A/D convertor circuit that are linked in sequence, described frequency selection circuit comprises multichannel resistance-capacitance circuit, described resistance-capacitance circuit is made up of second capacitance series the second resistance, one end connecting analog power cathode of the second resistance, described reference electrode is connected in series with a roadlock capacitive circuit, described multiple tested electrode is connected in series with remaining resistance-capacitance circuit respectively, the junction point of described the second electric capacity and the second resistance is connected a follow circuit as output, multiple follow circuits that described and multiple tested electrodes are connected connect a multichannel and select an analog switch, multichannel selects the output of an analog switch to connect the difference input of differential amplifier circuit together with the follow circuit output being connected with reference electrode, it is characterized in that, described method comprises: have a scalp impedance magnitude decision threshold table, obtain scalp impedance value between tested electrode and reference electrode by scalp impedance detection circuit, impedance value and threshold value table are compared to judgement, when impedance value meets contact while coming off threshold value, export the electrode contact signal that comes off, in the time that impedance value meets loose contact threshold value, export an electrode loose contact signal, in the time that impedance value meets contact good threshold, export an electrode contact good signal.
8. the electrode contact state judging method of the electroencephalograph based on electrode and scalp contact condition are judged according to claim 7: it is characterized in that, described method further comprises: scalp impedance detection circuit connects the multiple tested electrode that multiple tested electrodes are connected with EEG signals testing circuit to be shown one to one, by described scalp impedance detection circuit to the result of determination of tested electrode contact impedance with EEG signals testing circuit to the EEG signals of the tested electrode collection corresponding external equipment that outputs to one by one.
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| CN111067515B (en) * | 2019-12-11 | 2022-03-29 | 中国人民解放军军事科学院军事医学研究院 | Intelligent airbag helmet system based on closed-loop control technology |
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| CN111166306A (en) * | 2020-01-23 | 2020-05-19 | 北京津发科技股份有限公司 | Physiological signal acquisition method, computer device and storage medium |
| CN111481194A (en) * | 2020-04-23 | 2020-08-04 | 翟红 | Feedback acquisition system for electroencephalogram signals |
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Address after: Qin 066004 West Street in Hebei province Qinhuangdao City Economic and Technological Development Zone No. 112 Patentee after: Kangtai medical system (Qinhuangdao) Limited by Share Ltd Address before: Qin 066004 West Street in Hebei province Qinhuangdao City Economic and Technological Development Zone No. 112 Patentee before: Qinhuangdao Contec Medical Systems Co.,Ltd. |