WO2017166215A1 - 液面检测装置及检测方法和全自动取样装置 - Google Patents

液面检测装置及检测方法和全自动取样装置 Download PDF

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WO2017166215A1
WO2017166215A1 PCT/CN2016/078160 CN2016078160W WO2017166215A1 WO 2017166215 A1 WO2017166215 A1 WO 2017166215A1 CN 2016078160 W CN2016078160 W CN 2016078160W WO 2017166215 A1 WO2017166215 A1 WO 2017166215A1
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Prior art keywords
circuit
probe
resonant
capacitance
change
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PCT/CN2016/078160
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English (en)
French (fr)
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陈跃平
黄泳
朱星才
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深圳迈瑞生物医疗电子股份有限公司
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Priority to PCT/CN2016/078160 priority Critical patent/WO2017166215A1/zh
Priority to CN201680037323.5A priority patent/CN107735653B/zh
Publication of WO2017166215A1 publication Critical patent/WO2017166215A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
    • G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
    • G01F23/266—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors measuring circuits therefor

Definitions

  • the invention relates to a liquid level sensing device, in particular to a detection circuit and method for detecting a liquid level of a sample during a sampling process by a fully automatic sampling device.
  • Automatic biochemical analyzer, immunoanalyzer, etc. when analyzing body fluids, need to be sampled first, and the pipetting probe is driven down in the test tube under the driving of the motor. When it touches the liquid surface, it is cleaned to prevent the needle tube from getting too deep. The problem of increasing difficulty (if the cleaning is not clean will cause cross-contamination), the motor must stop, the needle tube draws body fluid and then returns upwards under the driving of the motor, so in the automatic biochemical analysis, the liquid level detection must be carried out, and the needle tube contacts the liquid surface. When it is necessary, the contact liquid level indication signal is output to the motor control unit to control the motor to stop.
  • the main liquid level detection technology of the automatic biochemical and immunoanalyzer is usually the technical scheme shown in Figure 1.
  • Figure 1 provides a capacitive liquid level detection circuit, which is composed of an oscillation and frequency dividing circuit. Phase-locked loop 9, low-pass filter 10, high-pass filter 11, amplification 12, AD conversion 13, CPU processing 14, etc.
  • the method shown in Figure 1 uses a conventional probe capacitance detection method, which is not convenient in engineering. Directly measure the capacitance of the probe 3 and its variation. Therefore, the idea of the previous circuit scheme is to convert the capacitance into a voltage amount first, and then convert the voltage amount into a digital quantity by a common voltage type AD converter, and finally perform algorithm processing.
  • this circuit design method is costly, cumbersome to adjust, low in reliability, and has a complicated circuit structure and poor scalability.
  • the voltage-controlled oscillator in the core detection component "phase-locked loop" uses RC.
  • the type of oscillator has low anti-interference ability, and the detection sensitivity is limited by the resolution of the AD converter. It is impossible to detect a very small amount of liquid.
  • the invention provides a liquid level detecting device, a detecting method and a full-automatic sampling device, which simplifies the circuit structure, improves the anti-interference of the circuit, improves the detection resolution, and increases the expandability. Sex.
  • a first aspect of the present invention provides a liquid level detecting apparatus comprising:
  • An LC resonant driver coupled to the LC resonant circuit for providing a voltage or current that excites the probe and the LC resonant circuit to resonate and generate a resonant signal;
  • a shaping circuit coupled to the LC resonant circuit for converting the resonant signal into a digital signal and outputting the digital signal
  • a frequency measuring circuit connected to the shaping circuit for measuring the digital signal and outputting a change of a resonant frequency or a resonant frequency of the resonant signal
  • a processing circuit coupled to the output of the frequency measuring circuit for outputting an indication signal indicative of whether the probe is in contact with the measured liquid based on the resonant frequency or a change in resonant frequency.
  • a second aspect of the present invention provides a liquid level detecting method comprising:
  • Signal superimposing step superimposing a change in capacitance or capacitance due to a change in the distance between the probe and the measured liquid surface, superimposing on the LC resonant circuit, and obtaining a resonance signal mixed with a change in capacitance or capacitance generated by the probe ;
  • Conversion step converting the resonant signal into a digital signal
  • Frequency measuring step measuring the digital signal to obtain a change in a resonant frequency or a resonant frequency of the resonant signal;
  • Output step outputting an indication signal indicating whether the other end of the probe is in contact with the liquid to be measured, according to the change in the resonant frequency or the resonant frequency.
  • a third aspect of the invention provides a fully automatic sampling device comprising:
  • a needle motion control mechanism for receiving an indication signal from the output of the liquid level detecting device, and controlling movement of the probe relative to the liquid to be measured according to the indication signal.
  • the driving probe and the LC resonant circuit resonate and generate a resonant signal mixed with the probe capacitance information, and then convert the resonant signal into a digital signal, and finally determine according to the digital signal.
  • Resonant frequency or resonant frequency changes and according to The resonance frequency or the resonance frequency change obtains the detection result of the liquid contact at one end of the probe, so that the simplified analog circuit structure can be used to obtain the detection capacitance signal through an LC resonance circuit and its driving, thereby simplifying the structure of the analog circuit and improving the structure.
  • the anti-interference of the circuit The detection circuit no longer needs complicated analog circuits, and does not need to adjust the working point.
  • the structural simplification brings about a great improvement in cost, size and reliability.
  • FIG. 1 is a schematic structural view of a liquid level detecting device proposed by the prior art solution
  • FIG. 2 is a schematic structural view of a liquid level detecting device according to an embodiment of the present invention.
  • FIG. 3 is a schematic structural view of another liquid level detecting device according to an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of a topological structure of an LC resonant circuit in an embodiment of the present invention.
  • FIG. 5 is a schematic structural diagram of still another liquid level detecting device according to an embodiment of the present invention.
  • FIG. 6 is a schematic structural view of still another liquid level detecting device according to an embodiment of the present invention.
  • FIG. 10 is a schematic structural view of still another liquid level detecting device according to an embodiment of the present invention.
  • 7, 8, 9, and 11 are schematic structural views of various embodiments of the multi-channel detecting circuit structure of the present invention.
  • Automatic sampling devices are commonly used in automatic biochemical analyzers, fully automatic immunoassays, etc., which typically include aspiration probes, detection circuits, and needle motion control mechanisms. Obtained according to the detection circuit Whether the taken aspiration probe contacts the detection result of the liquid to be tested, the needle movement control mechanism controls the movement of the liquid absorption probe relative to the liquid to be measured.
  • the pipetting probe takes into account chemical compatibility, usually stainless steel or titanium alloy, which can be a single needle or a double layer pipetting probe.
  • the outer needle tube and the inner needle tube of the probe have a small length along the length of the needle tube, so that the inner needle tube can be shallowly inserted into the liquid surface to be measured while ensuring that the outer needle tube does not contact the liquid surface. Level detection.
  • FIG. 2 is a schematic structural diagram of a liquid level detecting device according to an embodiment of the present invention.
  • the liquid level detecting device in the embodiment of the present invention includes a probe 210, a detecting circuit 220, and a processing circuit 230, wherein:
  • the probe 210 is used for sucking the liquid to be tested and outputting its own capacitance.
  • the liquid-absorbent probe employs a double-layer pipetting probe, which is equivalent to a capacitor, including a conductive outer needle tube and a conductive inner needle tube and an intermediate insulating layer.
  • the probe 210 can be a two-layer syringe structure, the conductive inner needle of the probe 210 is connected to the LC resonant circuit 221, and the conductive outer needle can be grounded or not grounded.
  • the probe comprises a conductive inner needle tube and a conductive outer needle tube, the length of the conductive inner needle tube is longer than the length of the conductive outer needle tube, and the lengths of the conductive inner needle tube and the conductive outer needle tube differ by more than 3 cm.
  • the detection circuit 220 includes an LC resonance circuit 221 and an LC resonance driver 222, a shaping circuit 223, and a frequency measurement circuit 224.
  • the LC resonance circuit 221 is connected to one end of the probe 210.
  • the LC resonant driver 222 is coupled to the LC resonant circuit 221 for providing a voltage or current.
  • the excitation probe 210 and the LC resonant circuit 221 resonate and generate a resonant signal, and the resonant signal is mixed with information containing the probe capacitance.
  • the shaping circuit 223 is connected to the LC resonance circuit 221 for converting the resonance signal generated by the probe 210 and the LC resonance circuit 221 into a digital signal, and outputs the digital signal to the frequency measurement circuit 224.
  • the frequency measuring circuit 224 is coupled to the shaping circuit 223 for measuring the digital signal and outputting a change in the resonant frequency or resonant frequency of the resonant signal.
  • the processing circuit 230 is coupled to the output of the frequency measuring circuit 224 for outputting an indication signal indicative of whether the probe is in contact with the liquid being measured, based on a change in the resonant frequency or resonant frequency output by the frequency measuring circuit 224.
  • a change in capacitance or capacitance due to a change in the distance between the probe and the liquid surface to be measured is superimposed on the LC resonance circuit to obtain a resonance of the capacitance information or the capacitance change information generated by mixing the probe.
  • a signal that converts the resonant signal into a digital signal measures the digital signal to obtain a change in a resonant frequency or a resonant frequency of the resonant signal; and finally, based on a change in the resonant frequency or the resonant frequency, the output characterizes whether the other end of the probe contacts the liquid to be measured Indication signal.
  • the basic principle of the present embodiment will be described in detail by taking the LC resonance circuit 221 as an LC parallel resonance circuit as an example.
  • the LC resonant circuit 221 may be an LC parallel resonant circuit.
  • the LC resonant circuit may include an inductor L and a capacitor C. One end of the probe 210 and one end of the inductor L and the capacitor C respectively.
  • One end of the LC resonant driver 222 is connected to one end, and the other end of the inductor L and the other end of the capacitor C are respectively connected to the other end of the LC resonant driver 222.
  • the capacitor C, the inductor L and the LC resonant driver constitute a core front end detection circuit, and the LC resonant driver can adopt a constant current source. Under the excitation of the LC resonant driver, the capacitor C and the inductor L resonate, and the original resonant frequency for
  • L and C respectively represent the values of capacitor C and inductor L.
  • the probe is connected to the LC resonant circuit, and an additional capacitor C1 is introduced to the LC resonant circuit (ie, the self-capacitance of the probe 210 output).
  • LC resonant frequency is
  • the LC resonant circuit adopts the resonance principle, which is a second-order frequency selective circuit. Since the resonant current inside the capacitor C and the inductor L is much larger than the external excitation current, the stability and anti-interference ability of the oscillation waveform are much higher than the commonly used one.
  • the RC oscillator improves the anti-interference ability of the circuit, and the LC resonant circuit has a simple structure and reduces the circuit cost.
  • the output of the LC resonant circuit is usually a voltage signal, expressed as a sine wave, which is shaped into a digital signal by a shaping circuit to perform frequency measurement.
  • Frequency measurements include, but are not limited to, timing counting and phase-locked loop methods.
  • the timing counting method refers to: selecting a fixed period of time, accumulating the number of periodic signals, and dividing the counting value by the time to obtain the frequency.
  • the frequency measurement circuit 224 can be set to count the number of periodic signals of the digital signal within the preset duration by hardware circuit or software programming, and divide the number of periodic signals by the pre- Set the duration to calculate the change in the above resonant frequency or resonant frequency.
  • the counter may be used to count the number of periodic signals of the digital signal in the preset duration, and then the number of periodic signals obtained by the counter is divided by the preset duration by the divider, and the calculation is obtained.
  • the above resonance frequency or a change in the resonance frequency may be used to count the number of periodic signals of the digital signal in the preset duration, and then the number of periodic signals obtained by the counter is divided by the preset duration by the divider, and the calculation is obtained.
  • the frequency measuring circuit 224 can also measure the change in the resonant frequency or the resonant frequency by a phase locked loop method.
  • a phase-locked loop circuit 225 and a voltage measuring circuit 2251 are provided in the frequency measuring circuit 224.
  • the phase-locked loop circuit 225 and the voltage measuring circuit 2251 are sequentially connected in series, and are located between the shaping circuit 223 and the processing circuit 230.
  • the phase-locked loop circuit 225 converts the frequency change of the output signal of the shaping circuit into a voltage signal
  • the voltage measuring circuit 2251 acquires the voltage value of the voltage signal and presets the voltage value and the resonant frequency through the phase-locked loop circuit 224.
  • the ratio value is calculated by calculating the above resonance frequency or the resonance frequency. Further, the voltage value of the output signal of the shaping circuit may be proportional to the resonant frequency by frequency division and phase locking, and the resonant frequency may be calculated by dividing the voltage value of the output signal by the ratio of the voltage value to the resonant frequency.
  • the setting of the frequency measurement period or time by the user may be acquired by the human-machine interaction device, for example, The preset time in the number of periodic signals of the digital signal is arbitrarily set, and the user inputs an adjustment instruction for the preset duration before the start of the verification by the human-machine interaction device, and outputs the adjustment instruction to the frequency.
  • the measuring circuit the frequency measuring circuit counts the number of the periodic signals within a preset duration specified by the adjusting command, and is used for calculating a change of the resonant frequency or the resonant frequency. According to this method, the user can freely adjust the length of the frequency measurement and improve the measurement accuracy of the detection circuit.
  • the variation of the resonant frequency or the resonant frequency obtained in the calculation in this embodiment may be a value or a continuous waveform change in a certain time range.
  • the change in the resonant frequency may be the frequency of the currently calculated frequency relative to the previous time, or the amount of change in the currently calculated frequency relative to the original resonant frequency due to the capacitance and inductance values in the LC resonant driver.
  • the variation of the resonance frequency or the resonance frequency obtained by the above calculation has a certain proportional relationship with respect to the self capacitance C1 output from the probe 210.
  • the self-capacitance C1 outputted by the probe 210 can be calculated as:
  • the change of the self-capacitance C1 outputted by the probe 210 can be intuitively reflected, so that the proportional relationship between the two can be known according to the calibration method, etc., thereby calculating the resonance frequency or resonance based on the calculation.
  • the processing circuit 230 can determine whether the change of the resonant frequency or the resonant frequency satisfies the first preset condition, and if so, the probe contacts the liquid to be measured, and outputs an indication signal indicating that the probe contacts the liquid to be measured.
  • the first preset condition herein may be that the change of the resonant frequency or the resonant frequency is greater than a first preset threshold, or is within a first preset range, and the like.
  • the LC resonant circuit 221 can be an LC parallel resonant circuit, and the LC resonant driver 222 is a constant current source, and the LC parallel resonant circuit is connected in parallel with the LC resonant driver 222.
  • the shaping circuit 223 of this embodiment may be a Schmitt trigger or a hysteresis comparator or the like, and the shaping circuit 223 is configured to change the resonance signal into a binarized signal, thereby obtaining the above digital signal.
  • the frequency measuring circuit and the processing circuit of FIGS. 2 and 3 can be implemented by using digital circuits, for example, using one or more CPU processing chips. to realise.
  • LC resonant circuit 221, LC resonant driver 222, shaping circuit 223, frequency measuring circuit 224, and processing circuit 230 may also be integrated on the same integrated circuit chip.
  • the LC resonant circuit 221 may include two branches, one inductor branch, one capacitor branch, and the inductor branch includes at least one inductor or a tunable inductor.
  • the capacitor C11 and the capacitor C12 are used in FIG.
  • the resistor R11 is formed in series, and the capacitor branch includes at least one capacitor or a tunable capacitor.
  • two inductors L11 and an inductor L12 are connected in series.
  • the inductor branch and the capacitor branch are connected in parallel to form an LC resonant circuit.
  • One end of the probe 210 is respectively connected to one end of the inductor branch and one end of the capacitor branch (refer to FIG. 2 and FIG. 3, the capacitor branch and the inductor branch are connected in parallel to form both ends of the LC resonance circuit 221), or, as shown in FIG.
  • one end of the probe 210 can be selectively connected to any one of the inductive or capacitive branches.
  • the purpose is to superimpose the capacitance information generated on the probe into the LC resonance circuit to form a resonance signal.
  • the connection position of the probe 210 and the LC resonance circuit changes, the corresponding relationship in the above formula will also change accordingly. It can be obtained based on the circuit principle and will not be described here.
  • Figure 5 provides another embodiment of the present invention. Based on the embodiment shown in Figure 2, a change in capacitance information or capacitance that more accurately reflects the change in probe position based on the above-described variation of the resonant frequency or resonant frequency is added. information.
  • an arithmetic circuit 226 is added between the frequency measuring circuit 224 and the processing circuit 230 in FIG. 2 for calculating and outputting the probe according to the change of the resonant frequency or the resonant frequency obtained by the frequency measuring circuit 224.
  • the arithmetic circuit 226 can also be added between the frequency measuring circuit 224 and the processing circuit 230 in FIG.
  • the arithmetic circuit 226 belongs to a new portion of the detecting circuit 220. Based on this, the processing circuit 230 is connected to the arithmetic circuit 226.
  • the change in capacitance or capacitance outputted by the detecting circuit 220 mentioned in this embodiment may be a value or a waveform change within a certain time range.
  • the change in capacitance may be the change in the current calculated capacitance relative to the previous time, or the amount of change in the current calculated capacitance relative to the original capacitance of the probe when it is not in contact with the liquid surface.
  • the change in capacitance includes: a change in the capacitance that characterizes the difference between the capacitance of the detection capacitor after contact with the liquid surface and the capacitance value in contact with the liquid; or the change in the capacitance value after the detection capacitor contacts the liquid in a unit time. Rate of change.
  • the resonant frequency f' obtained by the frequency measuring circuit 224 and the capacitance and inductance parameter values in the LC resonant circuit are substituted into the above formula (3) according to the above formula (3).
  • An indication signal indicating whether the probe is in contact with the liquid to be measured is determined based on the calculated change in capacitance or capacitance.
  • the processing circuit 230 can determine whether the change in the capacitance or capacitance obtained by the above calculation satisfies the second preset condition, and if so, it indicates that the probe is in contact with the liquid to be measured, and outputs an indication signal indicating that the probe contacts the liquid to be measured.
  • the second preset condition here may be that the change of the capacitance or the capacitance is greater than a second preset threshold, or is within a second preset range, and the like.
  • calculating a capacitance change amount/capacitance change rate of the probe according to the resonance frequency determining the probe if the capacitance change amount/capacitance change rate exceeds a preset threshold
  • One end of the probe contacts the liquid level, and if the capacitance change/capacitance change rate does not exceed the preset threshold, it is determined that one end of the probe is not in contact with the liquid surface.
  • the capacitance change/capacitance change rate of the needle determines whether one end of the probe is in contact with the liquid surface.
  • the calculation method of the capacitance value C1 of the probe is:
  • the indication signal is output, and the indication signal can be output to the needle movement control mechanism, and the needle movement control mechanism controls the motor to stop according to the indication signal, so that the probe stops. In the corresponding position.
  • the frequency measuring circuit the arithmetic circuit 226, and the processing circuit in FIGS. 2 and 3 can be implemented by using digital circuits, for example, using one or more CPU processing chips are implemented.
  • portions of LC resonant circuit 221, LC resonant driver 222, shaping circuit 223, frequency measuring circuit 224, arithmetic circuit 226, and processing circuit 230 may also be integrated in one or more integrated On the circuit chip.
  • the driving probe and the LC resonant circuit resonate and generate a voltage signal, and then convert the voltage signal into a digital signal, and finally determine the resonant frequency of the detecting circuit according to the digital signal.
  • the resonance frequency the change of the capacitance on the probe is obtained, and the detection result of the liquid contact at one end of the probe is obtained, so that the detection signal is obtained only by one LC resonance circuit, the structure of the circuit is simplified, and the anti-interference of the circuit is improved.
  • each module such as the frequency measurement circuit and the LC resonance circuit in this embodiment
  • the probe and the circuit usually have a certain distance, and the two are connected by wires.
  • a coaxial cable or a shielded wire is added between the probe and the circuit. drive.
  • the shielded wire and the follower are used.
  • the outer shield of the shielded wire is driven by the follower instead of the ground. The follower follows the signal from the LC resonant circuit.
  • the follower mentioned here employs an operational amplifier circuit having a magnification of one.
  • FIG. 6 provides another embodiment of the present invention in which shield line 228 and follower 227 are added to detection circuit 220.
  • the manner in which the shield line 228 and the follower 227 are increased is as follows: One end of the probe 210 is connected to the LC resonance circuit 221 through a shield line 228, and the output end of the follower is connected to the outer shield of the shield line 228, and the input of the follower 227 The terminal is also connected to the junction of the LC resonance circuit 221 and the shield line 228, that is, one end of the probe 210 is connected to the input terminals of the LC resonance circuit 221 and the follower 227 through the shield line 228.
  • the LC resonant circuit may include two branches, one inductive branch, one capacitive branch, and an inductive branch.
  • the capacitor branch includes at least one capacitor or a tunable capacitor, and one end of the probe 210 is connected to one end of the inductor branch and one end of the capacitor branch through the shield line 228, respectively, or the probe 210
  • One end can be connected to any one of the junctions of the inductor branch or the capacitor branch through the shield line 228.
  • the function of the conductive outer needle tube can be used instead of the above-mentioned shield wire 228, and the embodiment shown in Fig. 6 can be deformed into the manner shown in Fig. 10.
  • the probe 210 includes a conductive inner needle tube 211 and a conductive outer needle tube 212.
  • One end of the conductive inner needle tube 211 of the probe 210 is connected to the input terminals of the LC resonance circuit 221 and the follower 227, and the output end of the follower 227 is connected to the conductive outer needle tube 212 of the probe 210.
  • the conductive outer needle tube 212 can be connected to the signal ground or not.
  • the manner in which the shielded wire 228 and the follower 227 are added in this embodiment, and the conductive outer needle 212 of the probe 210 is substituted for the shielded wire 228 can also be applied to the above-disclosed embodiments of FIG. 3, FIG. 5, etc., In any of the embodiments of the present disclosure, there is a connection between one end of the probe 210 and the LC resonant circuit 221.
  • Other structural relationships of the present embodiment can be referred to the respective embodiments in the foregoing, and can also be arbitrarily combined with the related technical features in the foregoing various embodiments to constitute an embodiment disclosed in the specification of the present invention.
  • the method may further include:
  • a reminder circuit coupled to the processing circuit 230 for outputting the indication signal indicating whether the probe is in contact with the measured liquid level by an audio alert and/or a visual effect.
  • the alarm circuit is used to remind the user that the probe has touched the measured liquid level, or by displaying the relative positional relationship between the probe and the measured liquid level on the display, or displaying the resonance frequency or the resonant frequency change on the display. Waveforms and/or values, or waveforms and/or values of capacitance or capacitance changes obtained above calculated on the display.
  • one of the objects of the present invention is to provide a liquid level detecting method, the method comprising the following steps:
  • Signal superimposing step superimposing a change in capacitance or capacitance due to a change in the distance between the probe and the liquid surface to be measured, superimposing on the LC resonant circuit, and obtaining a resonance in which the capacitance information or the capacitance change information generated by the probe is mixed signal;
  • Conversion step converting the resonant signal into a digital signal
  • Frequency measuring step measuring the digital signal to obtain a change in a resonant frequency or a resonant frequency of the resonant signal;
  • Output step outputting an indication signal indicating whether the other end of the probe is in contact with the liquid to be measured, according to the change in the resonant frequency or the resonant frequency.
  • the foregoing method may further include the following steps:
  • Capacitance calculation step calculating a change in capacitance or capacitance generated by the probe according to the change of the resonant frequency or the resonant frequency;
  • the method further includes: acquiring a measurement time of the resonant frequency (for example, acquiring a measurement result of the measurement time by the user in a human-machine interaction manner), and measuring the number in the determined measurement time according to the acquired measurement time.
  • the resonant frequency or the resonant frequency is calculated by counting the number of periodic signals of the digital signal in the preset duration and dividing the number of periodic signals by the preset duration. The change in rate.
  • the human-computer interaction device can be used to obtain the adjustment result of the user-adjusted preset time length, so that the accuracy can be adjusted. For example, when the measured liquid is too small, the measurement accuracy can be improved by adjusting the preset duration.
  • the present invention brings the following advantages:
  • the idea of the previous circuit scheme is to convert the capacitance into a voltage amount first, and then convert the voltage amount into a digital quantity through a commonly used voltage type AD converter. Finally, the algorithm is processed.
  • the way in which the capacitance turns to the voltage includes, but is not limited to, the RC charge and discharge type (the different charge/discharge voltage peaks or effective values are obtained according to the RC time constant), and the phase-locked loop type (using the lock according to the RC time constant)
  • the phase loop maintains the input and output frequency and the phase matching characteristics to obtain different voltage controlled oscillator control voltages.
  • the invention jumps out of the idea of capacitor-voltage-AD conversion, and directly extracts the frequency to obtain the capacitance value by exciting the LC resonator, the circuit structure is greatly simplified, and the front-end component only needs one inductor L or one inductor branch, one capacitor C or a capacitor branch and the corresponding LC resonant driver, the back-end components only need the frequency measurement circuit and the corresponding data processing algorithm.
  • the system no longer requires complex analog circuits and no adjustments to the operating point. Structural simplification brings about improvements in cost, size, and reliability.
  • an LC oscillator with more preferred frequency characteristics is used instead of the conventional RC oscillator.
  • the LC oscillator has a high Q value (quality factor) based on the resonance principle.
  • the value of Q is between several tens and hundreds.
  • the loop resistance R typically does not exceed 10 ⁇
  • L is typically 10 uH
  • C is typically 15 pF
  • Q is not lower than 81.
  • the resonant circuit can spontaneously oscillate more stably and is less susceptible to external interference, and the anti-interference ability is improved.
  • the actual test shows that for the same probe, the liquid level detecting device adopting the scheme can easily obtain the radiation immunity of 5V/m or more, which is higher than the anti-interference ability level of 3V/m designed in the past.
  • the number of effective data bits can be significantly increased without changing the circuit and without increasing the cost, and the detection resolution can be improved to realize the detection of a very small amount of liquid.
  • T can be obtained 12 Bit count resolution
  • T* (2 ⁇ 4) or T*16 measurement time
  • the original solution must be upgraded by using a high-performance op amp and a high-resolution AD converter, which brings about a significant increase in cost in a 12-bit resolution scenario.
  • the active shielding layer driving when the distance between the probe and the detecting circuit board is long and the shielding line is needed, the distributed capacitance of the shielding line is eliminated, and the shielding effect is avoided, and the detection sensitivity is avoided.
  • Each of the above embodiments provides a detection mode of the single-channel detection circuit, but it is because the LC resonance circuit is used in the present invention, and the change of the probe capacitance is obtained based on the detection of the frequency of the resonance signal, thereby simplifying the circuit structure. For better expansion of the circuit structure to achieve a more accurate circuit expansion solution.
  • a liquid level detecting apparatus comprising:
  • the probe 210 is configured to suck the liquid to be tested and output the self-capacitance
  • At least two sets of the foregoing detecting circuits 220 wherein each set of detecting circuits 220 can adopt the structure of the detecting circuit 220 shown in any one of the foregoing embodiments based on FIG. 2;
  • the switch circuit 240 is disposed between the probe 210 and the detecting circuit 220.
  • the input end of the switch circuit 240 is connected to one end of the probe 210.
  • the switch circuit 240 includes multiple outputs, and the access terminals of each output are connected to a group.
  • the controller 250 is connected to the controlled end of the switch circuit 240, and is used for time-sharing control of the switch circuit to switch between multiple outputs, so that one end of the probe 210 and the connection channel between the multiple sets of detection circuits 220 are time-divisionally affected. Controlling the conduction, for example, by outputting the time-sharing control signal through the controller 250, and switching between the multiple outputs; and,
  • the processing circuit 230 is coupled to the outputs of the at least two sets of detection circuits 220 for outputting the other end of the characterization probe based on changes in the resonant frequency or resonant frequency output by the at least two sets of detection circuits 220 Whether to touch the indication signal of the liquid to be tested.
  • the analog switch circuit 240 sequentially connects the probes to different detection circuits 220, and then connects them.
  • the corresponding detection circuits of the respective detectors respectively detect the probe and output the detection result. This process is repeated cyclically, and the residence time on the output channel of each switching circuit is usually on the order of milliseconds, so that the total time of the cycle is controlled in a practical range.
  • the processing circuit 230 receives the detection results from the respective detection circuits and judges the consistency of the detection results. The detection results of the respective detection circuits are identical, and the processing circuit 230 outputs the coincident decision result.
  • the processing circuit 230 contacts the measured end of the output characterization probe when the change of the resonant frequency or the resonant frequency output by the at least two sets of detecting circuits simultaneously satisfies the first predetermined condition.
  • the indicator signal of the liquid is a predetermined condition.
  • the circuit parameters of the plurality of sets of detection circuits 220 may be uniform or inconsistent.
  • the sensitive frequency points corresponding to the circuit parameters of the at least two sets of the detecting circuits 220 are different.
  • the sensitive frequency point refers to the frequency point susceptible to interference, which is generally an integer multiple of the operating frequency of the circuit. At these frequency points, the circuit easily resonates with the interference frequency.
  • the circuit parameters herein may include any one of a frequency measurement time (ie, the preset duration described above), a parameter value of L and C of the LC resonance circuit, a voltage setting value of the phase locked loop circuit, a parameter value of the LC drive circuit, and the like. Parameter value.
  • the probe may be a double-layer needle tube structure, and the conductive inner needle tube of the probe is connected to the input end of the switch circuit.
  • the LC resonant circuit in each set of detecting circuits 220 may include an embodiment as described above with respect to the structure shown in FIG. 4, such as an LC resonant circuit in each set of detecting circuits 220.
  • the invention comprises: an inductor branch comprising at least one inductor or a tunable inductor, and a capacitor branch comprising at least one capacitor or a tunable capacitor, the inductor branch and the capacitor branch being connected in parallel; and an access terminal of each output of the switch circuit 240 Corresponding to one end of the inductor branch and one of the capacitor branches The terminals are connected, or can be connected to any one of the junctions of the inductor branch or the capacitor branch.
  • the multipath detecting circuit 220 can also be provided based on the structures shown in FIGS. 3 and 5.
  • the difference from FIG. 7 is that the detecting circuit 220 adopts the structure shown in FIG. 5, and includes a shaping circuit 223, a frequency measuring circuit 224, an arithmetic circuit 226, an LC resonant circuit, and an LC resonant driving circuit. 222. See the related description of Figures 7 and 5 for the remaining connection relationships.
  • the processing circuit 230 is configured to output a characteristic probe according to the change of the capacitance or capacitance of the output of the at least two sets of detection circuits. Whether the other end is in contact with the indication signal of the liquid to be tested. For example, in some embodiments of the present invention, the processing circuit 230 contacts the measured liquid at the other end of the characterization probe when the change in capacitance or capacitance output by the at least two sets of detection circuits simultaneously satisfies the second predetermined condition. Indication signal.
  • Other related descriptions can be found in the foregoing description, and will not be repeated here.
  • FIG. 7 another circuit structure is provided in another embodiment of the present invention, wherein the difference from the embodiment shown in FIG. 7 is that the present embodiment is based on the structure of the detecting circuit shown in FIG.
  • a multi-path detecting circuit is disposed, that is, a shielding line 228 and a follower 227 may be further included in each group of detecting circuits, and an access end of each output of the switching circuit passes through the shielding line and each group of detecting circuits.
  • the LC resonant circuit is connected and is also connected to the input end of the follower 227.
  • the output of the follower 227 is connected to the outer shield of the shielded wire.
  • FIGS. 7 and 6 For the connection relationship of the remaining circuit structures, reference is made to the related description of FIGS. 7 and 6.
  • the shielded line 228 and the follower 227 added in the detecting circuit shown in FIG. 6 can also be added to the circuit structure described in FIG. 8 and applied to various embodiments, and will not be exempl
  • the shield line 228 and the follower 227 may not be added in each group of detecting circuits, but integrated and uniformly added between the switch circuit 240 and the probe 210, so that the shield line 228 and the follower 227 can be saved.
  • the number of uses simplifies the circuit structure, making the circuit structure more compact.
  • a shield line 228 and a follower 227 are disposed between the switch circuit 240 and the probe 210, and the input end of the switch circuit 240 passes through the shield line and the probe.
  • the probe 210 includes a conductive inner needle tube 211 and a conductive outer needle tube 212.
  • One end of the conductive inner needle tube 211 of the probe 210 is connected to the input end of the switch circuit 240 and the input end of the follower 227, and the output end of the follower 227 is connected to the conductive outer needle tube 212 of the probe 210.
  • the conductive outer needle tube 212 can be connected to the signal ground or not.
  • the controller 250 can also be implemented by a digital circuit such as a separate CPU chip or a plurality of clock chips.
  • a digital circuit such as a separate CPU chip or a plurality of clock chips.
  • the processing unit 230 and the controller 250 described above may be integrated and unified on one CPU chip or a plurality of CPU chips to implement the related functions mentioned in the foregoing.
  • the present invention also provides a liquid level detection method, which includes:
  • Signal superimposing step setting a multi-channel LC resonant circuit to superimpose the capacitance or capacitance change caused by the change of the distance between the probe and the measured liquid surface, and superimpose it on the LC resonant circuit for a predetermined period of time. a plurality of sets of resonant signals having a change in capacitance or capacitance produced by the probe;
  • Conversion step respectively converting multiple sets of resonant signals into digital signals to obtain multiple sets of digital signals;
  • Frequency measuring step respectively measuring multiple sets of digital signals to obtain changes of multiple sets of resonant frequencies or resonant frequencies corresponding to multiple sets of resonant signals;
  • Output step outputting an indication signal indicating whether the other end of the probe is in contact with the liquid to be measured, according to changes in at least two sets of resonant frequencies or resonant frequencies.
  • the foregoing method may further include the following steps:
  • Capacitance calculation step calculating capacitance or capacitance changes generated by multiple sets of probes according to changes in resonant frequency or resonant frequency of multiple sets of resonant signals;
  • outputting step outputting an indication signal indicating whether the other end of the probe contacts the liquid to be measured according to at least two sets of capacitance or capacitance changes obtained by the calculation.
  • the method further includes: acquiring a measurement time of the resonant frequency (for example, acquiring a measurement result of the measurement time by the user in a human-machine interaction manner), and measuring the number in the determined measurement time according to the acquired measurement time.
  • the change of the resonant frequency or the resonant frequency is calculated by counting the number of periodic signals of the digital signal in the preset duration and dividing the number of periodic signals by the preset duration.
  • the preset duration can be adjusted and changed at will by user input, so that the accuracy can be adjusted. For example, when the measured liquid is too small, the measurement accuracy can be improved by adjusting the preset duration.
  • the switch circuit 240 can be connected to each group of detection circuits by using one or more single-pole multi-position switches, or by using multiple independent switch circuits, and the controlled ends of the multiple independent switch circuits are connected to the controller.
  • the controller is unified and time-divisionally controlled. Both of these schemes can achieve the above objectives, and the two schemes can be replaced equally.
  • the controller can be a time-sharing device or a plurality of timers, or a circuit structure implemented by a CPU.
  • the circuits in FIGS. 7 to 9, and 11 can be implemented by independent analog circuits or by an integrated chip.
  • the high integration, high performance, low cost, and simple structure of the technical solution in this embodiment can be used in the automatic liquid level detection in the biochemical analyzer.
  • the indication signal for characterizing whether the probe is in contact with the measured liquid level based on the above various embodiments is received by the needle motion control mechanism in the fully automatic sampling device, and the probe is controlled to move relative to the liquid to be measured according to the indication signal. For example, perform a stop motion, either up (away from the measured liquid level), or down (close to the measured liquid level), and so on.
  • the program may be stored in a computer readable storage medium, and the storage medium may include: Flash disk, Read-Only Memory (ROM), Random Access Memory (RAM), disk or optical disk.

Abstract

一种液面检测装置，包括：探针（210），用于吸取被测液体并输出自身电容，探测电路（220），用于提供一电压或电流，激励探针（210）和LC谐振电路（221），发生谐振并产生谐振信号；整形电路（223），与LC谐振电路（221）相连，用以将谐振信号转化为数字信号，并输出数字信号；以及频率测量电路（224），与整形电路（223）相连，用于测量数字信号，输出谐振信号的谐振频率或谐振频率的变化；处理电路（230），与探测电路（220）的输出相连，用于根据频率测量电路（224）输出的谐振频率或谐振频率的变化，输出表征探针（210）是否接触被测液体的指示信号。一种液面检测方法和全自动取样装置，简化了电路的结构，提高了电路的抗干扰性。

Description

液面检测装置及检测方法和全自动取样装置 技术领域
本发明涉及液面传感装置，尤其涉及用于全自动取样装置在取样过程中检测样本液面的检测电路及方法。
背景技术
全自动生化分析仪、免疫分析仪等在分析体液时，需要先采样，吸液探针在电机的带动下在试管中下行，当接触到液面时，为防止针管扎入过深带来清洗难度增加的问题(如果清洗不干净会引发交叉污染)，电机必须停止，针管吸取体液后在电机的带动下上行返回，所以在全自动生化分析时必须进行液面检测，在针管接触到液面时，需要输出接触液面指示信号给电机控制单元，以便控制电机停止。全自动生化、免疫分析仪现有的液面检测技术主中，通常采用如图1所示的技术方案，图1提供了一种电容液面检测电路，该电路由振荡及分频电路8、锁相环路9、低通滤波10、高通滤波11、放大12、AD转换13、CPU处理14等部分组成，图1所示的方式采用常规的探针电容检测方法，由于工程上并不方便直接测量探针3电容及其变化量，因此以往电路方案的思路为先将电容量转换成电压量，再通过常用的电压型AD转换器将电压量转换为数字量，最后进行算法处理。但是，这种电路设计方式成本高、调校繁琐、可靠性低，并且电路结构复杂，可扩展性较差，另外由于其核心检测部件“锁相环”中的压控振荡器采用的是RC型振荡器，其抗干扰能力较低，检测灵敏度受限于AD转换器分辨率，无法实现对极少量液体的检测。
因此，有必要对现有技术中的常规方式进行更进一步地改进。
发明内容
本发明提供了一种液面检测装置及检测方法和全自动取样装置，简化了电路结构，提高了电路的抗干扰性，提升了检测分辨率，还增加了可扩展 性。
本发明第一方面提供了一种液面检测装置，包括：
探针，用于吸取被测液体并输出自身电容，
与所述探针的一端相连的LC谐振电路，
与所述LC谐振电路相连的LC谐振驱动器，用于提供一电压或电流，激励所述探针和所述LC谐振电路发生谐振并产生谐振信号；
整形电路，与所述LC谐振电路相连，用以将所述谐振信号转化为数字信号，并输出所述数字信号；以及
频率测量电路，与所述整形电路相连，用于测量所述数字信号，输出所述谐振信号的谐振频率或谐振频率的变化；
处理电路，与所述频率测量电路的输出相连，用于根据所述谐振频率或谐振频率的变化，输出表征所述探针是否接触所述被测液体的指示信号。
本发明第二方面提供了一种液面检测方法，包括：
信号叠加步骤：将因探针与被测液面之间的距离变化而产生的电容或电容变化，叠加到LC谐振电路上，获得混合有所述探针产生的电容或电容变化情况的谐振信号；
转化步骤：将所述谐振信号转化为数字信号；
频率测量步骤：测量所述数字信号，获得所述谐振信号的谐振频率或谐振频率的变化；
输出步骤：根据所述谐振频率或谐振频率的变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
本发明第三方面提供了一种全自动取样装置，包括：
上述液面检测装置；
针管运动控制机构，用于接收来自所述液面检测装置输出的指示信号，根据所述指示信号控制探针相对于所述被测液体运动。
实施本发明实施例，首先在LC谐振驱动器的激励下，驱动探针和LC谐振电路发生谐振并产生混合有探针电容信息的谐振信号，然后将谐振信号转化为数字信号，最后根据数字信号确定谐振频率或谐振频率变化，并根据 谐振频率或谐振频率变化获取探针的一端接触液面的检测结果，从而可以利用简化的模拟电路结构，通过一个LC谐振电路及其驱动来获取检测电容信号，简化了模拟电路的结构，提高了电路的抗干扰性。检测电路不再需要复杂的模拟电路，也不需要进行工作点的调校，结构简化带来成本、尺寸、可靠性上的大大改善。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1是现有技术方案提出的一种液面检测装置的结构示意图；
图2是本发明实施例提出的一种液面检测装置的结构示意图；
图3是本发明实施例提出的另一种液面检测装置的结构示意图；
图4是本发明实施例中LC谐振电路的一种拓扑结构示意图；
图5是本发明实施例提出的又一种液面检测装置的结构示意图；
图6是本发明实施例提出的又一种液面检测装置的结构示意图；
图10是本发明实施例提出的又一种液面检测装置的结构示意图；
图7、图8、图9、图11是本发明的多路探测电路结构的各个实施例结构示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
通常在全自动生化分析仪、全自动免疫仪等设备中会使用全自动取样装置，其通常包括吸液探针、检测电路及针管运动控制机构。根据检测电路获 取的吸液探针是否接触被测液体的检测结果，针管运动控制机构控制吸液探针相对于所述被测液体运动。吸液探针考虑到化学兼容性，通常为不锈钢或钛合金，其可以为单管针或双层吸液探针。通常探针的外层针管和内层针管沿针管长度方向上长度差距不大，于是在保证外层针管不会接触到液面的同时，内层针管可以浅层插入到被测液面并进行液面检测。但是，一些特殊检验项目需要内层针管深层次插入到被测液面下方一定距离，那么原有结构探针将被替换掉，适配这种检验项目的探针，其内层针管沿针管长度方向上超过外层针管的长度大大增加，而在为了保证外层针管在检测液面时不接触被测液面，则在采用原图1所示的检测电路时，会出现极大的信号干扰，存在明显的检测误差，为避免此种情况中的检测误差，非常有必要对原图1中的检测电路进行结构改进。
请参考图2，图2是本发明一实施例中提出的一种液面检测装置的结构示意图。如图2所示，本发明实施例中的液面检测装置包括探针210、探测电路220、以及处理电路230，其中：
探针210，用于吸取被测液体并输出自身电容。为了提高吸液探针电容检测的抗干扰能力，在一些实施例中，吸液探针采用双层吸液探针，其相当于一个电容器，包括导电外针管和导电内针管以及中间绝缘层。在本发明的一些实施例中，探针210可以为双层针管结构，探针210的导电内针管连接LC谐振电路221，而导电外针管可以接地，或者不接地。更进一步地，在本发明的一些实施例中，探针包括导电内针管和导电外针管，导电内针管的长度比导电外针管的长度长，且导电内针管和导电外针管的长度相差超过3厘米。
探测电路220包括LC谐振电路221以及LC谐振驱动器222、整形电路223和频率测量电路224。LC谐振电路221与探针210的一端相连。LC谐振驱动器222与LC谐振电路221相连，用于提供一电压或电流，激励探针210和LC谐振电路221发生谐振并产生谐振信号，同时该谐振信号中混杂含有探针电容的信息。
整形电路223与LC谐振电路221相连，用以将探针210和LC谐振电路221共同产生的谐振信号转化为数字信号，并输出数字信号至频率测量电路224。频率测量电路224与整形电路223相连，用于测量数字信号，输出谐振信号的谐振频率或谐振频率的变化。
处理电路230与频率测量电路224的输出相连，用于根据频率测量电路224输出的谐振频率或谐振频率的变化，输出表征探针是否接触被测液体的指示信号。
在本实施例中，将因探针与被测液面之间的距离变化而产生的电容或电容变化，叠加到LC谐振电路上，获得混合有探针产生的电容信息或电容变化信息的谐振信号，将该谐振信号转化为数字信号；测量数字信号，获得谐振信号的谐振频率或谐振频率的变化；最后，根据谐振频率或谐振频率的变化，输出表征探针的另一端是否接触被测液体的指示信号。以下将以LC谐振电路221为LC并联谐振电路为例来详细说明本实施例的基本原理。
本实施例中，LC谐振电路221可以为LC并联谐振电路，例如，如图2所示，上述LC谐振电路可以包括电感L和电容C，探针210的一端分别与电感L的一端、电容C的一端以及LC谐振驱动器222的一端连接，电感L的另一端以及电容C的另一端分别与LC谐振驱动器222的另一端连接。
需要说明的是，电容C、电感L和LC谐振驱动器组成了核心前端检测电路，在LC谐振驱动器可以采用恒流源，在LC谐振驱动器的激励下，电容C与电感L发生谐振，原始谐振频率为
Figure PCTCN2016078160-appb-000001
其中L、C分别表示电容C、电感L的值，另外，探针连接到LC谐振电路中，向LC谐振电路引入了额外的电容C1(即表示探针210输出的自身电容)，此时新的LC谐振频率为
Figure PCTCN2016078160-appb-000002
其中，LC谐振电路采用的是共振原理，为二阶选频电路，由于电容C、电感L内部的谐振电流远大于外部激励电流，因此振荡波形的稳定性和抗干扰能力远高于常用的一阶RC振荡器，从而提高了本电路的抗干扰能力，并且LC谐振电路结构简单，降低了电路成本。
LC谐振电路的输出通常为电压信号，表示为正弦波，通过整形电路整形为数字信号后，进行频率测量。频率的测量包括但不限于定时计数法和锁相环法。其中，定时计数法是指：选定一段固定时间，对周期信号个数进行累计，将计数值除以时间得到频率。为实现这一方法，可以通过硬件电路或软件编程的方式，将频率测量电路224设置为通过统计预设时长内的上述数字信号的周期信号个数，并将周期信号个数除以所述预设时长，计算得到上述谐振频率或谐振频率的变化。若采用硬件电路的方式，可以是采用计数器来统计预设时长内的上述数字信号的周期信号个数，然后再通过除法器将计数器获得的周期信号个数除以所述预设时长，计算获得上述谐振频率或谐振频率的变化。
或者，频率测量电路224还可以通过锁相环法来测量谐振频率或谐振频率的变化。例如，如图3所示，在频率测量电路224中设置锁相环电路225和电压测量电路2251，锁相环电路225和电压测量电路2251依次串联，并位于整形电路223和处理电路230之间，锁相环电路225通过将上述整形电路的输出信号的频率变化转化为电压信号，电压测量电路2251获取所述电压信号的电压值，并通过锁相环电路224预设的电压值与谐振频率的比例值，计算上述谐振频率或谐振频率的变化。进一步地，还可以通过分频和锁相使得上述整形电路的输出信号的电压值与谐振频率成正比，将输出信号的电压值除以上述电压值与谐振频率的比例值计算得到上述谐振频率。
在本发明实施例中，可以通过延长谐振频率的测量时间，在不改变电路、不增加成本的条件下显著提高有效数据位数，提升检测分辨率，实现对极微量液体的检测。因此，在本发明的一些实施例中，通过人机交互设备可以获取用户对频率测量周期或时间的设定，例如对上述通过统计预设时长内的上 述数字信号的周期信号个数步骤中的预设时间进行随意设定，用户通过人机交互设备在检验开始前输入对所述预设时长的调节指令，并将该调节指令输出至所述频率测量电路，频率测量电路在该调节指令指定的预设时长内统计所述周期信号个数，用于计算谐振频率或谐振频率的变化。根据此方式用户可以随意调节频率测量的时长，提高探测电路的测量精度。
本实施例中计算获得的谐振频率或谐振频率的变化可以是一个值，也可表达为一定时间范围内连续的波形变化。而谐振频率的变化可以为当前计算获得的频率相对于之前时刻的频率变化，或者当前计算获得的频率相对于因LC谐振驱动器中电容和电感值所引起的原始谐振频率的变化量。根据上述公式(2)，可获知，上述计算获得的谐振频率或谐振频率的变化相对于探针210输出的自身电容C1存在一定的比例关系。
根据前述公式，在f'、L、C均已知的情况下，可以计算出探针210输出的自身电容C1为：
Figure PCTCN2016078160-appb-000003
于是根据计算获得的谐振频率或谐振频率的变化，可以直观的反应探针210输出的自身电容C1的变化，因此根据定标等方法可以获知两者的比例关系，从而基于计算出谐振频率或谐振频率的变化，来判定探针是否接触被测液体的指示信号。例如，处理电路230可以判断上述谐振频率或谐振频率的变化是否满足第一预设条件，若是，则表示探针接触到被测液体，输出表征探针接触被测液体的指示信号。这里的第一预设条件可以是上述谐振频率或谐振频率的变化大于第一预设阈值，或者位于第一预设范围内，等等。
本实施例的一个变形实施例中，LC谐振电路221可以为LC并联谐振电路，以及LC谐振驱动器222为恒流源，LC并联谐振电路与LC谐振驱动器222并联。
本实施例的整形电路223可以为施密特触发器或迟滞比较器等等，整形电路223用于将谐振信号变化为二值化信号，从而获得上述数字信号。
当然，除了LC谐振电路221、LC谐振驱动器222、整形电路为模拟电路外，图2和图3中的频率测量电路和处理电路可以采用数字电路来实现，例如，采用一个或多个CPU处理芯片来实现。
此外，在本发明的一些实施例中，LC谐振电路221、LC谐振驱动器222、整形电路223、频率测量电路224和处理电路230还可以集成在同一个集成电路芯片上。
当LC谐振电路221采用LC并联谐振电路时，除了采用图2和图3中简单的LC谐振拓扑结构，还可以采用如图4所示的方式。例如，在一些实施例中，LC谐振电路可以包括两条支路，一条电感支路，一条电容支路，电感支路含有至少一个电感或可调电感，例如图4中采用电容C11、电容C12和电阻R11串联构成，电容支路包含至少一个电容或可调电容，例如图4中采用两个电感L11和电感L12串联构成。而电感支路和电容支路并联形成LC谐振电路。探针210的一端分别与电感支路的一端和电容支路的一端相连(参照图2和图3，电容支路和电感支路并联形成LC谐振电路221的两端)，或者，如图4所示，探针210的一端可选择连接在电感支路或电容支路中的任意一个结点位置。其目的在于将探针上产生的电容信息叠加到LC谐振电路中形成谐振信号，当然，如果探针210与LC谐振电路的连接位置发生了改变，那么上述公式中的对应关系也会相应改变，可基于电路原理推到获得，在此不再累述。
图5提供了本发明的另一个实施例，在图2所示的实施例基础上，增加了基于上述谐振频率或谐振频率的变化计算获得更加精确反映探针位置变化的电容信息或电容的变化信息。
如图5所示，在图2中的频率测量电路224和处理电路230之间增加运算电路226，用于根据上述频率测量电路224获得的谐振频率或谐振频率的变化，计算并输出所述探针输出的电容或电容的变化。同理，在图3中的频率测量电路224和处理电路230之间也可以增加运算电路226。运算电路226属于探测电路220新增的部分。基于此，处理电路230则与运算电路226连 接，用于根据探测电路220输出的电容或电容的变化，输出表征探针是否接触所述被测液体的指示信号。这样的结果更加直接，且还不需要进行额外的定标操作来衡量频率变化与电容变化的关系，而可以直接利用数字电路测量获得的谐振频率或谐振频率变化，来直接计算获得探针210输出的电容或电容的变化，直观反映探针与液面的位置变化，整个过程基于简单的计算，而不需要查表操作，过程更简洁，运算速度更快。
本实施例中提到的探测电路220输出的电容或电容的变化，可以是一个值，也可表达为一定时间范围内的波形变化。而电容的变化可以为当前计算获得的电容相对于之前时刻的电容的变化，或者当前计算获得的电容相对于探针非接触液面时地原始电容的变化量。例如，电容的变化包含：表征探测电容接触到液面后的电容值与触到液面前的电容值之差的电容变化量；或者表征单位时间内探测电容接触到液面前后的电容值变化量的变化率。
对于当前计算获得的电容，可以依据上述公式(3)，将上述频率测量电路224获得的谐振频率f`和LC谐振电路中的电容和电感参数值代入上述公式(3)后计算获得。
基于计算出的电容或电容的变化，来判定探针是否接触被测液体的指示信号。例如，处理电路230可以判断上述计算获得的电容或电容的变化是否满足第二预设条件，若是，则表示探针接触到被测液体，输出表征探针接触被测液体的指示信号。这里的第二预设条件可以是上述电容或电容的变化大于第二预设阈值，或者位于第二预设范围内，等等。
还比如，在一些实施例中，根据所述谐振频率，计算所述探针的电容变化量/电容变化率；若所述电容变化量/电容变化率超过预设阈值，则确定所述探针的一端接触到液面，若所述电容变化量/电容变化率未超过预设阈值，则确定所述探针的一端未接触到液面。
需要说明的是，当探针的一端接触到液面时，探针的电容值C1发生变化，从而引起探测电路的谐振频率也发生变化，因此，通过获取探测电路的谐振 频率，可以计算得到探针的电容变化量/电容变化率，进而判断探针的一端是否接触到液面。其中，探针的电容值C1计算方法为：
Figure PCTCN2016078160-appb-000004
最后，当所述检测结果为所述探针的一端接触到液面时，输出指示信号，可以将指示信号输出到针管运动控制机构，针管运动控制机构根据指示信号控制电机停止，令探针停止在相应的位置上。
当然，除了LC谐振电路221、LC谐振驱动器222、整形电路为模拟电路外，图2和图3中的频率测量电路、运算电路226和处理电路可以采用数字电路来实现，例如，采用一个或多个CPU处理芯片来实现。
此外，在本发明的一些实施例中，LC谐振电路221、LC谐振驱动器222、整形电路223、频率测量电路224、运算电路226和处理电路230中的部分还可以集成在同一个或多个集成电路芯片上。
在本发明实施例中，首先在LC谐振驱动器的激励下，驱动探针和LC谐振电路发生谐振并产生电压信号，然后将电压信号转化为数字信号，最后根据数字信号确定探测电路的谐振频率，并根据谐振频率获取探针上电容的变化，获得探针的一端接触液面的检测结果，从而只通过一个LC谐振电路来获取检测信号，简化了电路的结构，提高了电路的抗干扰性。
本实施例中的频率测量电路、LC谐振电路等各个模块的变形也可以参照前文中针对图2的相关说明，在此不再累述。
需要说明的是，在实际使用场景中，探针与电路通常具有一定距离，二者通过导线连接，为了达到良好的抗干扰效果，因此在探针与电路之间增加同轴电缆或屏蔽线来驱动。但是，如果电缆较长，电缆的分布电容容易降低检测灵敏度，因此采用屏蔽线和跟随器的方式，屏蔽线的外屏蔽层被跟随器所驱动而不是接地，跟随器跟随来自LC谐振电路的信号，使得屏蔽线的外屏蔽层与内芯之间没有电位差，亦即没有电场存在，屏蔽线自身的电容被消除，从而达到抗干扰的目的。这里提到的跟随器采用放大倍数为一的运算放大电路。
因此，图6提供了本发明的另一个实施例，在图2所示的实施例中，在探测电路220中增加屏蔽线228和跟随器227。屏蔽线228和跟随器227的增加方式如下所示：探针210的一端通过屏蔽线228与LC谐振电路221相连，跟随器的输出端与屏蔽线228的外屏蔽层连接，跟随器227的输入端也连接LC谐振电路221和屏蔽线228相连的结点，即探针210的一端通过屏蔽线228与LC谐振电路221和跟随器227的输入端相连。有关探针210的一端通过屏蔽线228与LC谐振电路221相连的具体方式可参见前述实施例，例如，LC谐振电路可以包括两条支路，一条电感支路，一条电容支路，电感支路含有至少一个电感或可调电感，电容支路包含至少一个电容或可调电容，探针210的一端通过屏蔽线228分别与电感支路的一端和电容支路的一端相连，或者探针210的一端通过屏蔽线228可选择连接在电感支路或电容支路中的任意一个结点位置。
更进一步地，当吸液探针采用双层吸液探针，导电外针管的作用可以用来替代上述屏蔽线228，于是图6所示的实施例可以变形为图10所示的方式。
在图10中，探针210包括导电内针管211和导电外针管212。探针210的导电内针管211的一端与LC谐振电路221和跟随器227的输入端相连，跟随器227的输出端与探针210的导电外针管212连接。导电外针管212可以接信号地，也可以不接信号地。其余的连接结构参见前文有关图6的相关说明。
当然，本实施例中增加的屏蔽线228和跟随器227，以及将探针210的导电外针管212替代屏蔽线228的方式还可以应用于图3、图5等上述公开的实施例中，增加在本发明公开的任意一个实施例中，位于探针210的一端与LC谐振电路221的连接之间。本实施例的其他结构关系可参见前文中的各个实施例，并且还可以与前述各个实施例中的相关技术特征任意组合，从而构成在本发明说明书公开的实施例。
另外，基于图2、图3、图5、图6或图10所示的各个实施例，在本发明的一些实施例中，还可以包括：
与处理电路230相连的提醒电路，用于通过音频提醒和/或可视化效果输出上述表征探针是否接触到被测液面的指示信号。例如，通过报警电路，来提醒使用者探针已接触到被测液面，或者通过在显示器上显示探针与被测液面的相对位置关系，或者在显示器上显示谐振频率或谐振频率变化的波形和/或数值，或者在显示器上显示上述计算获得的电容或电容变化的波形和/或数值等等。
基于上述各个实施例，本发明的目的之一还提供了一种液面检测方法，所述方法包括以下步骤：
信号叠加步骤：将因探针与被测液面之间的距离变化而产生的电容或电容变化，叠加到LC谐振电路上，获得混合有所述探针产生的电容信息或电容变化信息的谐振信号；
转化步骤：将所述谐振信号转化为数字信号；
频率测量步骤：测量所述数字信号，获得所述谐振信号的谐振频率或谐振频率的变化；
输出步骤：根据所述谐振频率或谐振频率的变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
当然，在本发明的一些实施例中，上述方法还可以包括以下步骤：
电容计算步骤：根据所述谐振频率或谐振频率的变化，计算获得所述探针产生的电容或电容变化；
并在所述输出步骤中：根据计算获得的所述电容或电容变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
此外，在频率测量步骤中，还包括，获取谐振频率的测量时间(例如通过人机交互方式获取用户对测量时间的调节结果)，依据获取的测量时间，在确定的测量时间内测量所述数字信号，获得所述谐振信号的谐振频率或谐振频率的变化。从而可以提高探针是否接触被测液体的检测结果的精确度。例如，在频率测量步骤中，通过统计预设时长内的上述数字信号的周期信号个数，并将周期信号个数除以所述预设时长，计算得到上述谐振频率或谐振频 率的变化。然而，可以利用人机交互设备来获取用户输入的有关调节预设时长的调整结果，从而实现精确度可调，例如当被测液体过少时，可以通过调节预设时长来提高测量精度。
至于上述信号叠加步骤、转化步骤、频率测量步骤、输出步骤、电容计算步骤中的具体计算过程可以参见前文有关整形电路、频率测量电路、运算电路和处理电路等模块的相关说明，在此不再累述。
与现有技术中采用的检测电路相比，本发明带来了以下好处：
第一，由于工程上并不方便直接测量电容及其变化量，因此以往电路方案的思路为先将电容量转换成电压量，再通过常用的电压型AD转换器将电压量转换为数字量，最后进行算法处理。其中电容量转电压量的方式包括但不限于RC充放电式(根据RC时间常数的不同，得到不同的充放电电压峰值或有效值)、锁相环式(根据RC时间常数的不同，利用锁相环保持输入输出频率、相位一致的特性得到不同的压控振荡器控制电压)。本发明跳出这种电容-电压-AD转换的思路，通过激励LC谐振器，直接测量频率进而获取电容值，电路结构极大简化，前端元件仅需一个电感L或一支电感支路、一个电容C或一支电容支路及相应的LC谐振驱动器，后端元件只需频率测量电路及相应数据处理算法。系统不再需要复杂的模拟电路，也不需要进行工作点的调校。结构简化带来成本、尺寸、可靠性的改善。
第二，采用具有更优选频特性的LC振荡器取代传统的RC振荡器。LC振荡器基于共振原理，具有较高的Q值(品质因数)。L和C环路内部电流Ic与外部电流Is及Q值的关系为：Ic＝Q*Is。具体地，LC电路中
Figure PCTCN2016078160-appb-000005
根据工程上常用的器件参数，Q的值在几十到几百之间，例如，环路电阻R典型不超过10Ω，L典型为10uH，C典型为15pF，则Q不低于81。这种情况下，谐振电路能较为稳定地发生自振荡而不易受外界干扰影响，抗干扰能力获得提升。实际测试表明，对于相同的探针，采用该方案的液面检测装置可以轻易获得5V/m以上的辐射抗扰能力，高于以往设计3V/m的抗扰能力水平。
第三，通过延长频率测量时间，可以在不改变电路、不增加成本的条件下显著提高有效数据位数，提升检测分辨率，实现对极微量液体的检测，例如，假设测量时间T能获得12位计数分辨率，那么用T*(2^4)即T*16的测量时间，就能获得相比原来16倍的计数值，进而将测量分辨率提高4位，达到16位。而原方案必须通过采用高性能运放和高分辨率AD转换器才能获得相应提升，在12位以上分辨率的使用场景中，带来成本的明显提升。
第四，通过有源屏蔽层驱动，在探针与检测电路板卡距离较远、需要采用屏蔽线时，消除屏蔽线分布电容，起到屏蔽效果的同时，避免降低检测灵敏度。
上述各个实施例中均提供的是单路探测电路的检测方式，但是正是因为本发明中利用LC谐振电路、并基于对谐振信号频率的检测来获取探针电容的变化，从而简化了电路结构，便于更好的扩展电路结构实现更高精度的电路扩展方案。
例如，如图7所示，在本发明的其中一些实施例中，提供了一种液面检测装置包括：
探针210，用于吸取被测液体并输出自身电容；
至少两组上述探测电路220，其中，每一组探测电路220均可以采用前文中基于图2所述的任意一个实施例所示的探测电路220的结构；
设置在探针210与探测电路220之间的开关电路240，该开关电路240的输入端连接探针210的一端，该开关电路240包含多路输出，每一路输出的接入端对应连接一组探测电路220中的LC谐振电路；
控制器250，与开关电路240的受控端连接，用于分时控制开关电路在多路输出间进行切换，使探针210的一端分别与多组探测电路220之间的连接通道分时受控导通，例如，通过控制器250输出分时控制信号，可以在多路输出之间循环切换；并且，
处理电路230，与至少两组探测电路220的输出相连，用于根据至少两组探测电路220输出的谐振频率或谐振频率的变化，输出表征探针的另一端 是否接触被测液体的指示信号。
为了提高液面检测结果的精确度，本实施例中，在进行液面检测时，在控制器250的分时控制下，模拟开关电路240将探针依次连接到不同的探测电路220上，接通的相应探测电路均分别对探针进行检测，输出检测结果。此过程反复不断地循环进行，每个开关电路的输出通道上的滞留时间通常为毫秒量级，使得循环一次的总时间控制在一个有实用意义的范围。处理电路230接收来自各个探测电路的检测结果，并对检测结果的一致性进行判断。在各探测电路的检测结果是一致的，处理电路230输出该一致的判决结果。例如，在本发明的其中一些实施例中，处理电路230在至少两组探测电路输出的谐振频率或谐振频率的变化同时满足上述第一预设条件时、输出表征探针的另一端接触被测液体的指示信号。
多组探测电路220的电路参数可以是一致的，也可以是不一致的。在本发明的其中一个实施例中，上述至少两组上述探测电路220的电路参数对应的敏感频点不相同。敏感频点是指易受干扰的频率点，一般为电路工作频率的整数倍，在这些频率点上，电路容易与干扰频率发生共振。利用电路参数不一致的多组探测电路220，分别进行检测后取一致性检测结果来输出表征探针的另一端接触被测液体的指示信号，可以更加提高液面检测的精度。这里的电路参数可以包括频率测量时间(即上述预设时长)、LC谐振电路的L和C的参数值、锁相环电路的电压设定值、LC驱动电路的参数值等等中的任意一个参数值。
本实施例中，探针可以为双层针管结构，探针的导电内针管连接开关电路的输入端。
基于上述结构，在本发明的一些实施例中，每一组探测电路220中的LC谐振电路可以包括如前文有关图4所示结构的实施例，例如每一组探测电路220中的LC谐振电路包括：含有至少一个电感或可调电感的电感支路，和包含至少一个电容或可调电容的电容支路，电感支路和电容支路并联；开关电路240中的每一路输出的接入端对应连接电感支路的一端和电容支路的一 端相连，或者可选择连接在电感支路或电容支路中的任意一个结点位置。
当然，还可以基于图3和图5所示的结构，设置多路探测电路220。例如，如图8所示，与图7的不同之处在于，探测电路220采用图5所示的结构，包括整形电路223、频率测量电路224、运算电路226和LC谐振电路、LC谐振驱动电路222。其余连接关系参见图7和图5的相关说明。当然由于在探测电路中增加了运算电路226，使得探测电路220输出的结果为电容或电容变化，则处理电路230用于根据至少两组探测电路输出的电容或电容的变化，输出表征探针的另一端是否接触被测液体的指示信号。例如，在本发明的其中一些实施例中，处理电路230在至少两组探测电路输出的电容或电容的变化同时满足上述第二预设条件时，输出表征探针的另一端接触被测液体的指示信号。其他相关说明可参见前文说明，在此不再累述。
此外，在本发明另一实施例中还提供了另一种电路结构，其中，与图7所示的实施例的不同之处在于，本实施例基于图6所示的探测电路结构，在液面检测中设置了多路探测电路，即在每一组探测电路中还可以包括屏蔽线228和跟随器227，开关电路中的每一路输出的接入端通过屏蔽线与每一组探测电路中的LC谐振电路相连、且还和跟随器227的输入端相连，跟随器227的输出端与屏蔽线的外屏蔽层连接，其余电路结构的连接关系参见图7和图6的相关说明。当然，图6所示的在探测电路中增加的屏蔽线228和跟随器227，还可以添加到图8所述的电路结构中，并应用于各个实施例中，在此不再一一举例说明。
更进一步地，屏蔽线228和跟随器227可以不添加在每一组探测电路中，而是整合出来统一增加在开关电路240与探针210之间，这样可以节省屏蔽线228和跟随器227的使用数量，简化电路结构，使得电路结构更加紧凑。如图9所示，在图7或者图8所示的电路结构基础上，在开关电路240与探针210之间设置屏蔽线228和跟随器227，开关电路240中输入端通过屏蔽线与探针的一端相连，跟随器227的输出端与屏蔽线的外屏蔽层连接，跟随器227的输入端还与开关电路240的输入端和屏蔽线228相连，其余电路结 构的连接关系参见图7或图8的相关说明，在此不再累述。
当然，如前文所示，当吸液探针采用双层吸液探针，导电外针管的作用可以用来替代上述屏蔽线228，于是图9所示的实施例可以变形为图11所示的方式。在图11中，探针210包括导电内针管211和导电外针管212。探针210的导电内针管211的一端与开关电路240的输入端和跟随器227的输入端相连，跟随器227的输出端与探针210的导电外针管212连接。导电外针管212可以接信号地，也可以不接信号地。其余的连接结构参见前文有关图9的相关说明。
上述各个实施例中，控制器250也可采用独立的CPU芯片或者多个时钟芯片等数字电路来实现。当然为了简化电路结构，处理单路230和上述控制器250可以集成在一起，统一在一个CPU芯片或多个CPU芯片上来实现前文中提到的相关功能。
在上述多路探测电路设计的结构中，本发明还提供了一种液面检测方法，其包括：
信号叠加步骤：设置多路LC谐振电路，将因探针与被测液面之间的距离变化而产生的电容或电容变化，分时叠加到LC谐振电路上，在预设时间段内获得混合有探针产生的电容或电容变化情况的多组谐振信号；
转化步骤：分别将多组谐振信号转化为数字信号，获得多组数字信号；
频率测量步骤：分别测量多组数字信号，获得多组谐振信号对应的多组谐振频率或谐振频率的变化；
输出步骤：根据至少两组谐振频率或谐振频率的变化，输出表征探针的另一端是否接触被测液体的指示信号。
当然，在本发明的一些实施例中，上述方法还可以包括以下步骤：
电容计算步骤：根据多组谐振信号的谐振频率或谐振频率的变化，计算获得多组探针产生的电容或电容变化；
并在所述输出步骤中：根据计算获得的至少两组电容或电容变化，输出表征探针的另一端是否接触被测液体的指示信号。
此外，在频率测量步骤中，还包括，获取谐振频率的测量时间(例如通过人机交互方式获取用户对测量时间的调节结果)，依据获取的测量时间，在确定的测量时间内测量所述数字信号，获得所述谐振信号的谐振频率或谐振频率的变化。从而可以提高探针是否接触被测液体的检测结果的精确度。例如，在频率测量步骤中，通过统计预设时长内的上述数字信号的周期信号个数，并将周期信号个数除以所述预设时长，计算得到上述谐振频率或谐振频率的变化。而上述预设时长可以通过用户输入来随意调整和改变，从而实现精确度可调，例如当被测液体过少时，可以通过调节预设时长来提高测量精度。
至于上述信号叠加步骤、转化步骤、频率测量步骤、输出步骤、电容计算步骤中的具体计算过程可以参见前文有关整形电路、频率测量电路、运算电路和处理电路等模块的相关说明，在此不再累述。
正是因为本发明基于图2或图5所示的简化的电路结构，才使得可以更好的实现如图7至图9、和图11所示的各个实施例中的多组探测电路结构，提升了液面检测的测量精度。上述开关电路240可以采用一个或多个单刀多置开关，或者采用多路独立的开关电路分别与每一组探测电路相连，并将多路独立的开关电路的受控端都接在控制器上，受控制器统一分时控制，此两种方案均可以实现上述目的，两种方案可等同替换。控制器可以是分时器或多个计时器，或者由一个CPU实现的电路结构。当然，图7至图9、和图11中的各个电路可以采用独立的模拟电路来实现，也可以通过一个集成芯片来实现。在生化分析仪中的液面自动检测上可以使用本实施例中的高集成度、高性能、低成本、结构简单的技术方案。
基于上述各个实施例所提供的用于表征探针是否接触到被测液面的指示信号，被全自动取样装置中的针管运动控制机构接收后，根据指示信号控制探针相对于被测液体运动，例如，执行停止运动，或者上行(远离被测液面)，或者下行(靠近被测液面)等等。
需要说明的是，对于前述的各个方法实施例，为了简单描述，故将其都 表述为一系列的动作组合，但是本领域技术人员应该知悉，本发明并不受所描述的动作顺序的限制，因为依据本发明，某一些步骤可以采用其他顺序或者同时进行。其次，本领域技术人员也应该知悉，说明书中所描述的实施例均属于优选实施例，所涉及的动作和模块并不一定是本发明所必须的。
在上述实施例中，对各个实施例的描述都各有侧重，某个实施例中没有详细描述的部分，可以参见其他实施例的相关描述。
本领域普通技术人员可以理解上述实施例的各种方法中的全部或部分步骤是可以通过程序来指令相关的硬件来完成，该程序可以存储于一计算机可读存储介质中，存储介质可以包括：闪存盘、只读存储器(Read-Only Memory，ROM)、随机存取器(Random Access Memory，RAM)、磁盘或光盘等。
以上对本发明实施例所提供的内容下载方法及相关设备、系统进行了详细介绍，本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本发明的限制。

Claims (27)

  1. 一种液面检测装置，其特征在于，所述液面检测装置包括：
    探针，用于吸取被测液体并输出自身电容，
    与所述探针的一端相连的LC谐振电路，
    与所述LC谐振电路相连的LC谐振驱动器，用于提供一电压或电流，激励所述探针和所述LC谐振电路发生谐振并产生谐振信号；
    整形电路，与所述LC谐振电路相连，用以将所述谐振信号转化为数字信号，并输出所述数字信号；以及
    频率测量电路，与所述整形电路相连，用于测量所述数字信号，输出所述谐振信号的谐振频率或谐振频率的变化；
    处理电路，与所述频率测量电路的输出相连，用于根据所述谐振频率或谐振频率的变化，输出表征所述探针是否接触所述被测液体的指示信号。
  2. 如权利要求1所述的装置，其特征在于，所述探针为双层针管结构，所述探针的导电内针管连接所述LC谐振电路。
  3. 如权利要求1所述的装置，其特征在于，所述液面检测装置还包括：
    连接所述频率测量电路的运算电路，用于根据所述谐振频率或谐振频率的变化，输出所述探针输出的电容或电容的变化；并且，
    所述处理电路与所述运算电路连接，用于根据所述电容或电容的变化，输出表征所述探针是否接触所述被测液体的指示信号。
  4. 如权利要求1所述的装置，其特征在于，所述液面检测装置还包括：
    与所述处理电路相连的提醒电路，用于通过音频提醒和/或可视化效果输出所述指示信号。
  5. 如权利要求1所述的装置，其特征在于，所述LC谐振电路包括：含 有至少一个电感或可调电感的电感支路，和包含至少一个电容或可调电容的电容支路，所述电感支路和电容支路并联；
    所述探针的一端分别与所述电感支路的一端和所述电容支路的一端相连，或者所述探针的一端可选择连接在所述电感支路或所述电容支路中的任意一个结点位置。
  6. 如权利要求1所述的装置，其特征在于，所述液面检测装置还包括屏蔽线和跟随器，
    所述探针的一端通过所述屏蔽线与所述LC谐振电路和所述跟随器的输入端相连，
    所述跟随器的输出端与所述屏蔽线的外屏蔽层连接。
  7. 如权利要求1所述的装置，其特征在于，所述液面检测装置还包括跟随器，
    所述探针包括导电内针管和导电外针管，所述探针的导电内针管的一端与所述LC谐振电路和所述跟随器的输入端相连，所述跟随器的输出端与所述导电外针管连接。
  8. 如权利要求1所述的装置，其特征在于，所述LC谐振电路为LC并联谐振电路，所述LC谐振驱动器为恒流源，所述LC并联谐振电路与所述恒流源并联。
  9. 如权利要求1所述的装置，其特征在于，所述频率测量电路通过统计预设时长内的所述数字信号的周期信号个数，并将所述周期信号个数除以所述预设时长，计算得到所述谐振频率或谐振频率的变化。
  10. 如权利要求9所述的装置，其特征在于，通过人机交互设备可获取用户对所述预设时长的调节指令，所述频率测量电路在所述调节指令指定的预设时长内统计所述周期信号个数。
  11. 如权利要求1所述的装置，其特征在于，所述频率测量电路还包括：依次串联的锁相环电路和电压测量电路；
    所述锁相环电路，用于通过将所述整形电路的输出信号的频率变化转化为电压信号；
    所述电压测量电路，用于获取所述电压信号的电压值，并通过所述锁相环电路预设的电压值与谐振频率的比例值，计算所述谐振频率或谐振频率的变化。
  12. 如权利要求1或3所述的装置，其特征在于，所述处理电路在所述谐振频率或谐振频率的变化满足第一预设条件时、或者在所述电容或电容的变化满足第二预设条件时，输出表征所述探针的另一端接触所述被测液体的指示信号。
  13. 如权利要求1所述的装置，其特征在于，所述液面检测装置还包括：
    至少两组所述探测电路，所述探测电路包括所述LC谐振电路、所述整形电路和所述频率测量电路；
    设置在所述探针与所述探测电路之间的开关电路，该开关电路的输入端连接所述探针的一端，该开关电路包含多路输出，每一路输出的接入端对应连接一组所述探测电路中的所述LC谐振电路；
    控制器，与所述开关电路的受控端连接，用于分时控制所述开关电路在所述多路输出间进行切换；并且，
    所述处理电路，与至少两组所述探测电路的输出相连，用于根据所述至少两组所述探测电路输出的谐振频率或谐振频率的变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
  14. 如权利要求13所述的装置，其特征在于，所述至少两组所述探测电路的电路参数对应的敏感频点不相同。
  15. 如权利要求13所述的装置，其特征在于，所述探测电路还包括：
    连接所述频率测量电路的运算电路，用于根据所述谐振频率或谐振频率的变化，输出所述探针输出的电容或电容的变化；并且，
    所述处理电路与所述运算电路连接，用于根据所述电容或电容的变化，输出表征所述探针是否接触所述被测液体的指示信号。
  16. 如权利要求13所述的装置，其特征在于，所述探针为双层针管结构，所述探针的导电内针管连接所述开关电路的输入端。
  17. 如权利要求13所述的装置，其特征在于，每一组所述探测电路还包括：
    连接所述频率测量电路的运算电路，用于根据所述谐振频率或谐振频率的变化，输出所述探针输出的电容或电容的变化；并且，
    所述处理电路用于根据所述至少两组所述探测电路输出的所述电容或电容的变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
  18. 如权利要求13所述的装置，其特征在于，每一组所述探测电路中的所述LC谐振电路包括：含有至少一个电感或可调电感的电感支路，和包含至少一个电容或可调电容的电容支路，所述电感支路和电容支路并联；
    所述开关电路中的所述每一路输出的接入端对应连接所述电感支路的一端和所述电容支路的一端相连，或者可选择连接在所述电感支路或所述电容支路中的任意一个结点位置。
  19. 如权利要求13所述的装置，其特征在于，所述液面检测装置还包括：跟随器，
    所述探针包括导电内针管和导电外针管，所述探针的导电内针管的一端与所述开关电路的输入端和所述跟随器的输入端相连，所述跟随器的输出端与所述探针的导电外针管连接。
  20. 如权利要求13或15所述的装置，其特征在于，所述处理电路在所述至少两组所述探测电路输出的所述谐振频率或谐振频率的变化同时满足第一预设条件时、或者在所述至少两组所述探测电路输出的所述电容或电容的变化同时满足第二预设条件时，输出表征所述探针的另一端接触所述被测液体的指示信号。
  21. 如权利要求13所述的装置，其特征在于，所述探针包括导电内针管和导电外针管，所述导电内针管的长度比导电外针管的长度长，且所述导电内针管和导电外针管的长度相差超过3厘米。
  22. 一种液面检测方法，其特征在于，所述方法包括：
    信号叠加步骤：将因探针与被测液面之间的距离变化而产生的电容或电容变化，叠加到LC谐振电路上，获得混合有所述探针产生的电容或电容变化情况的谐振信号；
    转化步骤：将所述谐振信号转化为数字信号；
    频率测量步骤：测量所述数字信号，获得所述谐振信号的谐振频率或谐振频率的变化；
    输出步骤：根据所述谐振频率或谐振频率的变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
  23. 如权利要求22所述的方法，其特征在于，所述方法还包括：
    电容计算步骤：根据所述谐振频率或谐振频率的变化，计算获得所述探针产生的电容或电容变化；
    并在所述输出步骤中：根据计算获得的所述电容或电容变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
  24. 如权利要求20所述的方法，其特征在于，所述信号叠加步骤中还包括：
    设置多路LC谐振电路，将所述探针产生的电容或电容变化分时叠加到 所述多路LC谐振电路，用于在预设时间段内获得多组所述谐振信号；
    分别对所述多组所述谐振信号依次进行转化步骤、频率测量步骤，获得多组所述谐振信号的谐振频率或谐振频率的变化；
    并在所述输出步骤中：根据至少两组所述谐振频率或谐振频率的变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
  25. 如权利要求20所述的方法，其特征在于，在所述频率测量步骤中包括：
    获取用户调整的谐振频率的测量时间，在获取的测量时间内测量所述数字信号，获得所述谐振信号的谐振频率或谐振频率的变化。
  26. 如权利要求22所述的方法，其特征在于，所述方法还包括：
    根据所述多组所述谐振信号的谐振频率或谐振频率的变化，计算获得多组所述探针产生的电容或电容变化；
    并在所述输出步骤中：根据计算获得的至少两组所述电容或电容变化，输出表征所述探针的另一端是否接触所述被测液体的指示信号。
  27. 一种全自动取样装置，其特征在于，所述全自动取样装置包括：
    权利要求1至权利要求21所述的任意一权利要求所述的液面检测装置；
    针管运动控制机构，用于接收来自所述液面检测装置输出的指示信号，根据所述指示信号控制探针相对于所述被测液体运动。
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