CN201917376U - Capacitive liquid level sensor - Google Patents
Capacitive liquid level sensor Download PDFInfo
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- CN201917376U CN201917376U CN201120010237XU CN201120010237U CN201917376U CN 201917376 U CN201917376 U CN 201917376U CN 201120010237X U CN201120010237X U CN 201120010237XU CN 201120010237 U CN201120010237 U CN 201120010237U CN 201917376 U CN201917376 U CN 201917376U
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- liquid level
- capacitance
- microprocessor
- inductive switch
- induction electrode
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Abstract
The utility model relates to a capacitive liquid level sensor, which comprises a liquid level inductive switch (20) and a microprocessor (21). The liquid level inductive switch (20) is provided with an inductive electrode (201) which is connected with the microprocessor (21). One inductive electrode of the capacitive liquid level sensor is disposed in a closed container, in a closed pipe or on the surface of a closed vessel, and liquid level detection is implemented according to the capacitive touch sensitive principle. Compared with a traditional 'liquid level sensor', the capacitive liquid level sensor has only one inductive electrode, is small in size, high in accuracy, simple in circuit structure, high in interference resistance, and is of a noncontact type and simple and convenient in mounting, use and maintenance, and product reliability is improved, product service life is prolonged and product cost is reduced.
Description
Technical field
The utility model relates to liquid level control field, more specifically, relates to a kind of capacitance level transducer.
Background technology
There is a kind of capacitance type sensor in traditional liquid level control field, and its principle is as follows, from physics as can be known, and when ignoring the edge effect of two parallel metal sheets, two capacitors that parallel metal sheet constitutes, show that as Fig. 1 its electric capacity C is:
C＝ε
oε
rS/D (1)
ε
o: permittivity of vacuum, ε
o=8.85*10
-12(F/m);
ε
r: the relative dielectric constant of medium between pole plate, vacuum medium, ε
r=1;
Area (the m that the S=pole plate hides mutually
2);
D=polar plate spacing (m);
Existing capacitance type sensor is exactly according to three parameters (S, D, ε in the formula (1)
r) in any one amount change, cause that electric capacity C changes.That is to say, if the variation of detected parameter (as displacement, pressure, liquid level etc.) causes S, D, ε
rChange one of in three parameters, just can utilize the change of corresponding electric capacity to realize parameter measurement.Therefore, Chang Yong capacitance type sensor can be divided into three major types usually: pole span change type capacitive transducer (changing D), area change type capacitive transducer (changing S) and media variations type capacitive transducer (change ε
r).This sensor has individual common characteristic, and needing two induction electrodes, the capacitance of surveying is electric capacitys between two induction electrodes all.In some airtight volume, pipeline or vessel, very difficulty or for a long time induction electrode is placed in the solution of another one induction electrode is installed, situations such as corrosion can take place in induction electrode.
The utility model content
At the above-mentioned defective of existing liquid level sensor, the utility model provides a kind of improved capacitance level transducer, is single induction electrode of the working method of a kind of employing " capacitance charge transfer ", and volume is little simultaneously, the capacitance level transducer that cost is low.
A kind of capacitance level transducer of the present utility model comprises liquid level inductive switch (20) and microprocessor (21); Wherein said liquid level inductive switch (20) has induction electrode (201); Induction electrode (201) connects described microprocessor (21); Microprocessor (21) connects liquid level inductive switch (20) by input/output end port (210), to described liquid level inductive switch (20) repeated charge and the inductance capacitance (Cf) that detects described induction electrode (201) generate the liquid level detection signal (AD0, ADf).
Preferably, described microprocessor (21) further comprises: capacitance charge carry circuit (211), to stray capacitance (Ch) repeated charge and the electric charge transfer of described liquid level inductive switch (20) and microprocessor (21); Analog to digital converter (212), and the input signal values of liquid level inductive switch (20) after sampling acquisition electric charge shifts repeatedly (ADl, ADh); Digital signal processing module (213), to sampling sampling repeatedly keep the described input signal values that analog to digital converter (212) conversion back obtained (ADl, ADh) deposit, difference comparison operation and digital filtering processing obtain the Level Detection signal (AD0, ADf).
Preferably, described charge transfer circuit (211) comprises that first discharges and recharges terminal (RA0), first gauge tap (K1), and second discharges and recharges terminal (RA1), second gauge tap (K2) and charge transfer switch (K0); Wherein first discharge and recharge terminal (RA0) by described first gauge tap (K1) connection described liquid level inductive switch (20); Second discharges and recharges terminal (RA1) connects microprocessor by second gauge tap (K2) stray capacitance (Ch); Charge transfer switch (K0) connects described liquid level inductive switch (20) and described stray capacitance (Ch) and controls the electric charge transfer of the two.
Preferably, described digital signal processing module (213) comprises register (2131), deposit the described input signal values that keeps being obtained after analog to digital converter (212) conversion through sampling repeatedly (ADl, ADh); Differential ratio is than computing module (2132), and keep back obtained some of analog to digital converter (212) conversion (ADl ADh) carries out the difference comparison operation and obtains several differential signals (ADn) to described input signal values to sampling repeatedly; Digital filtering processing module (2133), to described several differential signals (ADn) carry out digital filtering handle to obtain described Level Detection signal (AD0, ADf).
Preferably, described induction electrode (201) is a sheet metal.
Preferably, described induction electrode (201) is provided with the very thin insulation crust of sealing.
Capacitance level transducer of the present utility model has adopted the principle of work of " capacitance charge transfer ", when the liquid in the container surpasses or is lower than described induction electrode, the capacitance that the microprocessor input/output end port is connected changes, thereby detect the variation of internal tank liquid level accurately, the utility model capacitance level transducer adopts an induction electrode, be placed on the surface of airtight volume, pipeline or vessel, utilize the capacitance touch principle of induction to carry out Level Detection.Compare with traditional " liquid level sensor ", have only an induction electrode, volume is very little, the accuracy height, circuit structure is simple, and antijamming capability is strong, has increased reliability of products and life-span, reduced cost of products, and be contactless, installed, use, keeped in repair all simple and convenient.
Description of drawings
Fig. 1 is the structural representation of capacitor
Fig. 2 is the structural representation of the capacitance level transducer of the utility model embodiment;
Fig. 3 is the structural representation of digital signal processing module;
Fig. 4 is a synoptic diagram of using the liquid level intelligent controller of above-mentioned capacitance level transducer.
Embodiment
By describing technology contents of the present utility model, structural attitude in detail, realized purpose and effect, give explanation below in conjunction with embodiment and conjunction with figs. are detailed.
Embodiment 1,
Fig. 2, Fig. 3 and Fig. 4 are the structural representations of the capacitance level transducer of the utility model embodiment.A kind of capacitance level transducer comprises liquid level inductive switch (20) and microprocessor (21); Wherein said liquid level inductive switch (20) has induction electrode (201); Induction electrode (201) is a sheet metal, and it is provided with the very thin insulation crust of sealing 202.Described sheet metal and insulation crust 202 all are placed on the surface of volume, pipeline or the vessel of carrying liquid.
Induction electrode (201) connects described microprocessor (21); Microprocessor (21) connects liquid level inductive switch (20) by input/output end port (210), there is fixing outer scattered stray capacitance (Co) in its connection line, concordant with liquid level inductive switch (20) or when surpassing when the liquid level of the liquid in the container 32 31, the shell of spacer insulator layer (202) and vessel between induction electrode (201) and the liquid 31, form inductance capacitance (Cf) between induction electrode (201) and the liquid 31, when liquid 31 liquid levels were lower than inductive switch (20), inductance capacitance Cf value was zero.
Described microprocessor (21) further comprises: the stray capacitance (Ch) of capacitance charge carry circuit (211), microprocessor (21), analog to digital converter (212) and digital signal processing module (213).Described charge transfer circuit (211) comprises that first discharges and recharges terminal (RA0), first gauge tap (K1), and second discharges and recharges terminal (RA1), second gauge tap (K2) and charge transfer switch (K0); Wherein first discharge and recharge terminal (RA0) by described first gauge tap (K1) connection described liquid level inductive switch (20); Second discharges and recharges terminal (RA1) connects microprocessor by second gauge tap (K2) stray capacitance (Ch); Charge transfer switch (K0) connects described liquid level inductive switch (20) and described stray capacitance (Ch) and controls the electric charge transfer of the two.
Capacitance charge carry circuit (211) is to stray capacitance (Ch) repeated charge and the electric charge transfer of described liquid level inductive switch (20) and microprocessor (21); Analog to digital converter (212), and the input signal values of liquid level inductive switch (20) after sampling acquisition electric charge shifts repeatedly (ADl, ADh); Digital signal processing module (213), to sampling repeatedly keep the described input signal values that analog to digital converter (212) conversion back obtained (ADl, ADh) deposit, difference comparison operation and digital filtering processing obtain the Level Detection signal (AD0, ADf).
Described digital signal processing module (213) comprises register (2131), deposit the described input signal values that keeps being obtained after analog to digital converter (212) conversion through sampling repeatedly (ADl, ADh); Differential ratio is than computing module (2132), and keep back obtained some of analog to digital converter (212) conversion (ADl ADh) carries out the difference comparison operation and obtains several differential signals (ADn) to described input signal values to sampling repeatedly; Digital filtering processing module (2133), to described several differential signals (ADn) carry out digital filtering handle to obtain described Level Detection signal (AD0, ADf).
Capacitance level transducer of the present utility model adopts " capacitance charge transfer " working method, directly linked to each other with induction electrode in the liquid level inductive switch by microprocessor (CPU), described microprocessor has I/O (I/O) port of analog to digital converter 212 (A/D) translation function.When the higher conductor (as: water of specific inductive capacity, formic acid, methyl alcohol, ethanol, acetone, liquid ammonia, n-hexyl alcohol, glycerine, ore, or latex etc. is at container, in the time of in pipeline or the vessel, the higher conductor of specific inductive capacity is coupled between insulator (insulation crust 202 and vessel shell) and induction electrode 201 and produces inductance capacitance Cf, the capacitance of input/output end port 210 connections of microprocessor 21 is changed, the inductance capacitance Cf that is produced between liquid that the liquid level change that detects microprocessor 21 causes and the induction electrode 201, thus the detection signal of representing fluid level condition generated.Owing to have outside distribution stray capacitance Co at liquid level inductive switch 20, and microprocessor chip inside has stray capacitance Ch, the inductance capacitance Cf that is produced between liquid 31 and the induction electrode 201 and outside distribution stray capacitance Co and stray capacitance Ch differ little, in order to eliminate Ch and Co influence to Level Detection, microprocessor 21 adopts difference A/D comparison operation method to detect inductance capacitance Cf, thereby reaches the purpose of detecting liquid level.
As shown in Figure 2, capacitance level transducer of the present utility model comprises liquid level inductive switch 20 and microprocessor 21; Wherein said liquid level inductive switch 20 has induction electrode 201; Induction electrode 201 connects described microprocessor 21.When liquid level in the container 32 rises to concordant below induction electrode or surpass induction electrode 201, the inductance capacitance Cf that is produced between liquid 31 and the induction electrode 201 can be from certain value that is raised to above freezing, when liquid level in the container 32 is reduced to induction electrode when below, then inductance capacitance Cf=0.Liquid level inductive switch 20 also has outside distribution stray capacitance Co.As Fig. 2, microprocessor 21 connects liquid level inductive switch 20 by its input/output end port 210.Microprocessor 21 carries out repeated charge by 210 pairs of described liquid level inductive switches 20 of its input/output end port, and detects the inductance capacitance Cf of described induction electrode 201 repeatedly, according to variation generation liquid level detection signal AD0 or the Adf of inductance capacitance Cf.
Wherein, the structure of described microprocessor 21 further comprises: capacitance charge carry circuit 211, and analog to digital converter 212 and digital signal processing module 213, and the chip internal of microprocessor 21 also has stray capacitance Ch.
Capacitance charge carry circuit 211 is connected to outside described liquid level inductive switch 20 by input/output end port 210, and control discharges and recharges repeatedly with electric charge the stray capacitance Ch of described liquid level inductive switch 20 and microprocessor 21 and shifts.Particularly, described charge transfer circuit 211 comprises that first discharges and recharges terminal RA0, the first gauge tap K1, and second discharges and recharges terminal RA1, the second gauge tap K2 and charge transfer switch K0; Wherein first discharge and recharge terminal RA0 and connect described liquid level inductive switch 20 by the described first gauge tap K1; Second discharges and recharges terminal RA1 connects microprocessor by the second gauge tap K2 stray capacitance Ch; Charge transfer switch K0 connects inductance capacitance Cf and the outside distribution stray capacitance Co and the described stray capacitance Ch of described liquid level inductive switch 20, and the electric charge of controlling the two shifts, thereby makes inductance capacitance Cf and outside distribution stray capacitance Co and described stray capacitance Ch reach charge balance.
Analog to digital converter 212 is sampled repeatedly, maintenance, analog to digital conversion (A/D conversion), obtaining the transfer of process electric charge reaches after the charge balance, liquid level inductive switch 20 some to input signal values ADl and ADh also are the input signal values on inductance capacitance Cf and the outside distribution stray capacitance Co.
Digital signal processing module 213, to sampling repeatedly keep that analog to digital converter (212) conversion back obtained described some to input signal values deposit, difference comparison operation and digital filtering handle, and obtains Level Detection signal AD0 or ADf.
When operate as normal, the charge transfer switch K0 in the charge transfer circuit 211 disconnects, the first gauge tap K1 and the second gauge tap K2 closure; First level that discharges and recharges terminal RA0 is changed to " 0 ", makes inductance capacitance Cf and outside distribution stray capacitance Co discharge; Second level that discharges and recharges terminal RA1 is changed to " 1 ", makes stray capacitance Ch charging.Then, the first gauge tap K1 and the second gauge tap K2 disconnect, charge transfer switch K closure, stray capacitance Ch is charged to inductance capacitance Cf and outside distribution stray capacitance Co, behind three's charge balance, analog to digital converter 212 is sampled, maintenance, A/D conversion, obtains the first input signal values ADh on inductance capacitance Cf and the outside distribution stray capacitance Co.
Afterwards, the charge transfer switch K0 in the charge transfer circuit 211 disconnects, the first gauge tap K1 and the second gauge tap K2 closure; First level that discharges and recharges terminal RA0 is changed to " 1 ", makes inductance capacitance Cf and outside distribution stray capacitance Co charging; Second level that discharges and recharges terminal RA1 is changed to " 0 ", makes stray capacitance Ch discharge.Then, the first gauge tap K1 and the second gauge tap K2 disconnect, charge transfer switch K0 closure, inductance capacitance Cf and outside distribution stray capacitance Co are charged to stray capacitance Ch, behind three's charge balance, analog to digital converter 212 is sampled once more, maintenance, A/D conversion, obtains the second input signal values ADl on inductance capacitance Cf and the outside distribution stray capacitance Co.、
The structure of digital signal processing module 213 comprises register 2131 as shown in Figure 3, and differential ratio is than computing module 2132 and digital filtering processing module 2133.Register 2131 deposit through sample repeatedly, maintenance, A/D conversion, the described input signal values ADh and the ADl that are obtained; Differential ratio is somely carried out the difference comparison operation to the first and second input signal values ADh and ADl than what computing module obtained more than 2132 pairs after over-sampling keeps analog to digital converter (212) conversion, obtain several differential signals ADn.Digital filtering processing module 2133, again to through sample repeatedly, maintenance, A/D conversion, several differential signals ADn that is obtained carries out dynamic tracking and digital filtering is handled, filtering common mode, differential mode interference, and obtaining final Level Detection signal AD0 or ADf, this Level Detection signal AD0 or ADf have reflected the electric capacity of liquid level inductive switch 20.Wherein, if the liquid in containers height below induction electrode 201, promptly Cf is 0, Co remains unchanged, the Level Detection signal AD0 that obtain this moment also is constant; If the liquid in containers height flushes or surpass induction electrode 201, then generate inductance capacitance Cf between liquid and the induction electrode 201, will change the electric capacity of liquid level inductive switch 20, be that capacitance value is (Cf+Co), the Level Detection signal ADf that generate this moment also can with AD0 have bigger different, thereby can reach the purpose of contactless detecting liquid in containers liquid level.
As shown in Figure 4, the utility model also provides a kind of liquid level intelligent controller of using above-mentioned capacitance level transducer, comprising: liquid level inductive switch 20, microprocessor 21, light-emitting diode display 22 and Drive and Control Circuit 23; Wherein: described liquid level inductive switch 20 has induction electrode 201; Induction electrode 201 connects described microprocessor 21; Microprocessor 21 connects liquid level inductive switch 20 by input/output end port 210, and described liquid level inductive switch 20 is discharged and recharged and detect the inductance capacitance Cf of described induction electrode 201, thereby generates liquid level detection signal AD0 or ADf; Light-emitting diode display 22 dynamically shows under the control of microprocessor 21; Drive and Control Circuit 23 is carried out the drive controlling that liquid 31 pumps into or pumps under the control of microprocessor 21.Wherein, the inner structure of microprocessor 21 is identical with Fig. 3 related content with Fig. 2 with working method, does not repeat them here.
Embodiment 2,
All the other are identical with embodiment 1, and difference is that described induction electrode 201 is rectangular sheet, its outer insulation course 202 that covers, described insulation course 202 is made for insulating material such as PET, PC, PE or PS, can adopt hot pressing to be adhesive on the induction electrode 201, and its thickness generally is no more than 0.2mm.Induction electrode 201 is insulated layer 202 parcel covering fully, place it in vessel surface, its length direction is vertical with surface level, when the higher conductor (as: water of specific inductive capacity, formic acid, methyl alcohol, ethanol, acetone, liquid ammonia, n-hexyl alcohol, glycerine, ore, or latex etc.) at container, in the time of in pipeline or the vessel, the higher conductor of specific inductive capacity is coupled between insulator (insulation course 202 and vessel shell) and induction electrode 201 and produces inductance capacitance Cf, the capacitance of input/output end port 210 connections of microprocessor 21 is changed, this capacitance changes with the coupling area between liquid 31 and the induction electrode 201, the inductance capacitance Cf that is produced between liquid 31 that the liquid level change that detects microprocessor 21 causes and the induction electrode 201, thus the detection signal of representing fluid level condition generated.Owing to have outside distribution stray capacitance Co at liquid level inductive switch 20, and microprocessor chip inside has stray capacitance Ch, the inductance capacitance Cf that is produced between liquid 31 and the induction electrode 201 and outside distribution stray capacitance Co and stray capacitance Ch differ little, in order to eliminate Ch and Co influence to Level Detection, microprocessor 21 adopts difference A/D comparison operation method to detect inductance capacitance Cf, thereby reaches the purpose of detecting liquid level.Present embodiment can show the numerical value of liquid level in real time, rather than just monitors some liquid level point.
Capacitance level transducer of the present utility model has adopted the principle of work of " capacitance charge transfer ", when the liquid level in the container surpasses or is lower than described induction electrode, the capacitance that the microprocessor input/output end port is connected changes, thereby detects the variation of internal tank liquid level accurately.The utility model capacitance level transducer adopts an induction electrode, is placed on the surface of airtight volume, pipeline or vessel, utilizes the capacitance touch principle of induction to carry out Level Detection.Compare with traditional " liquid level sensor ", have only an induction electrode, volume is very little, the accuracy height, circuit structure is simple, and antijamming capability is strong, has increased reliability of products and life-span, reduced cost of products, and be contactless, installed, use, keeped in repair all simple and convenient.
The above only is embodiment of the present utility model; be not so limit claim of the present utility model; every equivalent structure or equivalent flow process conversion that utilizes the utility model instructions and accompanying drawing content to be done; or directly or indirectly be used in other relevant technical fields, all in like manner be included in the scope of patent protection of the present utility model.
Claims (6)
1. a capacitance level transducer is characterized in that, comprises liquid level inductive switch (20) and microprocessor (21); Wherein said liquid level inductive switch (20) has induction electrode (201); Induction electrode (201) connects described microprocessor (21); Microprocessor (21) connects liquid level inductive switch (20) by input/output end port (210), to induction electrode (201) repeated charge of described liquid level inductive switch (20) and the inductance capacitance (Cf) that detects described induction electrode (201) generate the liquid level detection signal (AD0, ADf).
2. capacitance level transducer according to claim 1, it is characterized in that, described microprocessor (21) further comprises: capacitance charge carry circuit (211), to stray capacitance (Ch) repeated charge and the electric charge transfer of described liquid level inductive switch (20) and microprocessor (21); Analog to digital converter (212), and the input signal values of liquid level inductive switch (20) after sampling acquisition electric charge shifts repeatedly (ADl, ADh); Digital signal processing module (213), to sampling repeatedly keep the described input signal values that analog to digital converter (212) conversion back obtained (ADl, ADh) deposit, difference comparison operation and digital filtering processing obtain the Level Detection signal (AD0, ADf).
3. capacitance level transducer according to claim 2, it is characterized in that described charge transfer circuit (211) comprises that first discharges and recharges terminal (RA0), first gauge tap (K1), second discharges and recharges terminal (RA1), second gauge tap (K2) and charge transfer switch (K0); Wherein first discharge and recharge terminal (RA0) by described first gauge tap (K1) connection described liquid level inductive switch (20); Second discharges and recharges terminal (RA1) connects microprocessor by second gauge tap (K2) stray capacitance (Ch); Charge transfer switch (K0) connects described liquid level inductive switch (20) and described stray capacitance (Ch) and controls the electric charge transfer of the two.
4. capacitance level transducer according to claim 2, it is characterized in that, described digital signal processing module (213) comprises register (2131), deposit the described input signal values that keeps being obtained after analog to digital converter (212) conversion through sampling repeatedly (ADl, ADh); Differential ratio is than computing module (2132), and keep back obtained some of analog to digital converter (212) conversion (ADl ADh) carries out the difference comparison operation and obtains several differential signals (ADn) to described input signal values to sampling repeatedly; Digital filtering processing module (2133), to described several differential signals (ADn) carry out digital filtering handle to obtain described Level Detection signal (AD0, ADf).
5. according to the arbitrary described capacitance level transducer of claim 1 to 4, it is characterized in that described induction electrode (201) is a sheet metal.
6. capacitance level transducer according to claim 5 is characterized in that, described induction electrode (201) is provided with the very thin insulation crust of sealing (202).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120010237XU CN201917376U (en) | 2011-01-14 | 2011-01-14 | Capacitive liquid level sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120010237XU CN201917376U (en) | 2011-01-14 | 2011-01-14 | Capacitive liquid level sensor |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102589644A (en) * | 2011-01-14 | 2012-07-18 | 苏州路之遥科技股份有限公司 | Capacitance type liquid level sensor |
| CN103049154A (en) * | 2012-11-21 | 2013-04-17 | 温州长江汽车电子有限公司 | Touch signal acquisition method for capacitive touch switch |
| CN103940491A (en) * | 2014-05-08 | 2014-07-23 | 北华航天工业学院 | Harvester barn material level detection system |
| CN105277255A (en) * | 2015-11-19 | 2016-01-27 | 钱和革 | Capacitive testing circuit, liquid level detecting circuit, use method thereof, cup and equipment |
| CN106178203A (en) * | 2016-08-30 | 2016-12-07 | 苏州品诺维新医疗科技有限公司 | A kind of medical liquid atomizing equipment and operational approach thereof |
| CN106289450A (en) * | 2016-07-27 | 2017-01-04 | 上海航天设备制造总厂 | Point type electric capacity Low Temperature Liquid bit changer |
| CN106768175A (en) * | 2017-02-28 | 2017-05-31 | 北京晨淼科技有限公司 | A kind of SMD capacitance liquid level meter and level measuring method |
| CN107782408A (en) * | 2016-08-29 | 2018-03-09 | 佛山市顺德区美的电热电器制造有限公司 | Liquid level detection circuit, liquid-level detecting method and wall-breaking machine |
| US9983042B2 (en) | 2015-12-01 | 2018-05-29 | Industrial Technology Research Institute | Apparatus for detecting liquid level |
| CN110702188A (en) * | 2019-10-09 | 2020-01-17 | 江苏科技大学 | Device and method for measuring oil quantity of oil tank of zero-turning-radius mower |
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| CN102589644A (en) * | 2011-01-14 | 2012-07-18 | 苏州路之遥科技股份有限公司 | Capacitance type liquid level sensor |
| CN103049154A (en) * | 2012-11-21 | 2013-04-17 | 温州长江汽车电子有限公司 | Touch signal acquisition method for capacitive touch switch |
| CN103940491B (en) * | 2014-05-08 | 2018-09-14 | 廊坊新峰达科技有限公司 | Harvester silo material-level detection system |
| CN103940491A (en) * | 2014-05-08 | 2014-07-23 | 北华航天工业学院 | Harvester barn material level detection system |
| CN105277255A (en) * | 2015-11-19 | 2016-01-27 | 钱和革 | Capacitive testing circuit, liquid level detecting circuit, use method thereof, cup and equipment |
| US9983042B2 (en) | 2015-12-01 | 2018-05-29 | Industrial Technology Research Institute | Apparatus for detecting liquid level |
| CN106289450A (en) * | 2016-07-27 | 2017-01-04 | 上海航天设备制造总厂 | Point type electric capacity Low Temperature Liquid bit changer |
| CN106289450B (en) * | 2016-07-27 | 2019-01-18 | 上海航天设备制造总厂 | Point type capacitor low temperature liquid-level converter |
| CN107782408A (en) * | 2016-08-29 | 2018-03-09 | 佛山市顺德区美的电热电器制造有限公司 | Liquid level detection circuit, liquid-level detecting method and wall-breaking machine |
| CN107782408B (en) * | 2016-08-29 | 2023-12-19 | 佛山市顺德区美的电热电器制造有限公司 | Liquid level detection circuit, liquid level detection method and wall breaking machine |
| CN106178203A (en) * | 2016-08-30 | 2016-12-07 | 苏州品诺维新医疗科技有限公司 | A kind of medical liquid atomizing equipment and operational approach thereof |
| CN106768175A (en) * | 2017-02-28 | 2017-05-31 | 北京晨淼科技有限公司 | A kind of SMD capacitance liquid level meter and level measuring method |
| CN106768175B (en) * | 2017-02-28 | 2019-04-12 | 北京晨淼科技有限公司 | A kind of patch type capacitance liquid level meter and level measuring method |
| CN112571969A (en) * | 2019-09-30 | 2021-03-30 | 精工爱普生株式会社 | Physical quantity detection device and printing device |
| CN110702188A (en) * | 2019-10-09 | 2020-01-17 | 江苏科技大学 | Device and method for measuring oil quantity of oil tank of zero-turning-radius mower |
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