CN107228699A - Liquid-level detecting method and liquid level detection device - Google Patents

Liquid-level detecting method and liquid level detection device Download PDF

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Publication number
CN107228699A
CN107228699A CN201610171192.1A CN201610171192A CN107228699A CN 107228699 A CN107228699 A CN 107228699A CN 201610171192 A CN201610171192 A CN 201610171192A CN 107228699 A CN107228699 A CN 107228699A
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capacitance
detection unit
value
liquid
self
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CN107228699B (en
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何世娴
李奇峰
杨云
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BYD Semiconductor Co Ltd
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BYD Co Ltd
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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

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Power Engineering (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

The invention discloses a kind of liquid-level detecting method and liquid level detection device, method comprises the following steps：The self-capacitance value and mutual capacitance value of capacitance present detection unit are detected respectively；Determine whether that liquid covers the capacitance present detection unit according to the relation between the mutual capacitance value of the relation between the self-capacitance value of the capacitance present detection unit and corresponding self-capacitance a reference value and the capacitance present detection unit and corresponding mutual capacitance a reference value；If it is determined that there is liquid to cover the capacitance present detection unit, then detect the self-capacitance value and mutual capacitance value of the capacitance detection unit adjacent with the capacitance present detection unit respectively upwards, until when judging no liquid covering capacitance detection unit, liquid level information is obtained according to the previous capacitance detection unit that corresponding capacitance detection unit when being covered with no liquid is adjacent.Thus, interference of the environment to level sensing can be prevented effectively from, the degree of accuracy of level sensing is improved.

Description

Liquid-level detecting method and liquid level detection device
Technical field
The present invention relates to observation and control technology field, more particularly to a kind of liquid-level detecting method and a kind of liquid level detection device.
Background technology
Correlation technique proposes a kind of capacitive liquid level survey meter of intelligence, and the program is become electric capacity by capacitive frequency change-over circuit Change is converted to frequency change, and uses temperature sensor detection temperature, and then CPU changes and passed through according to frequency Software formula calculates liquid level, and the liquid level calculated is compensated and is segmented amendment according to temperature and by software formula.
But, the problem of correlation technique is present is to add temperature sensor, so that circuit is more complicated, and electric capacity Accuracy of detection is also limited by the precision of temperature sensor, so as to influence level sensing accuracy.
The content of the invention
It is contemplated that at least solving one of technical problem in correlation technique to a certain extent.Therefore, one of the present invention Purpose is to propose a kind of liquid-level detecting method, and this method can accurately judge that liquid level changes, and be prevented effectively from environment and liquid level is examined The interference of survey.
It is another object of the present invention to propose a kind of liquid level detection device.
To reach above-mentioned purpose, one aspect of the present invention embodiment proposes a kind of liquid-level detecting method, capacitance present is detected respectively The self-capacitance value and mutual capacitance value of detection unit；According to the self-capacitance value of the capacitance present detection unit and corresponding self-capacitance Relation between the mutual capacitance value and corresponding mutual capacitance a reference value of relation and the capacitance present detection unit between a reference value Determine whether that liquid covers the capacitance present detection unit；If it is determined that there is liquid to cover the capacitance present detection unit, Then detect the self-capacitance value and mutual capacitance value of the capacitance detection unit adjacent with the capacitance present detection unit respectively upwards, directly It is adjacent according to corresponding capacitance detection unit when being covered with no liquid to when judging no liquid covering capacitance detection unit Previous capacitance detection unit obtains liquid level information.
The liquid-level detecting method proposed according to embodiments of the present invention, respectively detect capacitance present detection unit self-capacitance value and mutually Capacitance, then according to the relation between the self-capacitance value of capacitance present detection unit and corresponding self-capacitance a reference value and currently Relation between the mutual capacitance value of capacitance detection unit and corresponding mutual capacitance a reference value determines whether that liquid covering is described current Capacitance detection unit, if it is determined that there is liquid to cover the capacitance present detection unit, is then detected and capacitance present respectively upwards The self-capacitance value and mutual capacitance value of the adjacent capacitance detection unit of detection unit, until judging no liquid covering capacitance detecting list When first, liquid level letter is obtained according to the adjacent previous capacitance detection unit of corresponding capacitance detection unit when being covered with no liquid Breath.Thus, the situation of change of the mutual capacitance of this method joint and self-capacitance detects liquid level, can be prevented effectively from environment and liquid level is examined The interference of survey, improves the degree of accuracy of level sensing.Also, this method need not increase extra external devices such as temperature Sensor, circuit is simple, and algorithm is reliable.
To reach above-mentioned purpose, another aspect of the present invention embodiment proposes a kind of liquid level detection device, multiple capacitance detecting lists Member；Control module, the control module is connected with the multiple capacitance detection unit, and the control module is used to detect respectively The self-capacitance value and mutual capacitance value of capacitance present detection unit, and self-capacitance value according to the capacitance present detection unit with it is right The mutual capacitance value and corresponding mutual capacitance a reference value of relation and the capacitance present detection unit between the self-capacitance a reference value answered Between relation determine whether that liquid covers the capacitance present detection unit, if liquid covers the capacitance present detection Unit, the control module then detects the electricity certainly of the capacitance detection unit adjacent with the capacitance present detection unit respectively upwards Capacitance and mutual capacitance value, until when judging the covering capacitance detection unit without liquid, according to when being covered with no liquid pairs The adjacent previous capacitance detection unit of the capacitance detection unit answered obtains liquid level information.
The liquid level detection device proposed according to embodiments of the present invention, control module detects the electricity certainly of capacitance present detection unit respectively Capacitance and mutual capacitance value, then according to the pass between the self-capacitance value of capacitance present detection unit and corresponding self-capacitance a reference value System and the relation between the mutual capacitance value and corresponding mutual capacitance a reference value of capacitance present detection unit determine whether that liquid is covered The capacitance present detection unit, if it is determined that there is liquid to cover the capacitance present detection unit, then upwards respectively detection with The self-capacitance value and mutual capacitance value of the adjacent next capacitance detection unit of capacitance present detection unit, until judging no liquid When covering capacitance detection unit, according to the adjacent previous capacitance detecting of corresponding capacitance detection unit when being covered with no liquid Unit obtains liquid level information.Thus, the situation of change of the device joint mutual capacitance and self-capacitance detects liquid level, can effectively keep away Exempt from interference of the environment to level sensing, improve the degree of accuracy of level sensing.Also, the device need not increase extra outer Portion's device such as temperature sensor, circuit is simple, and algorithm is reliable.
Brief description of the drawings
Fig. 1 is the flow chart of liquid-level detecting method according to embodiments of the present invention；
Fig. 2 is the scheme of installation of multiple capacitance detection units according to an embodiment of the invention；
Fig. 3 is the flow chart of liquid-level detecting method according to an embodiment of the invention；
Fig. 4 is the fundamental diagram of the liquid-level detecting method according to a specific embodiment of the invention；
Fig. 5 is the block diagram of liquid level detection device according to embodiments of the present invention；
Fig. 6 is the part-structure schematic diagram of liquid level detection device according to an embodiment of the invention；And
Fig. 7 is the schematic diagram of self-capacitance model according to an embodiment of the invention and mutual capacitance model.
Embodiment
Embodiments of the invention are described below in detail, the example of the embodiment is shown in the drawings, wherein identical from beginning to end Or similar label represents same or similar element or the element with same or like function.Retouched below with reference to accompanying drawing The embodiment stated is exemplary, it is intended to for explaining the present invention, and be not considered as limiting the invention.
Below with reference to the accompanying drawings come describe the embodiment of the present invention proposition liquid-level detecting method and liquid level detection device.
Fig. 1 is the flow chart of liquid-level detecting method according to embodiments of the present invention.The method of embodiments of the invention utilizes mutual electricity Hold and self-capacitance changes in liquid level and capacitance variations otherness during environmental change carries out detection liquid level, that is, say, according to mutual electricity The principle features of appearance, mutual capacitance value will not change when liquid level changes, and according to the principle features of self-capacitance, liquid level occurs Self-capacitance value changes during change.Based on this, liquid-level detecting method of the embodiment of the present invention is by mutual capacitance and the situation of change of self-capacitance It is combined to detect liquid level.
As shown in figure 1, the liquid-level detecting method of the embodiment of the present invention comprises the following steps：
S1：The self-capacitance value and mutual capacitance value of capacitance present detection unit are detected respectively.
That is, can first start mutual capacitance mode, the mutual capacitance value of capacitance present detection unit is detected under mutual capacitance mode, Restart self-capacitance pattern, the self-capacitance value of electric circuit inspection capacitance present detection unit is detected under self-capacitance pattern.
According to one embodiment of present invention, level sensing is carried out by multiple capacitance detection units, capacitance present is detected respectively The self-capacitance value and mutual capacitance value of detection unit, i.e. step S1 include：By the capacitance present detection in multiple capacitance detection units Other capacitance detection units are grounded by unit as excitation end, to detect the self-capacitance value of capacitance present detection unit；Will Each capacitance detection unit is as excitation end in multiple capacitance detection units, to detect the mutual capacitance of capacitance present detection unit Value.
That is, as shown in fig. 7, capacitance present detection unit such as C1 as excitation end and other capacitance detection units For example in the case that C2-C6 is as ground, the electric capacity detected may be defined as self-capacitance, so only to capacitance present detection unit When applying pumping signal, by detecting that the electric capacity of capacitance present detection unit can obtain the self-capacitance of capacitance present detection unit； In the case where multiple capacitance detection units such as C1-C6 is used as excitation end simultaneously, any two capacitance detection unit is eliminated Between the electric capacity of capacitive effect be defined as mutual capacitance, when so applying pumping signal to each capacitance detection unit, pass through inspection The mutual capacitance of capacitance present detection unit can be obtained by surveying the electric capacity of capacitance present detection unit.
In the specific example of the present invention, as shown in Fig. 2 multiple capacitance detection units are brought into close contact with testing container, For example by 3M glues, also, multiple capacitance detection units can be according to ascent direction of the liquid in testing container successively Arrangement, such as multiple capacitance detection units can be arranged in order in the vertical direction of the bottom of testing container, be covered by liquid level The quantity of capacitance detection unit will change with the change of liquid level.It should be appreciated that multiple capacitance detection units with it is to be measured The set-up mode of container is not limited to laminating type.
Also, self-capacitance value when self-capacitance value when capacitance detection unit is covered by liquid level by liquid level with not covered is inconsistent, Say, the self-capacitance value of capacitance detection unit will change when liquid level rises or falls, and mutual capacitance value will not change. But, when environment changes, the self-capacitance value and mutual capacitance value of capacitance detection unit can change, therefore pass through The influence of environment can be eliminated by monitoring the self-capacitance value and mutual capacitance value of capacitance detection unit, accurately identify liquid level information.
S2：According to the relation and capacitance present between the self-capacitance value of capacitance present detection unit and corresponding self-capacitance a reference value Relation between the mutual capacitance value of detection unit and corresponding mutual capacitance a reference value determines whether liquid covering capacitance present detection Unit.
It should be appreciated that when capacitance present detection unit is covered with the liquid, judging that liquid is at least up to capacitance present detection The location of unit, and when capacitance present detection unit is not covered with the liquid, it is single that judgement does not rise to capacitance present detection It is the location of first.
It should be noted that capacitance present detection unit can be in the bottom or top of testing container or middle optional position.
S3：If it is determined that there is liquid to cover capacitance present detection unit, then detect respectively upwards and capacitance present detection unit phase The self-capacitance value and mutual capacitance value of adjacent capacitance detection unit, until when judging no liquid covering capacitance detection unit, according to The previous capacitance detection unit that corresponding capacitance detection unit is adjacent when being covered with no liquid obtains liquid level information.
Further, according to one embodiment of present invention, if it is determined that covering capacitance present detection unit without liquid, then The self-capacitance value and mutual capacitance value of the capacitance detection unit adjacent with capacitance present detection unit are detected respectively downwards, until judging When having liquid covering capacitance detection unit, liquid level information is obtained according to corresponding capacitance detection unit when having liquid covering.
It should be noted that the ascent direction of liquid level is upward referred to, direction as shown by the arrows in Figure 2, in this way, upwards Detection is the capacitance detection unit above detection capacitance present detection unit.Correspondingly, downwards in as Fig. 2 shown in arrow Opposite direction, in this way, downwards detection be detection capacitance present detection unit below capacitance detection unit.That is, It can be detected since any of multiple capacitance detection units capacitance detection unit, if it is determined that there is liquid to cover capacitance present inspection Unit is surveyed, then detects self-capacitance value and mutual capacitance value with the adjacent capacitor detection unit above capacitance present detection unit respectively, Until judging no liquid covering capacitance present detection unit；If it is determined that covering capacitance present detection unit without liquid, then The self-capacitance value and mutual capacitance value with the adjacent capacitor detection unit below capacitance present detection unit are detected respectively, until judging There is liquid to cover capacitance present detection unit.
Below by since with implementation of the present invention is described in detail exemplified by detection the immediate capacitance detection unit in testing container bottom The liquid-level detecting method of example.
Specifically, can be since with judging corresponding electricity the immediate capacitance detection unit in testing container bottom step by step upwards successively Hold whether detection unit is covered with the liquid.Assuming that carrying out level sensing, N number of capacitance detecting list by N number of capacitance detection unit Member be designated as successively from bottom to top C1, C2, C3 ..., CN, N is integer more than 1, when capacitance present detection unit is During i-th of capacitance detection unit Ci, can be according to mutual capacitance value during i-th of capacitance detection unit Ci and the judgement of self-capacitance value It is no to there is liquid to cover i-th of capacitance detection unit Ci, if it is determined that there is liquid to cover i-th of capacitance detection unit Ci, then say Prescribed liquid at least rise/fall is further continued for detecting i+1 electric capacity respectively the location of to i-th capacitance detection unit Ci Detection unit C (i+1) mutual capacitance value and self-capacitance value, now according to i+1 capacitance detection unit C (i+1) from Capacitance and mutual capacitance value determine whether liquid cover i+1 capacitance detection unit C (i+1), with judge liquid whether on Rise/drop to the location of i+1 capacitance detection unit C (i+1).
Self-capacitance value and mutual capacitance value are so detected step by step and determine whether that liquid covers capacitance detection unit, once judge do not have There is liquid to cover capacitance detection unit, with regard to according to detecting adjacent previous of corresponding capacitance detection unit when no liquid is covered Individual capacitance detection unit obtains liquid level information, for example, the 1st is to the corresponding judged result of i-th of capacitance detection unit There is liquid covering, and the corresponding judged result of i+1 capacitance detection unit covers for no liquid, then examines i-th of electric capacity The corresponding liquid level information of unit is surveyed as the current level information of container.
Specifically, mutual capacitance value and self-capacitance value that can be in the way of poll to multiple capacitance detection units detect successively, A self-capacitance value and mutual capacitance value are often detected, with regard to judging whether to detect according to the self-capacitance value and mutual capacitance value that detect Corresponding capacitance detection unit is covered with the liquid, when judging continuous N (N is positive integer) individual capacitance detection unit by liquid Body is covered, and the N+1 capacitance detection unit be when being covered with the liquid, according to the corresponding liquid level of n-th capacitance detection unit Gear exports liquid level information.
It should be appreciated that one liquid level gear of each capacitance detection unit correspondence in multiple capacitance detection units, and each electricity Hold the corresponding liquid level gear of detection unit preset in advance in a program, as shown in Fig. 2 capacitance detection unit can for 6 i.e. C1, C2, C3, C4, C5 and C6,6 capacitance detection units correspond to 6 liquid level gears respectively, and 6 liquid level gears are by suitable Sequence is incremented by successively or successively decreases, for example, C1 correspondence liquid level 1, C2 correspondence liquid level 2, C3 correspondence liquid level 3, C4 correspondence liquid level 4, C5 correspondence liquid levels 5 liquid level 6 corresponding with C6, and liquid level 1<Liquid level 2<Liquid level 3<Liquid level 4<Liquid level 5<Liquid level 6.
It is to be further understood that the quantity and size of capacitance detection unit are adjustable, capacitance detection unit is more, and i.e. N is bigger, The liquid level gear that can be detected is more, and level sensing precision is higher.Also, capacitance detection unit area is bigger, electric capacity inspection The sensitivity for surveying unit is higher.
Thus, the liquid-level detecting method of the embodiment of the present invention, combines the situation of change of mutual capacitance value and self-capacitance value to detect liquid Position, can be prevented effectively from interference of the environment such as temperature to level sensing, improve the degree of accuracy of level sensing, to volume production not Uniformity also has good compensating action.Also, this method need not increase extra external devices such as temperature sensor, Circuit is simple, and algorithm is reliable.
According to one embodiment of present invention, according to the self-capacitance value of capacitance present detection unit and corresponding self-capacitance a reference value Between relation and the mutual capacitance value of capacitance present detection unit determined whether with the relation between corresponding mutual capacitance a reference value Liquid covers the capacitance present detection unit, i.e. step S2 includes：Obtain capacitance present detection unit mutual capacitance value with it is right The first difference i.e. mutual capacitance variable quantity between the mutual capacitance a reference value answered；Obtain capacitance present detection unit self-capacitance value with The second difference between corresponding self-capacitance a reference value is self-capacitance variable；If the first difference be less than the first predetermined threshold value and Second difference is more than the second predetermined threshold value, then judges have liquid to cover capacitance present detection unit.
Also, if the first difference is more than or equal to the first predetermined threshold value or the second difference is less than or equal to the second predetermined threshold value, then sentence Disconnected no liquid covers the capacitance present detection unit, and corresponding mutual capacitance a reference value is updated into capacitance present detection list The mutual capacitance value of member, and corresponding self-capacitance a reference value is updated to the self-capacitance value of capacitance present detection unit, will more Mutual capacitance a reference value and self-capacitance a reference value after new are used for level sensing next time.
If that is, the mutual capacitance variable quantity of capacitance present detection unit is less than the first predetermined threshold value and the capacitance detecting list The self-capacitance variable of member is more than the second predetermined threshold value, then illustrates the self-capacitance value and mutual capacitance value of capacitance present detection unit Change is caused by liquid change, judges that capacitance present detection unit detects liquid, and calculate capacitance present detection unit Whether the mutual capacitance variable quantity and self-capacitance variable of adjacent capacitor detection unit above are to judge the capacitance detection unit by liquid Body is covered, and such cycle criterion is not covered with the liquid until determining capacitance detection unit.And judging capacitance detection unit not When being covered with the liquid, the previous capacitance detection unit that corresponding capacitance detection unit is adjacent during according to not being covered with the liquid is obtained Liquid level information is taken, and is updated respectively according to the mutual capacitance value of corresponding capacitance detection unit when being not detected by liquid and self-capacitance value Corresponding mutual capacitance a reference value and self-capacitance a reference value, under the mutual capacitance a reference value and self-capacitance a reference value after renewal are used for Level sensing.
It should be noted that the corresponding mutual capacitance a reference value of multiple capacitance detection units may be configured as same mutual capacitance a reference value, The corresponding self-capacitance a reference value of multiple capacitance detection units may be alternatively provided as same self-capacitance a reference value, so that register Space is relatively small；The corresponding mutual capacitance a reference value of multiple capacitance detection units may be configured as mutually different mutual capacitance a reference value, The corresponding self-capacitance a reference value of multiple capacitance detection units may be configured as mutually different self-capacitance a reference value, so that detection The degree of accuracy is of a relatively high.
It should be noted that, the facilities of mutual capacitance a reference value and self-capacitance a reference value can be set according to the actual requirements.Also, The mutual capacitance value of each capacitance detection unit is chosen when the initial set value of mutual capacitance a reference value can be according to no liquid, self-capacitance base The self-capacitance value of each capacitance detection unit is chosen when the initial set value of quasi- value can be according to no liquid.
Specifically, the method for the embodiment of the present invention carries out level sensing, N number of capacitance detecting using N number of capacitance detection unit Unit is followed successively by the 1st capacitance detection unit, the 2nd capacitance detection unit, the 3rd capacitance detecting from container bottom up Unit ..., n-th capacitance detection unit.Following flow can specifically be used：Start mutual capacitance mode first, obtain the The mutual capacitance value Rawdata1 (i) of i (i can be 1 any integer value into N) individual capacitance detection unit, by i-th of electricity The mutual capacitance value Rawdata1 (i) for holding detection unit is compared to calculate the with corresponding mutual capacitance a reference value Base1 (i) I the first difference differ1 (i)=| Rawdata1 (i)-Base1 (i) |, and preserve and calculate i-th of first difference differ1 (i)。
Secondly, restart self-capacitance pattern, the self-capacitance value Rawdata2 (i) of i-th of capacitance detection unit is obtained, by i-th The self-capacitance value Rawdata2 (i) of individual capacitance detection unit is compared in terms of with corresponding self-capacitance a reference value Base2 (i) Calculate i-th second difference differ2 (i)=| Rawdata2 (i)-Base2 (i) |, and preserve i-th second calculated Difference differ2 (i).
Again, judge whether i-th of capacitance detection unit is covered with the liquid, if i-th of first difference differ1 (i) are less than First predetermined threshold value Vref1 is differ1 (i)<Vref1, and i-th of second difference differ2 (i) are more than the second default threshold Value is differ2 (i)>Vref2, then judge that i-th of capacitance detection unit is covered with the liquid.Otherwise, if i-th first poor Value differ1 (i) is differ1 (i) >=Vref1 more than or equal to the first predetermined threshold value Vref1, or i-th of second difference differ2 (i) it is differ2 (i)≤Vref2 more than the second predetermined threshold value, then judges that i-th of capacitance detection unit is not covered with the liquid.
Also, after judging that i-th of capacitance detection unit is covered with the liquid, according to above the step of continue to detect i+1 The self-capacitance value and mutual capacitance value of capacitance detection unit are simultaneously judged.And judging i-th of capacitance detection unit not by liquid After covering, using the corresponding liquid level gear of the i-th -1 capacitance detection unit as the current level of container, and mutual capacitance base is updated Quasi- value and self-capacitance a reference value, wherein, if mutual capacitance a reference value is different, only update i-th of capacitance detection unit Corresponding mutual capacitance a reference value, using the mutual capacitance value detected as mutual capacitance a reference value, and if mutual capacitance a reference value is homogeneous Together, then the mutual capacitance a reference value is updated, the mutual capacitance value detected is regard as mutual capacitance a reference value；Similarly, if self-capacitance A reference value is different, then the corresponding self-capacitance a reference value of i-th of capacitance detection unit is only updated, by the self-capacitance detected Value if self-capacitance a reference value all same, then updates the self-capacitance a reference value as self-capacitance a reference value, by what is detected Self-capacitance value is used as self-capacitance a reference value.
Wherein, in first time calculating process, the initial mutual capacitance a reference value Base1 of use and initial self-capacitance a reference value Base2 It can be built in advance in EEPROM, the mutual capacitance value sampled after upper electricity during no liquid can also be set as initial mutual capacitance The self-capacitance value sampled when a reference value Base1, no liquid is set as initial self-capacitance a reference value Base2.
It should be noted that the first predetermined threshold value Vref1 and the second predetermined threshold value Vref2 setting are relevant with sensitivity, if Vref1 and Vref2 sets too small, Rule of judgment (differ1<) and (differ2 Vref1>Vref2) it is easy to meet, then trickle ring Border change can also be changed by the judgement of mistake for liquid level, and if Vref1 and Vref2 sets excessive, Rule of judgment (differ1<) and (differ2 Vref1>Vref2) it is difficult to meet, then without output or output error liquid level when liquid level changes.
Also, the first predetermined threshold value Vref1 and the second predetermined threshold value Vref2 can be set according to actual test result, specifically, When capacitance detection unit is not covered with the liquid, the first mutual capacitance measured value and first of the capacitance detection unit can be measured respectively Self-capacitance measured value, and when the capacitance detection unit is covered with the liquid, second that the capacitance detection unit is measured respectively is mutual Measurement capacitance and the second self-capacitance measured value, so can be according between the first mutual capacitance measured value and the second mutual capacitance measured value Difference the first predetermined threshold value Vref1 is set, and can be according to the difference between the first self-capacitance measured value and the second self-capacitance measured value Value sets the second predetermined threshold value Vref2, if the difference between such as the first mutual capacitance measured value and the second mutual capacitance measured value is 20, then the first predetermined threshold value Vref1 can choose the value between 20-30；If the first self-capacitance measured value and the second self-capacitance are surveyed Difference between value is 100, then the second predetermined threshold value Vref2 can choose the value between 70-100.
Specifically, it is assumed that the mutual capacitance a reference value of multiple capacitance detection units be same mutual capacitance a reference value Base1, from Electric capacity a reference value is same self-capacitance a reference value Base2, as shown in figure 3, the liquid-level detecting method bag of the embodiment of the present invention Include following steps：
S100：Power-up initializing, reads default mutual capacitance a reference value Base1 and self-capacitance a reference value Base2.
S101：Start mutual capacitance mode, obtain the mutual capacitance value Rawdata1 (i) of i-th of capacitance detection unit, will be mutually electric Capacitance Rawdata1 (i) and mutual capacitance a reference value Base1 is compared to calculate i-th of first difference differ1 (i) =| Rawdata1 (i)-Base1 |, and preserve calculate i-th of first difference differ1 (i).
S102：Start self-capacitance pattern, the self-capacitance value of i-th of capacitance detection unit is obtained, by i-th of self-capacitance value value Rawdata2 (i) and self-capacitance a reference value Base2 be compared with calculate i-th second difference differ2 (i)=| Rawdata2 (i)-Base2 |, and preserve i-th of the second difference differ2 (i) calculated.
S103：Judge whether i-th first difference differ1 (i) are less than the first predetermined threshold value Vref1, and judge i-th the Whether two difference differ2 (i) are more than the second predetermined threshold value Vref2.
If it is, performing step S104；If it is not, then performing step S105.
S104：Judge that i-th of capacitance detection unit is not covered with the liquid, i=i+1, and return to step S101.
Wherein, in i=N, i is reset to 1.
S105：Judge that i-th of capacitance detection unit is not covered with the liquid, i is reset to 1.
S106：Update mutual capacitance a reference value Base1 and self-capacitance a reference value Base2, return to step S101.
The operation principle of the liquid level detection device of the embodiment of the present invention is described in detail with reference to Fig. 2 and Fig. 4.
As shown in Figure 4, it is assumed that mutual capacitance a reference value Base1=2000, the first predetermined threshold value during no liquid under mutual capacitance mode Vref1=50；Self-capacitance a reference value Base2=3000, the second predetermined threshold value Vref2=400 during no liquid under self-capacitance pattern.
As shown in Figures 2 and 4, t1-t2 moment, liquid level rises to capacitance detection unit C1 position, first opens mutual capacitance mould Formula, obtains capacitance detection unit C1 mutual capacitance value Rawdata1 (1), Rawdata1 (1)=1990, and then obtains the 1 the first difference differ1 (1), i.e. differ1 (1)=| 1990-2000 |=10；Self-capacitance pattern is then turned on, electric capacity is obtained Detection unit C1 self-capacitance value Rawdata2 (1), Rawdata2 (1)=3500, and then obtain the 1st the second difference Differ2 (1), i.e. differ2 (1)=| 3500-3000 |=500, again according to the 1st the first difference and the 1st the second difference Judge that capacitance detection unit C1 is covered to liquid, i.e., the 1st the first difference meets differ1 (1)=10<50, the 1st Second difference differ2 (1) meets differ2 (1)=500>400, liquid level Rule of judgment is met, can determine whether that liquid level is increased to Capacitance detection unit C1 position.
At t3~t4 moment, mutual capacitance mode is first opened, obtains capacitance detection unit C2 mutual capacitance value Rawdata1 (2), Rawdata1 (2)=1930, and then acquisition the 2nd the first difference differ1 (2), i.e. differ1 (2)=| 1930-2000 |=70； Self-capacitance pattern is then turned on, capacitance detection unit C2 self-capacitance value Rawdata2 (2), Rawdata2 (2)=3100 is obtained, And then acquisition the 2nd the second difference differ2 (2), i.e. differ2 (2)=| 3100-3000 |=100, again according to the 2nd First difference and the 2nd the second difference judge that capacitance detection unit C2 is not covered with the liquid, i.e. differ1 (2)=70>50, Differ2 (2)=100<400, liquid level Rule of judgment is unsatisfactory for, judges that liquid level is not raised to capacitance detection unit C2 position. So, with reference to the judgement at t1-t2 moment and t3~t4 moment, the liquid level information recognized is that capacitance detection unit C1 is corresponding Liquid level gear.
Then, at the t5 moment, because judging that capacitance detection unit C2 is not covered with the liquid, mutual capacitance a reference value is updated Base1=1930, self-capacitance a reference value Base2=3100.
Thus, the liquid detecting method of the embodiment of the present invention combines the situation of change of mutual capacitance value and self-capacitance value to detect liquid level, Interference of the environment to level sensing can be prevented effectively from, the degree of accuracy of level sensing is improved.
In addition, it should be noted that, appoint from the capacitance detection unit at the top of testing container or from the middle of testing container The capacitance detection unit of meaning position proceeds by the implementation described by the specific implementation and above-described embodiment of detection judgement It is similar, no longer it is described in detail here.
To sum up, the liquid-level detecting method proposed according to embodiments of the present invention, detects the self-capacitance of capacitance present detection unit respectively Value and mutual capacitance value, then according to the relation between the self-capacitance value of capacitance present detection unit and corresponding self-capacitance a reference value Relation between the mutual capacitance value of capacitance present detection unit and corresponding mutual capacitance a reference value determines whether that liquid covering is worked as Preceding capacitance detection unit, if it is determined that there is liquid to cover capacitance present detection unit, then detection is examined with capacitance present respectively upwards The self-capacitance value and mutual capacitance value of the adjacent capacitance detection unit of unit are surveyed, until judging no liquid covering capacitance detection unit When, liquid level information is obtained according to the previous capacitance detection unit that corresponding capacitance detection unit when being covered with no liquid is adjacent. Thus, this method combines the situation of change of mutual capacitance value and self-capacitance value to detect liquid level, can be prevented effectively from environment and liquid level is examined The interference of survey, improves the degree of accuracy of level sensing.Also, this method need not increase extra external devices such as temperature Sensor, circuit is simple, and algorithm is reliable.
Fig. 5 is the block diagram of liquid level detection device according to embodiments of the present invention.As shown in figure 5, liquid level detection device Including capacitive detection module, multiple capacitance detection units 10 and control module 20.
In the specific example of the present invention, as shown in Fig. 2 multiple capacitance detection units 10 are closely pasted with testing container 4 Close, such as by 3M glues, also, the rising that multiple capacitance detection units 10 can be according to liquid in testing container 4 Direction is arranged in order, such as multiple capacitance detection units 10 can be arranged in order in the vertical direction of the bottom of testing container 4, The quantity of the capacitance detection unit covered by liquid level will change with the change of liquid level.It should be appreciated that multiple electric capacity inspections The set-up mode for surveying unit and testing container is not limited to laminating type.
Also, self-capacitance value when self-capacitance value when capacitance detection unit is covered by liquid level by liquid level with not covered is inconsistent, Say, the self-capacitance value of capacitance detection unit will change when liquid level rises or falls.Moreover, when environment changes, The self-capacitance and mutual capacitance value of capacitance detection unit can change, therefore control module 20 is by monitoring capacitance detection unit Self-capacitance and mutual capacitance value can accurately identify liquid level information.
As shown in figure 5, control module 20 is connected with multiple capacitance detection units 10, control module 20 is used for detection respectively and worked as The self-capacitance value and mutual capacitance value of preceding capacitance detection unit, and self-capacitance value according to capacitance present detection unit with it is corresponding from Relation between the mutual capacitance value of relation and capacitance present detection unit between electric capacity a reference value and corresponding mutual capacitance a reference value Determine whether that liquid covers capacitance present detection unit, if it is determined that there is liquid to cover capacitance present detection unit, control mould Block 20 then detects the self-capacitance value and mutual capacitance value of the capacitance detection unit adjacent with capacitance present detection unit respectively upwards, directly To when judging no liquid covering capacitance detection unit, before corresponding capacitance detection unit is adjacent when being covered according to no liquid One capacitance detection unit obtains liquid level information.
Further, according to one embodiment of present invention, if it is determined that covering capacitance present detection unit, control without liquid Molding block 20 then detects downwards self-capacitance value and the mutual capacitance of the capacitance detection unit adjacent with capacitance present detection unit respectively Value, until when judging to have liquid covering capacitance detection unit, liquid is obtained according to corresponding capacitance detection unit when having liquid covering Position information.
It should be appreciated that when capacitance present detection unit is covered with the liquid, control module 20 judges that liquid is at least up to and worked as The location of preceding capacitance detection unit, and when capacitance present detection unit is not covered with the liquid, control module 20 judges not The location of capacitance present detection unit of rising.It should be noted that capacitance present detection unit can be in testing container Bottom or top or middle optional position.
It should be noted that the ascent direction of liquid level is upward referred to, direction as shown by the arrows in Figure 2, in this way, upwards Detection is the capacitance detection unit above detection capacitance present detection unit.Correspondingly, downwards in as Fig. 2 shown in arrow Opposite direction, in this way, downwards detection be detection capacitance present detection unit below capacitance detection unit.
That is, control module 20 can first start mutual capacitance mode to detect capacitance present detection unit under mutual capacitance mode Mutual capacitance value, restart self-capacitance pattern with self-capacitance pattern detect electric circuit inspection capacitance present detection unit from electricity Capacitance.Also, it can be detected since any of multiple capacitance detection units 10 capacitance detection unit, if it is determined that there is liquid Capacitance present detection unit is covered, then detection is detected control module 20 with the adjacent capacitor above capacitance present detection unit respectively The self-capacitance value and mutual capacitance value of unit, until judging no liquid covering capacitance present detection unit；If it is determined that without liquid Body covers capacitance present detection unit, and control module 20 then with the adjacent capacitor below capacitance present detection unit examine respectively by detection The self-capacitance value and mutual capacitance value of unit are surveyed, until judging there is liquid to cover capacitance present detection unit.
Below by since with implementation of the present invention is described in detail exemplified by detection the immediate capacitance detection unit in testing container bottom The liquid-level detecting method of example.Specifically, control module 20 can be since with the immediate capacitance detection unit of container bottom successively Judge whether corresponding capacitance detection unit is covered with the liquid step by step upwards.Assuming that carrying out liquid level by N number of capacitance detection unit Detection, N number of capacitance detection unit be designated as successively from bottom to top C1, C2, C3 ..., CN, N is integer more than 1, When capacitance present detection unit is i-th of capacitance detection unit Ci, control module 20 can be according to i-th of capacitance detection unit Mutual capacitance value and self-capacitance value during Ci determine whether that liquid covers i-th of capacitance detection unit Ci, if it is determined that there is liquid I-th of capacitance detection unit Ci is covered, then illustrates the position residing for liquid at least rise/fall to i-th of capacitance detection unit Ci Put, control module 20 is further continued for timesharing detection i+1 capacitance detection unit C (i+1) mutual capacitance value and self-capacitance value, Now control module 20 determines whether liquid according to i+1 capacitance detection unit C (i+1) self-capacitance value and mutual capacitance value Body covering i+1 capacitance detection unit C (i+1), to judge liquid, whether rise/fall is to i+1 capacitance detecting list The location of first C (i+1).
So control module 20 detects self-capacitance value and mutual capacitance value and determines whether that liquid covers capacitance detection unit step by step, Once no liquid covering capacitance detection unit is judged, with regard to according to corresponding capacitance detection unit when detecting no liquid covering Adjacent previous capacitance detection unit obtains liquid level information, for example, the 1st is sentenced to i-th of capacitance detection unit is corresponding Disconnected result is to have liquid covering, and the corresponding judged result of i+1 capacitance detection unit covers for no liquid, control Module 20 using the corresponding liquid level information of i-th of capacitance detection unit as container current level information.
Specifically, control module 20 can be in the way of poll to multiple capacitance detection units 10 mutual capacitance value and self-capacitance Value is detected successively, often detects a self-capacitance value and mutual capacitance value, with regard to according to the self-capacitance value and mutual capacitance detected Value judges whether that detecting corresponding capacitance detection unit is covered with the liquid, when judging continuous N (N is positive integer) individual electricity Hold detection unit to be covered with the liquid, and the N+1 capacitance detection unit be when being covered with the liquid, control module 20 According to the corresponding liquid level gear output liquid level information of n-th capacitance detection unit.
It should be appreciated that one liquid level gear of each capacitance detection unit correspondence in multiple capacitance detection units 10, and each The corresponding liquid level gear of capacitance detection unit is preset in a program, as shown in Fig. 2 capacitance detection unit 10 can be for 6 i.e. C1, C2, C3, C4, C5 and C6,6 capacitance detection units 10 correspond to 6 liquid level gears, and 6 liquid levels respectively Gear is incremented by successively in order or successively decreases, for example, C1 correspondences liquid level 1, C2 correspondences liquid level 2, C3 correspondences liquid level 3, C4 Correspondence liquid level 4, C5 correspondence liquid levels 5 liquid level 6 corresponding with C6, and liquid level 1<Liquid level 2<Liquid level 3<Liquid level 4<Liquid level 5<Liquid Position 6.
It is to be further understood that the quantity and size of capacitance detection unit are adjustable, capacitance detection unit is more, and i.e. N is bigger, The liquid level gear that can be detected is more, and level sensing precision is higher.Also, capacitance detection unit area is bigger, electric capacity inspection The sensitivity for surveying unit is higher.
Thus, the liquid level detection device of the embodiment of the present invention, combines the situation of change of mutual capacitance value and self-capacitance value to detect liquid Position, can be prevented effectively from interference of the environment such as temperature to level sensing, improve the degree of accuracy of level sensing, to volume production not Uniformity also has good compensating action.Also, the device need not increase extra external devices such as temperature sensor, Circuit is simple, and algorithm is reliable.
According to one embodiment of present invention, control module 20 is further configured for：Obtain the mutual electricity of capacitance present detection unit The first difference between capacitance and corresponding mutual capacitance a reference value is mutual capacitance variable quantity, and obtains capacitance present detection unit The second difference between self-capacitance value and corresponding self-capacitance a reference value is self-capacitance variable, if the first difference is less than first Predetermined threshold value and the second difference are more than the second predetermined threshold value, and control module 20 then judges have liquid to cover capacitance present detection singly Member.
Also, if the first difference is more than or equal to the first predetermined threshold value or the second difference is less than or equal to the second predetermined threshold value, control Module 20 then judges that no liquid covers the capacitance present detection unit, and corresponding mutual capacitance a reference value is updated to currently The mutual capacitance value of capacitance detection unit, and corresponding self-capacitance a reference value is updated to the self-capacitance of capacitance present detection unit Value, is used for level sensing next time by the mutual capacitance a reference value and self-capacitance a reference value after renewal.
If that is, the mutual capacitance variable quantity of capacitance present detection unit is less than the first predetermined threshold value and the capacitance detecting list The self-capacitance variable of member is more than the second predetermined threshold value, then illustrates the self-capacitance value and mutual capacitance value of capacitance present detection unit Change is caused by liquid change, and control module 20 judges that capacitance present detection unit detects liquid, and calculates current electricity Hold the mutual capacitance variable quantity and self-capacitance variable of the adjacent capacitor detection unit above detection unit to judge the capacitance detecting list Whether member is covered with the liquid, and such cycle criterion is not covered with the liquid until determining capacitance detection unit.And determining electricity When appearance detection unit is not covered with the liquid, corresponding capacitance detection unit is adjacent when control module 20 is not according to being covered with the liquid Previous capacitance detection unit obtain liquid level information, and according to the mutual electricity of corresponding capacitance detection unit when being not detected by liquid Capacitance and self-capacitance value update corresponding mutual capacitance a reference value and self-capacitance a reference value respectively, by the mutual capacitance benchmark after renewal Value and self-capacitance a reference value are used for level sensing next time.
It should be noted that the corresponding mutual capacitance a reference value of multiple capacitance detection units 10 may be configured as same mutual capacitance benchmark Value, the corresponding self-capacitance a reference value of multiple capacitance detection units 10 may be alternatively provided as same self-capacitance a reference value, so that Register space is relatively small；The corresponding mutual capacitance a reference value of multiple capacitance detection units 10 may be configured as mutually different mutual electricity Hold a reference value, the corresponding self-capacitance a reference value of multiple capacitance detection units 10 may be configured as mutually different self-capacitance a reference value, So that accuracy in detection is of a relatively high.
It should be noted that, the facilities of mutual capacitance a reference value and self-capacitance a reference value can be set according to the actual requirements.Also, The mutual capacitance value of each capacitance detection unit is chosen when the initial set value of mutual capacitance a reference value can be according to no liquid, self-capacitance base The self-capacitance value of each capacitance detection unit is chosen when the initial set value of quasi- value can be according to no liquid.
Specifically, the device of the embodiment of the present invention carries out level sensing, N number of capacitance detecting using N number of capacitance detection unit Unit is followed successively by the 1st capacitance detection unit, the 2nd capacitance detection unit, the 3rd capacitance detecting from container bottom up Unit ..., n-th capacitance detection unit.Control module 20 can specifically use following flow：Control module 20 is first Start mutual capacitance mode, obtain the mutual capacitance value of i-th (i can be 1 any integer value into N) individual capacitance detection unit Rawdata1 (i), by the mutual capacitance value Rawdata1 (i) of i-th of capacitance detection unit and corresponding mutual capacitance a reference value Base1 (i) be compared with calculate i-th first difference differ1 (i)=| Rawdata1 (i)-Base1 (i) |, and preserve meter Calculate i-th of first difference differ1 (i).
Secondly, control module 20 restarts self-capacitance pattern, obtains the self-capacitance value Rawdata2 of i-th of capacitance detection unit (i), by the self-capacitance value Rawdata2 (i) of i-th of capacitance detection unit and corresponding self-capacitance a reference value Base2 (i) Be compared with calculate i-th second difference differ2 (i)=| Rawdata2 (i)-Base2 (i) |, and preserve and calculate I-th of second difference differ2 (i).
Again, control module 20 judges whether i-th of capacitance detection unit is covered with the liquid, if i-th of first difference differ1 (i) it is differ1 (i) less than the first predetermined threshold value Vref1<Vref1, and i-th second difference differ2 (i) are more than the Two predetermined threshold values are differ2 (i)>Vref2, then judge that i-th of capacitance detection unit is covered with the liquid.Otherwise, if i-th Individual first difference differ1 (i) is differ1 (i) >=Vref1 more than or equal to the first predetermined threshold value Vref1, or i-th Two difference differ2 (i) are differ2 (i)≤Vref2 more than the second predetermined threshold value, then judge i-th of capacitance detection unit not It is covered with the liquid.
Also, after judging that i-th of capacitance detection unit is covered with the liquid, control module 20 according to above the step of continue Detect the self-capacitance value and mutual capacitance value of i+1 capacitance detection unit and judged.And judging i-th of capacitance detecting list After member is not covered with the liquid, the working as container using the corresponding liquid level gear of the i-th -1 capacitance detection unit of control module 20 Preceding liquid level, and mutual capacitance a reference value and self-capacitance a reference value are updated, wherein, if mutual capacitance a reference value is different, only The corresponding mutual capacitance a reference value of i-th of capacitance detection unit is updated, using the mutual capacitance value detected as mutual capacitance a reference value, And if mutual capacitance a reference value all same, then the mutual capacitance a reference value is updated, it regard the mutual capacitance value detected as mutual capacitance base Quasi- value；Similarly, if self-capacitance a reference value is different, the corresponding self-capacitance base of i-th of capacitance detection unit is only updated Quasi- value, using the self-capacitance value detected as self-capacitance a reference value, and if self-capacitance a reference value all same, then updating should be certainly Electric capacity a reference value, regard the self-capacitance value detected as self-capacitance a reference value.
Wherein, in first time calculating process, the initial mutual capacitance a reference value Base1 of use and initial self-capacitance a reference value Base2 It can be built in advance in EEPROM, the mutual capacitance value sampled after upper electricity during no liquid can also be set as initial mutual capacitance The self-capacitance value sampled when a reference value Base1, no liquid is set as initial self-capacitance a reference value Base2.
It should be noted that the first predetermined threshold value Vref1 and the second predetermined threshold value Vref2 setting are relevant with sensitivity, if Vref1 and Vref2 sets too small, Rule of judgment (differ1<) and (differ2 Vref1>Vref2) it is easy to meet, then trickle ring Border change can also be changed by the judgement of mistake for liquid level, and if Vref1 and Vref2 sets excessive, Rule of judgment (differ1<) and (differ2 Vref1>Vref2) it is difficult to meet, then without output or output error liquid level when liquid level changes.
Also, the first predetermined threshold value Vref1 and the second predetermined threshold value Vref2 can be set according to actual test result, specifically, When capacitance detection unit is not covered with the liquid, the first mutual capacitance measured value and first of the capacitance detection unit can be measured respectively Self-capacitance measured value, and when the capacitance detection unit is covered with the liquid, second that the capacitance detection unit is measured respectively is mutual Measurement capacitance and the second self-capacitance measured value, so can be according between the first mutual capacitance measured value and the second mutual capacitance measured value Difference the first predetermined threshold value Vref1 is set, and can be according to the difference between the first self-capacitance measured value and the second self-capacitance measured value Value sets the second predetermined threshold value Vref2, if the difference between such as the first mutual capacitance measured value and the second mutual capacitance measured value is 20, then the first predetermined threshold value Vref1 can choose the value between 20-30；If the first self-capacitance measured value and the second self-capacitance are surveyed Difference between value is 100, then the second predetermined threshold value Vref2 can choose the value between 70-100.
According to one embodiment of present invention, control module 20 is further configured for：Will be current in multiple capacitance detection units Other capacitance detection units are grounded by capacitance detection unit as excitation end, to detect the electricity certainly of capacitance present detection unit Capacitance, and using each capacitance detection unit in multiple capacitance detection units as excitation end, to detect that capacitance present is detected The mutual capacitance value of unit.
That is, as shown in fig. 7, as excitation end, other capacitance detection units are used as ground in capacitance present detection unit In the case of, the electric capacity detected may be defined as self-capacitance, when so only applying pumping signal to capacitance present detection unit, Control module 20 is by detecting that the electric capacity of capacitance present detection unit can obtain the self-capacitance of capacitance present detection unit；Many Individual capacitance detection unit is used as excitation end simultaneously in the case that, the capacitive effect between any two capacitance detection unit is eliminated Electric capacity be defined as mutual capacitance, so to each capacitance detection unit apply pumping signal when, control module 20 by detection work as The electric capacity of preceding capacitance detection unit can obtain the mutual capacitance of capacitance present detection unit.
According to one embodiment of present invention, as shown in Figure 2 and Figure 6, multiple capacitance detection units 10 may be provided at circuit board On 2, i.e., speech can print multiple capacitance detection units 10 on circuit board 2, and circuit board 2 is connected to control mould by winding displacement 1 Block 20.Wherein, winding displacement 1 comprising power supply, capacitive detection module wire.
Or, according to another embodiment of the invention, multiple capacitance detection units 10 may be provided at together with control module 20 On one circuit board 2.Specifically, can be with when control module 20 is from hardware circuit farther out or when capacitance detection unit is a lot Multiple capacitance detection units 10 and control module 20 are both placed on circuit board 2.
In addition, it should be noted that, appoint from the capacitance detection unit at the top of testing container or from the middle of testing container The capacitance detection unit of meaning position proceeds by the implementation described by the specific implementation and above-described embodiment of detection judgement It is similar, no longer it is described in detail here.
To sum up, the liquid level detection device proposed according to embodiments of the present invention, control module detects capacitance present detection unit respectively Self-capacitance value and mutual capacitance value, then according to the self-capacitance value of capacitance present detection unit and corresponding self-capacitance a reference value it Between relation and the mutual capacitance value of capacitance present detection unit determine whether liquid with the relation between corresponding mutual capacitance a reference value Body covers the capacitance present detection unit, if it is determined that having liquid to cover the capacitance present detection unit, then upwards respectively The self-capacitance value and mutual capacitance value of the detection capacitance detection unit adjacent with capacitance present detection unit, until judging no liquid When covering capacitance detection unit, corresponding capacitance detection unit adjacent previous capacitance detecting list when being covered according to no liquid Member obtains liquid level information.Thus, the situation of change of the device joint mutual capacitance and self-capacitance detects liquid level, can be prevented effectively from Interference of the environment to level sensing, improves the degree of accuracy of level sensing.Also, the device need not increase extra outside Device such as temperature sensor, circuit is simple, and algorithm is reliable.
In the description of the invention, it is to be understood that term " " center ", " longitudinal direction ", " transverse direction ", " length ", " width ", " thickness ", " on ", " under ", "front", "rear", "left", "right", " vertical ", " level ", " top ", " bottom " " interior ", " outer ", The orientation or position relationship of the instruction such as " clockwise ", " counterclockwise ", " axial direction ", " radial direction ", " circumference " are based on shown in the drawings Orientation or position relationship, are for only for ease of the description present invention and simplify description, rather than indicate or imply signified device or Element must have specific orientation, with specific azimuth configuration and operation, therefore be not considered as limiting the invention.
In addition, term " first ", " second " be only used for describe purpose, and it is not intended that indicate or imply relative importance or The implicit quantity for indicating indicated technical characteristic.Thus, " first " is defined, the feature of " second " can be expressed or hidden Include at least one this feature containing ground.In the description of the invention, " multiple " are meant that at least two, such as two, three It is individual etc., unless otherwise specifically defined.
In the present invention, unless otherwise clearly defined and limited, the art such as term " installation ", " connected ", " connection ", " fixation " Language should be interpreted broadly, for example, it may be fixedly connected or be detachably connected, or integrally；Can be machinery Connection or electrical connection；Can be joined directly together, can also be indirectly connected to by intermediary, can be two members The interaction relationship of connection or two elements inside part, unless otherwise clear and definite restriction.For the ordinary skill of this area For personnel, the concrete meaning of above-mentioned term in the present invention can be understood as the case may be.
In the present invention, unless otherwise clearly defined and limited, fisrt feature can be "above" or "below" second feature First and second features are directly contacted, or the first and second features pass through intermediary mediate contact.Moreover, first is special Levy second feature " on ", " top " and " above " but fisrt feature directly over second feature or oblique upper, or only Only represent that fisrt feature level height is higher than second feature.Fisrt feature second feature " under ", " lower section " and " below " Can be fisrt feature immediately below second feature or obliquely downward, or be merely representative of fisrt feature level height less than second Feature.
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specific example ", Or the description of " some examples " etc. means to combine specific features, structure, material or the feature bag that the embodiment or example are described It is contained at least one embodiment of the present invention or example.In this manual, to the schematic representation of above-mentioned term necessarily It is directed to identical embodiment or example.Moreover, specific features, structure, material or the feature of description can be any Combined in an appropriate manner in individual or multiple embodiments or example.In addition, in the case of not conflicting, the skill of this area Not be the same as Example or the feature of example and non-be the same as Example or example described in this specification can be combined by art personnel And combination.
Although embodiments of the invention have been shown and described above, it is to be understood that above-described embodiment be it is exemplary, It is not considered as limiting the invention, one of ordinary skill in the art within the scope of the invention can be to above-described embodiment It is changed, changes, replacing and modification.

Claims (13)

1. a kind of liquid-level detecting method, it is characterised in that comprise the following steps：
The self-capacitance value and mutual capacitance value of capacitance present detection unit are detected respectively；
According to the relation between the self-capacitance value of the capacitance present detection unit and corresponding self-capacitance a reference value and described current Relation between the mutual capacitance value of capacitance detection unit and corresponding mutual capacitance a reference value determines whether that liquid covering is described current Capacitance detection unit；
If it is determined that there is liquid to cover the capacitance present detection unit, then detection detects single with the capacitance present respectively upwards The self-capacitance value and mutual capacitance value of the adjacent capacitance detection unit of member, until when judging no liquid covering capacitance detection unit, Liquid level information is obtained according to the previous capacitance detection unit that corresponding capacitance detection unit when being covered with no liquid is adjacent.
2. liquid-level detecting method according to claim 1, it is characterised in that if it is determined that covering described work as without liquid Preceding capacitance detection unit, then detect downwards the self-capacitance of the capacitance detection unit adjacent with the capacitance present detection unit respectively Value and mutual capacitance value, until when judging to have liquid covering capacitance detection unit, according to corresponding capacitance detecting when having liquid covering Unit obtains liquid level information.
3. liquid-level detecting method according to claim 1, it is characterised in that described to detect single according to the capacitance present Member self-capacitance value and corresponding self-capacitance a reference value between relation and the capacitance present detection unit mutual capacitance value with it is right Relation between the mutual capacitance a reference value answered determines whether that liquid covers the capacitance present detection unit, including：
Obtain the first difference between the mutual capacitance value of the capacitance present detection unit and corresponding mutual capacitance a reference value；
Obtain the second difference between the self-capacitance value of the capacitance present detection unit and corresponding self-capacitance a reference value；
If first difference is less than the first predetermined threshold value and second difference is more than the second predetermined threshold value, judgement has liquid Body covers the capacitance present detection unit.
4. liquid-level detecting method according to claim 3, it is characterised in that if first difference is more than or equal to institute State the first predetermined threshold value or second difference is less than or equal to second predetermined threshold value, then judge electric capacity before no liquid covering Detection unit, and corresponding mutual capacitance a reference value is updated to the mutual capacitance value of the capacitance present detection unit, and will be right The self-capacitance a reference value answered is updated to the self-capacitance value of the capacitance present detection unit, by the mutual capacitance a reference value after renewal It is used for level sensing next time with self-capacitance a reference value.
5. the liquid-level detecting method according to any one of claim 1-4, it is characterised in that pass through multiple capacitance detectings Unit progress level sensing, the self-capacitance value and mutual capacitance value of the capacitance present detection unit of detection respectively, including：
It regard the capacitance present detection unit in the multiple capacitance detection unit as excitation end, and other capacitance detecting lists Member ground connection, to detect the self-capacitance value of the capacitance present detection unit；
Using each capacitance detection unit in the multiple capacitance detection unit as excitation end, to detect that the capacitance present is examined Survey the mutual capacitance value of unit.
6. a kind of liquid level detection device, it is characterised in that including：
Multiple capacitance detection units；
Control module, the control module is connected with the multiple capacitance detection unit, and the control module is used to detect respectively The self-capacitance value and mutual capacitance value of capacitance present detection unit, and self-capacitance value according to the capacitance present detection unit with it is right The mutual capacitance value and corresponding mutual capacitance a reference value of relation and the capacitance present detection unit between the self-capacitance a reference value answered Between relation determine whether that liquid covers the capacitance present detection unit, if it is determined that there is liquid to cover the current electricity Hold detection unit, the control module then detects the capacitance detection unit adjacent with the capacitance present detection unit respectively upwards Self-capacitance value and mutual capacitance value, until when judging that no liquid covers capacitance detection unit, during according to being covered with no liquid The adjacent previous capacitance detection unit of corresponding capacitance detection unit obtains liquid level information.
7. liquid level detection device according to claim 6, it is characterised in that if it is determined that covering described work as without liquid Preceding capacitance detection unit, the control module then detects downwards the capacitance detecting adjacent with the capacitance present detection unit respectively The self-capacitance value and mutual capacitance value of unit, until when judging to have the liquid cover capacitance detection unit, according to when having a liquid covering pairs The capacitance detection unit answered obtains liquid level information.
8. liquid level detection device according to claim 6, it is characterised in that the control module is further configured for：
The first difference between the mutual capacitance value of the capacitance present detection unit and corresponding mutual capacitance a reference value is obtained, and is obtained The second difference between the self-capacitance value of the capacitance present detection unit and corresponding self-capacitance a reference value is taken, if described One difference is less than the first predetermined threshold value and second difference is more than the second predetermined threshold value, and the control module then judges there is liquid Cover the capacitance present detection unit.
9. liquid level detection device according to claim 8, it is characterised in that if first difference is more than or equal to institute State the first predetermined threshold value or second difference is less than or equal to second predetermined threshold value, the control module then judges no liquid Capacitance detection unit before body covering, and corresponding mutual capacitance a reference value is updated to the mutual capacitance of the capacitance present detection unit It is worth, and corresponding self-capacitance a reference value is updated to the self-capacitance value of the capacitance present detection unit, after renewal Mutual capacitance a reference value and self-capacitance a reference value level sensing next time.
10. the liquid level detection device according to any one of claim 6-9, it is characterised in that the control module is entered One step is configured to：
It regard the capacitance present detection unit in the multiple capacitance detection unit as excitation end, and other capacitance detecting lists Member ground connection, to detect the self-capacitance value of the capacitance present detection unit, and will be each in the multiple capacitance detection unit Capacitance detection unit is as excitation end, to detect the mutual capacitance value of the capacitance present detection unit.
11. liquid level detection device according to claim 6, it is characterised in that the multiple capacitance detection unit is with treating Xylometer is fitted.
12. liquid level detection device according to claim 11, it is characterised in that the multiple capacitance detection unit according to Ascent direction of the liquid in the testing container is arranged in order.
13. the liquid level detection device according to claim 11 or 12, it is characterised in that the capacitance present detection is single Member is in the bottom or top of the testing container or middle optional position.
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