CN115931985A - Atomization amount measuring device based on capacitor, atomizer and atomization control method - Google Patents
Atomization amount measuring device based on capacitor, atomizer and atomization control method Download PDFInfo
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Abstract
The invention relates to the field of atomization control, in particular to an atomization quantity measuring device based on a capacitor, an atomizer and an atomization control method. According to the invention, a plurality of liquid detection point groups are arranged on the structure of the atomized medicine cabin, each liquid detection point group has different capacitance when liquid exists or does not exist, the variation of the capacitance of each liquid detection point group along with the frequency can be calculated according to the difference of the position capacitance of each liquid detection point group, the main controller switches each liquid detection point group to the capacitance frequency conversion circuit at regular time for signal output, and the main controller continuously acquires the frequency variation of each liquid detection point group to calculate the atomization amount in the working time of the atomizer, so that an accurate atomization amount value is obtained, and the atomizer can be conveniently adjusted.
Description
Technical Field
The invention relates to the field of atomization control, in particular to an atomization quantity measuring device based on a capacitor, an atomizer and an atomization control method.
Background
In the prior stage, the traditional Chinese medicine ophthalmology therapeutic apparatus adopts piezoelectric ceramic micro-grid atomization to decompose the purified traditional Chinese medicine into tiny fog particles so as to improve the absorption efficiency of the medicine through cornea and mucosa, accelerate the promotion of eye metabolism and effectively improve the anoxic state of eye tissues and blood circulation. At present, the commonly used micro-grid atomizing sheet causes piezoelectric ceramic high-frequency vibration by applying a high-frequency voltage signal on piezoelectric ceramic to drive a metal sheet to vibrate, and liquid generates micron-level particles to generate atomization through thousands of micropores in the center of the metal sheet under the action of the high-frequency vibration.
However, due to the design and manufacturing process of the driving circuit and the atomizing sheet, the atomizing sheet can generate different and equal atomizing quantities under the same driving frequency.
If the atomization amount is unstable, the cornea is unevenly absorbed, so that the micro-grid atomization sheet needs to be controlled to uniformly administer the micro-grid atomization sheet to achieve the optimal effect of treating eye diseases. Therefore, the present invention provides an atomization amount measuring device, an atomizer and an atomization control method based on a capacitor, so as to overcome the above problems.
Disclosure of Invention
The invention aims to solve the problem that the atomization amount of an atomizer fluctuates under the same driving frequency in the prior art, and provides an atomization amount measuring device based on a capacitor, the atomizer and an atomization control method.
In order to achieve the above purpose, the invention provides the following technical scheme:
a capacitance-based atomization quantity measuring device comprises a capacitance group liquid measuring device, a capacitance frequency conversion circuit, a main controller and an atomized medicine bin;
the capacitor bank liquid measuring device is used for collecting the capacitance of the atomized medicine bin and sending the capacitance to the capacitor frequency conversion circuit; the capacitance group liquid measuring device comprises a plurality of liquid detection groups which are connected in parallel, and the liquid detection groups are uniformly arranged on the range scale of the atomized medicine bin;
the capacitance frequency conversion circuit is used for converting the capacitance into a corresponding square wave signal and sending the square wave signal into the main controller;
and the main controller is used for calculating the volume of the liquid in the atomized medicine bin and the atomized amount according to the square wave signal. According to the invention, a plurality of liquid detection point groups are arranged on the structure of the atomized medicine cabin, each liquid detection point group has different capacitance when liquid exists or does not exist, the variation of the capacitance of each liquid detection point group along with the frequency can be calculated according to the difference of the position capacitance of each liquid detection point group, the main controller switches each liquid detection point group to the capacitance frequency conversion circuit at regular time for signal output, and the main controller continuously acquires the frequency variation of each liquid detection point group to calculate the atomization amount in the working time of the atomizer, so that an accurate atomization amount value is obtained, and the atomizer can be conveniently adjusted.
As a preferable scheme of the invention, the liquid detection group comprises an electronic change-over switch and two probes; two ends of the electronic change-over switch are respectively and electrically connected with the two probes; the distance between the two probes is a preset value, and the connecting line is parallel to the horizontal plane.
As a preferred aspect of the present invention, the capacitance frequency conversion circuit includes a timer chip, a capacitance matching resistor, a resistor RB, and a resistor RC;
the first end of the capacitor matching resistor is connected with a +5V power supply; the DISCH interface of the timer chip is electrically connected with the second end of the capacitor matching resistor and the first end of the resistor RB respectively; the second end of the resistor RB is electrically connected with the capacitor bank liquid measuring device, the THRES interface of the timer chip and the TRIG interface respectively; the OUT interface of the timer chip is electrically connected with the resistor RC and the main controller in sequence;
the resistance value of the capacitor matching resistor is controlled according to the signal of the main controller, and the resistance value of the capacitor matching resistor is in positive correlation with the capacitance of the capacitor group liquid measuring device.
As a preferred embodiment of the present invention, a parameter expression of the square wave signal output by the capacitance-to-frequency conversion circuit is as follows:
high level period tH: tH = (RA + RB) C · ln2 ≈ 0.693 (RA + RB) C;
low level period tL: tL = (RB) C · ln2 ≈ 0.693 (RB) C;
square wave period T: t = tH + tL = ln2 (RA +2 RB) C ≈ 0.693 (RA +2 RB) C;
square wave frequency f: f is approximately equal to 1.44/(RA +2 RB) C;
the waveform duty ratio DT = tH/(tH + tL) =1- (RB/(RA +2 RB));
RA and RB are resistance values of the capacitor matching resistor and the resistor RB respectively; and C is the capacitance of the capacitance group liquid measuring device.
As a preferred scheme of the invention, the main controller is a Cortex-M3 inner core single chip microcomputer.
An atomizer comprises an atomization driving circuit and any one of the atomization amount measuring devices based on the capacitor;
the atomization driving circuit is electrically connected with the main controller and the atomized medicine bin respectively; and the atomization driving circuit is used for receiving the PWM signal sent by the main controller and adjusting the atomization efficiency according to the PWM signal. The invention monitors the real-time change of the liquid medicine through the atomization measuring device based on the capacitance, and adjusts the driving power of the atomization sheet through the atomization driving circuit according to the change result, thereby ensuring the consistency of the atomization amount.
As a preferred scheme of the present invention, the atomization driving circuit includes a digital-to-analog conversion unit, a voltage driving unit, a dual current source and a power management unit, which are electrically connected in sequence;
the input of the digital-to-analog conversion unit is a PWM signal, and the output end of the power supply management unit is electrically connected with the atomizing sheet;
the voltage driving unit comprises a chip U1, and the chip U1 is an LM321 chip;
specifically, the + IN port of the chip U1 is electrically connected with the digital-to-analog conversion unit;
the V-port of the chip U1 is grounded;
the-IN port of the chip U1 is electrically connected with the OUT port;
the V + port of the chip U1 is electrically connected with an external power supply and the first filter circuit respectively; the first filter circuit comprises a grounding capacitor C3;
and the OUT port of the chip U1 is sequentially electrically connected with the resistor R3 and the double current sources.
A method of controlling atomisation, the method being based on a atomiser as claimed in any one of the preceding claims, including the steps of:
s1: initializing the atomizer;
s2: collecting the capacitance in the atomized medicine bin and generating a square wave signal with corresponding frequency;
s3: and acquiring the real-time atomization amount of the atomizer according to the square wave signal, and adjusting the atomization amount of the atomizer to be maintained at a preset value through the atomization driving circuit.
The invention obtains the real-time atomization amount of the atomizer through the atomization amount measuring device, and then continuously controls the output proportion of the atomization driving circuit through the position type PID algorithm to achieve the purpose of constant atomization amount. The work of the atomizing plate is more stable, the working noise of the atomizing plate is reduced, the fog sprayed by the atomizing plate is softer, the particle size is smaller, and the atomizing plate is beneficial to absorption of human eyes.
As a preferred embodiment of the present invention, the real-time atomization amount = a range difference/a corresponding atomization time of the liquid detection group.
As a preferable aspect of the present invention, in S3, the main controller adjusts the atomization power of the atomizer by adjusting a PWM wave duty ratio input to the atomization driving circuit.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, a plurality of liquid detection point groups are arranged on the structure of the atomized medicine cabin, each liquid detection point group has different capacitance when liquid exists or does not exist, the variation of the capacitance of each liquid detection point group along with the frequency can be calculated according to the difference of the position capacitance of each liquid detection point group, the main controller switches each liquid detection point group to the capacitance frequency conversion circuit at regular time for signal output, and the main controller continuously acquires the frequency variation of each liquid detection point group to calculate the atomization amount in the working time of the atomizer, so that an accurate atomization amount value is obtained, and the atomizer can be conveniently adjusted.
2. The invention monitors the real-time change of the liquid medicine by the atomization measuring device based on the capacitance, and adjusts the driving power of the atomization sheet by the atomization driving circuit according to the change result, thereby ensuring the consistency of the atomization amount.
3. The invention obtains the real-time atomization amount of the atomizer through the atomization amount measuring device, and then continuously controls the output proportion of the atomization driving circuit through the position type PID algorithm to achieve the purpose of constant atomization amount. The work of the atomizing plate is more stable, the working noise of the atomizing plate is reduced, the fog sprayed by the atomizing plate is softer, the particle size is smaller, and the atomizing plate is beneficial to absorption of human eyes.
Drawings
Fig. 1 is a schematic structural diagram of a capacitance-based atomization amount measuring device according to embodiment 1 of the present invention;
fig. 2 is an electrical schematic diagram of a capacitance frequency conversion circuit in the capacitance-based atomization amount measuring apparatus according to embodiment 2 of the present invention;
fig. 3 is a schematic diagram illustrating a principle of a timer chip in the capacitance-based atomization amount measuring device according to embodiment 2 of the present invention;
FIG. 4 is a schematic view of an atomizer according to embodiment 3 of the present invention;
fig. 5 is an electrical schematic diagram of an atomization driving circuit in an atomizer according to embodiment 3 of the present invention;
fig. 6 is a schematic diagram illustrating a positional relationship between a liquid measuring device of a capacitor bank and an atomized medicine bin in an atomizer according to embodiment 4 of the present invention;
fig. 7 is an electrical schematic diagram of a capacitance-to-frequency conversion circuit in an atomizer according to embodiment 4 of the present invention;
fig. 8 is a schematic diagram of charge and discharge waveforms of a capacitance-to-frequency conversion circuit in an atomizer according to embodiment 4 of the present invention;
fig. 9 is a schematic flow chart of an atomization control method according to embodiment 5 of the present invention;
fig. 10 is a schematic flowchart of an atomization control method according to embodiment 6 of the present invention applied to a FreeRTOS operating system;
FIG. 11 is a schematic diagram of a localized PID algorithm in an atomization control method according to embodiment 6 of the present invention;
Detailed Description
The present invention will be described in further detail with reference to test examples and specific embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.
Example 1
As shown in fig. 1, a capacitance-based atomization amount measuring device includes a capacitance group liquid measuring device, a capacitance frequency conversion circuit, a main controller, and an atomized medicine bin.
The capacitor bank liquid measuring device is used for collecting the capacitance of the atomized medicine bin and sending the capacitance to the capacitor frequency conversion circuit; the capacitance group liquid measuring device comprises a plurality of liquid detection groups which are connected in parallel, and the liquid detection groups are uniformly arranged on the range scale of the atomized medicine bin.
The liquid detection group comprises an electronic change-over switch and two probes; two ends of the electronic change-over switch are respectively and electrically connected with the two probes; the distance between the two probes is a preset value, and the connecting line is parallel to the horizontal plane.
And the capacitance frequency conversion circuit is used for converting the capacitance into a corresponding square wave signal and sending the square wave signal into the main controller.
And the main controller is used for calculating the volume of the liquid in the atomized medicine bin and the atomized amount according to the square wave signal. In this embodiment, the main controller adopts a Cortex-M3 kernel single chip microcomputer.
Example 2
As shown in fig. 2, the present embodiment is different from embodiment 1 in that the capacitance-to-frequency conversion circuit includes a timer chip, a capacitance matching resistor, a resistor RB, and a resistor RC.
As shown in fig. 3, the timer chip (U1 in the figure) includes two voltage comparators CA and CB, a basic RS flip-flop, and a switching discharge tube Q1, and a reference voltage of the comparator is provided by a voltage divider formed by three resistors of 5.1K. Which make the reference levels of the non-inverting input terminal of the high level comparator CA and the inverting input terminal of the low level comparator CB to be 2/3VCC and 1/3VCC power supplies, respectively. The output ends of the comparators CA and CB control the state of the RS trigger and the switching state of the discharge tube Q1. When an input signal pin 6, namely high level, triggers input and exceeds a reference level 2/3VCC, the trigger is reset, an output pin 3 is low level, and meanwhile, a Q1 tube is conducted; when the level of the input signal pin 2 is lower than 1/3VCC, the trigger is set, the pin 3 outputs high level, and the Q1 tube is cut off. Therefore, in the present embodiment, by using the above characteristics of the timer, the capacitor C (i.e. the equivalent capacitor of the capacitor bank liquid measurement device) to be measured is connected to the pins 6 and 2 of the timer chip at the same time, and the other part of the charging resistor RA is connected between the pins 7 and 6 of the timer chip and the discharging resistor RB, and between the power supply and the pin 7 of the chip.
Specifically, the first end of the capacitor matching resistor is connected with a +5V power supply; the DISCH interface of the timer chip is electrically connected with the second end of the capacitor matching resistor and the first end of the resistor RB respectively; the second end of the resistor RB is electrically connected with the capacitor bank liquid measuring device, the THRES interface of the timer chip and the TRIG interface respectively; and the OUT interface of the timer chip is electrically connected with the resistor RC and the main controller in sequence.
The resistance value of the capacitor matching resistor is controlled according to the signal of the main controller, and the resistance value of the capacitor matching resistor is positively correlated with the capacitance of the capacitor group liquid measuring device.
The parameter expression of the square wave signal output by the capacitance frequency conversion circuit is as follows:
high level period tH: tH = (RA + RB) C · ln2 ≈ 0.693 (RA + RB) C;
low level period tL: tL = (RB) C · ln2 ≈ 0.693 (RB) C;
square wave period T: t = tH + tL = ln2 (RA +2 RB) C ≈ 0.693 (RA +2 RB) C;
square wave frequency f: f is approximately equal to 1.44/(RA +2 RB) C;
the waveform duty ratio DT = tH/(tH + tL) =1- (RB/(RA +2 RB));
RA and RB are resistance values of the capacitor matching resistor and the resistor RB respectively; and C is the capacitance of the capacitance group liquid measuring device.
Example 3
As shown in fig. 4, an atomizer includes an atomization driving circuit and a capacitance-based atomization amount measuring device according to any one of embodiment 1 or embodiment 2.
The atomization driving circuit is electrically connected with the main controller and the atomized medicine bin respectively; and the atomization driving circuit is used for receiving the PWM signal sent by the main controller and adjusting the atomization efficiency according to the PWM signal.
As shown in fig. 5, the atomization driving circuit includes a digital-to-analog conversion unit, a voltage driving unit, a dual current source, and a power management unit, which are electrically connected in sequence;
the digital-to-analog conversion unit performs two-stage RC low-pass filtering on the input PWM signal to simulate a digital-to-analog conversion circuit, so that a direct-current component is reserved, and a PWM ripple value is reduced.
Specifically, the digital-to-analog conversion unit comprises a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; a first end of the resistor R1 is electrically connected with the input port, and a second end of the resistor R1 is electrically connected with the capacitor C1 and then grounded; a first end of the resistor R2 is electrically connected to a second end of the resistor R1, and second ends of the resistor R2 and the capacitor C2 are electrically connected to the voltage driving unit and the first end of the capacitor C2, respectively; the second terminal of the capacitor C2 is grounded.
The PWM signals after the two-stage RC low-pass filtering improve the driving capability through a chip U1 to form a voltage driver, and voltage is provided for the double current sources. Specifically, the voltage driving unit comprises a chip U1, and the chip U1 is an LM321 chip; and the + IN port of the chip U1 is electrically connected with the digital-to-analog conversion unit. The V-port of the chip U1 is grounded. the-IN port and the OUT port of the chip U1 are electrically connected. The V + port of the chip U1 is electrically connected with an external power supply and a first filter circuit respectively; the first filter circuit comprises a grounding capacitor C3; and an external power supply electrically connected with the V + port of the chip U1 is 5.0V. And the OUT port of the chip U1 is electrically connected with the resistor R3 and the double current sources in sequence.
The dual current source is a BCV61 transistor.
Specifically, the power management unit includes a chip U3, an inductor L1, a resistor R4, a resistor R5, a capacitor C4, a capacitor C5, a capacitor C6, a capacitor C7, and a capacitor C8. The chip U3 is a TMI3252 power management chip. The GND port of the chip U3 is grounded; the LX port of the chip U3 is electrically connected with the second end of the capacitor C6; the IN port of the chip U3 is electrically connected with an external power supply, the capacitor C4, the capacitor C5 and the first end of the resistor R4 respectively; the BS port of the chip U3 is electrically connected with the capacitor C6, the inductor L1 and the atomization sheet in sequence; the EN port of the chip U3 is electrically connected with the second end of the resistor R4; the FB port of the chip U3 is electrically connected with the output end of the double current source and the second end of the resistor R5 respectively; second ends of the capacitor C4 and the capacitor C5 are grounded; a first end of the resistor R5 is electrically connected with a second end of the inductor L1; the capacitor C7 is connected in parallel with two ends of the resistor R5; and two ends of the capacitor C8 are respectively connected with the second end of the inductor L1 and the ground wire.
And an external power supply electrically connected with the IN port of the chip U1 is 7.4V.
The working principle of the atomization driving circuit is as follows:
1. and a two-stage RC low-pass filtering analog digital-to-analog conversion circuit is carried out on the PWM signal output by the main controller, so that the direct-current component is reserved, and the PWM ripple value is reduced.
2. The PWM signals after the two-stage RC low-pass filtering improve the driving capability through the LM321 to form a voltage driver, and voltage is provided for the double-current-source BCV 61.
3. By continuously changing the duty ratio of PWM, the voltage of the U1OUT pin (the input voltage is controlled by the main controller to be 0-3.3V, and the voltage is controlled by the operational amplifier) is changed, and the current of the pin '1' of the primary current source is further changed, namely the current of the pin '2' with the size of 1:1 correspondingly output by the double-current-source BCV61 is measured. And finally, changing the voltage of an output end in a stepless change range from 0 to 5V by changing the size of a feedback signal of the DC-DC switch chip. I.e. (being the DC-DC power supply chip TMI3252-FB pin voltage). The output voltage of the DC-DC switch chip directly provides a power supply voltage between 0V and 5V for driving the atomizing plate, so that the aim of changing the atomizing power is fulfilled.
Example 4
This embodiment is an implementation manner of embodiment 4, and the liquid measuring device of the capacitor bank in the atomizer of this embodiment includes 4 liquid detection banks.
The capacitor bank liquid measuring device is arranged on the atomized medicine bin, the distance between the left detection point and the right detection point is 20mm, the diameter of each probe is 1mm, the left detection point is used for signal input, the right detection point is used for signal output, and the 4 groups of detection points are switched into the capacitor frequency conversion circuit in a time-sharing and grouping mode through the 4 groups of electronic conversion switches to perform signal conversion.
The schematic diagram of the capacitance frequency conversion circuit is shown in fig. 7, and the capacitance matching resistor RA is composed of capacitance matching resistors RA1, RA2, RA3 and RA4 and is connected to the 7 th pin of the U1 chip in a time-sharing manner according to the requirement through an electronic switch S1; the capacitor C is composed of capacitors CX1, CX2, CX3 and CX4 formed by 4 groups of contacts at the back of the medicine bin, and is connected to the No. 2 pin of the U1 chip in a time-sharing mode according to requirements through an electronic switch S2. In the figure, an SW-C signal is a single-path selection control signal of an electronic switch and is controlled by a main controller according to a logic algorithm, an F signal is a square wave signal output with different frequencies generated by accessing different capacitors, and the signal is directly sent to the main controller for data acquisition.
At this time, the capacitance frequency conversion circuit operates according to the following principle: the +5V power supply of the circuit charges a capacitor C through an RA resistor, a resistor selection switch S1, an RB resistor, an S2 capacitor selection switch and a circuit from the capacitor C to the ground (the capacitor C is a capacitor formed by 4 groups of capacitor detection points through liquid). The capacitor charging is increased according to an exponential law, when the capacitor C is charged to 2/3VCC, the high-level comparator CA in the U1 starts to act, the pin 3 of the U1 chip returns to low-level output from high level, the Q1 in the U1 chip starts to be conducted to discharge the capacitor C, and the discharge path is C capacitor-S2-RB resistor-chip pin 7 to discharge. When the voltage of the capacitor C is reduced to be less than 1/3VCC, the low-level comparator CB in the U1 starts to act to change the low level of the pin 3 of the output pin into the high level, the discharge tube Q1 is cut off, the power supply charges the capacitor C through RA-S1-RB-S2 again, then the process is repeated, and the square wave signal is continuously and periodically output at the pin 3 of the U1 chip. The charging and discharging waveform Uc and the output waveform Uo are shown in fig. 8.
Example 5
As shown in fig. 9, an atomization control method based on an atomizer as described in any one of the above includes the steps of:
s1: initializing the atomizer;
s2: collecting the capacitance in the atomized medicine bin and generating a square wave signal with corresponding frequency;
s3: and acquiring the real-time atomization amount of the atomizer according to the square wave signal, and adjusting the atomization amount of the atomizer to be maintained at a preset value through the atomization driving circuit.
The real-time atomization amount = the range difference/corresponding atomization time of the liquid detection group.
The main controller adjusts the atomization power of the atomizer by adjusting the duty ratio of the PWM wave input to the atomization driving circuit.
Example 6
This embodiment is a specific implementation manner of the method in embodiment 5, and in this embodiment, the liquid measuring device of the capacitor bank in the atomizer includes 4 liquid detection banks.
The method is implemented by a FreeRTOS operating system, the operating system can fully utilize CPU time resources, synchronous execution of multiple tasks is facilitated, collection of high-frequency data is not leaked, and real-time responsiveness of a program is high. As shown in fig. 10, in this embodiment, the three steps of the atomization control method are divided into 3 task systems, where the 1 st is that the system initialization task mainly includes initialization when the system enters a program, and the user key state is circularly monitored and then the corresponding program task is entered, and the priority level of the task is 1 (highest). The 2 nd task is a capacitance frequency acquisition task, mainly aiming at measuring the capacitance of 4 paths of liquid, and converting the capacitance into a corresponding frequency value, wherein the priority level of the task is 2. The 3 rd task is a capacitance judgment and result execution task, and the change of the liquid in the medicine bin is judged to execute a corresponding control task according to the frequency data acquired by the task 2, wherein the priority level of the task is 3. The 3 tasks are specifically as follows:
after a product in the 1 st task is connected with a DC7.4V lithium battery power supply, the whole system enters an initialization state, an initial value of an internal register of a main controller is mainly initialized, the system clock frequency is initialized to be 72MHZ according to an external crystal oscillator 8MHZ, all timer values are cleared to be in a 0 state, an atomization driving signal is turned off, proportion, integration, differentiation and cycle time variable values of a PID algorithm are initialized, and finally the main controller calls a FreeRTOS operating system to carry out a multi-thread task system to initialize the follow-up multi-task execution. Once the first task monitors that the reset key is pressed down, the program automatically identifies whether the key effectively starts atomization, after the key is effectively started, the main controller obtains the frequency corresponding to the current liquid capacity through the automatic capturing function of the timer, the frequency corresponding to the capacitance of the four groups of liquid probes is calculated according to the frequency formula f ≈ 1.44/(RA +2 RB) C, the liquid can be judged to be at the current structural capacity position, namely the position of an mL scale, and then the 1ms tick timer in the main controller is started to carry out time timing for 30 minutes and the atomization amount is mainly calculated according to the used time T 'QL =1mL liquid/atomization 1 mL'. And finally, informing the task 1 and the task 2 of starting formal data acquisition and data judgment by using mailbox information of an operating system and carrying out final logic control.
The 2 nd task mainly acquires capacitance data, 4 groups of liquid probes with a medicine bin arrangement rule are synchronously switched into a capacitance frequency conversion circuit through electronic switches S1 and S2 in turn according to sampling time, a hardware circuit outputs a square wave signal with a duty ratio DT = tH/(tH + tL) =1- (RB/(RA +2 RB)) from a U1 chip according to a formula f ≈ 1.44/(RA +2 RB) C and a matching resistor RA and a liquid capacitor C, the square wave signal with the frequency acquires a trigger internal timer by using a timer rising edge capturing function of a main controller and carries out uS accumulated timing, the capturing trigger is set as a falling edge function, the falling edge is set as the rising edge trigger again after being triggered, a complete waveform time can be calculated through the three procedures, and a frequency value corresponding to the capacity of the medicine bin in the time period can be calculated according to the formula f = 1/T. And respectively testing capacitance frequency values of the probe 1 position, the probe 2 position, the probe 3 position and the probe 4 position by using the program segments, storing the capacitance frequency values into a data cache table, and providing the capacitance frequency values for the task 3 for query and comparison.
And after the mailbox message of the task 1 is obtained, comparing the capacitance frequency of the liquid-free probe from the position of the No. 1-No. 4 probe, inquiring and comparing whether the capacitance frequency reaches the capacitance frequency value of the liquid-free probe at the moment or not according to a data cache table to adjust the atomization amount again, skipping a current logic execution program if the probe position at the moment is in a liquid-free state and the atomization amount adjustment is performed once, adjusting the atomization amount when the condition is met, and obtaining the used time T of the atomization amount QL =1mL of liquid/1 mL of atomization according to the used time T after the single liquid changes by 1 mL.
The position type PID algorithm is used to solve the PWM duty ratio required for driving the atomizing power according to the variation of the atomizing amount, and the principle is shown in fig. 11 and the following formula:
OUT＝(Kp*Ek)+(Kp*(T/Ti)∑Ek)+(Kp*(TD/T)(Ek-Ek_1))+OUT0
kp is a proportional coefficient; ek is the current deviation value; t is a PID calculation period; ti is the integration time; sigma Ek is historical deviation synthesis; TD is differential time; ek-Ek _1 is the most recent two deviations; OUT0 is a minimum output constant; OUT is a calculated output ratio value.
Repeated tests determine that the Kp coefficient is 30, the T period is 1000ms, the Ti time is 10000ms, the TD time is 100ms, the constant value of OUT0 is 1, and the difference value between the current atomization amount and the standard output amount can be obtained according to a formula OUT = (Kp × Ek) + (Kp × T/Ti) sigma Ek) + (Kp × TD/T) (Ek-Ek _ 1)) + OUT0 to obtain the change percentage, and the change percentage utilizes a PWM functional pin of the main controller to output a square wave signal with a corresponding duty ratio to the atomization power driving circuit to stabilize the atomization amount output.
And the PWM signal output by the main controller is subjected to two-stage RC low-pass filtering, so that a direct-current component is reserved, and the PWM ripple value is reduced. The PWM signals after the two-stage RC low-pass filtering improve the driving capability through the LM321 to form a voltage driver, and voltage is provided for the double-current-source BCV 61. By continuously changing the duty ratio of PWM, the voltage of the U1OUT pin (the input voltage is controlled by the main controller to be 0-3.3V, and the voltage is controlled by the operational amplifier) is changed, and the current of the pin '1' of the primary current source is further changed, namely the current of the pin '2' with the size of 1:1 correspondingly output by the double-current-source BCV61 is measured. And finally, changing the voltage of an output end in a stepless change range from 0 to 5V by changing the size of a feedback signal of the DC-DC switch chip. I.e. (being the DC-DC power supply chip TMI3252-FB pin voltage). The output voltage of the DC-DC switch chip directly provides a power supply voltage between 0V and 5V for driving the atomizing sheet, so that the aim of changing the atomizing power and the atomizing amount is fulfilled.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A capacitance-based atomization quantity measuring device is characterized by comprising a capacitance group liquid measuring device, a capacitance frequency conversion circuit, a main controller and an atomization medicine bin;
the capacitor bank liquid measuring device is used for collecting the capacitance of the atomized medicine bin and sending the capacitance to the capacitor frequency conversion circuit; the capacitance group liquid measuring device comprises a plurality of liquid detection groups which are connected in parallel, and the liquid detection groups are uniformly arranged on the range scale of the atomized medicine bin;
the capacitance frequency conversion circuit is used for converting the capacitance into a corresponding square wave signal and sending the square wave signal into the main controller;
and the main controller is used for calculating the liquid volume and the atomization amount in the atomized medicine bin according to the square wave signal.
2. A capacitance-based aerosol quantity measurement apparatus according to claim 1, wherein the liquid detection assembly includes an electronic transfer switch and two probes; two ends of the electronic change-over switch are respectively and electrically connected with the two probes; the distance between the two probes is a preset value, and the connecting line is parallel to the horizontal plane.
3. The capacitance-based aerosol quantity measuring device according to claim 1, wherein the capacitance frequency conversion circuit comprises a timer chip, a capacitance matching resistor, a resistor RB and a resistor RC;
the first end of the capacitor matching resistor is connected with a +5V power supply; the DISCH interface of the timer chip is electrically connected with the second end of the capacitor matching resistor and the first end of the resistor RB respectively; the second end of the resistor RB is electrically connected with the capacitor bank liquid measuring device, the THRES interface of the timer chip and the TRIG interface respectively; the OUT interface of the timer chip is electrically connected with the resistor RC and the main controller in sequence;
the resistance value of the capacitor matching resistor is controlled according to the signal of the main controller, and the resistance value of the capacitor matching resistor is in positive correlation with the capacitance of the capacitor group liquid measuring device.
4. The capacitance-based aerosol quantity measuring device according to claim 3, wherein the capacitance frequency conversion circuit outputs the square wave signal with the following parametric expression:
high level period t H ：t H ＝(RA+RB)C·ln2≈0.693(RA+RB)C；
Low level period t L ：t L ＝(RB)C·ln2≈0.693(RB)C；
Square wave period T: t = T H +t L ＝ln2(RA+2RB)C≈0.693(RA+2RB)C；
Square wave frequency f: f ≈ 1.44/(RA +2 RB) C;
waveform duty ratio DT = t H /(t H +t L )＝1-(RB/(RA+2RB))；
RA and RB are resistance values of the capacitor matching resistor and the resistor RB respectively; and C is the capacitance of the capacitance group liquid measuring device.
5. The capacitance-based atomization measuring device of claim 1, wherein the main controller is a Cortex-M3 kernel single chip microcomputer.
6. An atomizer comprising an atomization driving circuit and a capacitance-based atomization amount measuring device according to any one of claims 1 to 5;
the atomization driving circuit is electrically connected with the main controller and the atomized medicine bin respectively; and the atomization driving circuit is used for receiving the PWM signal sent by the main controller and adjusting the atomization efficiency according to the PWM signal.
7. The atomizer according to claim 6, wherein the atomization driving circuit comprises a digital-to-analog conversion unit, a voltage driving unit, a dual current source and a power management unit which are electrically connected in sequence;
the input of the digital-to-analog conversion unit is a PWM signal, and the output end of the power supply management unit is electrically connected with the atomizing sheet;
the voltage driving unit comprises a chip U1, and the chip U1 is an LM321 chip;
specifically, the + IN port of the chip U1 is electrically connected with the digital-to-analog conversion unit;
the V-port of the chip U1 is grounded;
the-IN port of the chip U1 is electrically connected with the OUT port;
the V + port of the chip U1 is electrically connected with an external power supply and the first filter circuit respectively; the first filter circuit comprises a grounding capacitor C3;
and the OUT port of the chip U1 is electrically connected with the resistor R3 and the double current sources in sequence.
8. A method for controlling atomization, which is based on the atomizer in claim 7, and comprises the following steps:
s1: initializing the atomizer;
s2: collecting the capacitance in the atomized medicine bin and generating square wave signals with corresponding frequency;
s3: and acquiring the real-time atomization amount of the atomizer according to the square wave signal, and adjusting the atomization amount of the atomizer to be maintained at a preset value through the atomization driving circuit.
9. The atomization control method of claim 8, wherein the real-time atomization amount = range difference between adjacent liquid detection sets/corresponding atomization time.
10. The atomization control method according to claim 8, wherein in S3, the main controller adjusts the atomization power of the atomizer by adjusting a PWM wave duty ratio input to the atomization driving circuit.
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| CN109620990A (en) * | 2018-12-26 | 2019-04-16 | 深圳飞安瑞科技股份有限公司 | A kind of ultrasonic wave fumigation device of constant spray amount |
| US20200209016A1 (en) * | 2018-12-31 | 2020-07-02 | Water Analytics, Inc. | Grease interceptor level analyzer |
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