CN110388966B - Airflow conversion detection circuit and device - Google Patents
Airflow conversion detection circuit and device Download PDFInfo
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- CN110388966B CN110388966B CN201910643870.3A CN201910643870A CN110388966B CN 110388966 B CN110388966 B CN 110388966B CN 201910643870 A CN201910643870 A CN 201910643870A CN 110388966 B CN110388966 B CN 110388966B
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- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
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Abstract
The invention discloses an airflow conversion detection circuit and a device, wherein the airflow conversion detection circuit comprises: the device comprises a detection chip and an airflow detection module for detecting airflow to obtain an airflow change signal; the first end of the detection chip is connected with the first end of the airflow detection module, the second end of the detection chip is connected with the second end of the airflow detection module, and the second end of the airflow detection module is grounded; the detection chip is used for adjusting the clock signal according to the airflow change signal detected by the airflow detection module after the airflow detection module is charged and discharged to generate the clock signal, and adjusting the output current according to the frequency change of the clock signal. The airflow conversion detection circuit can quantitatively detect the change of the airflow by detecting the output current, and can reduce the volume of the airflow conversion detection device by module integration so as to realize the detection of the airflow in a place with a narrow space range.
Description
Technical Field
The invention relates to the field of circuit electronics, in particular to an airflow conversion detection circuit and device.
Background
The sensor can convert the information to be detected into an electric signal or other forms for output according to a certain rule. In the prior art, the airflow sensing detector can only detect whether the airflow is enlarged or reduced, namely, the airflow sensing detector can only detect qualitatively, and the traditional airflow sensing detector adopts more electronic devices, so that the size is larger, and the airflow sensing detector is not suitable for places with dense equipment and narrow space.
Disclosure of Invention
The invention mainly aims to provide an airflow conversion detection circuit and an airflow conversion detection device, and aims to solve the problems that the existing airflow detector can only carry out qualitative detection and cannot be applied to places with dense equipment and narrow space.
In order to achieve the above object, the present invention provides an airflow transition detection circuit including: the device comprises a detection chip and an airflow detection module for detecting airflow to obtain an airflow change signal;
the first end of the detection chip is connected with the first end of the airflow detection module, the second end of the detection chip is connected with the second end of the airflow detection module, and the second end of the airflow detection module is grounded;
the detection chip is used for adjusting the clock signal according to the airflow change signal detected by the airflow detection module after the airflow detection module is charged and discharged to generate the clock signal, and adjusting the output current according to the frequency change of the clock signal.
Optionally, the detection chip includes: the device comprises a clock signal generating module, a periodic signal generating module, a clock frequency calculating module and a current adjusting module;
the first input end of the clock signal generation module is connected with the first end of the airflow detection module, the second input end of the clock signal generation module is connected with the second end of the airflow detection module, the output end of the clock signal generation module is connected with the first input end of the clock frequency calculation module, the output end of the periodic signal generation module is connected with the second input end of the clock frequency calculation module, and the output end of the clock frequency calculation module is connected with the current adjustment module;
the clock signal generation module is used for determining the frequency of a clock signal according to the airflow change signal and sending the clock signal of the frequency to the clock frequency calculation module;
the periodic signal generation module is used for outputting a periodic signal to the clock frequency calculation module;
the clock frequency calculation module is used for receiving the clock signal sent by the clock signal generation module and the periodic signal sent by the periodic signal generation module, and calculating the frequency variation of the clock signal in the period corresponding to the periodic signal so as to send the frequency variation to the current adjustment module;
and the current adjusting module is used for correspondingly adjusting the output current according to the frequency variation.
Optionally, the clock signal generation module includes a clock signal circuit;
the charging control end of the clock signal circuit is connected with the first end of the airflow detection module, the discharging control end of the clock signal circuit is connected with the second end of the airflow detection module, and the second end of the airflow detection module is grounded;
the clock signal circuit is used for correspondingly adjusting the clock signal output by the output end according to the airflow change signal detected by the airflow detection module after the airflow detection module is charged and discharged through the charging control end and the discharging control end so that the output end of the clock signal circuit outputs the clock signal with fixed frequency.
Optionally, the clock signal circuit includes a reference output circuit, a comparison circuit, a discharge circuit, and a clock buffer;
a first output end of the reference output circuit outputs a reference voltage, a second output end of the reference output circuit outputs a reference current, and the second output end of the reference output circuit is a charging control end of the clock signal circuit;
a first input end of the comparison circuit is connected with a first output end of the reference output circuit, and a second input end of the comparison circuit is connected with a second output end of the reference output circuit;
the first end of the clock buffer is connected with the output end of the comparison circuit, the second end of the clock buffer is the output end of the clock signal circuit, and the second end of the clock buffer outputs a clock signal;
the first end of the discharge circuit is connected with the second input end of the comparison circuit, the second end of the discharge circuit is the discharge control end of the clock signal circuit, and the controlled end of the discharge circuit is connected with the output end of the comparison circuit;
the comparison circuit is further used for controlling the discharge circuit to be turned off when the input voltage of the second input end of the comparison circuit is smaller than the reference voltage; and when the detection voltage is greater than the reference voltage, controlling the discharge circuit to be conducted.
Optionally, the airflow detection module comprises a pneumatic variable capacitor, and the capacitance value of the pneumatic variable capacitor changes along with the change of the airflow; when the capacitance value of the pneumatic variable capacitor is increased, the frequency of a clock signal output by the output end of the clock signal circuit is increased; when the capacitance value of the pneumatic variable capacitor becomes smaller, the frequency of the clock signal output by the output end of the clock signal circuit is reduced.
Optionally, the airflow transition detection circuit further comprises a controller, and the controller is connected with the reference output module;
the controller is further configured to control the second output terminal of the reference output module to output the reference current.
Optionally, the comparison circuit is a two-stage open-loop comparator.
Optionally, the periodic signal is a threshold signal output according to a preset period;
the clock frequency calculation module is further configured to determine, when receiving two adjacent threshold signals, frequencies of the two clock signals corresponding to time nodes receiving the two threshold signals, to respectively use the frequencies of the two clock signals as a first frequency and a second frequency, and send a frequency difference value between the first frequency and the second frequency to the current adjustment module, where the clock signal of the first frequency is a previous threshold signal in the two adjacent threshold signals;
the current adjusting module is further configured to correspondingly adjust the output current output by the output terminal according to the frequency difference.
Optionally, the clock frequency calculation module further includes a first latch and a second latch;
the clock frequency calculation module is further configured to store the first frequency and the second frequency in the first latch and the second latch, respectively, and calculate a difference between the first latch and the second latch to obtain the frequency difference.
Optionally, the current adjusting module is a PWM generator, and the PWM generator is configured to adjust a duty ratio of the output current according to the received frequency difference.
Further, to achieve the above object, the present invention also provides an airflow transition detection device including a housing and an airflow transition detection circuit provided in the housing, the airflow transition detection circuit being configured as the airflow transition detection circuit described above.
The airflow conversion detection circuit provided by the invention can generate a corresponding clock signal by charging and discharging the airflow detection module through the detection chip. When the airflow detection module detects that the airflow changes, the detection chip can adjust the frequency of the clock signal through the airflow change signal, and adjust the output current of the detection chip according to the amplitude of the frequency change of the clock signal when the frequency of the clock signal changes, so that the change of the airflow is converted into the change of the output current. By detecting the output current, the specific change condition of the air flow can be determined, namely, the qualitative detection and the quantitative detection are carried out on the change of the air flow. And the detection of the air current is carried out by adopting a module integration mode, and the volume of the air current conversion detection device can be reduced, so that the detection of the air current is realized in a narrow space range.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a block diagram of an embodiment of an airflow transition detection circuit according to the invention;
FIG. 2 is a schematic circuit diagram of a clock signal generating module of the air flow transition detecting circuit according to the present invention;
FIG. 3 is a schematic diagram of the circuit operation of the air flow transition detection circuit according to an embodiment of the present invention;
FIG. 4 is a schematic circuit diagram of a two-stage open-loop comparator;
fig. 5 is a schematic diagram of a corresponding relationship between a current duty ratio and an average current.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 1 | |
15 | |
| 10 | Clock |
151 | |
| 11 | |
16 | |
| 12 | |
20 | Periodic |
| 13 | |
30 | Clock |
| 131 | |
40 | |
| 14 | |
41 | |
| 141 | First switch tube |
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The invention provides an airflow conversion detection circuit which is applied to an airflow conversion detection device.
Referring to fig. 1, in an embodiment, the airflow transition detection circuit includes a detection chip 1 and an airflow detection module 15, and the airflow detection module 15 may detect an airflow to obtain an airflow variation signal. The first end of the detection chip 1 is connected with the first end of the airflow detection module 15, the second end of the detection chip 1 is connected with the second end of the airflow detection module 15, and the second end of the airflow detection module 15 is grounded. The output end of the detection chip 1 can output corresponding current. The detection chip 1 can perform cyclic charging and discharging on the airflow detection module 15, and a clock signal can be generated in the process that the detection chip 1 performs charging and discharging on the airflow detection module 15 once, so that the frequency of charging and discharging the airflow detection module 15 by the detection chip 1 is the frequency of the generated clock signal. When the airflow detecting module 15 detects that the airflow changes, a corresponding airflow change signal is generated, and the detecting chip 1 can adjust the frequency of the clock signal according to the airflow change signal. When the airflow changes, the detection chip 1 can also adjust the output current according to the frequency change of the clock signal.
In this embodiment, the detection chip 1 charges and discharges the airflow detection module 15, so as to generate a corresponding clock signal. When the airflow detecting module 15 detects that the airflow changes, the detecting chip 1 may adjust the frequency of the clock signal according to the airflow change signal, and adjust the output current of the detecting chip 1 according to the amplitude of the frequency change of the clock signal when the frequency of the clock signal changes, so as to convert the change of the airflow into the change of the output current. By detecting the output current, the specific change condition of the air flow can be determined, namely, the qualitative detection and the quantitative detection are carried out on the change of the air flow. And the detection of the air current is carried out by adopting a module integration mode, and the volume of the air current conversion detection device can be reduced, so that the detection of the air current is realized in a narrow space range.
Further, the detecting chip 1 includes a clock signal generating module 10, a periodic signal generating module 20, a clock frequency calculating module 30, and a current adjusting module 40. The output end of the clock signal generating module 10 is connected to the first input end of the clock frequency calculating module 30, the output end of the periodic signal generating module 20 is connected to the second input end of the clock frequency calculating module 30, and the output end of the clock frequency calculating module 30 is connected to the current adjusting module 40. The clock signal generation module 10 may detect the airflow variation, obtain a corresponding airflow variation signal according to the airflow variation, determine the frequency of the output clock signal according to the airflow variation signal, generate a clock signal of the frequency, and send the clock signal to the clock frequency calculation module 30. The periodic signal generating module 20 may continuously output the periodic signal to the clock frequency calculating module 30. After receiving the clock signal sent by the clock signal generation module 10 and the periodic signal sent by the periodic signal generation module 20, the clock frequency calculation module 30 determines a corresponding period according to the periodic signal, calculates a variation of the frequency of the clock signal in the period, and sends the calculated frequency variation to the current adjustment module 40. After receiving the frequency variation, the current adjusting module 40 adjusts the output current output by the output terminal according to the frequency variation. It can be understood that, when the frequency variation is zero, the output current outputted by the current adjustment module 40 will not change.
The airflow conversion detection circuit provided by the embodiment can be arranged in various places where airflow change needs to be detected. The clock signal generation module 10 continuously detects the airflow, and when the airflow changes, the clock signal generation module 10 generates an airflow change signal according to the airflow change, and correspondingly changes the frequency value of the output clock signal according to the airflow change signal. The clock frequency calculation module 30 may continuously receive the clock signal sent by the clock signal generation module 10, and when the clock frequency calculation module 30 receives the periodic signal sent by the periodic signal generation module 20, may determine a corresponding period according to the periodic signal, and determine a frequency variation of the clock signal in the period. After the clock frequency calculation module 30 sends the frequency variation to the current adjustment module 40, the current adjustment module 40 may correspondingly adjust the output current according to the frequency variation to convert the variation of the airflow into the variation of the output current, and by detecting the output current, the specific variation of the airflow may be determined, that is, the variation of the airflow may be qualitatively and quantitatively detected.
Further, referring to fig. 2, in a preferred embodiment, the clock signal generation module 10 includes a clock signal circuit 11. The charging control end of the clock signal circuit 11 is connected to the first end of the airflow detection module 15, the discharging control end of the clock signal circuit 11 is connected to the second end of the airflow detection module 15, and the second end of the airflow detection module 15 and the discharging control end of the clock signal circuit 11 are grounded. The clock signal circuit 11 can charge the airflow detection module 15 through the charging control terminal, and discharge the airflow detection module 15 through the discharging control terminal, and in the process of charging and discharging the airflow detection module 15, the clock signal circuit 11 can output a clock signal with fixed frequency from the output terminal according to the voltage at the two ends of the airflow detection module 15. When the airflow detected by the airflow detecting module 15 is not changed, the frequency of the clock signal is fixed; after the airflow detecting module 15 detects the airflow change and obtains the airflow change signal, the frequency of the clock signal output by the output terminal of the clock signal circuit 11 is also adjusted accordingly. By detecting the specific value and the variation trend of the frequency variation of the clock signal, whether the air flow is increased or decreased and the actual air flow variation can be obtained correspondingly, namely, the qualitative detection and the quantitative detection are carried out on the air flow variation.
With continued reference to fig. 2, the clock signal circuit 11 may include a reference output circuit 12, a comparison circuit 13, a discharge circuit 14, and a clock buffer 131. A first output terminal of the reference output circuit 12 may output a reference voltage, a second output terminal of the reference output circuit 12 may output a reference current, and the second output terminal of the reference output circuit 12 is further connected to a first terminal of the airflow detecting module 15 as a charging control terminal of the clock signal circuit 11. A first input of the comparison circuit 13 is connected to a first output of the reference output circuit 12, and a second input of the comparison circuit 13 is connected to a second output of the reference output circuit 12. A first terminal of the clock buffer 131 is connected to the output terminal of the comparison circuit 13, and a second terminal of the clock buffer 131 serves as the output terminal of the clock signal circuit 11 to output the clock signal. That is, the reference voltage is input to the first input terminal of the comparator circuit 13, and the voltage across the airflow detection module 15 when the airflow detection module 15 is charged and discharged by the reference output circuit 12 is input to the second input terminal of the comparator circuit 13. A first input terminal of the discharging circuit 14 is connected to a second input terminal of the comparing circuit 13, a second terminal of the discharging circuit 14 is a discharging control terminal of the clock signal circuit 11, and a controlled terminal of the discharging circuit 14 is connected to an output terminal of the comparing circuit 13. When the input voltage of the second input end of the comparison circuit 13, that is, the voltage at the two ends of the airflow detection module 15 is smaller than the reference voltage, the output end of the comparison circuit 13 outputs a low level to the controlled end of the discharge circuit 14, the discharge circuit 14 is turned off, and at this time, the reference output circuit 12 charges the airflow detection module 15; when the input voltage of the second input terminal of the comparison circuit 13 is greater than the reference voltage, the output terminal of the comparison circuit 13 outputs a high level to the controlled terminal of the discharge circuit 14, the discharge circuit 14 is turned on, and at this time, the second output terminal of the reference output circuit 12 is directly grounded through the discharge circuit 14 and does not charge the airflow detection module 15 any more. When the level output from the output terminal of the comparison circuit 13 changes between high and low levels, the clock buffer 131 may increase the voltage value of the high level signal, so that the clock signal output from the output terminal of the clock signal circuit 11 is more stable.
In the above embodiment, when the first output terminal of the reference output circuit 12 outputs the reference voltage to the first input terminal of the comparison circuit 13, the second output terminal of the reference output circuit 12 outputs the reference current, and at this time, the discharge circuit 14 is turned off, the reference output circuit 12 can charge the airflow detection module 15, the voltage of the first terminal of the airflow detection module 15 is increased during the charging process, and the second input terminal of the comparison circuit 13 is connected to the first terminal of the airflow detection module 15, that is, the input voltage of the second input terminal of the comparison circuit 13 is also gradually increased during the charging process. When the input voltage of the second input terminal of the comparison circuit 13 is greater than the reference voltage of the first input terminal, the output terminal of the comparison circuit 13 outputs a high level, and the controlled terminal of the discharge circuit 14 receives the high level to control the discharge circuit 14 to be turned on. When the discharging circuit 14 is turned on, the second output terminal of the reference output circuit 12 is grounded through the discharging circuit 14, and the airflow detecting module 15 is no longer charged, and meanwhile, the airflow detecting module 15 can form a loop through the discharging circuit 14 to discharge. At this time, the voltage value at the two ends of the airflow detecting module 15 is reduced, and the input voltage at the second input end of the comparing circuit 13 is smaller than the reference voltage, so that the output end of the comparing circuit 13 outputs a low level, and the controlled end of the discharging circuit 14 receives the low level to be turned off. The reference output circuit 12 will recharge the airflow detection module 15. The high-low level signal output by the output end of the comparison circuit 13 at a certain interval is the clock signal, and since the reference current output by the reference output circuit 12 is constant, when the airflow detection module 15 does not detect the airflow change, the time for the airflow detection module 15 to rise to the voltage exceeding the reference voltage during the charging process is also constant, that is, the interval period for the output end of the comparison circuit 13 to output the high level signal is fixed, and therefore the frequency of the clock signal is also fixed. When the airflow detecting module 15 detects a change in the airflow, the reference output circuit 12 charges the airflow detecting module 15 until the time when the voltage at the second input terminal of the comparing circuit 13 exceeds the reference voltage changes, and accordingly the period of outputting the high level signal also changes. Whether the airflow changes can be determined by measuring the frequency of the clock signal, and the change amount of the airflow is determined according to the change amplitude of the frequency of the clock signal. Through the combination of simple circuits, the airflow change can be detected through the frequency of the clock signal, and the airflow conversion detection circuit is simple in structure and low in power consumption. The integrated packaging mode of the clock signal circuit 11 can also enable the airflow conversion detection circuit to be applied to various places with smaller space ranges, and the practicability and the universality of the airflow conversion detection circuit are improved.
Further, the airflow detecting module 15 may be a pneumatic variable capacitor 151, and the capacitance value of the pneumatic variable capacitor 151 may be changed according to the airflow variation on the capacitor. When the airflow does not change, the reference output circuit 12 charges the pneumatic variable capacitor 151 so that the charging time required for the voltage value of the pneumatic variable capacitor 151 to exceed the reference voltage is t, and the frequency of the clock signal is f at this time0. When the airflow changes and the capacitance value of the pneumatic variable capacitor 151 increases, the charging time t required for the reference output circuit 12 to charge the pneumatic variable capacitor 151 so that the voltage value thereof exceeds the reference voltage is1At the time, the frequency of the clock signal is f1. It will be understood that when the capacitance value is represented by C0Increase to C1The charging time required to charge the capacitor to the same voltage will increase, i.e. t1>t，f1<f0. Based on the same principle, when the capacitance value of the pneumatic variable capacitor 151 is represented by C0Is reduced to C2While the capacitor charging time is reduced to t2Frequency of clock signal f2At this time t2<t，f2>f0. Fig. 3 shows a relationship between a change in capacitance value of the pneumatic variable capacitor 151 and a change in clock signal frequency.
Preferably, the discharge circuit 14 may further include a first switch tube 141, a first end of the first switch tube 141 is connected to the second input terminal of the comparison circuit 13, a second end of the first switch tube 141 is grounded, and a controlled end of the first switch tube 141 is connected to the output terminal of the comparison circuit 13. When the output end of the comparison circuit 13 outputs a low level, it indicates that the reference output circuit 12 is charging the airflow detection module 15, and at this time, the controlled end of the first switch tube 141 receives the low level, and the first switch tube 141 is turned off. When the airflow detection module 15 is charged until the output voltage is higher than the reference voltage, the output end of the comparison circuit 13 outputs a high level, the controlled end of the first switch tube 141 receives the high level, the first switch tube 141 is turned on, the reference output circuit 12 stops charging, and the airflow detection module 15 is discharged at the same time, so that the charging and discharging processes of the airflow detection module 15 are realized. The current structure design for controlling the work of the discharge circuit 14 through the high and low levels of the output end of the comparison circuit 13 is simple, and the charge and discharge time of the airflow detection module 15 can be accurately controlled, so that the cost of the circuit is reduced, and the stability and the accuracy of the circuit are improved.
Further, the airflow conversion detection circuit may further include a controller 16, and the controller 16 may be a Flash chip, a register, an ARM (Advanced RISC Machines, RISC microprocessors), a ROM (Read-Only Memory), a FUSE (user space file system), and the like. The controller 16 is connected to the reference output module and can send a control signal to control the reference current output by the reference output module, so as to adjust the charging time of the pneumatic variable capacitor 151 to adjust the frequency of the clock signal.
Referring to fig. 2 and 4 together, in a preferred embodiment, the comparison circuit 13 may be a two-stage open-loop comparator. Ib can control the working state of the comparator, Vin is a first input end of the comparator, Vip is a second input end of the comparator, when the voltage value of Vip is larger than that of Vin, Vout outputs a high-level signal, otherwise, a low-level signal is output. In the charging and discharging process of the airflow detection module 15, the high and low levels output by the comparison circuit 13 need to be switched continuously, the switching of high and low level signals can be more accurate by arranging a two-stage switch comparator, and the accuracy of the detection circuit is ensured when the frequency of a clock signal is higher.
With continued reference to fig. 1, in another embodiment, the periodic signal generation module 20 may output the threshold signal according to a preset period. The threshold signal may be a pulse signal, i.e. a pulse signal is generated every preset period. When the clock frequency calculation module 30 receives two adjacent threshold signals, the time between the two threshold signals is the period time corresponding to the periodic signal. The clock frequency calculation module 30 may determine the frequency of the clock signal transmitted by the clock signal generation module 10 when receiving the two threshold signals respectively. The two threshold signals are a first threshold signal and a second threshold signal, and then the frequencies of the corresponding clock signals are a first frequency and a second frequency. Specifically, the threshold signal received by the clock frequency calculation module 30 is the first threshold signal. After determining the first frequency and the second frequency, the clock frequency calculation module 30 may calculate a frequency difference between the first frequency and the second frequency, and send the frequency difference to the current adjustment module 40, so that the current adjustment module 40 adjusts the output current of the output terminal according to the frequency difference. And determining the variation of the airflow variation signal in the period time according to the calculated frequency difference so as to obtain the variation of the airflow. The change of the airflow can be converted into the change of the current by changing the output current through the frequency difference value, the change condition of the airflow and the amplitude of the airflow change can be determined by detecting the current, and the accurate quantitative detection of the airflow change is realized.
Further, the clock frequency calculation module 30 may further include a first latch (not shown) and a second latch (not shown), and the first latch and the second latch may store specific frequency values of the first frequency and the second frequency, respectively. The clock frequency calculation module 30 performs a subtraction operation on the values of the first latch and the second latch to obtain a frequency difference between the first frequency and the second frequency.
As shown in fig. 1, in a preferred embodiment, the current adjusting module 40 may be a PWM generator 41, and the PWM generator 41 may adjust the duty ratio of the output current according to the received frequency difference value. For example, the clock frequency calculation module 30 may preset a threshold value of the frequency difference, and when the calculated frequency difference is lower than the threshold value, the airflow variation amplitude is considered to be small, the duty ratio of the output current may not be changed by the PWM generator 41, and the threshold value of the frequency difference may be set to 32. When the frequency difference received by the PWM generator 41 is n, and n is greater than or equal to the threshold of the frequency difference, the PWM generator 41 can output the output according to the frequency differenceThe duty ratio of the current is adjusted to n/2NWhere N is 8, i.e. the duty cycle of the output current is N/256. As shown in fig. 5, the average value of the output current after pulse width modulation by PWM is: i is Iout n/256, which is the maximum amplitude of the output current. The duty ratio of the output current can be determined by detecting the average value of the output current, and then the frequency difference is calculated to determine the change condition of the airflow. The variation process of the air flow can be known according to the linear variation of the average value of the output current.
The present invention further provides an airflow conversion detection device, which includes a housing and an airflow conversion detection circuit disposed in the housing, and the structure of the airflow conversion detection circuit can refer to the above embodiments, and is not described herein again. It should be understood that, since the airflow transition detection device of the present embodiment adopts the technical solution of the airflow transition detection circuit, the airflow transition detection device has all the beneficial effects of the airflow transition detection circuit.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. An airflow transition detection circuit, comprising: the device comprises a detection chip and an airflow detection module for detecting airflow to obtain an airflow change signal; the detection chip comprises a clock signal generation module, a clock frequency calculation module and a current adjustment module;
the first input end of the clock signal generation module is connected with the first end of the airflow detection module, the second input end of the clock signal generation module is connected with the second end of the airflow detection module, the output end of the clock signal generation module is connected with the first input end of the clock frequency calculation module, the output end of the clock frequency calculation module is connected with the current adjustment module, and the second end of the airflow detection module is grounded;
the airflow detection module comprises a pneumatic variable capacitor, and the capacitance value of the pneumatic variable capacitor changes along with the change of the airflow;
the detection chip is used for adjusting the clock signal according to the airflow change signal detected by the airflow detection module after the airflow detection module is charged and discharged to generate the clock signal, and adjusting the output current according to the frequency change of the clock signal;
the clock signal generation module is used for determining the frequency of a clock signal according to the airflow change signal and sending the clock signal of the frequency to the clock frequency calculation module;
the clock frequency calculation module is used for receiving the clock signal sent by the clock signal generation module and calculating the frequency variation of the clock signal so as to send the frequency variation to the current adjustment module;
and the current adjusting module is used for correspondingly adjusting the output current according to the frequency variation.
2. The airflow transition detection circuit of claim 1, wherein said detection chip comprises a periodic signal generation module; the output end of the periodic signal generation module is connected with the second input end of the clock frequency calculation module;
the periodic signal generation module is used for outputting a periodic signal to the clock frequency calculation module;
the clock frequency calculation module is used for receiving the clock signal sent by the clock signal generation module and the periodic signal sent by the periodic signal generation module, and calculating the frequency variation of the clock signal in the period corresponding to the periodic signal so as to send the frequency variation to the current adjustment module.
3. The airflow transition detection circuit of claim 2, wherein said clock signal generation module comprises a clock signal circuit;
the charging control end of the clock signal circuit is connected with the first end of the airflow detection module, the discharging control end of the clock signal circuit is connected with the second end of the airflow detection module, and the second end of the airflow detection module is grounded;
the clock signal circuit is used for correspondingly adjusting the clock signal output by the output end according to the airflow change signal detected by the airflow detection module after the airflow detection module is charged and discharged through the charging control end and the discharging control end so that the output end of the clock signal circuit outputs the clock signal with fixed frequency.
4. The airflow transition detection circuit of claim 3, wherein said clock signal circuit comprises a reference output circuit, a comparison circuit, a discharge circuit, and a clock buffer;
a first output end of the reference output circuit outputs a reference voltage, a second output end of the reference output circuit outputs a reference current, and the second output end of the reference output circuit is a charging control end of the clock signal circuit;
a first input end of the comparison circuit is connected with a first output end of the reference output circuit, and a second input end of the comparison circuit is connected with a second output end of the reference output circuit;
the first end of the clock buffer is connected with the output end of the comparison circuit, the second end of the clock buffer is the output end of the clock signal circuit, and the second end of the clock buffer outputs a clock signal;
the first end of the discharge circuit is connected with the second input end of the comparison circuit, the second end of the discharge circuit is the discharge control end of the clock signal circuit, and the controlled end of the discharge circuit is connected with the output end of the comparison circuit;
the comparison circuit is further used for controlling the discharge circuit to be turned off when the input voltage of the second input end of the comparison circuit is smaller than the reference voltage; and when the detection voltage is greater than the reference voltage, controlling the discharge circuit to be conducted.
5. The airflow transition detection circuit of claim 4, wherein the frequency of the clock signal output by the output of the clock signal circuit increases as the capacitance value of the pneumatic variable capacitor increases; when the capacitance value of the pneumatic variable capacitor becomes smaller, the frequency of the clock signal output by the output end of the clock signal circuit is reduced.
6. The airflow transition detection circuit of claim 4, further comprising a controller coupled to the reference output module;
the controller is further configured to control the second output terminal of the reference output module to output the reference current.
7. The airflow transition detection circuit of any of claims 2-6 wherein the periodic signal is a threshold signal output at a predetermined period;
the clock frequency calculation module is further configured to determine, when receiving two adjacent threshold signals, frequencies of the two clock signals corresponding to time nodes receiving the two threshold signals, to respectively use the frequencies of the two clock signals as a first frequency and a second frequency, and send a frequency difference value between the first frequency and the second frequency to the current adjustment module, where the clock signal of the first frequency is a previous threshold signal in the two adjacent threshold signals;
the current adjusting module is further configured to correspondingly adjust the output current output by the output terminal according to the frequency difference.
8. The airflow transition detection circuit of claim 7, wherein said clock frequency calculation module further comprises a first latch, a second latch;
the clock frequency calculation module is further configured to store the first frequency and the second frequency in the first latch and the second latch, respectively, and calculate a difference between the first latch and the second latch to obtain the frequency difference.
9. The airflow transition detection circuit of claim 7, wherein the current adjustment module is a PWM generator configured to adjust a duty cycle of the output current based on the received frequency difference.
10. An airflow transition detection device, comprising a housing and an airflow transition detection circuit disposed in the housing, the airflow transition detection circuit being configured as the airflow transition detection circuit according to any one of claims 1-9.
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