CN214175265U - Humidity alarm circuit and device - Google Patents
Humidity alarm circuit and device Download PDFInfo
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- CN214175265U CN214175265U CN202120062740.3U CN202120062740U CN214175265U CN 214175265 U CN214175265 U CN 214175265U CN 202120062740 U CN202120062740 U CN 202120062740U CN 214175265 U CN214175265 U CN 214175265U
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Abstract
The application discloses humidity alarm circuit and device belongs to humidity control technical field. The humidity alarm circuit comprises a partial pressure detection circuit, a reference circuit, a comparison amplification circuit and an alarm circuit. The voltage division detection circuit comprises a humidity sensitive element, and the voltage of the humidity sensitive element changes along with the humidity of the environment where the humidity sensitive element is located. The reference circuit is used for outputting a reference voltage. The comparison amplifying circuit is used for judging the magnitude relation between the voltage of the humidity sensitive element and the reference voltage and controlling the alarm circuit to give an alarm when the voltage of the humidity sensitive element is greater than the reference voltage. According to the humidity alarm circuit, the humidity is monitored by comparing the magnitude relation between the voltage of the humidity sensitive element and the reference voltage judged by the amplifying circuit, analog-to-digital conversion is not needed to be carried out on the voltage of the humidity sensitive element, the problem that a single chip microcomputer cannot process weak analog signals due to the fact that the single chip microcomputer is limited by the accuracy of the analog-to-digital conversion is solved, and the accuracy of humidity alarm is improved.
Description
Technical Field
The application relates to the technical field of humidity monitoring, in particular to a humidity alarm circuit and a humidity alarm device.
Background
Humidity is a physical quantity that indicates the degree of dryness of the atmosphere. The humidity alarm is a device for monitoring humidity and alarming when the humidity exceeds a preset humidity threshold value.
In the related art, a humidity alarm generally comprises a single chip microcomputer and a humidity-sensitive resistor, wherein the single chip microcomputer monitors humidity by detecting voltage of the humidity-sensitive resistor, and gives an alarm when the humidity exceeds a preset humidity threshold value.
However, the single chip microcomputer is generally only used for processing digital signals, and therefore, when the single chip microcomputer detects the voltage of the humidity sensitive resistor, the voltage of the humidity sensitive resistor needs to be subjected to analog-to-digital conversion. Limited by the accuracy of analog-to-digital conversion, the single-chip microcomputer cannot process weak analog signals, which affects the accuracy of monitoring and alarming humidity by the single-chip microcomputer.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application provides a humidity alarm circuit and a humidity alarm device, and the humidity alarm circuit and the humidity alarm device can improve the accuracy of humidity alarm by judging the magnitude relation between the voltage of a humidity sensitive element and reference voltage through a comparison amplifying circuit. The technical scheme is as follows:
in a first aspect, a humidity alarm circuit is provided, the humidity alarm circuit comprising: the device comprises a voltage division detection circuit, a reference circuit, a comparison amplification circuit and an alarm circuit;
the voltage division detection circuit comprises a humidity sensitive element, wherein a first end of the humidity sensitive element is connected with a power supply VCC, a second end of the humidity sensitive element is connected with a ground wire GND, and the voltage of the humidity sensitive element changes along with the humidity of the environment where the humidity sensitive element is located;
the comparison amplification circuit comprises a first input end, a second input end and an output end; the first input end of the comparison amplifying circuit is connected with the first end of the humidity sensitive element so as to input the voltage of the humidity sensitive element; the second input end of the comparison amplification circuit is connected with the reference circuit so as to input the reference voltage output by the reference circuit;
the first end of the alarm circuit is connected with the output end of the comparison amplification circuit, and the second end of the alarm circuit is connected with the ground wire GND;
when the voltage of the humidity sensitive element is greater than the reference voltage, the comparison amplification circuit outputs a high-level signal, and the alarm circuit gives an alarm; when the voltage of the humidity sensitive element is less than or equal to the reference voltage, the comparison amplification circuit outputs a low-level signal, and the alarm circuit does not give an alarm.
In the application, the humidity alarm circuit comprises a partial pressure detection circuit, a reference circuit, a comparison amplification circuit and an alarm circuit. The voltage division detection circuit comprises a humidity sensitive element, and the voltage of the humidity sensitive element changes along with the change of the humidity of the environment where the humidity sensitive element is located. The reference circuit is used for outputting a reference voltage. The comparison amplifying circuit is used for judging the magnitude relation between the voltage of the humidity sensitive element and the reference voltage. When the voltage of the humidity sensitive element is greater than the reference voltage, the comparison amplifying circuit controls the alarm circuit to alarm; when the voltage of the humidity sensitive element is less than or equal to the reference voltage, the comparison amplifying circuit controls the alarm circuit not to alarm. According to the humidity alarm circuit, the humidity is monitored by comparing the magnitude relation between the voltage of the humidity sensitive element and the reference voltage judged by the amplifying circuit, analog-to-digital conversion is not needed to be carried out on the voltage of the humidity sensitive element, the problem that a single chip microcomputer cannot process weak analog signals due to the fact that the single chip microcomputer is limited by the accuracy of the analog-to-digital conversion is solved, and the accuracy of humidity alarm is improved.
Optionally, the voltage division detection circuit further includes: a resistor R1 and a capacitor C1;
a first end of the resistor R1 is connected with the power supply VCC, and a second end of the resistor R1 is connected with a first end of the humidity sensitive element;
a first plate of the capacitor C1 is connected with a first end of the humidity sensitive element, and a second plate of the capacitor C1 is connected with the ground GND;
the moisture sensitive element includes a dew sensor.
Optionally, the comparison amplifying circuit includes: the circuit comprises an operational amplifier A1, a resistor R2, a resistor R3, a resistor R4 and a capacitor C2;
a first end of the resistor R2 is connected with a first end of the humidity sensitive element, and a second end of the resistor R2 is connected with a non-inverting input end of the operational amplifier A1;
a first end of the resistor R3 is connected with the reference circuit, and a second end of the resistor R3 is connected with an inverting input end of the operational amplifier A1;
a first end of the resistor R4 is connected with a non-inverting input end of the operational amplifier A1, and a second end of the resistor R4 is connected with an output end of the operational amplifier A1;
the first plate of the capacitor C2 is connected with the non-inverting input end of the operational amplifier A1, and the second plate of the capacitor C2 is connected with the output end of the operational amplifier A1.
Optionally, the reference circuit comprises: an operational amplifier A2, a resistor R5 and a resistor R6;
a first end of the resistor R5 is connected with the power supply VCC, and a second end of the resistor R5 is connected with a non-inverting input end of the operational amplifier A2;
a first end of the resistor R6 is connected with a non-inverting input end of the operational amplifier A2, and a second end of the resistor R6 is connected with the ground GND;
the inverting input terminal of the operational amplifier A2 is connected to the output terminal of the operational amplifier A2, and the output terminal of the operational amplifier A2 is connected to the second input terminal of the comparison amplification circuit.
Optionally, at least one of the resistors R5 and R6 is an adjustable resistor.
Optionally, the alarm circuit comprises: resistor R7 and light emitting diode LED 1;
a first end of the resistor R7 is connected to an output end of the comparison and amplification circuit, an anode of the light emitting diode LED1 is connected to a second end of the resistor R7, and a cathode of the light emitting diode LED1 is connected to the ground GND.
Optionally, the humidity alarm circuit further comprises: a power indication circuit;
the first end of the power supply indicating circuit is connected with the power supply VCC, and the second end of the power supply indicating circuit is connected with the ground wire GND.
Optionally, the power indication circuit comprises: resistor R8 and light emitting diode LED 2;
the first end of the resistor R8 is connected with the power supply VCC, the anode of the light emitting diode LED2 is connected with the second end of the resistor R8, and the cathode of the light emitting diode LED2 is connected with the ground line GND.
In a second aspect, there is provided a humidity alarm device comprising a humidity alarm circuit as described in the first aspect.
Optionally, the humidity alarm device further comprises: a dustproof protective shell;
the dustproof protective shell comprises a shell and a cavity formed by surrounding the shell, the shell is provided with a small hole for communicating the cavity with the environment where the shell is located, and the humidity sensitive element is located in the cavity.
It is understood that the beneficial effects of the second aspect can be referred to the related description of the first aspect, and are not described herein again.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic circuit diagram of a humidity alarm of the related art;
FIG. 2 is a schematic structural diagram of a first humidity alarm circuit provided in an embodiment of the present application;
fig. 3 is a schematic structural diagram of a dew condensation sensor provided in an embodiment of the present application;
fig. 4 is a schematic cross-sectional structure diagram of a dew condensation sensor provided in an embodiment of the present application;
FIG. 5 is a graph of humidity versus resistance of a dew sensor according to an embodiment of the present disclosure;
FIG. 6 is a schematic structural diagram of a second humidity alarm circuit provided in an embodiment of the present application;
FIG. 7 is a schematic diagram of a third humidity alarm circuit provided in an embodiment of the present application;
FIG. 8 is a schematic diagram of a fourth humidity alarm circuit provided in an embodiment of the present application;
fig. 9 is a schematic perspective view of a dustproof protective shell according to an embodiment of the present application;
fig. 10 is a schematic cross-sectional view of a humidity alarm device according to an embodiment of the present disclosure.
Wherein, the meanings represented by the reference numerals of the figures are respectively as follows:
10. a humidity alarm circuit;
110. a voltage division detection circuit;
112. a moisture sensitive element;
1122. an insulating substrate;
1124. a first electrode;
1126. a second electrode;
1128. a moisture-sensitive film;
120. a reference circuit;
130. a comparison amplification circuit;
140. an alarm circuit;
150. a power indication circuit;
20. a humidity alarm device;
210. a dustproof protective shell;
211. a housing;
212. a cavity;
214. and (4) a small hole.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
It should be understood that reference to "a plurality" in this application means two or more. In the description of the present application, "/" means "or" unless otherwise stated, for example, a/B may mean a or B; "and/or" herein is only an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, for the convenience of clearly describing the technical solutions of the present application, the terms "first", "second", and the like are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance.
Before explaining the embodiments of the present application in detail, an application scenario of the embodiments of the present application will be described.
Humidity is a physical quantity that indicates the degree of dryness of the atmosphere. The humidity alarm is a device for monitoring humidity and alarming when the humidity exceeds a preset humidity threshold value. FIG. 1 is a schematic circuit diagram of a humidity alarm of the related art. Referring to fig. 1, in the related art, a humidity alarm includes a single chip, a humidity sensitive resistor RS, and an alarm circuit. The humidity sensitive resistor RS is connected in a closed circuit. When the humidity changes, the resistance of the humidity sensitive resistor RS also changes, and the voltage at the two ends of the humidity sensitive resistor RS also changes accordingly. The single chip microcomputer monitors the humidity by detecting the voltage of the humidity sensitive resistor RS. The single chip microcomputer can be set with a preset humidity threshold value, and when the humidity exceeds the preset humidity threshold value, the single chip microcomputer can control the alarm circuit to give an alarm.
The humidity sensitive resistor RS is connected in a closed circuit, and the voltage signal across it is an analog signal. However, the one-chip microcomputer is a microcomputer for processing digital signals. Therefore, the voltage of the humidity sensitive resistor RS needs to be firstly subjected to analog-to-digital conversion through the analog-to-digital conversion circuit and then input to the singlechip. In the process, if the voltage change of the humidity sensitive resistor RS is weak and is limited by the accuracy of analog-to-digital conversion and the accuracy of the single chip microcomputer for identifying weak signals, the single chip microcomputer cannot process the weak analog signals, and the accuracy of monitoring and alarming the humidity by the humidity alarm can be influenced.
Therefore, the embodiment of the application provides a humidity alarm circuit and a humidity alarm device, and the humidity alarm circuit and the humidity alarm device can improve the accuracy of humidity alarm by judging the magnitude relation between the voltage of the humidity sensitive element and the reference voltage through the comparison amplifying circuit.
The humidity alarm circuit 10 provided in the embodiment of the present application is explained in detail below. In various embodiments of the present application, the connection between two electrical devices is referred to as an electrical connection. Here, the electrical connection means that two electrical devices are connected by wire or wireless to transmit an electrical signal.
Fig. 2 is a schematic structural diagram of a humidity alarm circuit 10 according to an embodiment of the present disclosure. Referring to fig. 2, the humidity alarm circuit 10 includes a voltage division detection circuit 110, a reference circuit 120, a comparison amplification circuit 130, and an alarm circuit 140.
The voltage division detection circuit 110 is configured to detect the humidity of the environment and output an electrical signal according to the detected humidity. The voltage division detection circuit 110 includes a humidity sensitive element 112. The moisture sensitive element 112 has a first end and a second end. The first terminal of the humidity sensor 112 is connected to the power source VCC, and the second terminal of the humidity sensor 112 is connected to the ground GND. Generally, the humidity sensor 112 can be a positive characteristic element, that is, when the humidity of the environment in which the humidity sensor 112 is located increases, the voltage of the humidity sensor 112 also increases with the increase of the humidity; when the humidity of the environment in which the humidity sensor 112 is located decreases, the voltage of the humidity sensor 112 also decreases with the decrease in humidity. In the embodiment of the present application, the voltage of the humidity sensor 112 is a signal output by the voltage division detection circuit 110.
The reference circuit 120 is used to output a reference voltage. The reference voltage may be a fixed voltage or an adjustable voltage. In the humidity alarm circuit 10, the reference voltage output from the reference circuit 120 is a comparison target of the voltage of the humidity sensor 112. Generally, the humidity alarm circuit 10 needs to alarm when the humidity exceeds a preset humidity threshold. The reference voltage has a value equal to the voltage of the humidity sensor 112 when the humidity is equal to the preset humidity threshold.
The comparison amplification circuit 130 is used for inputting the voltage of the humidity sensitive element 112 and the reference voltage, judging the voltage difference between the voltage of the humidity sensitive element 112 and the reference voltage, and amplifying the voltage difference. The comparison amplification circuit 130 may have a first input terminal, a second input terminal, and an output terminal. The first input terminal of the comparison amplifying circuit 130 is connected to the first terminal of the humidity sensor 112, and is used for inputting the voltage of the humidity sensor 112. A second input terminal of the comparison amplification circuit 130 is connected to the reference circuit 120 for inputting a reference voltage. When the voltage of the humidity sensor 112 is greater than the reference voltage, the comparison and amplification circuit 130 amplifies the voltage difference between the two, and the output end of the comparison and amplification circuit 130 can output a high-level signal. When the voltage of the humidity sensitive element 112 is less than or equal to the reference voltage, the output terminal of the comparison amplification circuit 130 may output a low level signal.
The alarm circuit 140 is used to alarm when the voltage of the humidity sensitive element 112 is greater than the reference voltage. The alarm circuit 140 may have a first terminal and a second terminal. A first terminal of the alarm circuit 140 is connected to an output terminal of the comparison amplification circuit 130. A second terminal of the alarm circuit 140 is connected to the ground GND. When the comparison amplification circuit 130 outputs a high level signal, the alarm circuit 140 gives an alarm; on the contrary, when the comparison amplification circuit 130 outputs a low level signal, the alarm circuit 140 does not alarm.
When the humidity alarm circuit 10 of the present application is operated, the voltage of the humidity sensor 112 changes with the humidity of the environment where the humidity sensor 112 is located. When the voltage of the humidity sensitive element 112 is greater than the reference voltage, the comparison amplifying circuit 130 outputs a high level signal to control the alarm circuit 140 to alarm; when the voltage of the humidity sensor 112 is less than or equal to the reference voltage, the comparing and amplifying circuit 130 outputs a low level signal to control the alarm circuit 140 not to alarm. By adjusting the reference circuit 120, the value of the reference voltage outputted by the reference circuit 120 is the voltage of the humidity sensitive element 112 when the humidity is equal to the preset humidity threshold value. At this time, when the humidity of the environment where the humidity sensitive element 112 is located is greater than the preset humidity threshold, the alarm circuit 140 gives an alarm; when the humidity of the environment where the humidity sensitive element 112 is located is less than or equal to the preset humidity threshold, the alarm circuit 140 does not alarm. The humidity alarm circuit 10 monitors humidity by comparing the amplification circuit 130 to determine the relationship between the voltage of the humidity sensitive element 112 and the reference voltage, and does not require a single chip, so that analog-to-digital conversion of the voltage of the humidity sensitive element 112 is not required, the problem that the single chip cannot process weak analog signals due to the limitation of the accuracy of the analog-to-digital conversion is avoided, and the accuracy of humidity alarm is improved. Meanwhile, the comparison and amplification circuit 130 can amplify the voltage difference between the voltage of the humidity sensitive element 112 and the reference voltage, so as to improve the monitoring capability of the humidity alarm circuit 10 on weak humidity changes, thereby further improving the accuracy of humidity alarm.
Further, the humidity sensor 112 includes a positive characteristic humidity-sensitive resistor, humidity-sensitive capacitor, and the like. Taking the humidity sensor 112 as a positive characteristic, the resistance of the humidity sensor increases when the humidity of the environment in which the humidity sensor is located increases. At this time, the voltage across the humidity sensitive resistor also increases with the increase in the resistance value.
Further, the humidity sensitive element 112 may be a dew sensor. The dew sensor is also called a condensation sensor. Fig. 3 is a schematic top view of a dew condensation sensor according to an embodiment of the present disclosure; fig. 4 is a schematic longitudinal sectional view of the dew condensation sensor according to the embodiment of the present application. Referring to fig. 3 and 4, the dew sensor generally includes an insulating substrate 1122, a first electrode 1124, a second electrode 1126, and a moisture-sensitive film 1128. The first electrode 1124 and the second electrode 1126 are located on the same surface of the insulating substrate 1122. The first electrode 1124 and the second electrode 1126 each have a comb-shaped structure. In other words, the first electrode 1124 includes a main electrode and a plurality of saw-tooth electrodes. The sawtooth electrodes are spaced from each other and connected to the main electrode. The second electrode 1126 has the same structure as the first electrode 1124. The saw-tooth electrodes of the first electrode 1124 and the saw-tooth electrodes of the second electrode 1126 are alternately arranged on the insulating substrate 1122, but the first electrode 1124 and the second electrode 1126 are not connected to each other. The moisture-sensitive film 1128 is bonded to the insulating substrate 1122, so that the first electrode 1124 and the second electrode 1126 are enclosed between the moisture-sensitive film 1128 and the insulating substrate 1122, and the first electrode 1124 and the second electrode 1126 are electrically connected through the moisture-sensitive film 1128. Generally, the moisture-sensitive film 1128 is formed of a resin and conductive particles. When moisture is absorbed to the moisture-sensitive film 1128, the intervals between the plurality of conductive particles in the moisture-sensitive film 1128 are expanded, and the resistance value and the resistivity of the moisture-sensitive film 1128 are increased. At this time, the voltage across the dew condensation sensor also increases.
More specifically, the moisture sensitive element 112 may be a dew condensation sensor model HDS 10. The condensation touch sensor can work under direct current voltage, and is stable in quality and high in reliability. Fig. 5 shows a relationship curve between the humidity and the resistance of the environment in which the dew condensation sensor is located. As can be seen from the figure, the resistance value of the dew condensation sensor rapidly increases as the humidity increases, and thus, the accuracy of humidity monitoring and alarming by the humidity alarm circuit 10 can be improved.
In the application, the dew condensation sensor is adopted as the humidity sensitive element 112, and compared with a humidity sensitive resistor, the humidity sensing area of the humidity sensitive element 112 can be increased, so that the influence of dust on the accuracy of humidity alarm is reduced.
Fig. 6 is a schematic structural diagram of a humidity alarm circuit 10 according to an embodiment of the present application. Referring to fig. 6, in some embodiments, the voltage division detecting circuit 110 further includes a resistor R1 and a capacitor C1.
Specifically, the resistor R1 is connected between the power supply VCC and the first end of the humidity sensitive element 112. In other words, a first terminal of the resistor R1 is connected to the power source VCC, and a second terminal of the resistor R1 is connected to a first terminal of the humidity sensor 112. The second end of the humidity sensor 112 is connected to the ground GND.
The capacitor C1 is connected between the first terminal of the humidity sensor 112 and the ground GND. In other words, the first plate of the capacitor C1 is connected to the first terminal of the humidity sensor 112, and the second plate of the capacitor C1 is connected to the ground GND.
When the humidity alarm circuit 10 of the present application is in operation, the current in the power supply VCC flows into the ground GND through the resistor R1 and the humidity sensor 112 in sequence. Resistor R1 and humidity sensor 112 share the voltage in the power supply VCC. When the humidity of the environment in which the humidity sensor 112 is located increases, the voltage of the humidity sensor 112 also increases, and the voltage of the resistor R1 decreases. Conversely, when the humidity of the environment in which the humidity sensor 112 is located decreases, the voltage of the humidity sensor 112 decreases, and the voltage of the resistor R1 increases. The capacitor C1 has a voltage stabilizing function, so that the electric signal output from the first end of the humidity sensor 112 to the first input end of the comparison and amplification circuit 130 is more stable, thereby avoiding the fluctuation of the electric signal and improving the accuracy of humidity alarm.
Still referring to fig. 6, in some embodiments, the comparison amplification circuit 130 includes an operational amplifier a1, a resistor R2, a resistor R3, a resistor R4, and a capacitor C2.
Specifically, the operational amplifier a1 is used to calculate a voltage difference of the voltage of the humidity sensitive element 112 with respect to a reference voltage and amplify the voltage difference. The operational amplifier a1 has a non-inverting input, an inverting input, and an output. The resistor R2 is connected between the first terminal of the humidity sensitive element 112 and the non-inverting input of the operational amplifier a 1. In other words, a first terminal of the resistor R2 is connected to a first terminal of the humidity sensor 112, and a second terminal of the resistor R2 is connected to a non-inverting input terminal of the operational amplifier A1. A first terminal of the resistor R2 constitutes a first input terminal of the comparison amplification circuit 130.
The resistor R3 is connected between the reference circuit 120 and the inverting input of the operational amplifier a 1. In other words, a first terminal of the resistor R3 is connected to the reference circuit 120, and a second terminal of the resistor R3 is connected to the inverting input terminal of the operational amplifier a 1. A first terminal of the resistor R3 constitutes a second input terminal of the comparison amplification circuit 130.
The resistor R4 is connected between the non-inverting input of the operational amplifier a1 and the output of the operational amplifier a 1. In other words, the first terminal of the resistor R4 is connected to the non-inverting input terminal of the operational amplifier a1, and the second terminal of the resistor R4 is connected to the output terminal of the operational amplifier a 1.
The capacitor C2 is connected between the non-inverting input of the operational amplifier a1 and the output of the operational amplifier a 1. In other words, the first plate of the capacitor C2 is connected to the non-inverting input of the operational amplifier a1, and the second plate of the capacitor C2 is connected to the output of the operational amplifier a 1. The second plate of the capacitor C2, the second terminal of the resistor R4, and the output terminal of the operational amplifier a1 together form the output terminal of the comparing and amplifying circuit 130.
In the embodiment of the present application, the voltage difference of the voltage of the humidity sensitive element 112 with respect to the reference voltage is calculated by the operational amplifier a1 and amplified. The weak signal can be amplified into a high-level signal by the capability of the operational amplifier with infinite amplification factor, so that the accuracy of humidity monitoring and alarming can be improved.
Still referring to fig. 6, in some embodiments, the reference circuit 120 includes an operational amplifier a2, a resistor R5, and a resistor R6.
Specifically, the operational amplifier a2 has a non-inverting input terminal, an inverting input terminal, and an output terminal. The resistor R5 is connected between the power supply VCC and the non-inverting input of the operational amplifier a 2. In other words, a first terminal of the resistor R5 is connected to the power source VCC, and a second terminal of the resistor R5 is connected to the non-inverting input terminal of the operational amplifier a 2.
The resistor R6 is connected between the non-inverting input terminal of the operational amplifier a2 and the ground GND. In other words, the first terminal of the resistor R6 is connected to the non-inverting input terminal of the operational amplifier a2, and the second terminal of the resistor R6 is connected to the ground GND.
The inverting input terminal of the operational amplifier a2 is connected to the output terminal of the operational amplifier a2, and the output terminal of the operational amplifier a2 is connected to the second input terminal of the comparison amplification circuit 130. In other words, the output of the operational amplifier a2 constitutes the output of the reference circuit 120.
When the humidity alarm circuit 10 works, the current in the power supply VCC flows into the ground wire GND through the resistor R5 and the resistor R6 in sequence. Resistor R5 and resistor R6 share the voltage in the power supply VCC. The voltage of the resistor R6 is output as a reference voltage through the operational amplifier a 2.
Further, at least one of the resistor R5 and the resistor R6 is an adjustable resistor. In this case, the reference voltage can be adjusted by adjusting the resistance values of the resistor R5 and the resistor R6.
Still referring to fig. 6, in some embodiments, alarm circuit 140 includes a resistor R7 and a light emitting diode LED 1.
Specifically, resistor R7 and light emitting diode LED1 are connected in series to form alarm circuit 140. The alarm circuit 140 is connected between the output terminal of the comparison amplification circuit 130 and the ground GND. The resistor R7 is connected between the output end of the comparison amplifying circuit 130 and the light emitting diode LED 2; the light emitting diode LED2 is connected between the resistor R7 and the ground GND. In other words, the first terminal of the resistor R7 is connected to the output terminal of the comparison amplifier circuit 130, the anode of the light emitting diode LED1 is connected to the second terminal of the resistor R7, and the cathode of the light emitting diode LED1 is connected to the ground GND.
In other embodiments, the alarm circuit 140 may also include a buzzer in series or parallel with the light emitting diode LED1, or/and a wireless transmitter in series or parallel with the light emitting diode.
Fig. 7 is a schematic structural diagram of another humidity alarm circuit 10 according to an embodiment of the present disclosure. Referring to fig. 7, the humidity alarm circuit 10 of the present application may further include a power indication circuit 150.
Specifically, the power indication circuit 150 is used to indicate whether the power VCC has power. The power indicator circuit 150 has a first terminal and a second terminal. The first terminal of the power indication circuit 150 is connected to the power VCC, and the second terminal of the power indication circuit 150 is connected to the ground GND. When the power source VCC has power, the power source indication circuit 150 is powered on; conversely, when the power source VCC does not have power, the power source indication circuit 150 is not powered.
Further, as shown in fig. 8, which is a schematic structural diagram of another humidity alarm circuit 10 provided in the embodiment of the present application, the power indication circuit 150 includes a resistor R8 and a light emitting diode LED 2.
Specifically, resistor R8 and light emitting diode LED2 are connected in series to form power indicator circuit 150. The power supply indication circuit 150 is connected between a power supply VCC and a ground GND. The resistor R8 is connected between the power supply VCC and the LED 2; the light emitting diode LED2 is connected between the resistor R8 and the ground GND. In other words, a first terminal of the resistor R8 is connected to the power source VCC, an anode of the light emitting diode LED2 is connected to a second terminal of the resistor R8, and a cathode of the light emitting diode LED2 is connected to the ground GND.
In some other embodiments, the power indication circuit 150 may also include a wireless transmitter in series or parallel with the light emitting diode LED 2.
In the embodiment of the present application, the humidity alarm circuit 10 includes a voltage division detection circuit 110, a reference circuit 120, a comparison amplification circuit 130, and an alarm circuit 140. The voltage division detecting circuit 110 includes a humidity sensor 112, and the voltage of the humidity sensor 112 varies according to the humidity of the environment in which the humidity sensor 112 is located. The reference circuit 120 is used to output a reference voltage. The comparison amplifier circuit 130 is used to determine the magnitude relationship between the voltage of the humidity sensor 112 and the reference voltage. When the voltage of the humidity sensitive element 112 is greater than the reference voltage, the comparison amplifying circuit 130 controls the alarm circuit 140 to alarm; when the voltage of the humidity sensitive element 112 is less than or equal to the reference voltage, the comparing and amplifying circuit 130 controls the alarm circuit 140 not to alarm. The humidity alarm circuit 10 monitors humidity by comparing the amplification circuit 130 to determine the relationship between the voltage of the humidity sensitive element 112 and the reference voltage, without performing analog-to-digital conversion on the voltage of the humidity sensitive element 112, so as to avoid the problem that a single chip microcomputer cannot process weak analog signals due to the limitation of the accuracy of the analog-to-digital conversion, and improve the accuracy of humidity alarm. In the voltage division detection circuit 110, a dew condensation sensor is adopted as the humidity sensitive element 112, and compared with a humidity sensitive resistor, the humidity sensitive area of the humidity sensitive element 112 for detecting humidity can be increased, so that the influence of dust on the accuracy of humidity alarm is reduced. In the comparison amplification circuit 130, a voltage difference of the voltage of the humidity sensitive element 112 with respect to the reference voltage is calculated by the operational amplifier a1, and the voltage difference is amplified. The weak signal can be amplified into a high-level signal by the capability of the operational amplifier with infinite amplification factor, so that the accuracy of humidity monitoring and alarming can be improved. In the reference circuit 120, at least one of the resistor R5 and the resistor R6 is an adjustable resistor, so that the magnitude of the reference voltage can be adjusted, and the application range of the humidity alarm circuit 10 can be improved. The humidity alarm circuit 10 may further include a power indication circuit 150 for indicating whether the power source VCC has power, which may make the humidity alarm circuit 10 more convenient to use.
The embodiment of the present application further provides a humidity alarm device 20, where the humidity alarm device 20 includes the humidity alarm circuit 10 in any one of the above embodiments.
Specifically, the humidity alarm circuit 10 includes a voltage division detection circuit 110, a reference circuit 120, a comparison amplification circuit 130, and an alarm circuit 140. The voltage division detection circuit 110 includes a humidity sensor 112, a first terminal of the humidity sensor 112 is connected to a power source VCC, a second terminal of the humidity sensor 112 is connected to a ground GND, and a voltage of the humidity sensor 112 varies with humidity of an environment where the humidity sensor 112 is located. The comparison amplification circuit 130 includes a first input terminal, a second input terminal, and an output terminal; a first input terminal of the comparison amplification circuit 130 is connected to a first terminal of the humidity sensor 112 to input the voltage of the humidity sensor 112; a second input terminal of the comparison amplification circuit 130 is connected to the reference circuit 120 to input the reference voltage output by the reference circuit 120. A first terminal of the alarm circuit 140 is connected to the output terminal of the comparison amplifier circuit 130, and a second terminal of the alarm circuit 140 is connected to the ground GND. When the voltage of the humidity sensitive element 112 is greater than the reference voltage, the comparison amplification circuit 130 outputs a high level signal, and the alarm circuit 140 gives an alarm; when the voltage of the humidity sensor 112 is less than or equal to the reference voltage, the comparison amplification circuit 130 outputs a low level signal, and the alarm circuit 140 does not alarm.
In some embodiments, the voltage division detection circuit 110 further includes: resistor R1 and capacitor C1. A first terminal of the resistor R1 is connected to the power source VCC, and a second terminal of the resistor R1 is connected to a first terminal of the humidity sensitive element 112. A first plate of the capacitor C1 is connected to a first terminal of the humidity sensor 112, and a second plate of the capacitor C1 is connected to the ground GND.
In some embodiments, the moisture sensitive element 112 comprises a dew sensor.
In some embodiments, the comparison amplification circuit 130 includes: operational amplifier A1, resistor R2, resistor R3, resistor R4 and capacitor C2. A first terminal of the resistor R2 is connected to a first terminal of the humidity sensor 112, and a second terminal of the resistor R2 is connected to a non-inverting input of the operational amplifier A1. A first terminal of the resistor R3 is connected to the reference circuit 120, and a second terminal of the resistor R3 is connected to the inverting input terminal of the operational amplifier a 1. A first terminal of the resistor R4 is connected to the non-inverting input terminal of the operational amplifier a1, and a second terminal of the resistor R4 is connected to the output terminal of the operational amplifier a 1. The first plate of the capacitor C2 is connected to the non-inverting input of the operational amplifier a1, and the second plate of the capacitor C2 is connected to the output of the operational amplifier a 1.
In some embodiments, the reference circuit 120 includes: operational amplifier a2, resistor R5, and resistor R6. A first terminal of the resistor R5 is connected to the power supply VCC, and a second terminal of the resistor R5 is connected to the non-inverting input terminal of the operational amplifier a 2. A first end of the resistor R6 is connected to the non-inverting input terminal of the operational amplifier a2, and a second end of the resistor R6 is connected to the ground GND. The inverting input terminal of the operational amplifier a2 is connected to the output terminal of the operational amplifier a2, and the output terminal of the operational amplifier a2 is connected to the second input terminal of the comparison amplification circuit 130.
Further, at least one of the resistor R5 and the resistor R6 is an adjustable resistor.
In some embodiments, the alarm circuit 140 includes: resistor R7 and light emitting diode LED 1. A first end of the resistor R7 is connected to the output end of the comparison amplifier circuit 130, an anode of the light emitting diode LED1 is connected to a second end of the resistor R7, and a cathode of the light emitting diode LED1 is connected to the ground GND.
In some embodiments, the humidity alarm circuit 10 further comprises: a power indication circuit 150. The first terminal of the power indication circuit 150 is connected to the power VCC, and the second terminal of the power indication circuit 150 is connected to the ground GND.
Further, the power supply indication circuit 150 includes: resistor R8 and light emitting diode LED 2. A first end of the resistor R8 is connected to the power source VCC, an anode of the light emitting diode LED2 is connected to a second end of the resistor R8, and a cathode of the light emitting diode LED2 is connected to the ground GND.
Fig. 9 is a schematic perspective view of a dust-proof protective shell 210 in the humidity alarm device 20 according to the embodiment; fig. 10 is a schematic cross-sectional view of a humidity alarm device 20 according to an embodiment of the present application. Referring to fig. 9 and 10, in some embodiments, the humidity alarm device 20 of the present application further includes a dust-proof protective case 210.
Specifically, referring to fig. 9 and 10, the dust-proof protective shell 210 includes a shell 211 and a cavity 212 surrounded by the shell 211. The housing 211 has an aperture 214 that communicates the cavity 212 with the environment in which the housing 211 is located. In other words, the housing 211 has a cavity 212 formed therein that can be used for accommodation. Air molecules outside the housing 211 may enter the cavity 212 through the aperture 214. The humidity sensor 112 is located in the cavity 212 and can detect air humidity through an aperture 214 in the housing 211. The housing 211 can prevent dust in the air from falling on the surface of the humidity sensor 112, thereby prolonging the service life of the humidity sensor 112 and improving the accuracy of the humidity detection of the humidity sensor 112.
Further, all electrical components of the humidity alarm circuit 10 are located in the dust-proof protective case 210.
In the embodiment of the present application, the humidity alarm device 20 includes the humidity alarm circuit 10 in any one of the above-mentioned embodiments. The humidity alarm device 20 monitors humidity by comparing the magnitude relation between the voltage of the humidity sensitive element 112 and the reference voltage judged by the amplifying circuit 130, and does not need a single chip microcomputer, so that analog-to-digital conversion of the voltage of the humidity sensitive element 112 is not needed, the problem that the single chip microcomputer cannot process weak analog signals due to the limitation of the accuracy of the analog-to-digital conversion is solved, and the accuracy of humidity alarm is improved. Meanwhile, the comparison and amplification circuit 130 can amplify the voltage difference between the voltage of the humidity sensitive element 112 and the reference voltage, so as to improve the monitoring capability of the humidity alarm circuit 10 on weak humidity changes, thereby further improving the accuracy of humidity alarm. The housing 211 can prevent dust in the air from falling on the surface of the humidity sensor 112, thereby prolonging the service life of the humidity sensor 112 and improving the accuracy of the humidity detection of the humidity sensor 112. When all the electrical devices of the humidity alarm circuit 10 are located in the dustproof protective shell 210, the dust can be prevented from affecting the normal operation of other electrical devices in the humidity alarm circuit 10, so that the service life of the humidity alarm device 20 can be prolonged, and the humidity detection accuracy of the humidity alarm device 20 is improved.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (10)
1. A humidity alarm circuit, comprising: the device comprises a voltage division detection circuit, a reference circuit, a comparison amplification circuit and an alarm circuit;
the voltage division detection circuit comprises a humidity sensitive element, wherein a first end of the humidity sensitive element is connected with a power supply VCC, a second end of the humidity sensitive element is connected with a ground wire GND, and the voltage of the humidity sensitive element changes along with the humidity of the environment where the humidity sensitive element is located;
the comparison amplification circuit comprises a first input end, a second input end and an output end; the first input end of the comparison amplifying circuit is connected with the first end of the humidity sensitive element so as to input the voltage of the humidity sensitive element; the second input end of the comparison amplification circuit is connected with the reference circuit so as to input the reference voltage output by the reference circuit;
the first end of the alarm circuit is connected with the output end of the comparison amplification circuit, and the second end of the alarm circuit is connected with the ground wire GND;
when the voltage of the humidity sensitive element is greater than the reference voltage, the comparison amplification circuit outputs a high-level signal, and the alarm circuit gives an alarm; when the voltage of the humidity sensitive element is less than or equal to the reference voltage, the comparison amplification circuit outputs a low-level signal, and the alarm circuit does not give an alarm.
2. The humidity alarm circuit of claim 1, wherein the divided voltage detection circuit further comprises: a resistor R1 and a capacitor C1;
a first end of the resistor R1 is connected with the power supply VCC, and a second end of the resistor R1 is connected with a first end of the humidity sensitive element;
a first plate of the capacitor C1 is connected with a first end of the humidity sensitive element, and a second plate of the capacitor C1 is connected with the ground GND;
the moisture sensitive element includes a dew sensor.
3. The humidity alarm circuit of claim 1, wherein the comparison amplification circuit comprises: the circuit comprises an operational amplifier A1, a resistor R2, a resistor R3, a resistor R4 and a capacitor C2;
a first end of the resistor R2 is connected with a first end of the humidity sensitive element, and a second end of the resistor R2 is connected with a non-inverting input end of the operational amplifier A1;
a first end of the resistor R3 is connected with the reference circuit, and a second end of the resistor R3 is connected with an inverting input end of the operational amplifier A1;
a first end of the resistor R4 is connected with a non-inverting input end of the operational amplifier A1, and a second end of the resistor R4 is connected with an output end of the operational amplifier A1;
the first plate of the capacitor C2 is connected with the non-inverting input end of the operational amplifier A1, and the second plate of the capacitor C2 is connected with the output end of the operational amplifier A1.
4. The humidity alarm circuit of claim 1, wherein the reference circuit comprises: an operational amplifier A2, a resistor R5 and a resistor R6;
a first end of the resistor R5 is connected with the power supply VCC, and a second end of the resistor R5 is connected with a non-inverting input end of the operational amplifier A2;
a first end of the resistor R6 is connected with a non-inverting input end of the operational amplifier A2, and a second end of the resistor R6 is connected with the ground GND;
the inverting input terminal of the operational amplifier A2 is connected to the output terminal of the operational amplifier A2, and the output terminal of the operational amplifier A2 is connected to the second input terminal of the comparison amplification circuit.
5. The humidity alarm circuit of claim 4, wherein at least one of the resistors R5 and R6 is an adjustable resistor.
6. The humidity alarm circuit of claim 1, wherein the alarm circuit comprises: resistor R7 and light emitting diode LED 1;
a first end of the resistor R7 is connected to an output end of the comparison and amplification circuit, an anode of the light emitting diode LED1 is connected to a second end of the resistor R7, and a cathode of the light emitting diode LED1 is connected to the ground GND.
7. The humidity alarm circuit of claim 1, further comprising: a power indication circuit;
the first end of the power supply indicating circuit is connected with the power supply VCC, and the second end of the power supply indicating circuit is connected with the ground wire GND.
8. The humidity alarm circuit of claim 7, wherein said power indication circuit comprises: resistor R8 and light emitting diode LED 2;
the first end of the resistor R8 is connected with the power supply VCC, the anode of the light emitting diode LED2 is connected with the second end of the resistor R8, and the cathode of the light emitting diode LED2 is connected with the ground line GND.
9. A humidity alarm device comprising a humidity alarm circuit according to any one of claims 1 to 8.
10. A humidity alarm device according to claim 9 further comprising: a dustproof protective shell;
the dustproof protective shell comprises a shell and a cavity formed by surrounding the shell, the shell is provided with a small hole for communicating the cavity with the environment where the shell is located, and the humidity sensitive element is located in the cavity.
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|---|---|---|---|
| CN202120062740.3U CN214175265U (en) | 2021-01-11 | 2021-01-11 | Humidity alarm circuit and device |
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| CN202120062740.3U CN214175265U (en) | 2021-01-11 | 2021-01-11 | Humidity alarm circuit and device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112750287A (en) * | 2021-01-11 | 2021-05-04 | 莱福士电力电子设备（深圳）有限公司 | Humidity alarm circuit and device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112750287A (en) * | 2021-01-11 | 2021-05-04 | 莱福士电力电子设备（深圳）有限公司 | Humidity alarm circuit and device |
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