Temperature detection circuit and temperature adjusting device applied to greenhouse

Abstract

The utility model discloses a temperature detection circuit and a temperature adjusting device applied in a greenhouse, and belongs to the field of temperature detection, when a square wave generation module outputs a high level, a first switch module can control a measuring circuit to measure a first detection resistor, and when the square wave generation module outputs a low level, a second switch module can control a measuring circuit to measure a second detection resistor. The first switch module can control the measuring circuit to measure the second detection resistance. According to the scheme, the detection resistors are automatically switched through the square waves output by the square wave generation module, the first detection resistor and the second detection resistor alternately work for a half period in one period and do not work all the time, the situation that temperature detection is inaccurate due to self-heating of the detection resistors is avoided, the detection precision is improved, and the detection efficiency is improved. And the automatic switching does not need manual switching.

Description

Technical Field

[0001] The utility model relates to the field of temperature detection, in particular to a temperature detection circuit and a temperature regulating device used in a greenhouse. Background Art

[0002] Greenhouse cultivation is widely used in plant cultivation and breeding. Greenhouse cultivation can provide plants with ideal growth conditions, including ambient temperature, humidity and light, which can not only prevent plants from suffering from harsh environments, but also ensure the needs of plant growth.

[0003] Among them, the temperature condition mainly depends on the temperature control device, such as heater and air conditioner, and the premise for the temperature control device to adjust the temperature is that the temperature sensor can accurately measure the temperature in the greenhouse. With the development of automation, the temperature control device now has its own temperature sensor, and then adjusts the cooling or heating capacity of the temperature control device based on the measurement value of the temperature sensor.

[0004] Among them, commonly used temperature sensors include resistive temperature sensors, that is, when the temperature changes, the resistance value of the resistor in the sensor will also change, such as metal thermal resistor temperature sensors and thermistor temperature sensors.

[0005] However, since the temperature is measured by resistors, when current flows through them, the resistors will inevitably generate heat. In some cases, greenhouses need temperature control devices to work (such as heating in winter), so the resistive sensor needs to work all the time, that is, the resistive temperature sensor works for a long time and generates more heat. At this time, self-heating will also affect its resistance change, resulting in inaccurate measurement. Utility Model Content

[0006] In order to overcome the deficiencies of the prior art, the utility model provides a temperature detection circuit and a temperature regulating device applied in a greenhouse, so as to solve the problem of inaccurate temperature sensor measurement when the temperature regulating device in the existing greenhouse is always working.

[0007] The technical solution adopted by the utility model to solve its technical problems is:

[0008] On the one hand, a temperature detection circuit for use in a greenhouse is provided, comprising: a detection resistor whose resistance changes with temperature, a measurement circuit for measuring the change in resistance of the detection resistor, and a switch circuit for controlling whether the detection resistor is connected to the measurement circuit;

[0009] The detection resistor includes a first detection resistor and a second detection resistor;

[0010] The switch circuit comprises a square wave generating module and a first switch module; the square wave generating module is used to generate a square wave, and the maintenance time of the high level and the low level in each cycle of the square wave respectively occupies half a cycle;

[0011] The square wave generating module is electrically connected to the first switch module. When the square wave generating module outputs a high level, the first switch module controls the first detection resistor to be connected to the measurement circuit, and controls the second detection resistor to be disconnected from the measurement circuit; when the square wave generating module outputs a low level, the first switch module controls the second detection resistor to be connected to the measurement circuit, and controls the first detection resistor to be disconnected from the measurement circuit.

[0012] Furthermore, the switch circuit further comprises a signal modulation module, and the first switch module comprises a first switch and a second switch;

[0013] The square wave generating module is connected to the input end of the signal modulating module, and the signal modulating module includes two output ends; the first output end of the signal modulating module is electrically connected to the first switch; the second output end of the signal modulating module is electrically connected to the second switch;

[0014] When the square wave generating module outputs a high level, the first output terminal outputs a high level and the second output terminal outputs a low level; when the square wave generating module outputs a low level, the first output terminal outputs a low level and the second output terminal outputs a high level;

[0015] When the first switch receives a high-level signal, the first detection resistor is controlled to be connected to the measurement circuit; when the first switch receives a low-level signal, the first detection resistor is controlled to be disconnected from the measurement circuit; when the second switch receives a high-level signal, the second detection resistor is controlled to be connected to the measurement circuit; when the second switch receives a low-level signal, the second detection resistor is controlled to be disconnected from the measurement circuit.

[0016] Further, the signal modulation module includes a first voltage comparator and a second voltage comparator; the output end of the first voltage comparator is a first output end, and the output end of the second voltage comparator is a second output end;

[0017] The square wave generating module is respectively connected to the positive phase input terminal of the first voltage comparator and the negative phase input terminal of the second voltage comparator, and the negative phase input terminal of the first voltage comparator and the positive phase input terminal of the second voltage comparator are respectively input with a first threshold level, and the first threshold level is less than the high level and greater than the low level.

[0018] Further, the signal modulation module includes an inverter;

[0019] The input end of the signal modulation module is directly connected to the first output end;

[0020] The input end of the signal modulation module is connected to the second output end through the inverter.

[0021] Further, the first switch module is a first relay, the first relay comprises a coil, an armature, a first moving contact and a second moving contact, and the square wave generating module is electrically connected to the coil;

[0022] When the armature is located at the first moving contact, the measuring circuit is connected to the first detection resistor; when the armature is located at the second moving contact, the measuring circuit is connected to the second detection resistor;

[0023] When the square wave generating module outputs a high level, the armature is located at the first moving contact, and when the square wave generating module outputs a low level, the armature is located at the second moving contact.

[0024] Furthermore, the output end of the measuring circuit is used to output voltage; the square wave generating module includes: a third voltage comparator, a second switch module, a first square wave generator and a second square wave generator; the first square wave generator is used to generate a square wave with a period of T1, and the second square wave generator is used to generate a square wave with a period of T2, and T1 is not equal to T2;

[0025] The non-inverting input terminal of the third voltage comparator is connected to the output terminal of the measuring circuit, and the inverting input terminal of the third voltage comparator inputs the second threshold level;

[0026] The output end of the third voltage comparator is connected to the second switch module;

[0027] When the third voltage comparator outputs a high level, the second switch module controls the first square wave generator to be electrically connected to the first switch module, and controls the second square wave generator to be electrically disconnected from the first switch module;

[0028] When the third voltage comparator outputs a low level, the second switch module controls the first square wave generator to be electrically disconnected from the first switch module, and controls the second square wave generator to be electrically connected to the first switch module.

[0029] Further, the second switch module includes a third switch and a fourth switch;

[0030] The output end of the third voltage comparator is connected to the third switch and the fourth switch respectively;

[0031] When the third voltage comparator outputs a high level, the third switch controls the first square wave generator to be electrically connected to the first switch module; the fourth switch controls the second square wave generator to be electrically disconnected from the first switch module;

[0032] When the third voltage comparator outputs a low level, the third switch controls the first square wave generator to be electrically disconnected from the first switch module; and the fourth switch controls the second square wave generator to be electrically connected to the first switch module.

[0033] Further, the second switch module is a second relay, the second relay comprises a coil, an armature, a third moving contact and a fourth moving contact, and the output end of the third voltage comparator is electrically connected to the coil;

[0034] When the armature is located at the third moving contact, the first square wave generator is electrically connected to the first switch module; when the armature is located at the fourth moving contact, the second square wave generator is electrically connected to the first switch module;

[0035] When the third voltage comparator outputs a high level, the armature is located at the third moving contact, and when the third voltage comparator outputs a low level, the armature is located at the fourth moving contact.

[0036] Furthermore, the detection resistor is a metal thermal resistor or a thermistor.

[0037] On the other hand, a temperature regulating device for use in a greenhouse is provided, comprising: the temperature detection circuit as described above.

[0038] This application adopts the above technical solution, which has at least the following beneficial effects:

[0039] The technical solution of the present application provides a temperature detection circuit and a temperature regulating device used in a greenhouse, including: a detection resistor whose resistance changes with temperature, a measuring circuit for measuring the change in resistance of the detection resistor, and a switch circuit for controlling whether the detection resistor is connected to the measuring circuit; wherein the detection resistor includes a first detection resistor and a second detection resistor, and the switch circuit includes a square wave generating module and a first switch module, and the square wave generating module can output high-level and low-level square waves; when the square wave generating module outputs a high level, the first switch module can control the measuring circuit to measure the first detection resistor, and when the square wave generating module outputs a low level, the first switch module can control the measuring circuit to measure the second detection resistor. Since the high level and low level of the square wave generated by the square wave generating module each account for half, the working time of the first detection resistor and the second detection resistor is the same, and the working time of the first detection resistor and the second detection resistor can be controlled by only controlling the size of the period of the square wave generated by the square wave generating module. The present application scheme automatically switches the detection resistor through the square wave output by the square wave generating module. Within one cycle, the first detection resistor and the second detection resistor work alternately for half a cycle and will not work continuously, thereby avoiding the situation where inaccurate temperature detection is caused by self-heating of the detection resistor, improving the detection accuracy, and the automatic switching does not require manual switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 This is a schematic diagram of a temperature detection circuit structure provided by an embodiment of the utility model;

[0042] Figure 2 This is a schematic diagram of a temperature detection circuit structure of a first switch module using a first switch and a second switch provided in an embodiment of the utility model;

[0043] Figure 3 This is a schematic diagram of a temperature detection circuit structure of another first switch module provided by an embodiment of the utility model using a first switch and a second switch;

[0044] Figure 4 This is a schematic diagram of a temperature detection circuit structure in which a first switch adopts a relay provided by an embodiment of the utility model;

[0045] Figure 5 It is a schematic diagram of a temperature detection circuit structure in which a square wave generating module provided by an embodiment of the utility model includes two square wave generators;

[0046] Figure 6 It is a schematic diagram of a temperature detection circuit structure in which a specific square wave generating module provided by an embodiment of the utility model includes two square wave generators;

[0047] Figure 7 It is a schematic diagram of the structure of a temperature detection circuit of another square wave generating module provided by an embodiment of the utility model, including two square wave generators. Description of the drawings:

[0049] 1-measurement circuit, 2-square wave generating module, 3-first switch module, 4-inverter, 5-second switch module, 6-first square wave generator, 7-second square wave generator, R1-first detection resistor, R2-second detection resistor, K1-first switch, K2-second switch, K3-first relay, K4-third switch, K5-fourth switch, K6-second relay, U1-first voltage comparator, U2-second voltage comparator, U3-third voltage comparator, V1-first threshold level, V2-second threshold level. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present utility model is described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0051] In the prior art, in order to avoid self-heating, the solution adopted is to use a constant current source to power the resistive temperature sensor to ensure that the current flowing through the resistor is constant, and then provide compensation. However, in fact, even if the current is constant, the heat generated will increase when the working time is long. Even if compensation is provided, the measurement accuracy cannot be guaranteed.

[0052] Reference Figure 1 An embodiment of the utility model provides a temperature detection circuit for use in a greenhouse, comprising: a detection resistor whose resistance changes with temperature, a measurement circuit 1 for measuring the change in resistance of the detection resistor, and a switch circuit for controlling whether the detection resistor is connected to the measurement circuit; it should be emphasized that the present application does not improve the measurement circuit, and it uses existing technology, such as directly measuring the voltage of the detection resistor, and when the detection resistor changes, the voltage across it also changes accordingly.

[0053] The detection resistor includes a first detection resistor R1 and a second detection resistor R2; it should be noted that the detection resistor is a metal thermal resistor or a thermistor. Metal thermal resistors are usually made of metal resistance materials, such as platinum, nickel and chromium. Its temperature change causes a change in resistance, thereby measuring temperature. The working principle of metal thermal resistors is based on the thermoelectric effect, which refers to the electromotive force generated when there is a temperature difference between two different materials. For metal thermal resistors, their essence is a wire made of metal material. When the wire is subjected to temperature changes, the resistance of the wire itself will also change. Such as Pt100. Thermistor is a temperature sensor based on the thermal effect. Its working principle is to measure temperature by using the change in resistance value when the temperature changes. Unlike metal thermal resistors, thermistors are usually made of semiconductors or oxide materials. The most common ones are NTC (negative temperature coefficient) and PTC (positive temperature coefficient). The resistance value of NTC decreases with increasing temperature, while the resistance value of PTC increases with increasing temperature.

[0054] The switching circuit includes a square wave generating module 2 and a first switching module 3; the square wave generating module is used to generate a square wave, and the maintenance time of the high level and the low level in each cycle of the square wave respectively occupies half a cycle; the square wave generating module generates square waves, which is also a commonly used technical means in this field. The present application only needs to adjust its cycle and does not require creative labor.

[0055] The square wave generating module is electrically connected to the first switch module. When the square wave generating module outputs a high level, the first switch module controls the first detection resistor to be connected to the measurement circuit, and controls the second detection resistor to be disconnected from the measurement circuit; when the square wave generating module outputs a low level, the first switch module controls the second detection resistor to be connected to the measurement circuit, and controls the first detection resistor to be disconnected from the measurement circuit.

[0056] The temperature detection circuit provided in the embodiment of the present application is essentially based on the existing circuit, adding a detection resistor and a switch circuit for controlling the switching of two detection resistors. When the square wave generating module outputs a high level, the first switch module can control the measurement circuit to measure the first detection resistor, and when the square wave generating module outputs a low level, the first switch module can control the measurement circuit to measure the second detection resistor. Since the high level and low level of the square wave generated by the square wave generating module each account for half, the working time of the first detection resistor and the second detection resistor is the same, and the working time of the first detection resistor and the second detection resistor can be controlled by only controlling the size of the period of the square wave generated by the square wave generating module. The present application scheme automatically switches the detection resistor through the square wave output by the square wave generating module. In one cycle, the first detection resistor and the second detection resistor work in turn for half a cycle, and will not work all the time, thereby avoiding the situation where the temperature detection is inaccurately measured due to the self-heating of the detection resistor, improving the detection accuracy, and the automatic switching does not require manual switching.

[0057] In order to more specifically illustrate the solution of the present application, the present application provides several more detailed embodiments for illustration.

[0058] like Figure 2 or Figure 3 As shown, the switch circuit further includes a signal modulation module, and the first switch module includes a first switch K1 and a second switch K2;

[0059] The square wave generating module is connected to the input end of the signal modulating module, and the signal modulating module includes two output ends; the first output end of the signal modulating module is electrically connected to the first switch; the second output end of the signal modulating module is electrically connected to the second switch;

[0060] When the square wave generating module outputs a high level, the first output terminal outputs a high level and the second output terminal outputs a low level; when the square wave generating module outputs a low level, the first output terminal outputs a low level and the second output terminal outputs a high level;

[0061] When the first switch receives a high-level signal, the first detection resistor is controlled to be connected to the measurement circuit; when the first switch receives a low-level signal, the first detection resistor is controlled to be disconnected from the measurement circuit; when the second switch receives a high-level signal, the second detection resistor is controlled to be connected to the measurement circuit; when the second switch receives a low-level signal, the second detection resistor is controlled to be disconnected from the measurement circuit.

[0062] In one embodiment, if Figure 2As shown, the signal modulation module includes a first voltage comparator and a second voltage comparator; the output end of the first voltage comparator is a first output end, and the output end of the second voltage comparator is a second output end; the square wave generating module is respectively connected to the positive phase input end of the first voltage comparator and the inverting input end of the second voltage comparator, and the inverting input end of the first voltage comparator and the positive phase input end of the second voltage comparator are respectively input with a first threshold level V1, and the first threshold level is less than the high level and greater than the low level.

[0063] In another embodiment, if Figure 3 As shown, the signal modulation module includes an inverter;

[0064] The input end of the signal modulation module is directly connected to the first output end;

[0065] The input end of the signal modulation module is connected to the second output end through the inverter 4 .

[0066] As an optional implementation of the present application, the first switch module may use a relay including two moving contacts, as shown in FIG. Figure 4 As shown, the first switch module is the first relay K3, the first relay includes a coil, an armature, a first moving contact and a second moving contact, and the square wave generating module is electrically connected to the coil; it should be noted that the high level output by the general square wave generating module cannot directly drive the coil to move the armature, and an amplification circuit needs to be added in the middle. The specific setting can be based on actual needs.

[0067] When the armature is located at the first moving contact, the measuring circuit is connected to the first detection resistor; when the armature is located at the second moving contact, the measuring circuit is connected to the second detection resistor;

[0068] When the square wave generating module outputs a high level, the armature is located at the first moving contact, and when the square wave generating module outputs a low level, the armature is located at the second moving contact.

[0069] In actual use, the suitable temperature required by plants during the day and night is different, and some may be quite different. If the temperature to be maintained is high and the square wave period is large, the detection resistor will work for a longer time. If the square wave period is set to be smaller, the first detection resistor and the second detection resistor will switch too frequently.

[0070] Therefore, in order to solve the above problems, the present application provides a solution in which the square wave generating module adopts two square wave generators, and the output of the measuring circuit in the embodiment of the present application is a voltage analog quantity, such as Figure 5As shown, the square wave generating module includes: a third voltage comparator U3, a second switch module 5, a first square wave generator 6 and a second square wave generator 7; the first square wave generator is used to generate a square wave with a period of T1, and the second square wave generator is used to generate a square wave with a period of T2, and T1 is not equal to T2; it can be understood that the high level and low level of the square waves generated by the first square wave generator and the second square wave generator are the same.

[0071] The non-inverting input terminal of the third voltage comparator is connected to the output terminal of the measuring circuit, and the inverting input terminal of the third voltage comparator inputs the second threshold level V2;

[0072] The output end of the third voltage comparator is connected to the second switch module;

[0073] When the third voltage comparator outputs a high level, the second switch module controls the first square wave generator to be electrically connected to the first switch module, and controls the second square wave generator to be electrically disconnected from the first switch module;

[0074] When the third voltage comparator outputs a low level, the second switch module controls the first square wave generator to be electrically disconnected from the first switch module, and controls the second square wave generator to be electrically connected to the first switch module.

[0075] Since the voltage output by the measurement circuit represents the current temperature, the detection resistor with a larger resistance as the temperature increases is used as an example. The larger the resistance, the higher the voltage across the two ends. When the voltage output by the measurement circuit is greater than the second threshold level, it means that the current temperature exceeds the temperature corresponding to the second threshold level. At this time, the first square wave generator is used (its period T1 is less than the period T2 of the second square wave generator. The smaller the period, the shorter the working time of each detection resistor). When the voltage output by the measurement circuit is less than the second threshold level, it means that the current temperature is less than the temperature corresponding to the second threshold level. At this time, the second square wave generator is used. This ensures that when the temperature is high, the detection resistor switches faster, and when the temperature is low, the detection resistor switches slower.

[0076] In one embodiment, if Figure 6 As shown, the second switch module includes a third switch K4 and a fourth switch K5;

[0077] The output end of the third voltage comparator is connected to the third switch and the fourth switch respectively;

[0078] When the third voltage comparator outputs a high level, the third switch controls the first square wave generator to be electrically connected to the first switch module; the fourth switch controls the second square wave generator to be electrically disconnected from the first switch module;

[0079] When the third voltage comparator outputs a low level, the third switch controls the first square wave generator to be electrically disconnected from the first switch module; and the fourth switch controls the second square wave generator to be electrically connected to the first switch module.

[0080] In another embodiment, if Figure 7 As shown, the second switch module is a second relay K6, and the second relay includes a coil, an armature, a third moving contact and a fourth moving contact, and the output end of the third voltage comparator is electrically connected to the coil; it can be understood that a voltage amplification circuit can be set between the output end of the third voltage comparator and the coil.

[0081] When the armature is located at the third moving contact, the first square wave generator is electrically connected to the first switch module; when the armature is located at the fourth moving contact, the second square wave generator is electrically connected to the first switch module;

[0082] When the third voltage comparator outputs a high level, the armature is located at the third moving contact, and when the third voltage comparator outputs a low level, the armature is located at the fourth moving contact.

[0083] It should be noted that the present application mentions that the working mode of the first voltage comparator, the second voltage comparator and the third voltage comparator is that when the level of the non-inverting input terminal of any voltage comparator is higher than the level of the inverting input terminal, a high level is output, otherwise a low level is output.

[0084] Based on the same inventive concept, the present application also provides a temperature regulating device for use in a greenhouse, comprising: a temperature detection circuit as provided in any of the above embodiments.

[0085] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0086] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0087] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0088] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0089] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0090] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0091] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0092] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0093] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A temperature detection circuit used in a greenhouse, characterized in that: It comprises: a detection resistor whose resistance changes with temperature, a measuring circuit for measuring the change of the resistance of the detection resistor, and a switch circuit for controlling whether the detection resistor is connected to the measuring circuit; The detection resistor includes a first detection resistor and a second detection resistor; The switch circuit includes a square wave generating module and a first switch module; The square wave generating module is used to generate a square wave, and the maintenance time of the high level and the low level in each cycle of the square wave respectively occupies half a cycle; The square wave generating module is electrically connected to the first switch module. When the square wave generating module outputs a high level, the first switch module controls the first detection resistor to be connected to the measurement circuit, and controls the second detection resistor to be disconnected from the measurement circuit; when the square wave generating module outputs a low level, the first switch module controls the second detection resistor to be connected to the measurement circuit, and controls the first detection resistor to be disconnected from the measurement circuit.

2. The temperature detection circuit according to claim 1, characterized in that: The switch circuit further includes a signal modulation module, wherein the first switch module includes a first switch and a second switch; The square wave generating module is connected to the input end of the signal modulating module, and the signal modulating module includes two output ends; the first output end of the signal modulating module is electrically connected to the first switch; the second output end of the signal modulating module is electrically connected to the second switch; When the square wave generating module outputs a high level, the first output terminal outputs a high level and the second output terminal outputs a low level; when the square wave generating module outputs a low level, the first output terminal outputs a low level and the second output terminal outputs a high level; When the first switch receives a high-level signal, the first detection resistor is controlled to be connected to the measurement circuit; when the first switch receives a low-level signal, the first detection resistor is controlled to be disconnected from the measurement circuit; when the second switch receives a high-level signal, the second detection resistor is controlled to be connected to the measurement circuit; when the second switch receives a low-level signal, the second detection resistor is controlled to be disconnected from the measurement circuit.

3. The temperature detection circuit according to claim 2, characterized in that: The signal modulation module includes a first voltage comparator and a second voltage comparator; the output end of the first voltage comparator is a first output end, and the output end of the second voltage comparator is a second output end; The square wave generating module is respectively connected to the positive phase input terminal of the first voltage comparator and the negative phase input terminal of the second voltage comparator, and the negative phase input terminal of the first voltage comparator and the positive phase input terminal of the second voltage comparator are respectively input with a first threshold level, and the first threshold level is less than the high level and greater than the low level.

4. The temperature detection circuit according to claim 2, characterized in that: The signal modulation module includes an inverter; The input end of the signal modulation module is directly connected to the first output end; The input end of the signal modulation module is connected to the second output end through the inverter.

5. The temperature detection circuit according to claim 1, characterized in that: The first switch module is a first relay, the first relay comprises a coil, an armature, a first moving contact and a second moving contact, and the square wave generating module is electrically connected to the coil; When the armature is located at the first moving contact, the measuring circuit is connected to the first detection resistor; when the armature is located at the second moving contact, the measuring circuit is connected to the second detection resistor; When the square wave generating module outputs a high level, the armature is located at the first moving contact, and when the square wave generating module outputs a low level, the armature is located at the second moving contact.

6. The temperature detection circuit according to claim 1, characterized in that: The output end of the measuring circuit is used to output voltage; the square wave generating module includes: a third voltage comparator, a second switch module, a first square wave generator and a second square wave generator; the first square wave generator is used to generate a square wave with a period of T1, and the second square wave generator is used to generate a square wave with a period of T2, and T1 is not equal to T2; The non-inverting input terminal of the third voltage comparator is connected to the output terminal of the measuring circuit, and the inverting input terminal of the third voltage comparator inputs the second threshold level; The output end of the third voltage comparator is connected to the second switch module; When the third voltage comparator outputs a high level, the second switch module controls the first square wave generator to be electrically connected to the first switch module, and controls the second square wave generator to be electrically disconnected from the first switch module; When the third voltage comparator outputs a low level, the second switch module controls the first square wave generator to be electrically disconnected from the first switch module, and controls the second square wave generator to be electrically connected to the first switch module.

7. The temperature detection circuit according to claim 6, characterized in that: The second switch module includes a third switch and a fourth switch; The output end of the third voltage comparator is connected to the third switch and the fourth switch respectively; When the third voltage comparator outputs a high level, the third switch controls the first square wave generator to be electrically connected to the first switch module; the fourth switch controls the second square wave generator to be electrically disconnected from the first switch module; When the third voltage comparator outputs a low level, the third switch controls the first square wave generator to be electrically disconnected from the first switch module; and the fourth switch controls the second square wave generator to be electrically connected to the first switch module.

8. The temperature detection circuit according to claim 6, characterized in that: The second switch module is a second relay, the second relay comprises a coil, an armature, a third moving contact and a fourth moving contact, and the output end of the third voltage comparator is electrically connected to the coil; When the armature is located at the third moving contact, the first square wave generator is electrically connected to the first switch module; when the armature is located at the fourth moving contact, the second square wave generator is electrically connected to the first switch module; When the third voltage comparator outputs a high level, the armature is located at the third moving contact, and when the third voltage comparator outputs a low level, the armature is located at the fourth moving contact.

9. The temperature detection circuit according to claim 1, characterized in that: The detection resistor is a metal thermal resistor or a thermistor.

10. A temperature regulating device used in a greenhouse, characterized in that: include: A temperature detection circuit as claimed in any one of claims 1 to 9.

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