Temperature detection device and intelligent household appliance

Abstract

The utility model relates to a temperature detection device and an intelligent household electrical appliance, the device comprises a plurality of temperature detection modules, each temperature detection module comprises a thermistor, a first voltage dividing unit and a switching circuit, and the first end of the thermistor is used for being connected with a power supply; the second end of the thermistor is connected with the first end of the first voltage dividing unit and the first end of the switching circuit, and the second end of the first voltage dividing unit is grounded; the same input end of the controller is connected with the second end of each switching circuit, and a plurality of control ends of the controller are connected with the controlled ends of the switching circuits in a one-to-one correspondence mode. By adopting the device, the development cost is reduced while the multi-path AD detection function is realized.

Description

Technical Field

[0001] The present application relates to the technical field of detection circuits, and in particular to a temperature detection device and a smart home appliance. Background Art

[0002] Analog-to-Digital Converter (ADC) is an indispensable part of electronic devices. It can convert continuous analog signals (such as temperature) into discrete digital signals and is widely used in signal measurement, processing and transmission. However, in practical applications, there are some technical challenges in the digital processing of multi-channel analog signals.

[0003] At present, most AD value detection is realized by voltage division method. Each AD value requires a pin with AD detection function. When the AD value to be detected exceeds the number of AD pins of the microcontroller unit (MCU), the model selection range of the MCU will be limited and the development cost will be increased. In order to realize multi-channel AD detection, some solutions will use special multi-channel AD detection chips. Although the above method can realize multi-channel AD detection, it will undoubtedly increase the development cost.

[0004] Therefore, how to ensure the multi-channel AD detection function while reducing the development cost and avoiding restrictions on the model selection of the microcontroller has become an urgent problem to be solved. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a temperature detection device and an intelligent household appliance, which are helpful to reduce the development cost while realizing the multi-channel AD detection function.

[0006] The above technical problems are solved by the following technical solutions:

[0007] A temperature detection device, comprising:

[0008] A plurality of temperature detection modules, wherein the temperature detection modules include a thermistor, a first voltage divider unit and a switch circuit, wherein the first end of the thermistor is used to connect to a power supply, the second end of the thermistor is respectively connected to the first end of the first voltage divider unit and the first end of the switch circuit, and the second end of the first voltage divider unit is grounded;

[0009] A controller, wherein the same input terminal of the controller is respectively connected to the second terminal of each switch circuit, and multiple control terminals of the controller are respectively connected to the controlled terminals of each switch circuit in a one-to-one correspondence.

[0010] The temperature detection device described in the utility model has the following beneficial effects compared with the background technology:

[0011] By connecting multiple temperature detection modules to the same input end of the controller, and connecting the multiple control ends of the controller to the controlled ends of each switch circuit one by one, the on and off of the switch circuits in all the temperature detection modules can be controlled. When the controller needs to read the AD value corresponding to the temperature detected by one of the temperature detection modules, the connection between the other temperature detection modules and the controller can be disconnected, thereby avoiding interference from other temperature detection modules and improving the accuracy of temperature detection. By selecting one of the multiple switch circuits to be turned on in time-sharing by preset timing or selecting one of the switch circuits to be turned on according to user needs, one AD port of the controller can achieve the effect of time-sharing detection of multiple AD values, thereby improving the efficiency of temperature detection. It can be seen that the temperature detection device of the embodiment of the utility model provides a hardware architecture that can reduce development costs while realizing the multi-channel AD detection function.

[0012] In one embodiment, the switch circuit comprises:

[0013] A first switch tube, wherein a first electrode of the first switch tube is connected to a second end of the thermistor, and a second electrode of the first switch tube is connected to the same input end of the controller;

[0014] A first current limiting resistor, wherein a first end of the first current limiting resistor is connected to the third electrode of the first switch tube, and a second end of the first current limiting resistor is correspondingly connected to the control end of the controller.

[0015] In the above implementation, when the first switch tube is turned on, the first current limiting resistor can limit the impact of the current, protect the first switch tube and the controller, and improve the stability and reliability of the entire device.

[0016] In one embodiment, the switch circuit includes a plurality of first switch tubes connected in series between a first end and a second end of the switch circuit, and a third electrode of each first switch tube is connected to a first end of a first current limiting resistor.

[0017] In the above implementation, by using multiple first switch tubes connected in series in the switch circuit, it is possible to avoid mis-conduction or conduction failure of a single switch tube, thereby enhancing the reliability of switch tube control. Moreover, when one switch tube is turned on due to the access to a negative voltage, the other switch tube will not be turned on, thereby blocking the signal, improving the signal isolation effect, and avoiding interference with other circuits.

[0018] In one embodiment, the temperature detection module further includes:

[0019] A second voltage dividing unit, wherein a first end of the second voltage dividing unit is connected to a second end of the switch circuit, and a second end of the second voltage dividing unit is grounded.

[0020] In the above implementation, a second voltage divider unit is provided, and the voltage divider value can be accurately adjusted according to the change of thermistor resistance value, thereby realizing accurate measurement of temperature. When detecting other temperature detection modules, the second end of the switch circuit of the temperature detection module is in a suspended state, which is easily interfered by external signals. The second voltage divider unit is provided after the second end of the switch circuit, which can prevent the second end of the switch circuit from being interfered by external signals when it is suspended, thereby protecting the AD sampling accuracy of other temperature detection modules.

[0021] In one embodiment, the temperature detection module further includes:

[0022] A diode, an anode of the diode is connected to the second end of the switch circuit, and a cathode of the diode is connected to the same input end of the controller.

[0023] In the above embodiment, by providing a diode in each temperature detection module, the input end of the controller can be prevented from being affected by the reverse voltage, thereby protecting the input end of the controller from damage. Secondly, due to the presence of the diode, the reverse voltage at the input end of the controller due to external interference or other reasons can be avoided, thereby improving the reliability of temperature detection.

[0024] In one embodiment, the device further comprises:

[0025] An operational amplifier, wherein the negative input terminal of the operational amplifier is connected to the second terminal of the switch circuit, the positive input terminal and the positive power supply terminal of the operational amplifier are used to access the power supply, the negative power supply terminal of the operational amplifier is grounded, and the output terminal of the operational amplifier is connected to the same input terminal of the controller;

[0026] Feedback impedance, which is connected between the negative input and output of the operational amplifier;

[0027] Among them, the temperature detection module also includes:

[0028] An input impedance, wherein a first end of the input impedance is connected to a second end of the switch circuit, and a second end of the input impedance is connected to a negative input end of the operational amplifier.

[0029] In the above implementation, an operational amplifier and a feedback impedance are provided in the temperature detection module, which can adapt to temperature detection with amplification requirements, so that a smaller temperature signal can be effectively amplified to meet the controller's requirements for input signals.

[0030] In one embodiment, the switch circuit comprises:

[0031] A second switch tube, wherein a first electrode of the second switch tube is connected to a second end of the thermistor;

[0032] a third switch tube, wherein a first electrode of the third switch tube is respectively connected to a second electrode of the second switch tube and an input end of the operational amplifier, and a second electrode of the third switch tube is grounded;

[0033] a fourth switch tube, wherein a first electrode of the fourth switch tube is connected to a third electrode of the second switch tube, and a second electrode of the fourth switch tube is grounded;

[0034] a second current limiting resistor, wherein a first end of the second current limiting resistor is respectively connected to the third electrode of the third switch tube and the third electrode of the fourth switch tube, and a second end of the second current limiting resistor is connected to the control end of the controller;

[0035] The third pole of the second switch tube is also used to connect to the power supply.

[0036] In the above implementation, the switch circuit composed of the second switch tube, the third switch tube, the fourth switch tube and the second current limiting resistor can prevent the signals of other temperature detection modules from affecting the gain characteristics of the operational amplifier, thereby ensuring the accuracy of AD sampling.

[0037] In one embodiment, the temperature detection module further includes:

[0038] A voltage follower is connected in series between the second end of the switch circuit and the input end of the operational amplifier.

[0039] In the above implementation, the voltage follower has the characteristics of high input impedance and low output impedance, which can realize lossless transmission of signals, thereby ensuring the stability and reliability of temperature signals during transmission. Secondly, the voltage follower can play an isolation role, preventing the subsequent circuit from affecting the previous circuit, thereby improving the precision and accuracy of temperature detection.

[0040] In one embodiment, the device further comprises:

[0041] The filter circuit is connected in series between the second end of the switch circuit and the same input end of the controller.

[0042] In the above implementation, by setting up a filtering circuit, the noise and interference generated in the switching circuit can be filtered out, thereby improving the accuracy and reliability of temperature detection. Secondly, the degree of signal distortion can be reduced, ensuring the authenticity and accuracy of the temperature signal, thereby improving the accuracy of temperature detection.

[0043] A smart home appliance, comprising:

[0044] Such as the temperature detection device in the above embodiment.

[0045] The intelligent household appliance of the utility model can achieve the effect of one AD port of one controller detecting multiple AD values ​​in time-sharing manner by adopting the temperature detection device, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0047] Figure 1 is a schematic structural diagram of a temperature detection device in one embodiment;

[0048] Figure 2 is a schematic structural diagram of a temperature detection device in another embodiment;

[0049] Figure 3 FIG. 4 is a schematic diagram of the structure of a temperature detection device in yet another embodiment.

[0050] Description of reference numerals:

[0051] Temperature detection module-2, thermistor-200, first voltage divider unit-202, switch circuit-204, second voltage divider unit-206, voltage follower-208, filter circuit-210, power supply-300, controller-4, operational amplifier-6, feedback impedance-8. DETAILED DESCRIPTION

[0052] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0054] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0055] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0056] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0057] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0058] In an exemplary embodiment, Figure 1 As shown, the present application provides a temperature detection device, which includes multiple temperature detection modules 2 and a controller 4. The temperature detection module 2 includes a thermistor 200, a first voltage divider unit 202 and a switch circuit 204, the first end of the thermistor 200 is used to connect to the power supply 300, the second end of the thermistor 200 is respectively connected to the first end of the first voltage divider unit 202 and the first end of the switch circuit 204, and the second end of the first voltage divider unit 202 is grounded; the same input end of the controller 4 is respectively connected to the second end of each switch circuit 204, and the multiple control ends of the controller 4 are respectively connected to the controlled end of each switch circuit 204 in a one-to-one correspondence.

[0059] For example, Figure 1 As shown, by connecting multiple temperature detection modules 2 including a thermistor 200, a first voltage divider unit 202 and a switch circuit 204 to the same input terminal of the controller 4, when it is necessary to detect the AD value corresponding to the temperature detected by one of the temperature detection modules 2, the connection between the other temperature detection modules 2 and the same input terminal of the controller 4 can be disconnected by controlling the switch circuits 204 in the other temperature detection modules 2, so that the controller 4 only reads the AD value corresponding to the temperature detected by the above-mentioned one temperature detection module 2, thereby avoiding interference from other temperature detection modules 2. Based on the above-mentioned similar detection methods, by setting the controller 4, multiple switch circuits 204 can be selectively turned on in time-sharing according to a preset timing, or a certain switch circuit can be selectively turned on according to the user's blood cow, thereby achieving the effect of one AD port of the controller 4 detecting multiple AD values ​​in time-sharing. It should be noted that the above-mentioned controller 4 may refer to a single-chip microcomputer, in which the controller 4 is configured as follows. Figure 2Taking the circuit structure shown as an example, the thermistor may refer to thermistor NCT1, thermistor NTC2 and thermistor NTC3.

[0060] In the above embodiment, by connecting multiple temperature detection modules 2 to the same input end of the controller 4, and connecting the multiple control ends of the controller to the controlled ends of each switch circuit one by one, the on and off of the switch circuits 204 in all the temperature detection modules 2 are controlled. When the controller needs to read the AD value corresponding to the temperature detected by one of the temperature detection modules, the connection between the other temperature detection modules 2 and the controller 4 can be disconnected, thereby avoiding the interference of other temperature detection modules 2 and improving the accuracy of temperature detection. By selecting one of the multiple switch circuits to be turned on in time-sharing by preset timing or selecting one of the switch circuits to be turned on according to user needs, an AD port of the controller 4 can achieve the effect of time-sharing detection of multiple AD values, thereby improving the efficiency of temperature detection. It can be seen that the temperature detection device of the embodiment of the utility model provides a hardware architecture that can reduce development costs while realizing the multi-channel AD detection function.

[0061] In an exemplary embodiment, Figure 2 As shown, the switch circuit 204 includes a first switch tube and a first current limiting resistor. The first electrode of the first switch tube is connected to the second end of the thermistor 200, and the second electrode of the first switch tube is connected to the same input end of the controller 4; the first end of the first current limiting resistor is connected to the third electrode of the first switch tube, and the second end of the first current limiting resistor is connected to the control end of the controller 4 accordingly.

[0062] For example, Figure 2 Taking the circuit structure schematic diagram shown as an example, in this topology circuit, the switch tube Q3, the switch tube Q5, and the switch tube Q7 are all first switch tubes, and the resistors R5, R9, and R13 are all second switch tubes. By connecting the multiple control terminals of the controller 4 to the controlled terminals of each switch circuit 204 in a one-to-one correspondence, the on-off state of the first switch tube can be accurately controlled, thereby realizing accurate control of the connection and disconnection of the temperature detection module 2. When the first switch tube is turned on, the first current limiting resistor can limit the impact of the current, protect the first switch tube and the controller 4, and improve the stability and reliability of the entire device.

[0063] In an exemplary implementation, Figure 2 As shown, the switch circuit 204 includes a plurality of first switch tubes connected in series between a first end and a second end of the switch circuit 204 , and a third electrode of each first switch tube is connected to a first end of a first current limiting resistor.

[0064] For example, Figure 2Taking the circuit structure diagram shown in the figure as an example, in one temperature detection module 2, the switch tube Q1 and the switch tube Q2 are both first switch tubes, and correspondingly, in other temperature detection modules 2, the switch tube Q3 and the switch tube Q4 are both first switch tubes, and the switch tube Q5 and the switch tube Q6 are both first switch tubes. On this basis, it can avoid mis-conduction or conduction failure when only one switch tube realizes on-off control. In addition, two first switch tubes connected in series can form a back-to-back structure, such as Figure 2 As shown in the switch tube Q1 and the switch tube Q2, when the S pole of the switch tube Q1 is connected to a negative voltage and the input signal of the controlled end EN_R1 of the switch circuit 204 is a low level signal 0V, the switch tube Q1 will be in the on state, and the switch tube Q2 will not be turned on, thereby blocking the signal.

[0065] In the above embodiment, by using multiple first switch tubes connected in series in the switch circuit 204, it is possible to avoid the situation where a single switch tube is mis-turned on or fails to turn on, thereby enhancing the reliability of the switch tube control. Moreover, when a switch tube is turned on due to the access to a negative voltage, the other switch tube will not be turned on, thereby blocking the signal, improving the signal isolation effect, and avoiding interference with other circuits.

[0066] In an exemplary implementation, Figure 2 As shown, the temperature detection module 2 further includes a second voltage dividing unit 206. A first end of the second voltage dividing unit 206 is connected to a second end of the switch circuit 204, and a second end of the second voltage dividing unit 206 is grounded.

[0067] For example, in addition to the first voltage divider unit 202, a second voltage divider unit 206 may be provided to accurately adjust the voltage divider value according to the change in the resistance value of the thermistor 200, thereby achieving accurate measurement of the temperature. Figure 2 Taking the circuit structure diagram shown as an example, the first voltage divider unit 202 can be composed of a resistor R2 and a resistor R3 connected in parallel, and the second voltage divider unit 206 can be a resistor R4. Secondly, when detecting other temperature detection modules 2, the second end of the switch circuit 204 in the temperature detection module 2 is in a suspended state, which is easily interfered by external signals. The second voltage divider unit 206 is arranged after the second end of the switch circuit 204 to prevent the second end of the switch circuit 204 from being interfered by external signals when it is suspended, thereby affecting the AD sampling of other temperature detection modules 2.

[0068] In the above embodiment, the second voltage divider unit 206 is provided, and the voltage divider value can be accurately adjusted according to the change of the resistance value of the thermistor 200, thereby realizing accurate measurement of temperature. When detecting other temperature detection modules 2, the second end of the switch circuit 204 in the temperature detection module 2 is in a suspended state, which is easily interfered by external signals. The second voltage divider unit 206 is provided after the second end of the switch circuit 204, which can prevent the second end of the switch circuit 204 from being interfered by external signals when it is suspended, thereby protecting the AD sampling accuracy of other temperature detection modules 2.

[0069] In an exemplary implementation, Figure 2 As shown, the temperature detection module 2 further includes a diode. The anode of the diode is connected to the second end of the switch circuit 204 , and the cathode of the diode is connected to the same input end of the controller 4 .

[0070] For example, Figure 2 Taking the circuit structure diagram shown in FIG. 1 as an example, each temperature detection module 2 includes a diode, such as a diode D1, a diode D2, and a diode D3. The diode has unidirectional conductivity. By arranging a diode in each temperature detection module 2, the input end of the controller 4 can be prevented from being affected by the reverse voltage, thereby protecting the input end of the controller 4 from damage. Secondly, due to the presence of the diode, the reverse voltage at the input end of the controller 4 due to external interference or other reasons can be avoided, thereby improving the reliability of temperature detection.

[0071] In an exemplary implementation, Figure 3 As shown, the device also includes an operational amplifier 6 and a feedback impedance 8. The negative input terminal of the operational amplifier 6 is connected to the second terminal of the switch circuit 204, the positive input terminal and the positive power supply terminal of the operational amplifier 6 are used to access the power supply, the negative power supply terminal of the operational amplifier 6 is grounded, and the output terminal of the operational amplifier 6 is connected to the same input terminal of the controller 4; the feedback impedance 8 is connected across the negative input terminal and the output terminal of the operational amplifier 6; wherein the temperature detection module 2 also includes an input impedance. The first end of the input impedance is connected to the second end of the switch circuit 204, and the second end of the input impedance is connected to the negative input terminal of the operational amplifier 6.

[0072] For example, Figure 3As shown, the feedback impedance may refer to the resistor RD, the resistor RA, the resistor RB and the resistor RC are the input impedances of each temperature detection module respectively. When any temperature detection module is turned on, the resistor corresponding to the temperature detection module can be used as the input impedance of the operational amplifier. When the signal detected by the thermistor 200 of the temperature detection module is small, it needs to be amplified before it can be recognized by the controller 4. Therefore, in order to adapt to the detection with amplification requirements, an operational amplifier 6 and a feedback impedance 8 can also be set, and at the same time, an input impedance (such as resistor RA, resistor RB and resistor RC) is set corresponding to each temperature detection module 2 to achieve signal amplification.

[0073] In the above implementation, an operational amplifier 6 and a feedback impedance 8 are provided in the temperature detection module 2 to adapt to temperature detection with amplification requirements, so that a smaller temperature signal can be effectively amplified to meet the controller 4's requirements for input signals.

[0074] In an exemplary implementation, Figure 3 As shown, the switch circuit 204 includes a second switch tube, a third switch tube, a fourth switch tube and a second current limiting resistor. The first electrode of the second switch tube is connected to the second end of the thermistor 200; the first electrode of the third switch tube is respectively connected to the second electrode of the second switch tube and the input end of the operational amplifier, and the second electrode of the third switch tube is grounded; the first electrode of the fourth switch tube is connected to the third electrode of the second switch tube, and the second electrode of the fourth switch tube is grounded; the first end of the second current limiting resistor is respectively connected to the third electrode of the third switch tube and the third electrode of the fourth switch tube, and the second end of the second current limiting resistor is connected to the control end of the controller 4; wherein the third electrode of the second switch tube is also used to connect to the power supply.

[0075] Among them, Figure 3 As an example, in the temperature detection module including thermistor NTC1, switch tube Q1 is the second switch tube, switch tube Q2 is the third switch tube, switch tube Q4 is the fourth switch tube, and resistor R3 is the second current limiting resistor. For the specific components referred to by the second switch tube, the third switch tube, the fourth switch tube and the second current limiting resistor in other temperature detection modules, those skilled in the art can refer to the following. Figure 3 I learned about it and will not repeat it here.

[0076] For example, as described above, an operational amplifier needs to be set based on the signal amplification requirement, but due to the inherent characteristics of the operational amplifier, Figure 3Taking the circuit structure shown as an example, when the signal of the temperature detection module 2 including thermistor NTC1 is being detected, if the signal of other temperature detection modules 2 is a floating signal, it will affect the gain characteristics of the operational amplifier 6, thereby causing inaccurate AD sampling. Therefore, when the temperature detection device includes the operational amplifier 6, the switch circuit 204 composed of the second switch tube, the third switch tube, the fourth switch tube and the second current limiting resistor can adapt to the amplification requirements and ensure sampling accuracy.

[0077] In the above implementation, the switch circuit 204 composed of the second switch tube, the third switch tube, the fourth switch tube and the second current limiting resistor can prevent the signals of other temperature detection modules 2 from affecting the gain characteristics of the operational amplifier, thereby ensuring the accuracy of AD sampling.

[0078] In an exemplary implementation, Figure 3 As shown, the temperature detection module 2 further includes a voltage follower 208. The voltage follower 208 is connected in series between the second end of the switch circuit 204 and the input end of the operational amplifier.

[0079] In the above implementation, the voltage follower 208 has the characteristics of high input impedance and low output impedance, which can realize lossless transmission of the signal, thereby ensuring the stability and reliability of the temperature signal during the transmission process. Secondly, the voltage follower 208 can play an isolation role to prevent the subsequent circuit from affecting the previous circuit, thereby improving the precision and accuracy of temperature detection.

[0080] In an exemplary implementation, Figure 2 and Figure 3 As shown, the device further includes a filter circuit 210. The filter circuit 210 is connected in series between the second end of the switch circuit 204 and the same input end of the controller 4.

[0081] Exemplarily, the filter circuit 210 may refer to an RC filter circuit 210. By setting the filter circuit 210, the noise and interference generated in the switching circuit 204 can be filtered out, thereby improving the accuracy and reliability of temperature detection. Secondly, the degree of signal distortion can be reduced to ensure the authenticity and accuracy of the temperature signal, thereby improving the accuracy of temperature detection.

[0082] A smart home appliance comprises the temperature detection device in the above embodiment.

[0083] Exemplarily, smart home appliances may refer to equipment such as dishwashers that have temperature detection requirements. By adopting the above-mentioned temperature detection device, it is possible to achieve the effect of one AD port of a controller 4 detecting multiple AD values ​​in a time-sharing manner, greatly reducing the number of AD interfaces required for the controller, thereby reducing the hardware cost of smart home appliances.

[0084] In order to describe the solution of the present application in more detail, the solution is described in detail below in conjunction with a specific embodiment and the accompanying drawings.

[0085] like Figure 2 As shown, taking the temperature detection device including three-way temperature detection module 2 as an example, when the detected temperature analog signal does not need to be amplified, the three-way NTC ports (NTC1, NTC2 and NTC3) are connected as follows Figure 2 The circuit shown is connected to the same AD port of the controller 4 (MCU). The controlled end (EN_Rn (n≥1)) in each switch circuit is connected to the control end (ordinary I / O port) of the MCU. When the resistance value of the first thermistor NTC1 is detected to change, the MCU controls the I / O ports of EN_R2 and EN_R3 to output a low level. At this time, the MCU outputs a high level to EN_R1. When the MCU outputs a low level to EN_R2 and EN_R3, the switch tubes Q3, Q4 and the switch tubes Q5, Q6 are cut off. When a high level is output to EN_R1, the switch tubes Q1 and Q2 are turned on. In this way, the AD port of the MCU cannot detect the temperature analog signals of thermistors NTC2 and NTC3, and can only detect the temperature analog signal of thermistor NTC1, so that the temperature analog signals of thermistors NTC2 and NTC3 cannot interfere with the temperature analog signal of thermistor NTC1, thereby improving the detection accuracy.

[0086] Based on the above control, the voltage of thermistor NTC1 can be measured by the following voltage division calculation formula of thermistor NTC1:

[0087]

[0088]

[0089] Among them, Figure 2 As shown, R2 is the resistance value of resistor R2, R3 is the resistance value of resistor R3, R4 is the resistance value of resistor R4, R is the total resistance value of resistors R2, R3 and R4, R NTC is the current resistance of thermistor NCT1.

[0090] For a 12-bit MCU, the AD value corresponding to thermistor NCT1 can be obtained based on the following formula combined with the above expression of the voltage of thermistor NTC1:

[0091] NTC1 AD值 =4095*R 并 / (R 并 +R NTC1 )

[0092] Based on the above similar detection and calculation methods, when the AD value of thermistor NTC2 is to be detected, the MCU can output a low level to EN_R1 and EN_R3, and a high level to EN_R2. Similarly, at this time, the switch tubes Q1, Q2 and the switch tubes Q5, Q6 are in the cut-off state, and the switch tubes Q3, Q4 are in the on state. At this time, the AD port of the MCU only detects the AD value of thermistor NTC2. Similarly, the thermistor NTC3 can also be detected in the above manner.

[0093] Therefore, by regularly controlling EN_Rn (n≥1) through the MCU, one channel can be controlled to be high level and the others to be low level in turn, so as to detect multiple NTC channel ports using the AD port of one MCU, and to detect and feedback the changes of the AD value of each NTC channel port in real time.

[0094] When the detected AD value signal needs to be amplified, such as Figure 3 As shown, connect the 3-way NTC port as follows Figure 3 The circuit shown is connected to an AD port of the MCU. Among them, the three-way voltage follower can be set according to actual needs. EN_Rn (n≥1) is connected to the common I / O port of the MCU. When detecting the change in the resistance value of the first thermistor NTC1, the MCU outputs a high level to EN_R2 and EN_R3, and outputs to a low level EN_R1. When the MCU outputs a high level to EN_R2 and EN_R3, the switch tubes Q5, Q6 and the switch tubes Q8, Q9 are in the on state, and the switch tubes Q4, Q7 are in the off state. When the output is to the low level EN_R1, the switch tube Q1 is in the on state, and the switch tubes Q2, Q3 are in the off state. In this way, the temperature analog signals of thermistors NTC2 and NTC3 cannot be detected, and only the temperature analog signal of thermistor NTC1 can be detected, thereby preventing the temperature analog signals of thermistors NTC2 and NTC3 from interfering with the temperature analog signal of thermistor NTC1. Then the temperature analog signal of the thermistor NTC1 is amplified by the back-end operational amplifier, and the tiny temperature analog signal is amplified to a level that can be recognized by the MCU, thereby realizing the amplified detection of the temperature analog signal of the thermistor NCT1.

[0095] Based on the above control, the voltage of thermistor NTC1 can be measured by the following voltage division calculation formula of thermistor NTC1:

[0096]

[0097] Among them, Figure 3 As shown, R1 is the resistance value of resistor R1, R NTC1 is the resistance of thermistor NTC1.

[0098] At this time, the output voltage after amplification by the operational amplifier is:

[0099]

[0100] Among them, Figure 3 As shown, RD is the resistance value of resistor RD, RA is the resistance value of resistor RA, VCC is the voltage of the positive power supply terminal of the operational amplifier, Vi is the voltage of the negative input terminal of the operational amplifier, and i=NTC1, NTC2, NTC3.

[0101] Based on the voltage V0 output by the operational amplifier after amplification obtained by the above calculation and the above-mentioned similar AD value calculation method, the AD value corresponding to the temperature analog signal of the thermistor NTC1 can be calculated.

[0102] By Figure 2 or Figure 3 The structure of the temperature detection device shown in the figure enables multiple temperature detection modules to share one AD interface of the controller, greatly reducing the number of AD interfaces of the required controller, thereby reducing the hardware cost. Secondly, multiple switch circuits are turned on one by one through preset timing, thereby avoiding interference from other temperature detection modules and improving the accuracy of temperature detection.

[0103] It should be noted that the number of temperature detection modules in the above-mentioned temperature detection device embodiments can be adaptively adjusted according to actual design requirements. Figure 2 and Figure 3 The circuit structure shown is only for illustration and is not intended to be a specific limitation.

[0104] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. 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 description of the above terms does not necessarily refer to the same embodiment or example.

[0105] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A temperature detection device, characterized in that: The device comprises: A plurality of temperature detection modules (2), the temperature detection modules (2) comprising a thermistor (200), a first voltage divider unit (202) and a switch circuit (204), the first end of the thermistor (200) being used to connect to a power supply, the second end of the thermistor (200) being respectively connected to the first end of the first voltage divider unit (202) and the first end of the switch circuit (204), and the second end of the first voltage divider unit (202) being grounded; A controller (4), wherein the same input end of the controller (4) is respectively connected to the second end of each of the switch circuits (204), and the plurality of control ends of the controller (4) are respectively connected to the controlled end of each of the switch circuits (204) in a one-to-one correspondence.

2. The device according to claim 1, characterized in that The switch circuit (204) comprises: a first switch tube, wherein a first electrode of the first switch tube is connected to a second end of the thermistor (200), and a second electrode of the first switch tube is connected to the same input end of the controller (4); A first current limiting resistor, wherein a first end of the first current limiting resistor is connected to the third electrode of the first switch tube, and a second end of the first current limiting resistor is correspondingly connected to a control end of the controller (4).

3. The device according to claim 2, characterized in that The switch circuit (204) comprises a plurality of first switch tubes connected in series between a first end and a second end of the switch circuit (204), and a third electrode of each of the first switch tubes is connected to a first end of the first current limiting resistor.

4. The device according to any one of claims 1 to 3, characterized in that The temperature detection module (2) further comprises: A second voltage dividing unit (206), wherein a first end of the second voltage dividing unit (206) is connected to a second end of the switch circuit (204), and a second end of the second voltage dividing unit (206) is grounded.

5. The device according to claim 4, characterized in that The temperature detection module (2) further comprises: A diode, wherein the anode of the diode is connected to the second end of the switch circuit (204), and the cathode of the diode is connected to the same input end of the controller (4).

6. The device according to claim 1, characterized in that The device also includes: An operational amplifier (6), wherein the negative input terminal of the operational amplifier (6) is connected to the second terminal of the switch circuit (204), the positive input terminal and the positive power supply terminal of the operational amplifier (6) are used to connect to a power supply, the negative power supply terminal of the operational amplifier (6) is grounded, and the output terminal of the operational amplifier (6) is connected to the same input terminal of the controller (4); A feedback impedance (8), the feedback impedance (8) being connected between the negative input terminal and the output terminal of the operational amplifier (6); Wherein, the temperature detection module (2) further comprises: An input impedance, wherein a first end of the input impedance is connected to a second end of the switch circuit (204), and a second end of the input impedance is connected to a negative input end of the operational amplifier (6).

7. The device according to claim 6, characterized in that The switch circuit (204) comprises: a second switch tube, wherein a first electrode of the second switch tube is connected to a second end of the thermistor (200); a third switch tube, wherein a first electrode of the third switch tube is respectively connected to a second electrode of the second switch tube and an input end of the operational amplifier (6), and a second electrode of the third switch tube is grounded; a fourth switch tube, wherein a first electrode of the fourth switch tube is connected to a third electrode of the second switch tube, and a second electrode of the fourth switch tube is grounded; a second current limiting resistor, wherein a first end of the second current limiting resistor is respectively connected to the third electrode of the third switch tube and the third electrode of the fourth switch tube, and a second end of the second current limiting resistor is connected to the control end of the controller (4); Wherein, the third pole of the second switch tube is also used to connect to the power supply.

8. The device according to claim 6, characterized in that The temperature detection module (2) further comprises: A voltage follower (208), wherein the voltage follower (208) is connected in series between the second end of the switch circuit (204) and the input end of the operational amplifier (6).

9. The device according to claim 1, characterized in that The device also includes: A filter circuit (210), the filter circuit (210) is connected in series between the second end of the switch circuit (204) and the same input end of the controller (4).

10. A smart home appliance, characterized in that: The smart home appliance comprises: A temperature detection device as claimed in any one of claims 1 to 9.

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