Temperature acquisition circuit and device

Abstract

The invention discloses a temperature acquisition circuit and device. The circuit comprises a temperature measuring element, a temperature acquisition module, a signal conversion module and a signal processing module. The temperature measuring element is used for sensing external temperature changes in real time and converting the external temperature changes into resistance signals. The input end of the temperature acquisition module is directly coupled with the temperature measuring element, and the temperature acquisition module is used for acquiring a resistance signal generated by the temperature measuring element and converting the resistance signal into a single-ended frequency signal. The input end of the signal conversion module is connected with the output end of the temperature acquisition module, and the signal conversion module is used for converting the single-end frequency signal into a differential signal so as to suppress common-mode noise. The input end of the signal processing module is connected with the output end of the signal conversion module, the differential signals output by the signal conversion module are processed through a preset algorithm, and finally temperature data are obtained. According to the circuit, the problems of inaccurate acquisition precision and poor signal transmission anti-interference capability when different wire systems are used for temperature acquisition in the existing scheme are solved.

Description

Technical Field

[0001] This invention relates to the field of temperature detection technology, and in particular to a temperature acquisition circuit and device. Background Technology

[0002] Existing temperature acquisition solutions are mostly based on the collaborative working mechanism of a current source and a temperature sensor. The current source flows through the temperature sensor, and the voltage value across the sensor is then collected to obtain the current temperature data. Depending on the wiring configuration, existing solutions are mainly divided into two-wire, three-wire, and four-wire systems. While the two-wire RTD measurement method is simple to wire, it cannot eliminate the error caused by the resistance of the wires, introducing error from both wires during the measurement process. It is only suitable for scenarios where high temperature measurement accuracy is not required. The three-wire system introduces the error of the resistance of one wire during temperature acquisition, improving accuracy compared to the two-wire system, but still has limitations. The four-wire system avoids the error caused by the resistance of the wires, but the wiring process is complex, and the implementation cost is relatively high.

[0003] In terms of signal transmission, existing solutions mostly employ single-ended signal transmission or pseudo-differential transmission. These two methods have weak resistance to external interference and are easily affected by external factors, leading to signal distortion. Furthermore, existing solutions require a stable current source, the stability of which directly affects the quality of the acquired signal; any instability in the current source will result in signal deviation. Moreover, introducing a current source significantly increases the overall circuit cost. Therefore, there is an urgent need to develop a novel temperature acquisition solution that requires no current source, is not limited by wiring, and has strong anti-interference capabilities. Summary of the Invention

[0004] The purpose of this invention is to provide a temperature acquisition circuit and device. This circuit innovatively utilizes the frequency characteristics of the output signal of the 555 timer and combines it with a specific algorithmic relationship between frequency and temperature to solve the technical problems of existing temperature acquisition schemes, such as dependence on current sources, limitations imposed by wiring, and poor anti-interference capabilities.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] This invention provides a temperature acquisition circuit and device, which includes: a temperature measuring element, a temperature acquisition module, a signal conversion module, and a signal processing module;

[0007] The temperature measuring element is used to sense changes in external temperature in real time and convert those changes into a measurable resistance signal.

[0008] The input terminal of the temperature acquisition module is directly coupled to the temperature measuring element, and is used to acquire the resistance signal generated by the temperature measuring element and convert the resistance signal into a single-ended frequency signal.

[0009] The input terminal of the signal conversion module is connected to the output terminal of the temperature acquisition module, and is used to convert the single-ended frequency signal into a differential signal to suppress common-mode noise;

[0010] The input terminal of the signal processing module is connected to the output terminal of the signal conversion module. The differential signal output by the signal conversion module is processed using a preset algorithm to finally obtain temperature data.

[0011] In one embodiment of the present invention, the single-ended frequency signal is linearly mapped to the external temperature change, and the frequency value of the single-ended frequency signal changes synchronously with the temperature change.

[0012] In one embodiment of the present invention, the temperature acquisition module includes a current-limiting resistor, a timing capacitor, and a 555 timer chip;

[0013] The first end of the current-limiting resistor is connected to the power input terminal of the 555 timer chip, and the second end is connected to the first end of the temperature measuring element and the discharge terminal of the 555 timer chip.

[0014] The first terminal of the timing capacitor is connected to the second terminal of the temperature measuring element and the first and second input terminals of the 555 timer chip, and the second terminal is connected to ground.

[0015] The output of the 555 timer chip is connected to the input of the signal conversion module.

[0016] In one embodiment of the present invention, the temperature measuring element includes a temperature sensor, a resistance temperature detector (RTD), or a thermistor.

[0017] In one embodiment of the present invention, the temperature acquisition module further includes a filter capacitor, the first end of which is connected to the control voltage terminal of the 555 timer chip, and the second end is connected to ground, for stabilizing the internal reference voltage of the 555 timer chip.

[0018] In one embodiment of the present invention, the signal conversion module includes a fully differential amplifier, the input terminal of which is connected to the output terminal of the temperature acquisition module, and the output terminal of which is connected to the input terminal of the signal processing module, for converting the single-ended frequency signal into a differential signal.

[0019] In one embodiment of the present invention, the fully differential amplifier is powered by a dual power supply.

[0020] In one embodiment of the present invention, the signal processing module includes an analog-to-digital converter and a microcontroller;

[0021] The input terminal of the analog-to-digital conversion unit is connected to the output terminal of the signal conversion module, and is used to convert the differential signal output by the signal conversion module into a digital signal;

[0022] The input terminal of the microcontroller is connected to the output terminal of the analog-to-digital converter, and the digital signal is processed using a preset algorithm to calculate and output the temperature value.

[0023] In one embodiment of the present invention, the circuit further includes a display module, the input terminal of which is connected to the output terminal of the signal processing module, for displaying the temperature value output by the signal processing module.

[0024] Based on the same inventive concept, another embodiment of the present invention provides a temperature acquisition device, including a temperature acquisition circuit and a housing as described in any of the above embodiments, wherein the temperature acquisition circuit is disposed inside the housing.

[0025] As described above, the present invention provides a temperature acquisition circuit, including a temperature measuring element, a temperature acquisition module, a signal conversion module, and a signal processing module. The temperature measuring element is used to sense changes in external temperature in real time and convert these changes into a measurable resistance signal. The input terminal of the temperature acquisition module is directly coupled to the temperature measuring element, used to acquire the resistance signal generated by the temperature measuring element, and convert the resistance signal into a single-ended frequency signal. The input terminal of the signal conversion module is connected to the output terminal of the temperature acquisition module, used to convert the single-ended frequency signal into a differential signal to suppress common-mode noise. The input terminal of the signal processing module is connected to the output terminal of the signal conversion module, and uses a preset algorithm to process the differential signal output by the signal conversion module to finally obtain temperature data. This temperature acquisition circuit avoids the dependence on current sources in existing temperature acquisition schemes, eliminating the need for an additional stable current source, thereby reducing the overall cost of the circuit and avoiding signal deviations caused by unstable current sources. Furthermore, this temperature acquisition circuit is not limited by wiring type; regardless of the wiring connection method used, it can accurately acquire temperature, avoiding accuracy fluctuations and cost increases caused by differences in wiring type. In terms of signal transmission, this temperature acquisition circuit has stronger anti-interference capabilities. Compared with existing single-ended signal transmission and pseudo-differential transmission methods, it can better resist external interference, reduce signal distortion, and ensure that the acquired temperature data is accurate and reliable. Of course, any product implementing this invention does not necessarily need to achieve all of the above-mentioned advantages simultaneously. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the temperature acquisition circuit provided for an exemplary embodiment of this application.

[0028] Figure 2 A circuit diagram of a temperature acquisition module provided for an exemplary embodiment of this application.

[0029] Figure 3 A circuit diagram of a signal conversion module provided for an exemplary embodiment of this application.

[0030] Figure 4 A circuit diagram of an analog-to-digital converter unit provided for an exemplary embodiment of this application.

[0031] The attached figures are labeled as follows:

[0032] 100 temperature measuring element

[0033] 200 Temperature Acquisition Module

[0034] 300 signal conversion module

[0035] 400 signal processing module

[0036] 410 Analog-to-Digital Converter

[0037] 420 microcontroller Detailed Implementation

[0038] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0039] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0040] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, publicly known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0041] To address the common technical problems of existing temperature acquisition schemes, such as reliance on current sources, limitations imposed by wiring, and poor anti-interference capabilities, this invention innovatively proposes a temperature acquisition circuit, primarily applicable to industrial control fields, such as temperature monitoring scenarios for fan controllers. This circuit is based on the frequency characteristics of the 555 timer output signal. By establishing an algorithmic mapping relationship between frequency and temperature, in practical applications, only the frequency signal output by the 555 timer needs to be acquired and processed by a preset algorithm to achieve real-time acquisition of high-precision temperature values.

[0042] In one exemplary embodiment of this application, please refer to Figure 1 As shown, the temperature acquisition circuit mainly includes a temperature measuring element 100, a temperature acquisition module 200, a signal conversion module 300, and a signal processing module 400. The temperature measuring element 100 is used to sense changes in external temperature in real time and convert these changes into a measurable resistance signal. The input terminal of the temperature acquisition module 200 is directly coupled to the temperature measuring element 100, and it is used to acquire the resistance signal generated by the temperature measuring element 100 and convert the resistance signal into a single-ended frequency signal. The input terminal of the signal conversion module 300 is connected to the output terminal of the temperature acquisition module 200, and it is used to convert the single-ended frequency signal into a differential signal to suppress common-mode noise. The input terminal of the signal processing module 400 is connected to the output terminal of the signal conversion module 300, and it uses a preset algorithm to process the differential signal output by the signal conversion module 300 to finally obtain the temperature data.

[0043] It should be noted that in this embodiment, the single-ended frequency signal has a linear mapping relationship with the external temperature change, and the frequency value of the single-ended frequency signal changes synchronously with the temperature change. Furthermore, the differential transmission method used in this embodiment has significant advantages. Differential signals have a strong ability to suppress common-mode noise during transmission, effectively resisting various interference factors such as external electromagnetic interference and power supply noise, thereby greatly improving the stability and reliability of signal transmission.

[0044] In one exemplary embodiment of this application, please refer to Figure 2 As shown, Figure 2A circuit diagram showing the coupling between the temperature acquisition module 200 and the temperature measuring element 100 is shown. The temperature acquisition module 200 includes a current-limiting resistor R1, a timing capacitor C1, and a 555 timer chip U1. The first end of the current-limiting resistor R1 is connected to the power input terminal VCC of the 555 timer chip U1, and the second end is connected to the first terminal of the temperature measuring element 100 and the discharge terminal DISCH of the 555 timer chip U1. The first end of the timing capacitor C1 is connected to the second terminal of the temperature measuring element 100 and the first input terminal TRIG and the second input terminal THRES of the 555 timer chip U1, and the second end is connected to ground GND. The output terminal OUT of the 555 timer chip U1 is connected to the input terminal INP of the signal conversion module 300. It should be noted that the temperature measuring element 100 includes a temperature sensor, a resistance temperature detector (RTD), or a thermistor. The thermal resistor can be a PT100 or PT1000, and the thermistor can be a negative temperature coefficient thermistor (NTC) or a positive temperature coefficient thermistor (PTC). In this embodiment, please refer to... Figure 2 As shown, the temperature measuring element 100 is an NTC thermistor.

[0045] It should be noted that the 555 timer chip U1 integrates two voltage comparators, an RS flip-flop, a discharge transistor, and a resistor divider network. The resistor divider network typically consists of three 5kΩ resistors connected in series, providing reference voltages of 1 / 3VCC and 2 / 3VCC to the 555 timer chip U1. For details, please refer to [link to relevant documentation]. Figure 2 As shown, the 555 timer chip U1 is set to operate in astable mode. In astable mode, the comparators and flip-flops inside the 555 timer chip U1 work together to enable the chip to oscillate and output a continuously changing frequency signal. In this embodiment, the output signal OUT_PUT of the 555 timer chip U1 exhibits an alternating high and low level state, i.e., a square wave signal. The frequency of the square wave signal is determined by the current-limiting resistor R1, the NTC thermistor, and the timing capacitor C1. The frequency calculation formula for the output signal OUT_PUT is: f = 1.44 / ((R1 + NTC) × C1). It is worth noting that in this embodiment, the current-limiting resistor R1 and the timing capacitor C1 are both set to fixed values. Since the resistance value of the NTC thermistor has a one-to-one correspondence with the external temperature, the frequency signal f calculated by the frequency calculation formula also corresponds one-to-one with the external temperature.

[0046] In an exemplary embodiment of this application, please continue to refer to Figure 2 As shown, the temperature acquisition module also includes a filter capacitor C2. The first end of the filter capacitor C2 is connected to the control voltage terminal CONT of the 555 timer chip U1, and the second end is connected to the ground terminal GND, which is used to stabilize the internal reference voltage of the 555 timer chip U1.

[0047] In one exemplary embodiment of this application, please refer to Figure 3 As shown, the signal conversion module 300 includes a fully differential amplifier U2. The input terminal INP of the fully differential amplifier U2 is connected to the output terminal of the temperature acquisition module 200, and the output terminal of the fully differential amplifier U2 is connected to the input terminal of the signal processing module 400, for converting the single-ended frequency signal into a differential signal. It should be noted that in this embodiment, the fully differential amplifier U2 is powered by a dual power supply.

[0048] For details, please continue reading Figure 3 As shown, the input terminal INP of the fully differential amplifier U2 is connected to the output terminal of the temperature acquisition module 200. During operation, the temperature acquisition module 200 collects real-time changes in the external temperature and converts these changes into a single-ended frequency signal OUT_PUT for output. It should be noted that the frequency of the single-ended frequency signal OUT_PUT serves as the carrier of temperature information. However, single-ended signals are susceptible to external interference during transmission, leading to signal quality degradation. Therefore, in this embodiment, the input terminal INP of the fully differential amplifier U2 receives the single-ended frequency signal OUT_PUT output by the temperature acquisition module 200 and converts it into a differential signal (OUT_PUT+ / OUT_PUT-). It is understood that the differential signal is transmitted through two lines with equal amplitude and opposite phase. During transmission, external interference acts on both lines simultaneously. Since the interference has the same effect on both lines, differential operations at the receiving end can effectively cancel out the interference signal, thereby improving the signal's anti-interference capability and enhancing its stability and reliability. Understandably, differential signals are better suited for long-distance transmission, reducing signal attenuation and ensuring high signal quality when transmitted to the signal processing module 400. Furthermore, in this embodiment, the fully differential amplifier U2 employs a dual-power supply. Dual power supply provides stable and sufficient power to the fully differential amplifier U2. Compared to single power supply, dual power supply better meets the different voltage requirements of the internal circuitry of the fully differential amplifier U2, providing appropriate bias voltages for various parts of the amplifier.

[0049] In one exemplary embodiment of this application, please refer to Figure 4 As shown, the signal processing module 400 includes an analog-to-digital converter (ADC) 410 and a microcontroller unit (MCU) 420. The input terminal of the ADC 410 is connected to the output terminal of the signal conversion module 300, and is used to convert the differential signal output by the signal conversion module 300 into a digital signal. The input terminal of the microcontroller 420 is connected to the output terminal of the ADC 410, and processes the digital signal using a preset algorithm to calculate and output the temperature value.

[0050] For details, please continue reading Figure 4 As shown, the analog-to-digital converter (ADC) 410 samples the input differential signal (OUT_PUT+ / OUT_PUT-) in real time at a high sampling frequency, converting the continuously changing analog signal into a discrete digital signal. The input terminal of the microcontroller 420 is connected to the output terminal of the ADC 410, and is used to receive the digital signal obtained after the ADC processing. It is understood that the microcontroller 420 integrates powerful computing capabilities and multiple functional modules, enabling it to process the input digital signal using a preset algorithm and then calculate the temperature data. It should be noted that in this embodiment, the ADC 410 and the microcontroller 420 communicate via a Serial Peripheral Interface (SPI). Of course, in other embodiments, the communication method between the ADC 410 and the microcontroller 420 is not limited to SPI communication; other suitable communication methods can be used according to actual needs.

[0051] In an exemplary embodiment of this application, the temperature acquisition circuit further includes a display module (not shown), the input terminal of which is connected to the output terminal of the signal processing module 400, for displaying the temperature value output by the signal processing module 400.

[0052] Specifically, to achieve a clear presentation of temperature measurement results and facilitate timely access to temperature information for users, the temperature acquisition circuit also includes a display module (not shown). After completing the complex processing of the temperature signal and calculating the temperature value, the signal processing module 400 transmits the data signal containing the temperature value to the display module through its output terminal. It should be noted that, in this embodiment, the display module includes, but is not limited to, a liquid crystal display (LCD) or an organic light-emitting diode display (OLED).

[0053] In summary, the present invention provides a temperature acquisition circuit comprising a temperature measuring element 100, a temperature acquisition module 200, a signal conversion module 300, and a signal processing module 400. The temperature measuring element 100 is used to sense changes in external temperature in real time and convert these changes into a measurable resistance signal. The input terminal of the temperature acquisition module 200 is directly coupled to the temperature measuring element 100, and is used to acquire the resistance signal generated by the temperature measuring element 100 and convert the resistance signal into a single-ended frequency signal. The input terminal of the signal conversion module 300 is connected to the output terminal of the temperature acquisition module 200, and is used to convert the single-ended frequency signal into a differential signal to suppress common-mode noise. The input terminal of the signal processing module 400 is connected to the output terminal of the signal conversion module 300, and uses a preset algorithm to process the differential signal output by the signal conversion module 300 to finally obtain temperature data. This temperature acquisition circuit avoids the dependence on current sources in existing temperature acquisition schemes, eliminating the need for additional stable current source design, thereby reducing the overall cost of the circuit and avoiding signal deviations caused by unstable current sources. Furthermore, this temperature acquisition circuit is not limited by wiring type; regardless of the wiring connection method used, it can accurately acquire temperature data, avoiding accuracy fluctuations and increased costs caused by differences in wiring type. In terms of signal transmission, this temperature acquisition circuit has stronger anti-interference capabilities. Compared to existing single-ended signal transmission and pseudo-differential transmission methods, it can better resist external interference, reduce signal distortion, and ensure the accuracy and reliability of the acquired temperature data.

[0054] Based on the same inventive concept, another embodiment of the present invention provides a temperature acquisition device, including a temperature acquisition circuit and a housing as described in any of the above embodiments, wherein the temperature acquisition circuit is disposed inside the housing.

[0055] It should be noted that the temperature acquisition device includes the temperature acquisition circuit described in any of the above embodiments. Since the temperature acquisition device provided in this embodiment belongs to the same inventive concept as the temperature acquisition circuit provided in any of the above embodiments, it has at least the same beneficial effects, and will not be described in detail here.

[0056] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A temperature acquisition circuit, characterized in that, include: Temperature measuring element, temperature acquisition module, signal conversion module, and signal processing module; The temperature measuring element is used to sense changes in external temperature in real time and convert those changes into a measurable resistance signal. The input terminal of the temperature acquisition module is directly coupled to the temperature measuring element, and is used to acquire the resistance signal generated by the temperature measuring element and convert the resistance signal into a single-ended frequency signal. The input terminal of the signal conversion module is connected to the output terminal of the temperature acquisition module, and is used to convert the single-ended frequency signal into a differential signal to suppress common-mode noise; The input terminal of the signal processing module is connected to the output terminal of the signal conversion module. The differential signal output by the signal conversion module is processed using a preset algorithm to finally obtain temperature data.

2. The temperature acquisition circuit according to claim 1, characterized in that, The single-ended frequency signal has a linear mapping relationship with the external temperature change, and the frequency value of the single-ended frequency signal changes synchronously with the temperature change.

3. The temperature acquisition circuit according to claim 1, characterized in that, The temperature acquisition module includes a current-limiting resistor, a timing capacitor, and a 555 timer chip. The first end of the current-limiting resistor is connected to the power input terminal of the 555 timer chip, and the second end is connected to the first end of the temperature measuring element and the discharge terminal of the 555 timer chip. The first terminal of the timing capacitor is connected to the second terminal of the temperature measuring element and the first and second input terminals of the 555 timer chip, and the second terminal is connected to ground. The output of the 555 timer chip is connected to the input of the signal conversion module.

4. The temperature acquisition circuit according to claim 3, characterized in that, The temperature measuring element includes a temperature sensor, a resistance temperature detector (RTD), or a thermistor.

5. The temperature acquisition circuit according to claim 3, characterized in that, The temperature acquisition module also includes a filter capacitor. The first end of the filter capacitor is connected to the control voltage terminal of the 555 timer chip, and the second end is connected to ground, which is used to stabilize the internal reference voltage of the 555 timer chip.

6. The temperature acquisition circuit according to claim 1, characterized in that, The signal conversion module includes a fully differential amplifier. The input terminal of the fully differential amplifier is connected to the output terminal of the temperature acquisition module, and the output terminal is connected to the input terminal of the signal processing module. It is used to convert the single-ended frequency signal into a differential signal.

7. The temperature acquisition circuit according to claim 6, characterized in that, The fully differential amplifier is powered by a dual power supply.

8. The temperature acquisition circuit according to claim 1, characterized in that, The signal processing module includes an analog-to-digital converter and a microcontroller; The input terminal of the analog-to-digital conversion unit is connected to the output terminal of the signal conversion module, and is used to convert the differential signal output by the signal conversion module into a digital signal; The input terminal of the microcontroller is connected to the output terminal of the analog-to-digital converter, and the digital signal is processed using a preset algorithm to calculate and output the temperature value.

9. The temperature acquisition circuit according to claim 1, characterized in that, The circuit also includes a display module, the input of which is connected to the output of the signal processing module, for displaying the temperature value output by the signal processing module.

10. A temperature acquisition device, characterized in that, It includes the temperature acquisition circuit and housing as described in any one of claims 1 to 9, wherein the temperature acquisition circuit is disposed inside the housing.

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