An array-type flexible temperature sensor wireless acquisition system

Abstract

The present invention discloses an array-type flexible temperature sensor wireless acquisition system, wherein the flexible temperature sensor array is used to acquire temperature field signals, the analog switch module is used to switch the column leads in the temperature sensor array to ground or to a reference voltage, the channel selection module is used to select the row leads in the temperature sensor array to be grounded, the A / D conversion module is used to amplify the voltage signal output by the temperature sensor array and convert it into a digital signal, the MCU module is used to control the analog switch module, the channel selection module, and the A / D conversion module to acquire sensor signals, perform analytical calculations on the acquired data, and the line transmission module is used to wirelessly transmit the calculated results to a terminal device through a signal antenna. The present invention adopts an analog electronic switch and a channel selection switch, solves the crosstalk problem between sensors through analytical calculations, realizes the gating of the output signals of the n*m-way drive module, and realizes the acquisition of the temperature array sensor unit.

Description

Technical Field

[0001] The invention relates to the field of temperature detection, and in particular to an array type flexible temperature sensor wireless acquisition system. Background Art

[0002] Temperature is an important environmental parameter that affects our production and life. It also affects the properties of objects, especially in the process of heat conduction, where heat is exchanged between the object and the surrounding environment, resulting in a gradual change in temperature in the object, i.e., a temperature gradient. In addition, due to the different materials that make up the object, the object exhibits anisotropy during temperature conduction, i.e., the distribution of the same temperature is not distributed in a straight line, so different areas on the surface of the object have different temperatures. In order to gain a deeper understanding of the impact of temperature on the object, it is necessary to know the distribution of temperature on the surface of the object.

[0003] Temperature measurement can basically be divided into contact measurement and non-contact measurement. Contact measurement mainly measures the temperature of an object by direct contact between a thermal resistor or a thermocouple and the object being measured, while non-contact measurement mainly uses an infrared thermometer or an infrared thermal imager. Contact measurement and infrared thermometers can detect the temperature of a point on the surface of an object, while infrared thermal imagers can detect the overall temperature distribution of the surface of an object. Usually, the most commonly used is contact temperature measurement, but if you want to detect the temperature distribution and gradient on the surface of an object, single-point measurement has great limitations. First, the installation is more troublesome, and the temperature probes need to be installed one by one on the surface of the object, which is a lot of work. Second, there are more wirings, because each temperature sensor requires at least two wires. If the surface area of ​​the object being measured is large and the required resolution is high, the wiring work is very heavy. Although infrared thermal imagers can detect the temperature distribution and gradient on the surface of an object at one time, when infrared thermal imagers detect temperature, they need to be close to the object being inspected, and there must be no obstructions in the middle. For temperature measurement in some extreme environments, such as narrow space, high temperature, low temperature, toxic environment, etc., infrared thermal imagers are not applicable.

[0004] However, due to the common array resistance cross-coupling phenomenon in temperature array sensors, the current contact temperature acquisition equipment has too large external leads as the array size increases, resulting in a complex structure of peripheral components, and signals are mostly transmitted by wire, making measurement inconvenient. It can only be used for simple plane measurements and cannot cope with complex and changeable curved surface temperature field tests. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide an array-type flexible temperature sensor wireless acquisition system to solve the problems of multiple external leads of the temperature sensor array, crosstalk between sensors, complex and cumbersome data acquisition equipment, and narrow application range.

[0006] To this end, the technical solution adopted by the present invention is as follows: an array-type flexible temperature sensor wireless acquisition system, including a flexible temperature sensor array, an analog switch module, a channel selection module, an A / D conversion module, a power management module, an MCU module, a wireless transmission module, a lithium battery, a voltage stabilization module, and a charging interface;

[0007] The flexible temperature sensor array is used to collect temperature field signals;

[0008] The analog switch module is used to switch the column leads in the temperature sensor array to ground or to a reference voltage;

[0009] The channel selection module is used to select the row lead grounding in the temperature sensor array;

[0010] The A / D conversion module is used to amplify the voltage signal output by the temperature sensor array and convert it into a digital signal;

[0011] The MCU module is used to control the analog switch module, the channel selection module, and the A / D conversion module to collect sensor signals and perform analytical operations on the collected data;

[0012] The wireless transmission module is used to wirelessly transmit the results calculated by the MCU module to the terminal device through the signal antenna.

[0013] Furthermore, the analog switch module is a multi-channel single-pole double-throw analog switch, and each channel supports two-choice independent control.

[0014] Furthermore, the working process of the acquisition system includes the following steps:

[0015] 1) Column channel selection: The MCU module controls the analog switch module to select the first column lead to connect to the reference voltage, and select other column leads to directly ground;

[0016] 2) Row channel selection: MCU module controls the channel selection module to select the first row lead to the feedback resistor R f Grounding;

[0017] 3) Start collecting: The MCU module controls the A / D conversion module to collect the feedback resistor R f The voltage across the terminals is V 11 ;

[0018] 4) Polling collection: The MCU module controls the channel selection module to select the second to n rows of leads connected to the feedback resistor R f grounded, and then controls the A / D conversion module to collect the feedback resistor R f The voltage across the terminals is V 21 V 31 V 41 ……Vn1 ;

[0019] 5) Cyclic acquisition: The MCU module controls the analog switch module to sequentially select the second column lead to connect to the reference voltage, select the other column leads to directly ground, and measure R according to the above method. f The voltage across the terminals is V 12 V 22 ……V n2 , V 13 V 23 ……V n3 , ..., V 1m V 2m ……V nm , so far one collection is finished;

[0020] 6) Analytical calculation: For an n*m sensor array, the resistance value R of any sensor can be obtained by formula (1): ij ;

[0021]

[0022] Among them, V ref is the reference voltage, V ij is the feedback resistance R when scanning the i-th row and j-th column f Voltage across the board, R ij is the sensor resistance value of the i-th row and j-th column.

[0023] The present invention adopts the above technical solution, which has the following advantages:

[0024] 1. By using analog electronic switches and channel selection switches, the crosstalk problem between sensors is solved through analytical calculation, the selection of output signals of n*m driving modules is realized, and the acquisition of temperature array sensor units is realized.

[0025] 2. The peripheral components have a simple structure and a small number, and the Bluetooth wireless transmission method makes the device wearable;

[0026] 3. Use flexible temperature sensors to increase the measurement dimension and can be used to measure temperature fields on complex curved surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings.

[0028] Figure 1 This is the structural block diagram of the temperature array acquisition circuit;

[0029] Figure 2 This is the analog switch circuit diagram;

[0030] Figure 3 This is the voltage measurement equivalent circuit diagram;

[0031] Figure 4 This is the temperature and resistance characteristic curve of the temperature sensor.

[0032] Marked in the figure are: flexible temperature sensor 1, column lead 11, row lead 12, 4-channel single-pole double-throw analog switch 2, and 4-to-1 analog switch 3. DETAILED DESCRIPTION

[0033] The following is a best example of an array-type flexible temperature sensor wireless acquisition system described in the present invention, which does not limit the protection scope of the present invention.

[0034] Figure 1 A temperature field detection device based on a temperature sensor array is shown, including a flexible temperature sensor array, a channel selection module, an analog switch module, an A / D conversion module, a power management module, an MCU module, a wireless module, a lithium battery, a voltage stabilization module, and a charging interface;

[0035] The flexible temperature sensor array is used to collect temperature field signals;

[0036] The analog switch module is used to switch the temperature sensor array column channels;

[0037] The channel selection module is used to select the row channel of the temperature sensor array;

[0038] The A / D conversion module is used to amplify the analog voltage signal input by the temperature sensor group and convert it into a digital signal;

[0039] The MCU module is used to control the analog switch module, the channel selection module, and the A / D conversion module to collect sensor signals, perform analytical calculations on the collected data, and transmit the calculated results to the mobile device through the wireless module;

[0040] The flexible temperature sensor array is connected to the channel selection module and the analog switch module;

[0041] The channel selection module is connected with the A / D conversion module and the MCU module;

[0042] The analog switch module is connected to the voltage stabilizing module and the MCU module;

[0043] The voltage stabilizing module is respectively connected to the MCU module, the A / D conversion module, and the analog switch module to power the device and provide a stable voltage so as to obtain a more accurate signal;

[0044] The lithium battery is connected to the power management module and the voltage stabilization module to store electrical energy;

[0045] The power management module is connected to the lithium battery and the charging interface to connect to external functions for charging.

[0046] Figure 2 This is the schematic diagram of the analog switch circuit for the 4*4 temperature sensor array;

[0047] The working principle of the temperature sensor array acquisition circuit provided in this embodiment is as follows:

[0048] Figure 2 Among them, the flexible temperature sensor 1 is a thin film sensor with a paper-thin structure and an NTC effect, and its resistance decreases as the temperature increases. Figure 4 The characteristic curve of the temperature and resistance of the selected flexible temperature sensor is shown in Figure 2. It can be seen from the characteristic curve that the temperature and resistance are nonlinear, and the functional relationship between the temperature and resistance can be calculated using the SH model calculation method.

[0049] The functional relationship is: 1 / T = A + B*ln(R) + C*[ln(R)] 3 . Formula (2)

[0050] Where A = 0.8744102777*e-3;

[0051] B = 2.537694912*e-4;

[0052] C = 1.821320203*e-7.

[0053] The flexible temperature sensor 1 is connected in series and parallel to form an array. For a 4*4 sensor array, only 4+4=8 leads are required to be connected to peripheral components. Among them, the column lead 11 is connected to the 4-channel single-pole double-throw analog switch 2, and the row lead 12 is connected to the 4-to-1 analog switch 3.

[0054] One end of the 4-channel single-pole double-throw analog switch 2 is connected to the column lead 11, and the other end 8 is connected to the reference voltage and the ground respectively. Figure 2 shown.

[0055] One end of the 4-to-1 analog switch 3 is connected to the row lead 12, and the other end is connected to the feedback resistor and grounded. f The resistance value is selected according to the resistance characteristics of the temperature sensor. In this example, the feedback resistor R f It is a 12KΩ high precision and low temperature drift resistor.

[0056] The A / D conversion module is connected to the common end of the 4-to-1 analog switch to collect the feedback resistance R f The voltage V across the resistors;

[0057] The specific collection process is as follows:

[0058] First, the MCU module controls the analog switch module to select the first column lead to connect to the reference voltage, and the other column leads are directly grounded; the 4-to-1 analog switch selects the first row lead, and the feedback resistor R is collected through the A / D conversion module. f The voltage on both sides is V 11 ; The 4-to-1 analog switch selects the second, third, and fourth row leads through sequential polling, and collects the feedback resistor R through the A / D conversion module f The voltages on both sides are denoted as V 21 ,V 31 ,V 41 ;

[0059] Then select the second column lead to connect to the reference voltage, and the other column leads are directly grounded. Repeat the above steps to measure the feedback resistance R f Voltage on both sides V 12 , V 22 ,V 32 ,V 42 ;

[0060] Repeat the above steps and measure the feedback resistance R f Voltage on both sides V 13 , V 23 ,V 33 ,V 43 , V 14 , V 24 ,V 34 ,V 44 ;

[0061] This completes one measurement.

[0062] The feedback resistor R f The voltage V at both ends is only related to the resistance of the temperature sensor of the selected row, and has nothing to do with the resistance of the temperature sensor of the unselected row;

[0063] like Figure 3 As shown, when the first column lead and the first row lead are selected, the measured feedback resistance R f Voltage across the terminals V 11 For R 11 and R f ∥R 11 ∥R 12 ∥R 13 The voltage obtained by voltage division. Specifically:

[0064]

[0065] V 12 ,V 13 ,V 14 The same logic can be applied;

[0066] The simultaneous equations finally yield:

[0067]

[0068] For n*m array sensors, this method can also be used to calculate the resistance value of any sensor:

[0069]

[0070] The resistance distribution of the temperature sensor array is calculated one by one by formula (1), and the resistance distribution of the temperature sensor is calculated, and then the temperature distribution is calculated by formula (2);

[0071] The Bluetooth processing chip converts the voltage distribution into a resistance distribution using formula (1), and then converts the resistance distribution into a temperature distribution using formula (2);

[0072] The Bluetooth processing chip wirelessly transmits the obtained temperature distribution to the terminal device via a Bluetooth signal;

[0073] The terminal device, such as a mobile phone with Bluetooth function, wirelessly receives temperature distribution data sent from a Bluetooth processing chip through a Bluetooth signal, and then finally visualizes the temperature distribution through a customized app program, which can reflect the temperature distribution change status in real time.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An array-type flexible temperature sensor wireless acquisition system, including a flexible temperature sensor array, an analog switch module, a channel selection module, an A / D conversion module, a power management module, an MCU module, a wireless transmission module, a lithium battery, a voltage stabilization module, and a charging interface; The flexible temperature sensor array is used to collect temperature field signals; The analog switch module is used to switch the column leads in the temperature sensor array to ground or to a reference voltage; The channel selection module is used to select the row lead grounding in the temperature sensor array; The A / D conversion module is used to amplify the voltage signal output by the temperature sensor array and convert it into a digital signal; The MCU module is used to control the analog switch module, the channel selection module, and the A / D conversion module to collect sensor signals and perform analytical operations on the collected data; The wireless transmission module is used to wirelessly transmit the calculation results obtained by the MCU module to the terminal device through the signal antenna; Features: The working process of the acquisition system includes the following steps: 1) Column channel selection: The MCU module controls the analog switch module to select the first column lead to connect to the reference voltage. The other column leads are directly grounded; 2) Row channel selection: MCU module controls the channel selection module to select the first row lead to the feedback resistor R f Grounding; 3) Start collecting: The MCU module controls the A / D conversion module to collect the feedback resistor R f The voltage across the terminals is V 11 ; 4) Polling collection: The MCU module controls the channel selection module to select the second to n rows of leads connected to the feedback resistor R f grounded, and then controls the A / D conversion module to collect the feedback resistor R f The voltage across the terminals is V 21 V 31 V 41 ……V n1 ; 5) Cyclic acquisition: The MCU module controls the analog switch module to sequentially select the second column lead to connect to the reference voltage, select the other column leads to directly ground, and measure R according to the above method. f The voltage across the terminals is V 12 V 22 ……V n2 , V 13 V 23 ……V n3 , ..., V 1m V 2m ……V nm , so far one collection is finished; 6) Analytical calculation: For an n*m sensor array, the resistance value R of any sensor can be obtained by formula (1): ij ; Among them, V ref is the reference voltage, V ij is the feedback resistance R when scanning the i-th row and j-th column f Voltage across the board, R ij is the sensor resistance value of the i-th row and j-th column.

2. The array-type flexible temperature sensor wireless acquisition system according to claim 1, characterized in that: The analog switch module is a multi-channel single-pole double-throw analog switch, and each channel supports two-choice independent control.

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