A temperature monitoring and alarm system
By combining a voltage divider measurement circuit and a limit setting circuit with a timing circuit and an analog-to-digital converter, the accuracy and anti-interference issues of infant thermometers are solved, enabling accurate display and timely alarm even when the infant's body temperature changes significantly.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF SCI & TECH
- Filing Date
- 2025-05-21
- Publication Date
- 2026-06-30
AI Technical Summary
Existing infant thermometers are not very accurate due to factors such as usage standards, environmental influences, and reading errors. They also lack adjustable alarm temperature limits, have limited applicability, and are insufficient in terms of anti-interference and measuring range.
A voltage divider measurement circuit is used to reduce the impact of power fluctuations. The alarm temperature limit signal is input through the limit setting circuit and display module. The temperature signal is obtained by the timing circuit and converted into a digital signal by the analog-to-digital converter. The controller displays and alarms the signal, which expands the measurement range and improves anti-interference.
This technology improves the accuracy and interference resistance of temperature monitoring, expands the measurement range, and ensures timely temperature display and alarm reminders, even when infants experience large temperature variations.
Smart Images
Figure CN224435586U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of medical devices, and in particular to a temperature monitoring and alarm system. Background Technology
[0002] Infants have relatively weak immune systems and are susceptible to various diseases. Monitoring their body temperature can help parents detect abnormalities early, such as high fever, which is crucial for timely medical attention and treatment. However, conventional thermometers are not very accurate due to factors such as improper use, environmental influences, and reading errors. Therefore, many thermometers on the market use proprietary circuits for detection. For example, Chinese utility model patent CN212346509U discloses an electronic body temperature monitor, which includes a main unit, a temperature probe, and a display screen. It monitors the temperature through the temperature probe and then triggers an alarm through a control circuit board. However, infants' body temperature regulation is weaker than that of adults, and their normal body temperature range can vary significantly depending on their activity level and environment. This monitor does not have an adjustable alarm temperature limit, limiting its applicability. Furthermore, the direct measurement method using a thermistor places high demands on the circuitry, making it significantly susceptible to temperature fluctuations, resulting in poor anti-interference capabilities and a limited measuring range. Utility Model Content
[0003] The purpose of this invention is to provide a temperature monitoring and alarm system. This invention reduces the impact of power fluctuations through a voltage divider measurement circuit, improves anti-interference capabilities, and expands the measurement range to meet the needs of infants with large temperature variations.
[0004] The technical solution of this utility model is as follows: A temperature monitoring and alarm system includes a power supply and a controller connected together. The input terminal of the controller is connected to a limit value setting circuit, a timing circuit, and a temperature acquisition module. The output terminal of the controller is connected to a display module, a communication module, and an alarm circuit. The temperature acquisition module includes an analog-to-digital converter U2. The input terminal of the analog-to-digital converter U2 is connected to a voltage divider measurement circuit, and the output terminal of the analog-to-digital converter U2 is connected to the input terminal of the controller. The voltage divider measurement circuit includes a resistor R7, a thermistor R8, an adjusting potentiometer R9, a resistor R10, a capacitor C4, and an adjustable voltage regulator U4. One end of the thermistor R8 is connected to the input terminal of the analog-to-digital converter U2 and the cathode of the adjustable voltage regulator U4. The other end of the thermistor R8 is connected to the input terminal of the analog-to-digital converter U2, one end of capacitor C4, one end of resistor R10, and the cathode of the adjustable voltage regulator U4. The other ends of capacitor C4 and resistor R10 are grounded. One end of resistor R7 is connected to the power supply voltage, and the other end of resistor R7 is connected to the cathode of the adjustable voltage regulator U4. The adjusting potentiometer R9 is connected in parallel with the adjustable voltage regulator U4. The adjusting terminal of the adjusting potentiometer R9 is connected to the reference terminal of the adjustable voltage regulator U4, and the anode of the adjustable voltage regulator U4 is grounded.
[0005] In the temperature monitoring and alarm system described above, the limit setting circuit includes a setting button S2, an increase button S3, and a decrease button S4. The setting button S2, the increase button S3, and the decrease button S4 are connected to the high and low level receiving pins of the controller input terminal.
[0006] In the aforementioned temperature monitoring and alarm system, the timing circuit includes capacitors C1, C2, C3, Y1 crystal, and R1. One end of Y1 is connected to one end of capacitor C1 and the clock input pin of the controller input terminal, and the other end of Y1 is connected to one end of capacitor C2. The other ends of capacitors C1 and C2 are grounded. The positive terminal of electrolytic capacitor C3 is connected to the power supply voltage, and the negative terminal of electrolytic capacitor C3 is connected to the reset pin of the controller input terminal and one end of resistor R1. The other end of resistor R1 is grounded.
[0007] In the aforementioned temperature monitoring and alarm system, the display module includes a digital tube and a driving circuit. The driving circuit includes resistors R3, R4, R5, and R6, and PNP transistors Q1, Q2, Q3, and Q4. One end of resistors R3, R4, R5, and R6 is connected to the output terminal of the controller. The other end of resistor R3 is connected to the base of PNP transistor Q1, the other end of resistor R4 is connected to the base of PNP transistor Q2, the other end of resistor R5 is connected to the base of PNP transistor Q3, and the other end of resistor R6 is connected to the base of PNP transistor Q4. The emitters of PNP transistors Q1, Q2, Q3, and Q4 are connected to the power supply voltage. The collectors of PNP transistors Q1, Q2, Q3, and Q4 are connected to the input terminals of each light-emitting segment of the digital tube.
[0008] In the aforementioned temperature monitoring and alarm system, the alarm circuit includes an NPN transistor Q5, resistors R2 and R11, a diode D1, and a buzzer. The emitter of the NPN transistor Q5 is grounded, the base of the NPN transistor Q5 is connected to one end of resistor R2, the collector of the NPN transistor Q5 is connected to one end of the buzzer and one end of resistor R11, the other end of resistor R2 is connected to the output terminal of the controller, the other end of the buzzer is connected to the power supply voltage and the positive terminal of diode D1, and the negative terminal of diode D1 is connected to the other end of resistor R11.
[0009] Compared with existing technologies, this invention, before use, inputs the required alarm temperature limit signal to the controller through a limit setting circuit and display module based on the infant's activity status and environment. During monitoring, the controller acquires the temperature acquisition module signal within a precise time period through a timing circuit. The voltage divider measurement circuit adjusts the power supply voltage through voltage division measurement, thereby reducing the impact of power fluctuations on the monitoring process and increasing the range to meet the needs of infants with large temperature variations and rapid changes. The voltage signal measured by the voltage divider measurement circuit is converted into a digital signal by the analog-to-digital converter U2 and then enters the controller. The controller displays the temperature through the display module, transmits the signal range through the communication module, and actively alarms when the alarm temperature limit is exceeded through the alarm circuit. It uses multiple methods to provide timely display and reminders, resulting in excellent reliability. Attached Figure Description
[0010] Figure 1 This is a circuit diagram of the limit setting circuit and timing circuit of this utility model;
[0011] Figure 2 This is a circuit diagram of the temperature acquisition module of this utility model;
[0012] Figure 3 This is a circuit diagram of the display module of this utility model;
[0013] Figure 4 This is a circuit diagram of the alarm circuit of this utility model;
[0014] Figure 5 This is a circuit diagram of a circuit state control circuit.
[0015] The labels in the attached diagram are as follows: 1. Controller; 2. Limit setting circuit; 3. Timing circuit; 4. Temperature acquisition module; 5. Display module; 6. Communication module; 7. Alarm circuit; 8. Voltage divider measurement circuit; 9. Digital tube; 10. Drive circuit; 11. Buzzer; 12. Circuit status control circuit. Detailed Implementation
[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.
[0017] Example: A temperature monitoring and alarm system includes a power supply and a controller 1 connected to each other. The controller is an AT89C51 microcontroller with 4kbytes of programmable Flash read-only memory, compatible with the standard 8051 instruction set and pinout. It integrates Flash program memory, allowing for both in-system programming (ISP) and traditional programming methods. It features low-voltage power supply and small size, and can be powered by dry cell batteries, enabling the system to be designed as a portable handheld device. The controller can also be replaced with a miniature relay, such as the Hongfa 10HF46F, HF49FD, Omron 3MY2N-GS-R, or Finder4Finder. 55.34.9.024.0040, etc., all feature low voltage and low power characteristics. They achieve high / low level signal triggering through multi-contact operation, making them suitable for small electronic devices. These are technical components well-known and mastered by those skilled in the art, and will not be elaborated upon here. The input terminal of controller 1 is connected to a limit value setting circuit 2, a timing circuit 3, and a temperature acquisition module 4. The output terminal of controller 1 is connected to a display module 5, a communication module 6, and an alarm circuit 7. The communication module uses a Bluetooth module; see attached... Figure 2 As shown, the temperature acquisition module 4 includes an analog-to-digital converter U2, with a voltage divider measurement circuit 8 connected to the input terminal of the converter U2, and the output terminal of the converter U2 connected to the input terminal of the controller 1; as shown in the attached figure. Figure 1 As shown, the limit setting circuit 2 includes a setting button S2, an increase button S3, and a decrease button S4. The setting button S2, increase button S3, and decrease button S4 are connected to the high and low level receiving pins of the controller 1 input terminal. When the button is not pressed, it remains at a low level; when the button is pressed, it conducts and pulls the low level high, thus changing the signal output. (See attached diagram) Figure 1As shown, the timing circuit 3 includes capacitors C1, C2, electrolytic capacitor C3, a 12MHz crystal oscillator Y1, and resistor R1. One end of crystal oscillator Y1 is connected to one end of capacitor C1 and the clock input pin of the controller 1 input terminal, and the other end of crystal oscillator Y1 is connected to one end of capacitor C2. The other ends of capacitors C1 and C2 are grounded. The positive terminal of electrolytic capacitor C3 is connected to the power supply voltage, and the negative terminal of electrolytic capacitor C3 is connected to the reset pin of the controller 1 input terminal and one end of resistor R1. The other end of resistor R1 is grounded, forming an oscillation circuit. It utilizes the piezoelectric effect of crystal oscillator Y1 to generate a stable and accurate clock signal, providing a basis for the controller to accurately monitor the frequency. The voltage divider measurement circuit 8 includes a 220Ω resistor R7, a thermistor R8, an adjustment potentiometer R9, a 30KΩ resistor R10, capacitor C4, and an adjustable voltage regulator U4. One end of the thermistor R8 is connected to the input terminal of analog-to-digital converter U2 and the adjustable voltage regulator U4. The cathode of the adjustable voltage regulator U4 is connected to the cathode of the thermistor R8, one end of the thermistor R8 is connected to the input terminal of the analog-to-digital converter U2, one end of the capacitor C4, one end of the resistor R10, and the cathode of the adjustable voltage regulator U4. The other ends of the capacitor C4 and the other ends of the resistor R10 are grounded. One end of the resistor R7 is connected to the power supply voltage, and the other end of the resistor R7 is connected to the cathode of the adjustable voltage regulator U4. The adjusting potentiometer R9 is connected in parallel with the adjustable voltage regulator U4. The adjusting end of the adjusting potentiometer R9 is connected to the reference terminal of the adjustable voltage regulator U4, and the anode of the adjustable voltage regulator U4 is grounded. The adjustable voltage regulator U4 is used to generate a reference voltage for the analog-to-digital converter and to power the thermistor R8. The resistor R7 and the adjustable potentiometer R9 adjust the voltage of the adjustable voltage regulator U4 to 4V. During operation, when the temperature rises, the resistance of the thermistor R8 decreases, and the voltage across the series resistor R10 increases. The analog-to-digital converter U2 collects the voltage signal, converts it, and transmits the digital signal to the controller. (See attached diagram) Figure 3As shown, the display module 5 includes a digital tube 9 and a driving circuit 10. The driving circuit 10 includes resistors R3, R4, R5, and R6, and PNP transistors Q1, Q2, Q3, and Q4. One end of resistors R3, R4, R5, and R6 is connected to the output terminal of controller 1. The other end of resistor R3 is connected to the base of PNP transistor Q1, the other end of resistor R4 is connected to the base of PNP transistor Q2, and the other end of resistor R5 is connected to the base of PNP transistor Q3. The other end of resistor R6... The base of PNP transistor Q4 is connected to the power supply voltage. The collectors of PNP transistors Q1, Q2, Q3, and Q4 are connected to the input terminals of each light-emitting segment of the digital tube 9. PNP transistors Q1-Q4 constitute the driving circuit. The controller output signal, after being current-limited by a resistor, controls the base of the corresponding transistor. When the transistor is turned on, it provides sufficient current to the corresponding light-emitting segment of the digital tube, driving it to emit light and realize the display function; see attached. Figure 4 As shown, the alarm circuit 7 includes an NPN transistor Q5, resistors R2 and R11, a diode D1, and a buzzer 11. The emitter of the NPN transistor Q5 is grounded, the base of the NPN transistor Q5 is connected to one end of resistor R2, the collector of the NPN transistor Q5 is connected to one end of the buzzer 11 and one end of resistor R11, the other end of resistor R2 is connected to the output terminal of the controller 1, and the other end of the buzzer 11 is connected to the power supply voltage and the positive terminal of diode D1. The negative terminal of diode D1 is connected to the other end of resistor R11. After receiving the controller signal, the buzzer is turned on through the transistor to provide an audible alert. (See attached diagram) Figure 5 As shown, it also has a circuit state control circuit 12 connected to the power supply and controller, which can perform working modes such as sleep, shutdown and operation.
[0018] Working principle: After pressing the setting button S2, the display module 5 (digital tube) displays the current preset temperature value; the high / low level signal is triggered to the controller by pressing the increase button S3 or the decrease button S4; after setting, press the setting button S2 again to confirm; the crystal oscillator Y1 and capacitors C1 and C2 form an oscillation circuit to provide a stable clock signal (period of about 83ns) for the controller 1, ensuring the accuracy of the temperature acquisition frequency (e.g., 10 samples per second); the electrolytic capacitor C3 and resistor R1 form a reset circuit: when powered on, the electrolytic capacitor C3 charges, and the reset pin of the controller 1 remains at a high level, realizing power-on reset.
[0019] The adjustable voltage regulator U4, along with resistor R7 and potentiometer R9, forms a reference voltage source, outputting a stable 4V voltage to provide a reference voltage for thermistor R8 and analog-to-digital converter U2, preventing power fluctuations from directly affecting measurement accuracy. Thermistor R8 and resistor R10 form a voltage divider network. When the temperature changes, the resistance of R8 changes accordingly, causing a change in the voltage across R10. For example, when the temperature rises, the resistance of R8 decreases, and the voltage across R10 increases. This voltage is filtered by capacitor C4 (to remove high-frequency noise) before being input to analog-to-digital converter U2. Controller 1 reads the digital signal from analog-to-digital converter U2 periodically using an internal timer. The controller's calculation results drive the digital tube 9 for display via driver circuit 10. When the controller outputs a low-level signal, the corresponding transistor conducts, supplying power to the segment selection pin of the digital tube and lighting up the corresponding segment (e.g., displaying "36.5℃").
[0020] When controller 1 outputs a high-level signal to alarm circuit 7, the base of NPN transistor Q5 is turned on when it receives a high level, and a voltage difference is formed across buzzer 11, driving the buzzer to sound; diode D1 is used to protect the transistor and prevent the buzzer from generating a reverse electromotive force that could damage the component when the power is off.
[0021] The communication module 6 is connected to the controller 1 via a serial port. The controller sends commands to the communication module to transmit alarm information to the mobile APP.
[0022] The above embodiments merely illustrate the implementation of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. Furthermore, in these embodiments, "up," "down," "left," "right," "front," and "back" represent relative positions only, not absolute positions. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.
Claims
1. A temperature monitoring and alarm system, characterized in that: The system includes a controller (1), with a finite value setting circuit (2), a timing circuit (3), and a temperature acquisition module (4) connected to its input terminal. The controller (1) also has a display module (5), a communication module (6), and an alarm circuit (7) connected to its output terminal. The temperature acquisition module (4) includes an analog-to-digital converter (U2), with a voltage divider measurement circuit (8) connected to its input terminal. The output terminal of the U2 is connected to the input terminal of the controller (1). The voltage divider measurement circuit (8) includes a resistor R7, a thermistor R8, an adjusting potentiometer R9, a resistor R10, a capacitor C4, and an adjustable voltage regulator. In the adjustable voltage regulator U4, one end of the thermistor R8 is connected to the input terminal of the analog-to-digital converter U2 and the cathode of the adjustable voltage regulator U4. The other end of the thermistor R8 is connected to the input terminal of the analog-to-digital converter U2, one end of the capacitor C4, one end of the resistor R10, and the cathode of the adjustable voltage regulator U4. The other ends of the capacitor C4 and the other ends of the resistor R10 are grounded. One end of the resistor R7 is connected to the power supply voltage, and the other end of the resistor R7 is connected to the cathode of the adjustable voltage regulator U4. The adjusting potentiometer R9 is connected in parallel with the adjustable voltage regulator U4. The adjusting end of the adjusting potentiometer R9 is connected to the reference terminal of the adjustable voltage regulator U4, and the anode of the adjustable voltage regulator U4 is grounded.
2. The temperature monitoring and alarm system according to claim 1, characterized in that: The limit setting circuit (2) includes a setting button S2, an increase button S3, and a decrease button S4. The setting button S2, the increase button S3, and the decrease button S4 are connected to the high and low level receiving pins of the controller (1) input terminal.
3. The temperature monitoring and alarm system according to claim 1, characterized in that: The timing circuit (3) includes capacitor C1, capacitor C2, electrolytic capacitor C3, crystal oscillator Y1 and resistor R1. One end of crystal oscillator Y1 is connected to one end of capacitor C1 and the clock input pin of the controller (1). The other end of crystal oscillator Y1 is connected to one end of capacitor C2. The other ends of capacitor C1 and capacitor C2 are grounded. The positive terminal of electrolytic capacitor C3 is connected to the power supply voltage. The negative terminal of electrolytic capacitor C3 is connected to the reset pin of the controller (1) and one end of resistor R1. The other end of resistor R1 is grounded.
4. The temperature monitoring and alarm system according to claim 1, characterized in that: The display module (5) includes a digital tube (9) and a driving circuit (10). The driving circuit (10) includes resistors R3, R4, R5, and R6, PNP transistors Q1, Q2, Q3, and Q4. One end of resistors R3, R4, R5, and R6 is connected to the output terminal of the controller (1), the other end of resistor R3 is connected to the base of PNP transistor Q1, and the other end of resistor R4 is connected to... The base of PNP transistor Q2 is connected to the base of PNP transistor Q3, the other end of resistor R5 is connected to the base of PNP transistor Q4, the emitters of PNP transistors Q1, Q2, Q3 and Q4 are connected to the power supply voltage, and the collectors of PNP transistors Q1, Q2, Q3 and Q4 are connected to the input terminals of each light-emitting segment of the digital tube (9).
5. The temperature monitoring and alarm system according to claim 1, characterized in that: The alarm circuit (7) includes an NPN transistor Q5, a resistor R2, a resistor R11, a diode D1, and a buzzer (11). The emitter of the NPN transistor Q5 is grounded, the base of the NPN transistor Q5 is connected to one end of the resistor R2, the collector of the NPN transistor Q5 is connected to one end of the buzzer (11) and one end of the resistor R11, the other end of the resistor R2 is connected to the output terminal of the controller (1), the other end of the buzzer (11) is connected to the power supply voltage and the positive terminal of the diode D1, and the negative terminal of the diode D1 is connected to the other end of the resistor R11.