Soybean milk machine cup cover detection circuit

Abstract

The invention provides a soybean milk machine cup cover detection circuit, and the circuit specifically comprises a reed switch with authentication, which is disposed at the contact part of a soybean milk machine cup cover and a cup body, and is used for detecting whether the cup cover is correctly installed; the MCU processing chip is used for collecting a cover closing signal of the reed switch and preventing the soybean milk machine from being started by mistake; and the detection circuit with a pull-up function is used for receiving and detecting a signal of the reed switch and judging the state of the cup cover according to the signal, and the detection circuit comprises a pull-up resistor R3, a current-limiting resistor R4, a signal filter capacitor C2 and a 3P hollow socket CN1. According to the soybean milk machine cup cover detection circuit, the starting risk caused by the failure of the cup cover detection circuit is avoided, the product safety is improved, and the safety requirement of the new national standard is met.

Description

Technical Field

[0001] The present invention relates to the technical field of detection circuits, and particularly to a detection circuit for a soybean milk machine cup cover. Background Art

[0002] Currently, many small household electrical appliances and electric products in the market, such as soybean milk machines and wall breakers, adopt the weak current detection method of Hall elements to realize cup cover detection, and their detection circuits are as Figure 1 shown. However, with the update of the new national standard (GB / T 4706.1 - 2024), this type of product no longer meets the certification requirements. The new national standard requires dual failures. When the electronic switch fails, the appliance cannot become operable, that is, all the abnormal tests in Chapter 19 of the national standard need to be re - compliant. When the Hall device fails short - circuit, when the cup cover is lost, the appliance can be started normally by humans, which brings risks and causes the detection circuit not to meet the safety regulations; in the ordinary weak current signal, according to the common practice, it needs to directly return to the MCU pin. After adding the pad to the MCU pin, the creepage distance is <1.5mm, and the mutual short - circuit test also needs to be done. For example, short - circuiting to the ground signal output by adjacent pins will also cause the detection circuit to fail and the appliance to become operable, not meeting the safety regulations requirements. In addition, the ordinary wiring loop often cannot meet the requirements of functional insulation. That is, the existing general use of Hall elements to detect the cup cover state has the following defects: (1) Safety failure risk: When the Hall element is short - circuited, the device can still be started when the cup cover is not closed, violating the abnormal test requirements of Chapter 19 of the new national standard; (2) Insulation non - compliance: The traditional PCB wiring causes the creepage distance between the signal line and the adjacent line to be <1.5mm, not meeting the requirements of functional insulation; (3) Insufficient anti - interference: There is a risk of short - circuit between the adjacent signal lines of the MCU pin, resulting in detection failure.

[0003] In addition, with the wide application of soybean milk machines, their safety and reliability have become the focus of user attention. Chapter 22.40 of the new national standard puts forward higher requirements for the safety performance of soybean milk machines, especially for the cup cover detection function, to prevent the machine from becoming startable when the cup cover is not correctly installed or fails, thus avoiding potential safety hazards. However, the existing soybean milk machine cup cover detection circuits have problems such as low detection accuracy, weak anti - interference ability, and unreasonable PCB wiring design, not meeting the requirements of functional insulation, and being prone to signal interference and poor detection. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention proposes a detection circuit for a soybean milk machine cup cover, which avoids the start - up risk brought by the failure of the cup cover detection circuit, improves the safety of the product, and meets the safety requirements of the new national standard.

[0005] To implement the above technical solution, the present invention provides a detection circuit for a soymilk machine cup lid, including: a reed switch with authentication, installed at the contact part between the soymilk machine cup lid and the cup body, for detecting whether the cup lid is correctly installed; an MCU processing chip, for collecting the lid-closing signal of the reed switch to prevent the soymilk machine from starting accidentally; a detection circuit with a pull-up, for receiving the signal of the detection reed switch and judging the state of the cup lid according to the signal. The detection circuit includes a pull-up resistor R3, a current-limiting resistor R4, a signal filtering capacitor C2, and a 3P hollow socket CN1. Among them, the reed switch is connected to pin 1 and pin 3 of the 3P hollow socket CN1. Pin 2 of the 3P hollow socket CN1 is an empty pin, and pin 3 of the 3P hollow socket CN1 is also grounded. One end of the pull-up resistor R3 is connected to the +5V power supply, and the other end of the pull-up resistor R3 is respectively connected to pin 1 of the 3P hollow socket CN1 and one end of the current-limiting resistor R4. The other end of the current-limiting resistor R4 is connected to pin 4 of the MCU processing chip. The pins adjacent to pin 4 of the MCU processing chip are all set as empty pins, and the pins adjacent to pin 4 of the MCU processing chip for collecting the cup lid signal are not connected with any signal and power supply, and are set to a high-impedance state. One end of the signal filtering capacitor C2 is connected to the connection line between the pull-up resistor R3 and the current-limiting resistor R4, and the other end of the signal filtering capacitor C2 is grounded.

[0006] In the above technical solution, during actual operation, the state of the reed switch is detected in real time through the detection circuit with a pull-up, and the detected signal is transmitted to the MCU processing chip. The two ends of the reed switch are respectively connected to pin 1 and pin 3 of the 3P hollow socket CN1. When the cup lid is closed, the reed switch conducts, and the MCU processing chip detects a low-level signal, and at this time the circuit conducts. The pull-up resistor R3, the current-limiting resistor R4, and the signal filtering capacitor C2 in the detection circuit form a detection loop with RC filtering. Among them, the pull-up resistor R3 ensures that the input remains at a high level of 5V when the reed switch does not act. The current-limiting resistor R4 is used to protect the I / O of the MCU processing chip from being damaged. The signal filtering capacitor C2 is used to filter radio wave signals and improve the anti-interference ability of the detection circuit. The 3P hollow socket CN1 is used to connect the reed switch. Pin 1 is the signal pin, pin 2 is an empty pin, and pin 3 is connected to the ground and the other end of the reed switch. The 3P hollow ensures the creepage distance between the signal and GND, meeting the requirements of functional insulation. At the same time, the pins adjacent to pin 4 of the MCU processing chip for collecting the cup lid signal are not connected with any signal and power supply, and are set to a high-impedance state, which can ensure that there will be no failure during the short-circuit test, ensuring that the soymilk machine cannot be started when the cup lid is not correctly installed or fails, thus avoiding potential safety hazards and meeting the requirements of the new national standard.

[0007] Preferably, the method for setting the 4th pin of the MCU processing chip to the high-impedance state is as follows: Use software to set the 4th pin to disable the pull-up / pull-down resistor in the GPIOx_PUPDR register of the MCU. When the 4th pin is configured as an input and there is no internal or external pull-up / pull-down, the 4th pin is in the high-impedance state. This method can be achieved by configuring the state of the I / O port through software, which is convenient to set. And by setting the signal pin 4 of the MCU processing chip to the high-impedance state, it can be ensured that the system cannot be started when the cup lid is not correctly installed or fails, thereby preventing the soymilk maker from starting accidentally and improving the overall safety of the system.

[0008] Preferably, the creepage distance inside the 3P hollow socket CN1 is greater than 1.9 mm to meet the requirements of functional insulation.

[0009] Preferably, the wiring distance between the 4th pin of the MCU processing chip and the surrounding is greater than 1.9 mm to meet the requirements of functional insulation.

[0010] Preferably, the 4th pin of the MCU processing chip is separately packaged to meet the requirements of functional insulation.

[0011] The beneficial effects of a cup lid detection circuit for a soymilk maker provided by the present invention are as follows:

[0012] (1) This cup lid detection circuit for the soymilk maker uses a certified reed switch to replace the Hall element, eliminating the requirement for a short-circuit test.

[0013] (2) This cup lid detection circuit for the soymilk maker forms a detection loop with an RC filter by including a pull-up resistor R3, a current-limiting resistor R4, and a filter capacitor C2, improving the detection accuracy and anti-interference ability of the detection circuit.

[0014] (3) This cup lid detection circuit for the soymilk maker uses a 3P hollow socket, with the 2nd pin left empty to form a creepage channel greater than 1.9 mm, meeting the requirements of functional insulation.

[0015] (4) This cup lid detection circuit for the soymilk maker ensures that no signals or power are connected to the pins adjacent to the 4th pin of the MCU processing chip that collects the cup lid signal and sets them to the high-impedance state, which can guarantee no failure during the short-circuit test, ensure that the system cannot be started when the cup lid is not correctly installed or fails, thus avoiding potential safety hazards and meeting the requirements of the new national standard. Description of the Drawings

[0016] Figure 1 It is a detection circuit diagram using a Hall element in the prior art.

[0017] Figure 2 It is the circuit diagram of the present invention.

[0018] Figure 3 It is the PCB wiring diagram of the present invention. Detailed implementation mode

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] Embodiment: A detection circuit for the cup lid of a soymilk machine.

[0021] Refer to Figures 1 to 3 As shown, the present invention provides a detection circuit for the cup lid of a soymilk machine, specifically including:

[0022] A reed switch (model: MKA-07121) that has passed UL / CE certification, which is installed at the contact part between the cup lid and the cup body of the soymilk machine and is used to detect whether the cup lid is correctly installed. The present invention uses a certified reed switch to replace the Hall element, eliminating the short-circuit test requirement, and it is easy to install and cost-saving. Compared with the Hall solution, the component cost is reduced by about 37% (the unit price of the reed switch < $0.15, and the unit price of the Hall sensor > $0.24);

[0023] An MCU processing chip (model: STM32F030K6T6), which is used to collect the signal of the closed cup lid by the reed switch to prevent the soymilk machine from starting accidentally;

[0024] A pull-up detection circuit is used to receive the signal of the reed switch and judge the state of the cup lid according to the signal. The detection circuit includes a pull-up resistor R3 (resistance value range: 4.7 kΩ - 10 kΩ), a current-limiting resistor R4 (220 Ω ± 5%), a signal filtering capacitor C2 (capacitance value: 0.1 μF), and a 3P hollow socket CN1 (3P hollow XH socket (pitch: 2.54 mm)). Among them, the reed switch is connected to pins 1 and 3 of the 3P hollow socket CN1, pin 2 of the 3P hollow socket CN1 is an empty pin, pin 3 of the 3P hollow socket CN1 is also grounded, and the creepage distance inside the 3P hollow socket CN1 is greater than 1.9 mm to meet the functional insulation requirements. One end of the pull-up resistor R3 is connected to the +5V power supply, and the other end of the pull-up resistor R3 is respectively connected to pin 1 of the 3P hollow socket CN1 and one end of the current-limiting resistor R4. The pull-up resistor R3 is used to ensure that a 5V high-level input is maintained when the reed switch does not act. The other end of the current-limiting resistor R4 is connected to pin 4 of the MCU processing chip. The current-limiting resistor R4 is used to protect the I / O of the MCU processing chip from being damaged. The wiring distance between pin 4 of the MCU processing chip and the surrounding is greater than 1.9 mm, or pin 4 of the MCU processing chip is separately packaged to meet the requirements of functional insulation. The pins adjacent to pin 4 of the MCU processing chip are all set as empty pins, and the pins adjacent to pin 4 of the MCU processing chip that collects the cup lid signal are not connected to any signals and power supplies and are set to high impedance state to ensure that no failure occurs during the short-circuit test, ensure that the cup lid cannot be started when it is not correctly installed or fails, thereby avoiding potential safety hazards and meeting the requirements of the new national standard. One end of the signal filtering capacitor C2 is connected to the connection line between the pull-up resistor R3 and the current-limiting resistor R4, and the other end of the signal filtering capacitor C2 is grounded. The signal filtering capacitor C2 is used to filter the radio wave signal and improve the anti-interference ability of the detection circuit.

[0025] In this embodiment, the method of setting pin 4 of the MCU processing chip to the high impedance state is as follows: Use software to set pin 4 to disable the pull-up / pull-down resistor in the GPIOx_PUPDR register of the MCU. When pin 4 is configured as an input and there is no internal or external pull-up / pull-down, pin 4 is in the high impedance state. This method can be achieved by software configuration of the I / O port state, which is convenient to set. And by setting pin 4 of the signal pin of the MCU processing chip to the high impedance state, it can be ensured that the cup lid cannot be started when it is not correctly installed or fails, and thus the soybean milk machine can be prevented from starting accidentally, improving the overall safety of the system.

[0026] The working principle of the present invention is as follows: the state of the reed switch is detected in real time through a pull-up detection circuit, and the detected signal is transmitted to the MCU processing chip. The two ends of the reed switch are respectively connected to pin 1 and pin 3 of the 3P hollow socket CN1. When the cup cover is closed, the reed switch conducts, and the MCU processing chip detects a low-level signal, and the circuit conducts at this time. In the detection circuit, the pull-up resistor R3, the current-limiting resistor R4, and the signal filtering capacitor C2 form a detection loop with RC filtering. Among them, the pull-up resistor R3 ensures a 5V high-level input when the reed switch does not act, the current-limiting resistor R4 is used to protect the I / O of the MCU processing chip from being damaged, and the signal filtering capacitor C2 is used to filter radio wave signals to improve the anti-interference ability of the detection circuit. The 3P hollow socket CN1 is used to connect the reed switch. Pin 1 is the signal pin, pin 2 is the empty pin, and pin 3 is connected to the ground and the other end of the reed switch. The 3P hollow ensures the creepage distance between the signal and GND and meets the functional insulation requirements. At the same time, the pin adjacent to pin 4 of the MCU processing chip that collects the cup cover signal is not connected to any signal and power supply and is set to a high-impedance state, which can ensure that there is no failure during the short-circuit test, ensure that the cup cover cannot be started when it is not correctly installed or fails, thus avoiding potential safety hazards and meeting the requirements of the new national standard.

[0027] The cup cover detection circuit of this soymilk machine uses a certified reed switch to replace the Hall element, eliminating the requirement for short-circuit experiments. And the cup cover detection circuit of this soymilk machine forms a detection loop with RC filtering by including a pull-up resistor R3, a current-limiting resistor R4, and a filtering capacitor C2, improving the detection accuracy and anti-interference ability of the detection circuit. Moreover, the cup cover detection circuit of this soymilk machine uses a 3P hollow socket, and the second pin is left empty to form a creepage channel of >1.9mm, meeting the functional insulation requirements.

[0028] The above are the preferred embodiments of the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the drawings. Since the reed switch belongs to a kind of microswitch, using other types of microswitches to replace the reed switch in the present invention, any equivalent or modification completed without departing from the spirit disclosed in the present invention falls within the protection scope of the present invention.

Claims

1. A soymilk machine cup cover detection circuit, characterized in that include: A certified reed switch, installed at the contact point between the soymilk maker cup cover and the cup body, to detect whether the cup cover is correctly installed; An MCU processing chip is used to collect the cover closing signal of the reed switch to prevent the soybean milk machine from starting by mistake; A detection circuit with a pull-up function is used to receive a signal from a reed switch and determine the state of a cup cover according to the signal. The detection circuit includes a pull-up resistor R3, a current limiting resistor R4, a signal filter capacitor C2 and a 3P hollow socket CN1, wherein the reed switch is connected to pins 1 and 3 of the 3P hollow socket CN1, pin 2 of the 3P hollow socket CN1 is an empty pin, and pin 3 of the 3P hollow socket CN1 is also grounded. One end of the pull-up resistor R3 is connected to a +5V power supply, and the other end of the pull-up resistor R3 is respectively connected to pin 1 of the 3P hollow socket CN1 and one end of the current limiting resistor R4, the other end of the current limiting resistor R4 is connected to pin 4 of an MCU processing chip, the pins adjacent to pin 4 of the MCU processing chip are all set to empty pins, and the pins adjacent to pin 4 of the MCU processing chip that collects the cup cover signal are not connected to any signal or power supply and are set to a high impedance state, one end of the signal filter capacitor C2 is connected to the connecting line between the pull-up resistor R3 and the current limiting resistor R4, and the other end of the signal filter capacitor C2 is grounded.

2. The soybean milk machine cup cover detection circuit as claimed in claim 1, characterized in that: The way to set pin 4 of the MCU processing chip to high impedance is: use software to set pin 4 in the GPIOx_PUPDR register of the MCU to disable the pull-up / pull-down resistor. When pin 4 is configured as an input and there is no internal or external pull-up / pull-down, pin 4 is in a high impedance state.

3. The soybean milk machine cup cover detection circuit as claimed in claim 1, characterized in that: The creepage distance in the 3P hollow socket CN1 is greater than 1.9 mm.

4. The soybean milk machine cup cover detection circuit as claimed in claim 1, characterized in that: The distance between the MCU processing chip's 4 pins and the surrounding wiring is greater than 1.9mm.

5. The soybean milk machine cup cover detection circuit as claimed in claim 1, characterized in that: The 4 pins of the MCU processing chip are packaged separately.

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