A self-locking circuit

Abstract

This utility model provides a self-locking circuit, including a control chip MCU, a control module one, a control module two, and a self-locking circuit. One end of the control module one is connected to the control chip MCU, and the other end is connected to heating wire one H1. One end of the control module two is connected to the control chip MCU, and the other end is connected to heating wire two H2. The other ends of heating wire one H1 and heating wire two H2 are respectively connected to the live wire ACL. The self-locking circuit connects control point A between control module one and the control chip MCU. The self-locking circuit includes a transistor Q1 or a MOSFET. When the voltage at the voltage divider point is greater than the base B voltage of transistor Q1, transistor Q1 is turned on, and heating wire one H1 is not working. When the power supply is connected to a low voltage, the voltage at the voltage divider point is less than the base B voltage of transistor Q1, causing transistor Q1 to not conduct, and heating wire one H1 and heating wire two H2 work simultaneously. When the control chip MCU inputs a high voltage and sends a high-level signal to SCR1 due to a fault, the self-locking circuit forcibly pulls down the SCR1 level by turning on transistor Q1, ensuring that heating wire one H1 is not working.

Description

Technical Field

[0001] This utility model belongs to the technical field of beauty and hairdressing equipment, specifically relating to a self-locking circuit. Background Technology

[0002] A fan duct is a common device widely used in heat dissipation, ventilation, and heating. It typically contains two or more heating wires, the heating power of which needs to be precisely controlled according to specific requirements. Traditionally, the heating wires in a fan duct are controlled by adjusting the voltage; a high voltage controls the high-voltage heating wire, and a low voltage controls the low-voltage heating wire. Currently, voltage changes are entirely controlled by a control chip. If the control chip malfunctions, when the fan duct is connected to a high voltage source, the control chip simultaneously drives the low-voltage heating wire, causing the low-voltage heating wire to operate under high voltage, potentially leading to damage to the fan duct and other safety issues. Utility Model Content

[0003] (1) Technical problems to be solved

[0004] This invention provides a self-locking circuit, which aims to solve the problem of low-voltage heating wire operation caused by control chip failure when the air duct is connected to high voltage.

[0005] (2) Technical solution

[0006] This utility model provides a self-locking circuit, including a control chip MCU, a control module one, a control module two, and a self-locking circuit. One end of the control module one is connected to the control chip MCU, and the other end is connected to a heating wire H1. One end of the control module two is connected to the control chip MCU, and the other end is connected to the heating wire H2. The other ends of the heating wire H1 and the heating wire H2 are respectively connected to the live wire ACL. The self-locking circuit is connected at control point A, which is located between the control module one and the control chip MCU.

[0007] The self-locking circuit includes a transistor Q1 or a MOSFET, a first resistor R4 and a second resistor R6. One end of the first resistor R4 is connected to the live wire ACL, and the other end is connected to the second resistor R6. The other end of the second resistor R6 is grounded. The emitter E of the transistor Q1 is grounded, the collector C is connected to the control point A, and the base B is connected to the voltage divider point set between the first resistor R4 and the second resistor R6.

[0008] When the power supply is connected to a high voltage, the voltage at the voltage dividing point is greater than the voltage at the base B of the triode Q1, causing the triode Q1 to conduct, and the first heating wire H1 does not work; when the power supply is connected to a low voltage, the voltage at the voltage dividing point is less than the voltage at the base B of the triode Q1, causing the triode Q1 not to conduct, and the first heating wire H1 and the second heating wire H2 work simultaneously or only the heating wire H1 starts to work.

[0009] Further, the triode Q1 is an NPN type triode.

[0010] Further, it further includes an optocoupler module OC1. One end of the optocoupler module OC1 is connected to the control chip MCU, and the other end is connected to the other end of the control module 1.

[0011] Further, a third resistor R3 is connected between the optocoupler module OC1 and the control chip MCU.

[0012] Further, the control point A is provided between the third resistor R3 and the control chip MCU or between the third resistor R3 and the optocoupler module OC1.

[0013] Further, the control module 1 includes a first thyristor T1. The cathode of the first thyristor T1 is connected to the first heating wire H1, its anode is grounded, and its control electrode is connected to the optocoupler module OC1.

[0014] Further, it further includes an optocoupler module OC2. One end of the optocoupler module OC2 is connected to the other end of the control module 2, and the other end of the optocoupler module OC2 is connected to the control chip MCU.

[0015] Further, a fourth resistor R8 is connected between the optocoupler module OC2 and the control chip MCU.

[0016] Further, the control module 2 includes a second thyristor T2. The cathode of the second thyristor T2 is connected to the second heating wire H2, its anode is connected to the neutral line ACN, and its control electrode is connected to the optocoupler module OC2.

[0017] Further, the input voltage is U. When 90V < U < 130V, it is a low voltage, and when 220V < U < 250V, it is a high voltage.

[0018] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0019] When the control chip malfunctions due to a fault, the self-locking circuit causes the MCU to send a high-level SCR1 signal due to a fault. In this case, the self-locking circuit forces the SCR1 level to be low by turning on Q1, ensuring that the heating wire H1 is always closed and preventing high voltage from triggering falsely. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the system structure of this utility model.

[0021] Figure 2 This is a circuit diagram of the present invention. Figure 1 .

[0022] Figure 3 This is a circuit diagram of the present invention. Figure 2 .

[0023] Figure labels: 1-Control Module 1, 2-Control Module 2, 3-Self-locking circuit, 31-Voltage divider point. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0025] like Figure 1-3 As shown, this utility model provides a self-locking circuit, including a control chip MCU, a control module 1, a control module 2, and a self-locking circuit 3. One end of the control module 1 is connected to the control chip MCU, and the other end is connected to the heating wire H1. One end of the control module 2 is connected to the control chip MCU, and the other end is connected to the heating wire H2. The other ends of the heating wire H1 and the heating wire H2 are respectively connected to the live wire ACL. The self-locking circuit 3 is connected at control point A, which is located between the control module 1 and the control chip MCU.

[0026] The self-locking circuit 3 includes a transistor Q1 or a MOSFET, a first resistor R4 and a second resistor R6. One end of the first resistor R4 is connected to the live wire ACL, and the other end is connected to the second resistor R6. The other end of the second resistor R6 is grounded. The emitter E of the transistor Q1 is grounded, the collector C is connected to the control point A, and the base B is connected to the voltage divider point 31 located between the first resistor R4 and the second resistor R6.

[0027] When a high voltage is applied to the power supply, the voltage at the voltage divider point 31 is greater than the base B voltage of the transistor Q1, causing the transistor Q1 to conduct, and the heating wire H1 does not work; when a low voltage is applied to the power supply, the voltage at the voltage divider point 31 is less than the base B voltage of the transistor Q1, causing the transistor Q1 to not conduct, and the heating wire H1 and the heating wire H2 work simultaneously or only the heating wire H1 works.

[0028] In use, the control chip MCU sends an SCR1 signal to control control module 1, which in turn controls heating wire H1, and sends an SCR2 signal to control control module 2, which in turn controls the operation of heating wire H2. Since the air duct typically contains multiple heating wires with varying resistances and high-voltage withstand capabilities, in this embodiment, heating wire H1 is a low-resistance wire that can only operate under low voltage conditions, while heating wire H2 is a high-resistance wire that can withstand high voltage. When the control chip MCU experiences bugs or short circuits, i.e., when high voltage is applied, if the high-voltage control chip sends an SCR1 signal, causing the SCR1 signal to go high, it drives control module 1 to operate and thus turns on heating wire H1. If heating wire H1 operates, the increased current can lead to damage to the air duct. This invention addresses this by introducing a... A self-locking circuit 3 controls the low-resistance heating wire H1 to prevent it from working in a high-voltage environment. When a low-voltage AC power is connected, the transistor Q1 is turned off, and the control chip MCU sends an SCR1 signal at a high level to turn on control module 1 and an SCR2 signal at a high level to turn on control module 2, thereby controlling heating wire H1 and heating wire H2 to heat up. Alternatively, control module 1 may only send an SCR1 signal at a high level to turn on control module 1, so that only heating wire H1 works. When U is high, the transistor Q1 is turned on, and the control chip MCU sends an SCR1 signal that first flows through the self-locking circuit 3 to make SCR1 low, thus turning off the low-voltage circuit 1. At the same time, it sends an SCR2 signal to make SCR2 high, thus turning on the high-voltage circuit 2, so that heating wire H1 does not work and heating wire H2 turns on to heat up.

[0029] In this embodiment, when 90V < U < 130V, it is in a low - level state, and when 220V < U < 250V, it is in a high - level state. The triode Q1 is an NPN - type triode. Specifically, since the first resistor R4 is connected to the power supply pin ACL, that is, the positive pole of the power supply, and the second resistor R6 is grounded, the voltage at the voltage - dividing point 31 is the voltage of the second resistor R6. When the voltage at the voltage - dividing point 31 reaches the conduction threshold of the triode Q1, the triode Q1 conducts. In one embodiment, the resistance value of the first resistor R4 is 400R, and the resistance value of the second resistor R6 is 1.5R. When the voltage at the voltage - dividing point 31 does not reach the conduction threshold of the triode Q1, the triode Q1 is cut off. When in a low voltage, the voltage on the second resistor R6 is lower than the conduction threshold voltage of the triode Q1, that is, the triode is in a closed state, and the control chip MCU makes the SCR1 output high and low levels to make the heating wire H1 energized and de - energized. When a high voltage is input, the voltage at the voltage - dividing point 31 is higher than the conduction threshold voltage of the triode Q1, that is, the triode Q1 conducts, making the SCR1 always in a low - level state. Even if the control chip MCU is damaged and makes the SCR1 emit a high voltage, the self - locking circuit 3 conducts, making the SCR1 always in a low - level state, closing the low - voltage circuit 1, and the heating wire H1 cannot be energized to work, thus protecting the hair dryer.

[0030] Among them, the role of the first resistor R4 is to form a certain proportional voltage - dividing relationship with the second resistor R6, so that the voltage across the two ends of the second resistor R6 is different in the scenarios of high voltage and low voltage, and then make the triode Q1 close in the low - voltage scenario and open in the high - voltage scenario, thereby controlling the on - off of the heating wire H1 to achieve protection.

[0031] In summary, this circuit is used for a hair dryer, controls the low - voltage circuit 1, high - voltage circuit 2 or activates both simultaneously according to the range of the input voltage U. By setting the self - locking circuit 3, it protects the control chip MCU from damaging the circuit when the signal is disordered due to damage. When the SCR1 emits a high voltage at a high voltage, the self - locking circuit 3 makes the signal of the SCR1 in a low - level state. When the SCR2 generates heat, at a low voltage, both heating wires are activated simultaneously or only the heating wire H1 works, reducing energy waste, providing more flexible control options, improving the safety of the overall device, and further protecting the hair dryer.

[0032] Specifically, it further includes an opto - coupler module OC1. One end of the control module 1 is connected to the heating wire H1, and the control module 1 is used to control the voltage of the heating wire H1.

[0033] Furthermore, one end of the optocoupler module OC1 is connected to the control chip MCU, and the other end is connected to the other end of the control module 1. The optocoupler module OC1 connects the control chip MCU and the control module 1, acting as the on / off switch for the control signal. Through opto-isolation, the control chip MCU and the control module 1 are kept isolated, improving the safety and stability of the circuit.

[0034] Preferably, a third resistor R3 is connected between the optocoupler module OC1 and the control chip MCU. By setting the third resistor R3 for current limiting, excessive current is prevented when the output terminal of the optocoupler module OC1 is turned on, so as to avoid damage to the photosensitive device inside the optocoupler or the input pin of the control chip MCU. For example, if the output terminal of the optocoupler is directly short-circuited to ground, the third resistor R3 can limit the current within a safe range.

[0035] like Figure 2 As shown, in one embodiment, the control point A is located between the third resistor R3 and the optocoupler module OC1;

[0036] like Figure 3 As shown, in one embodiment, the control point A is located between the third resistor R3 and the control chip MCU;

[0037] Both of the above embodiments control the on / off state of the optocoupler module OC1 by connecting the self-locking circuit 3 between the optocoupler module OC1 and the control chip MCU. When the control chip MCU is at a high voltage, a high level is emitted at SCR1. The self-locking circuit 3 causes SCR1 to conduct and emit a low level, controlling the switch of the optocoupler module OC1 to close, preventing the transmission of optical signals to the control module 1, and thus the heating wire H1 cannot heat up.

[0038] Specifically, the control module 1 includes a first thyristor T1. The cathode of the first thyristor T1 is connected to the heating wire H1, its anode is connected to the neutral line ACN, and its control electrode is connected to the optocoupler module OC1. In use, the control chip MCU receives the corresponding voltage control signal and controls the on / off state of the optocoupler module OC1 through the self-locking circuit 3. When the optocoupler module OC1 is turned on, it generates a corresponding optical signal under the action of the control chip MCU. The signal is transmitted to the first thyristor T1 through opto-isolation. The first thyristor T1 adjusts the voltage output according to this optical signal to control the heating power of the heating wire H1.

[0039] Furthermore, pin 1 of the optocoupler module OC1 is connected to a third resistor R3, pin 2 of the optocoupler module OC1 is grounded, pin 3 of the optocoupler module OC1 is connected to a fifth resistor R5 between it and the control electrode of the first thyristor T1, and pin 4 of the optocoupler module OC1 is connected to a sixth resistor R2 between it and the cathode of the first thyristor T1. By setting the fifth resistor R5 and the sixth resistor R2, the current flowing through the light-emitting diode inside the optocoupler is limited to prevent the optocoupler module OC1 from burning out due to excessive current.

[0040] It also includes an optocoupler module OC2. One end of the control module 2 is connected to the heating wire 2 H2. One end of the optocoupler module OC2 is connected to the other end of the control module 2, and the other end of the optocoupler module OC2 is connected to the control chip MCU. By controlling the on and off of the control signal through the optocoupler module OC2, opto-isolation is achieved, which improves the safety of the circuit.

[0041] Preferably, a fourth resistor R8 is connected between the optocoupler module OC2 and the control chip MCU. By setting the fourth resistor R8 for current limiting, excessive current is prevented when the output terminal of optocoupler module OC2 is turned on, so as to avoid damage to the photosensitive device inside the optocoupler or the input pin of the control chip MCU.

[0042] Specifically, the control module 2 includes a second thyristor T2. The cathode of the second thyristor T2 is connected to the heating wire H2, its anode is connected to the neutral line ACN, and its control electrode is connected to the optocoupler module OC2. In use, the control chip MCU receives a corresponding voltage signal and turns on the optocoupler module OC2 through the SCR2. After receiving the signal, the optocoupler module OC2 generates a corresponding optical signal and transmits the signal to the second thyristor T2 through opto-isolation. The second thyristor T2 is used to control the heating power of the heating wire H2.

[0043] Furthermore, pin 1 of the optocoupler module OC2 is connected to the fourth resistor R8, pin 2 of the optocoupler module OC2 is grounded, pin 3 of the optocoupler module OC2 is connected to the control electrode of the second thyristor T2 by an eighth resistor R9, and pin 4 of the optocoupler module OC2 is connected to the cathode of the second thyristor T2 by a seventh resistor R7. By setting the seventh resistor R7 and the eighth resistor R9, the current flowing through the internal components of the optocoupler module T2 is limited to prevent the optocoupler module OC2 from burning out due to excessive current.

[0044] In summary, the air duct incorporates a dual-channel thyristor air duct control circuit, which includes two control circuits, each controlling one heating wire of the air duct. These two control circuits use thyristors and optocoupler modules, adjusting voltage and power output through PWM signals received from the control chip MCU. This allows each part of the air duct to be controlled independently, achieving precise temperature or speed adjustment. Furthermore, the self-locking circuit 3 further controls the switching of the optocoupler module OC1, thereby controlling whether the heating wire H1 heats up and shuts down, protecting the heating wire H1 from damage by ensuring it is switched off when at a high level.

[0045] The following is a detailed explanation of the working principle of this utility model;

[0046] The self-locking circuit 3 controls the low-resistance heating wire H1 to prevent it from working in a high-voltage environment. When U is low, i.e., when a low-voltage AC power is connected, the transistor Q1 is turned off, and the control chip MCU sends a high-level SCR1 signal to turn on the low-voltage circuit 1 and a high-level SCR2 signal to turn on the low-voltage circuit 1, thereby controlling the heating wires H1 and H2 to heat up. When U is high, the transistor Q1 is turned on, and the control chip MCU sends an SCR1 signal to make SCR1 low, thus turning off the low-voltage circuit 1. At the same time, it sends an SCR2 signal to make SCR2 high, controlling the control module 1 to turn on, so that the heating wire H1 does not work and the heating wire H2 turns on to heat up.

[0047] The innovation of this invention lies in the self-locking circuit, which enables the control chip to malfunction. When the MCU input voltage of the control chip malfunctions and sends a high-level signal to SCR1 due to a fault, the self-locking circuit forces the SCR1 level to be low by turning on Q1, ensuring that H1 is always closed and preventing high-voltage false triggering.

[0048] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

[0049] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A self-locking circuit, characterized in that, The system includes a control chip MCU, a control module 1 (1), a control module 2 (2), and a self-locking circuit (3). One end of the control module 1 (1) is connected to the control chip MCU, and the other end is connected to the heating wire 1 (H1). One end of the control module 2 (2) is connected to the control chip MCU, and the other end is connected to the heating wire 2 (H2). The other ends of the heating wire 1 (H1) and the heating wire 2 (H2) are respectively connected to the live wire (ACL). The self-locking circuit (3) is connected at the control point (A) between the control module 1 (1) and the control chip MCU. The self-locking circuit (3) includes a transistor (Q1) or a MOSFET, a first resistor (R4) and a second resistor (R6). One end of the first resistor (R4) is connected to the live wire (ACL), and the other end is connected to the second resistor (R6). The other end of the second resistor (R6) is grounded. The emitter (E) of the transistor (Q1) is grounded, the collector (C) is connected to the control point (A), and the base (B) is connected to the voltage divider point (31) between the first resistor (R4) and the second resistor (R6). When the power supply is connected to a high voltage, the voltage at the voltage divider point (31) is greater than the base (B) voltage of the transistor (Q1), causing the transistor (Q1) to conduct and the heating wire one (H1) to not work; when the power supply is connected to a low voltage, the voltage at the voltage divider point (31) is less than the base (B) voltage of the transistor (Q1), causing the transistor (Q1) to not conduct, and the heating wire one (H1) and the heating wire two (H2) work simultaneously or only the heating wire one (H1) works.

2. The self-locking circuit according to claim 1, characterized in that, The transistor (Q1) is an NPN transistor.

3. The self-locking circuit according to claim 1, characterized in that, It also includes an optocoupler module (OC1), one end of which is connected to the control chip MCU, and the other end is connected to the other end of the control module (1).

4. The self-locking circuit according to claim 3, characterized in that, A third resistor (R3) is connected between the optocoupler module 1 (OC1) and the control chip MCU.

5. A self-locking circuit according to claim 4, characterized in that, The control point (A) is located between the third resistor (R3) and the control chip MCU, or between the third resistor (R3) and the optocoupler module (OC1).

6. The self-locking circuit according to claim 4, characterized in that, The control module (1) includes a first thyristor (T1), the cathode of the first thyristor (T1) is connected to the heating wire (H1), its anode is grounded, and its control electrode is connected to the optocoupler module (OC1).

7. The self-locking circuit according to claim 1, characterized in that, It also includes an optocoupler module 2 (OC2), one end of which is connected to the other end of the control module 2 (2), and the other end of which is connected to the control chip MCU.

8. A self-locking circuit according to claim 7, characterized in that, A fourth resistor (R8) is connected between the optocoupler module 2 (OC2) and the control chip MCU.

9. A self-locking circuit according to claim 7, characterized in that, The control module two (2) includes a second thyristor (T2), the cathode of the second thyristor (T2) is connected to the heating wire two (H2), its anode is connected to the neutral line (ACN), and its control electrode is connected to the optocoupler module two (OC2).

10. A self-locking circuit according to claim 1, characterized in that, The accessed voltage is U. When 90V < U < 130V, it is low voltage. When 220V < U < 250V, it is high voltage.

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