Power failure alarm circuit and medical equipment

Abstract

The utility model provides a power-down alarm circuit and medical equipment, the power-down alarm circuit comprises a power supply control circuit, an alarm drive circuit and an alarm circuit, the power supply control circuit comprises a first switch device, a second switch device and a self-locking circuit, and the alarm drive circuit comprises an oscillator. Through the implementation of the scheme of the invention, when the equipment is normally started, the second switching device controls the first switching device to be switched off, so that the self-locking circuit works to continuously supply power to the oscillator, and then the master control circuit controls the oscillator to stop outputting the driving signal to the alarm circuit; when the equipment is powered down, the oscillator is controlled by the main control circuit to output a driving signal to the alarm circuit; when the alarm signal needs to be cancelled, the self-locking circuit can be released through the first switching device by connecting a power supply or pressing a key, so that the oscillator does not have a power supply and stops driving the alarm circuit, and therefore, a user can actively control equipment to stop outputting the alarm signal, and interference caused by an invalid alarm signal is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, in particular to a power-off alarm circuit and a medical device. Background Art

[0002] In the medical standards of medical devices, it is required that medical devices should have audible and visual alarms when the alternating current (AC) power is cut off. The AC power-off alarm in the related technology is usually realized by the way of supplying power to the alarm circuit by an internal battery, but the cost of this scheme is relatively high; or it is realized by the way of supplying power to the alarm circuit by a capacitor, but when the AC power-off alarm is triggered in this scheme, the alarm can only be cancelled when the AC power interface re-obtains power. If the AC power interface cannot obtain power, the alarm can only be cancelled after the capacitor runs out of power. The audible alarm generated during this process will continue to give ineffective alarms when the medical staff already know, which has a great impact on the work of the medical staff and the rest of the patients. Content of the Utility Model

[0003] The utility model provides a power-off alarm circuit and a medical device, aiming to solve the problem that the power-off alarm signal is inconvenient to cancel in the related technology.

[0004] To solve the above technical problems, the first aspect of the utility model provides a power-off alarm circuit, including: a power supply control circuit, an alarm driving circuit and an alarm circuit. The power supply control circuit includes a first switching device, a second switching device and a self-locking circuit. The alarm driving circuit includes an oscillator. The first end of the first switching device is electrically connected to a first power supply and is used to be electrically connected to an external key. The second end of the first switching device is electrically connected to the first end of the self-locking circuit. The second switching device is respectively electrically connected to the first power supply and a second power supply. The first end of the self-locking circuit is used to be electrically connected to an external main control circuit. The second end of the self-locking circuit is electrically connected to a third power supply. The third end of the self-locking circuit is electrically connected to the first end of the oscillator. The second end of the oscillator is electrically connected to the alarm circuit. The third end of the oscillator is used to be electrically connected to the main control circuit.

[0005] Further, the self-locking circuit includes a third switching device, a fourth switching device, a first diode and a first resistor. The first end of the third switching device is electrically connected to the third power supply. The second end of the third switching device is respectively electrically connected to the positive electrode of the first diode and the oscillator. The third end of the third switching device is electrically connected to the first end of the fourth switching device. The second end of the fourth switching device is electrically connected to the negative electrode of the first diode and is used to be electrically connected to the main control circuit. The third end of the fourth switching device is grounded. The common connection end of the fourth switching device and the first diode is grounded. The first resistor is electrically connected between the first end and the third end of the third switching device.

[0006] Further, the power supply control circuit further includes a second diode, a second resistor, a first capacitor, and a second capacitor; the positive electrode of the second diode is electrically connected to the first power supply, the negative electrode of the second diode is electrically connected to one end of the second resistor, the other end of the second resistor is electrically connected to the first end of the third switching device, one ends of the first capacitor and the second capacitor are both electrically connected to the other end of the second resistor, and the other ends of the first capacitor and the second capacitor are both grounded.

[0007] Further, the alarm driving circuit further includes a fifth switching device and a sixth switching device; the first end of the fifth switching device is used to be electrically connected to the main control circuit, the second end of the fifth switching device is electrically connected to the reset end of the oscillator, the first end of the sixth switching device is electrically connected to the output end of the oscillator, the second end of the sixth switching device is electrically connected to the alarm circuit, the third ends of the fifth switching device and the sixth switching device are both grounded, and the reset end and the power supply end of the oscillator are both electrically connected to the self-locking circuit.

[0008] Further, the alarm circuit includes a buzzer, an LED unit, a seventh switching device, and a third resistor; the first end of the buzzer is electrically connected to the self-locking circuit, the second end of the buzzer is respectively electrically connected to the second end of the sixth switching device and the first end of the seventh switching device, the second end of the seventh switching device is electrically connected to the third power supply, the third end of the seventh switching device is electrically connected to the LED unit, and the third resistor is electrically connected between the first end and the second end of the seventh switching device.

[0009] Further, the power-off alarm circuit further includes an eighth switching device; the first end of the eighth switching device is electrically connected to the first end of the seventh switching device, the second end of the eighth switching device is used to be electrically connected to the main control circuit, and the third end of the eighth switching device is grounded.

[0010] Further, the alarm driving circuit further includes a fourth resistor, a fifth resistor, a sixth resistor, and a third capacitor; one end of the fourth resistor is electrically connected to the self-locking circuit, the other end of the fourth resistor is electrically connected to the discharge end of the oscillator, one end of the fifth resistor is electrically connected to the discharge end of the oscillator, the other end of the fifth resistor is electrically connected to one end of the third capacitor, the other end of the third capacitor is grounded, the common connection end of the third capacitor and the fifth resistor is respectively electrically connected to the threshold end and the trigger end of the oscillator, and the sixth resistor is respectively electrically connected to the output end of the oscillator and the second end of the sixth switching device.

[0011] The second aspect of the present utility model provides a medical device, including the power-off alarm circuit as described in the first aspect of the present utility model.

[0012] As can be seen from the above description, when the device is normally powered on and working, the first switching device is controlled to be disconnected by the second switching device, so that the self-locking circuit works to continuously provide the power supply voltage for the oscillator, and then the master control circuit controls the oscillator to stop outputting the driving signal to the alarm circuit. At this time, the alarm circuit does not work; when the device loses power, the master control circuit controls the oscillator to output the driving signal to the alarm circuit. At this time, the alarm circuit works; when it is necessary to cancel the alarm signal, the power supply can be connected or the button can be pressed, and the self-locking circuit can be released through the first switching device. As a result, the oscillator has no power supply and stops driving the alarm circuit. Thus, the user can actively control the device to stop outputting the alarm signal and avoid interference caused by invalid alarm signals. Description of the Drawings

[0013] Figure 1 is a schematic structural diagram of a power-off alarm circuit according to an embodiment of the present utility model;

[0014] Figure 2 is a circuit schematic diagram of a power supply control circuit according to an embodiment of the present utility model;

[0015] Figure 3 is a circuit schematic diagram of an alarm driving circuit according to an embodiment of the present utility model;

[0016] Figure 4 is a circuit schematic diagram of an alarm circuit according to an embodiment of the present utility model.

[0017] In the drawings, each reference numeral represents: 100, power supply control circuit; 110 (Q3), first switching device; 120 (Q4), second switching device; 130, self-locking circuit; 200, alarm driving circuit; 210 (U1), oscillator; 300, alarm circuit; 400, button; 500, master control circuit; Q1, third switching device; Q2, fourth switching device; Q8, fifth switching device; Q6, sixth switching device; Q5, seventh switching device; Q7, eighth switching device; D2, first diode; D1, second diode; R3, first resistor; R1, second resistor; R13, third resistor; R16, fourth resistor; R20, fifth resistor; R19, sixth resistor; R8, seventh resistor; R2, eighth resistor; R7, ninth resistor; C1, first capacitor; C2, second capacitor; C9, third capacitor; LS1, buzzer. Detailed Embodiments

[0018] In order to make the purpose, technical solutions and advantages of the present utility model more clear and understandable, the present utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. In addition, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0019] In the related art, due to the problem that the power-off alarm signal is inconvenient to cancel, for this reason, this embodiment provides a power-off alarm circuit.

[0020] As Figure 1 shown is a schematic structural diagram of a power-off alarm circuit provided by this embodiment. Please refer to Figure 1 , the power-off alarm circuit includes: a power supply control circuit 100, an alarm drive circuit 200 and an alarm circuit 300. The power supply control circuit 100 includes a first switching device 110, a second switching device 120 and a self-locking circuit 130. The alarm drive circuit 200 includes an oscillator 210; the first end of the first switching device 110 is electrically connected to a first power supply and is used to be electrically connected to an external key 400. The second end of the first switching device 110 is electrically connected to the first end of the self-locking circuit 130. The second switching device 120 is respectively electrically connected to the first power supply and the second power supply. The first end of the self-locking circuit 130 is used to be electrically connected to an external main control circuit 500. The second end of the self-locking circuit 130 is electrically connected to a third power supply. The third end of the self-locking circuit 130 is electrically connected to the first end of the oscillator 210. The second end of the oscillator 210 is electrically connected to the alarm circuit 300. The third end of the oscillator 210 is used to be electrically connected to the main control circuit 500.

[0021] Specifically, in this embodiment, when the medical device is in a normal startup and working state, the first switching device 110 can be controlled to be disconnected through the second switching device 120, so that the self-locking circuit 130 works to continuously provide a power supply voltage for the oscillator 210, and then the main control circuit 500 is used to control the oscillator 210 to stop outputting a driving signal to the alarm circuit 300. At this time, the alarm circuit 300 does not work; when the device loses power, the main control circuit 500 is used to control the oscillator 210 to output a driving signal to the alarm circuit 300. At this time, the alarm circuit 300 works; when it is necessary to cancel the alarm signal, the power supply can be connected or the key 400 can be pressed, and the self-locking circuit 130 can be released through the first switching device 110, so that the oscillator 210 has no power supply and stops driving the alarm circuit 300. Thus, the user can actively control the device to stop outputting the alarm signal and avoid interference caused by invalid alarm signals.

[0022] As Figure 2The following is the circuit schematic diagram of a power supply control circuit provided by this embodiment. Please refer to Figure 2 , the self-locking circuit 130 includes a third switching device Q1, a fourth switching device Q2, a first diode D2, and a first resistor R3; the first end of the third switching device Q1 is electrically connected to the third power supply VCC_POL, the second end of the third switching device Q1 is respectively electrically connected to the positive electrode of the first diode D2 and the oscillator U1, the third end of the third switching device Q1 is electrically connected to the first end of the fourth switching device Q2, the second end of the fourth switching device Q2 is electrically connected to the negative electrode of the first diode D2 and is used for electrical connection with the main control circuit 500, the third end of the fourth switching device Q2 is grounded, the common connection end of the fourth switching device Q2 and the first diode D2 is grounded, and the first resistor R3 is electrically connected between the first end and the third end of the third switching device Q1.

[0023] Further, please refer to Figure 2 , the self-locking circuit 130 further includes an eighth resistor R2 and a ninth resistor R7; one end of the eighth resistor R2 is respectively electrically connected to the first diode D2 and the second end of the third switching device Q1, one end of the ninth resistor R7 is electrically connected to the negative electrode of the first diode D2, and the other end of the ninth resistor R7 is grounded.

[0024] Specifically, in this embodiment, when the medical device is in the normal power-on state, the second power supply DVCC_+5V controls the second switching device Q4 (i.e., 120) to conduct, so that the first power supply C_+5V is shielded, and thus the first switching device Q3 (i.e., 110) is turned off. At this time, the main control circuit 500, such as an MCU, outputs a high-level first control signal TTL3V3_VS_EN to the fourth switching device Q2 and the oscillator U1 (i.e., 210), causing the fourth switching device Q2 to conduct and the third switching device Q1 to conduct. The third power supply VCC_POL provides the power supply VS for the oscillator U1 and maintains self-locking through the first diode D2. However, the oscillator U1 stops driving the alarm circuit 300 due to the first control signal TTL3V3_VS_EN of the main control circuit 500, so the alarm circuit 300 does not work. Among them, the first power supply C_+5V can supply power when the device is connected to AC or DC, the second power supply DVCC_+5V supplies power after the user performs the power-on operation, and the third power supply VCC_POL can maintain the voltage output whether the device is powered off or not. When the medical device is in the power-off state, the first power supply C_+5V, the second power supply DVCC_+5V, and the first control signal TTL3V3_VS_EN cannot maintain a high level. At this time, the oscillator U1 starts to drive the alarm circuit 300, so the alarm circuit 300 enters the working state. When it is necessary to cancel the alarm signal, the first switching device Q3 can receive a high-level signal and conduct by reconnecting the power cord or pressing the corresponding button 400 (the button signal is TTL5V_PWR_SW), so that the fourth switching device Q2 is turned off and the third switching device Q1 is turned off to release the self-locking circuit 130. The third power supply VCC_POL stops providing the power supply VS for the oscillator U1, and the alarm circuit 300 stops working without drive. Thus, this embodiment provides a function of actively turning off the alarm signal for the medical device, enabling the user to quickly cancel the alarm signal and avoiding interference caused by invalid alarm signals. In addition, the first switching device Q3, the second switching device Q4, the third switching device Q1, and the fourth switching device Q2 in this embodiment can be NMOS transistors, NMOS transistors, PMOS transistors, and NMOS transistors respectively. The eighth resistor R2 and the ninth resistor R7 can be used to improve the stability of the circuit.

[0025] Furthermore, please refer to Figure 2 , the power supply control circuit 100 further includes a second diode D1, a second resistor R1, a first capacitor C1, and a second capacitor C2; the positive electrode of the second diode D1 is electrically connected to the first power supply C_+5V, the negative electrode of the second diode D1 is electrically connected to one end of the second resistor R1, the other end of the second resistor R1 is electrically connected to the first end of the third switching device Q1, and one ends of the first capacitor C1 and the second capacitor C2 are both electrically connected to the other end of the second resistor R1, and the other ends of the first capacitor C1 and the second capacitor C2 are both grounded.

[0026] Specifically, in this embodiment, a diode, resistor, and capacitor combination circuit is also provided at the source of the third switching device Q1, which can reduce the output noise of the third switching device Q1 and improve the performance of the subsequent circuit. Among them, the first capacitor C1 can be used to adjust the switching speed of the third switching device Q1, thereby adjusting the alarm time.

[0027] Furthermore, please refer to Figure 2 , the power supply control circuit 100 further includes a seventh resistor R8, a first filter circuit, a second filter circuit, a third filter circuit, and a fourth filter circuit; the first filter circuit is electrically connected between the fourth switching device Q2 and the main control circuit 500, the second filter circuit is electrically connected between the first switching device Q3 and the first power supply C_+5V, the third filter circuit is electrically connected between the first switching device Q3 and the key 400, the fourth filter circuit is electrically connected between the second switching device Q4 and the second power supply DVCC_+5V, one end of the seventh resistor R8 is electrically connected to the first end of the first switching device Q3, and the other end of the seventh resistor R8 is grounded.

[0028] Specifically, in this embodiment, the first filter circuit, the second filter circuit, and the third filter circuit all include a resistor and a diode, and the fourth filter circuit includes a resistor R10, a resistor R11, and a capacitor C3. The combination of these devices can be used to filter out high-frequency noise in the control signal and ensure the stability of the circuit. The seventh resistor R8 can be used to provide a pull-down resistor for the gate of the first switching device Q3 to prevent the first switching device Q3 from being mis-triggered.

[0029] As Figure 3 shown is the circuit schematic diagram of an alarm driving circuit provided in this embodiment. Please refer to Figure 3 , the alarm driving circuit 200 further includes a fifth switching device Q8 and a sixth switching device Q6. The first end of the fifth switching device Q8 is used to be electrically connected to the main control circuit 500, the second end of the fifth switching device Q8 is electrically connected to the reset end RESET of the oscillator U1, the first end of the sixth switching device Q6 is electrically connected to the output end OUT of the oscillator U1, the second end of the sixth switching device Q6 is electrically connected to the alarm circuit 300, the third ends of the fifth switching device Q8 and the sixth switching device Q6 are both grounded, and the reset end RESET and the power supply end VCC of the oscillator U1 are both electrically connected to the self-locking circuit 130.

[0030] Specifically, in this embodiment, the fifth switching device Q8 and the sixth switching device Q6 can both be NMOS transistors. When the fifth switching device Q8 receives the high-level first control signal TTL3V3_VS_EN output by the main control circuit 500, the fifth switching device Q8 conducts, thereby pulling down the reset terminal of the oscillator U1. As a result, the output terminal of the oscillator U1 outputs a low-level signal, causing the sixth switching device Q6 to cut off, and the alarm circuit 300 has no drive signal. When the device loses power, the first control signal TTL3V3_VS_EN at this time is at a low level, the fifth switching device Q8 cuts off, the output terminal of the oscillator U1 outputs a high-level signal, the sixth switching device Q6 conducts, and the alarm circuit 300 receives the drive signal and starts to work.

[0031] In addition, in this embodiment, the oscillator U1 is an NE555 oscillator. The reset terminal RESET of the oscillator U1 is also connected to the power supply VS through the resistor R16, the resistor R15, and the diode D8. A filter circuit is also provided between the fifth switching device Q8 and the main control circuit 500, that is, a filter circuit composed of the resistor R22, the resistor R24, and the capacitor C8, which can improve the working stability of the fifth switching device Q8.

[0032] Furthermore, please refer to Figure 3 , the alarm drive circuit 200 further includes a fourth resistor R16, a fifth resistor R20, a sixth resistor R19, and a third capacitor C9; one end of the fourth resistor R16 is electrically connected to the self-locking circuit 130, the other end of the fourth resistor R16 is electrically connected to the discharge terminal DISCH of the oscillator U1, one end of the fifth resistor R20 is electrically connected to the discharge terminal DISCH of the oscillator U1, the other end of the fifth resistor R20 is electrically connected to one end of the third capacitor C9, the other end of the third capacitor C9 is grounded, and the common connection end of the third capacitor C9 and the fifth resistor R20 is respectively electrically connected to the threshold terminal THRES and the trigger terminal TRIG of the oscillator U1. The sixth resistor R19 is respectively electrically connected to the output terminal OUT of the oscillator U1 and the second terminal of the sixth switching device Q6.

[0033] Specifically, in this embodiment, resistors and capacitors are also connected to each pin of the oscillator U1 to form a charge and discharge loop. By changing the values of the external resistors and capacitors (for example, adjusting the value of the fourth resistor R16 or the sixth resistor R19 or the third capacitor C9), the oscillation frequency and the duty cycle (the ratio of the high-level time to the low-level time) can be controlled to adjust the alarm duration.

[0034] As Figure 4 shown is the circuit schematic diagram of an alarm circuit provided in this embodiment. Please refer to Figure 3 and Figure 4, the alarm circuit 300 includes a buzzer LS1, an LED unit, a seventh switching device Q5, and a third resistor R13; the first end of the buzzer LS1 is electrically connected to the self-locking circuit 130, the second end of the buzzer LS1 is respectively electrically connected to the second end of the sixth switching device Q6 and the first end of the seventh switching device Q5, the second end of the seventh switching device Q5 is electrically connected to the third power supply VCC_POL, the third end of the seventh switching device Q5 is electrically connected to the LED unit, and the third resistor R13 is electrically connected between the first end and the second end of the seventh switching device Q5.

[0035] Further, please refer to Figure 4 , the power-off alarm circuit 300 further includes an eighth switching device Q7, the first end of the eighth switching device Q7 is electrically connected to the first end of the seventh switching device Q5, the second end of the eighth switching device Q7 is used to be electrically connected to the main control circuit 500, and the third end of the eighth switching device Q7 is grounded.

[0036] Specifically, in this embodiment, the buzzer LS1 and the LED provide the user with audible and visual alarm signals. When the sixth switching device Q6 is turned on, the buzzer LS1 starts to work, and the seventh switching device Q5 is turned on to make the LED unit work. Among them, the LED unit may include one or more LEDs. In addition, when the device is working normally and it is necessary to control the LED unit to work, the seventh switching device Q5 can also be controlled through the eighth switching device Q7. Among them, the seventh switching device Q5 and the eighth switching device Q7 can be a PMOS transistor and an NMOS transistor respectively. Therefore, the main control circuit 500 can output a high-level second control signal TTL3V3_REDLED_SW to control the eighth switching device Q7 to turn on, thereby controlling the seventh switching device Q5 to turn on to drive the LED unit into the working state.

[0037] In the power-off alarm circuit provided by the embodiment of the present invention, when the device is normally powered on and working, the second switching device is used to control the first switching device to disconnect, so that the self-locking circuit works to continuously provide the power supply voltage for the oscillator, and then the main control circuit controls the oscillator to stop outputting the driving signal to the alarm circuit. At this time, the alarm circuit does not work; when the device loses power, the main control circuit controls the oscillator to output the driving signal to the alarm circuit. At this time, the alarm circuit works; when it is necessary to cancel the alarm signal, the power supply can be connected or the button can be pressed, and the self-locking circuit can be released through the first switching device, so that the oscillator has no power supply and stops driving the alarm circuit. Thus, the user can actively control the device to stop outputting the alarm signal and avoid interference caused by invalid alarm signals.

[0038] The embodiment of the present invention also provides a medical device, and the medical device includes the above-mentioned power-off alarm circuit. Among them, the medical device can be a medical temperature controller.

[0039] It should be noted that each embodiment in the content of the present utility model is described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0040] It should also be noted that in the content of the present utility model, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0041] The above description of the disclosed embodiments enables those skilled in the art to implement or use the content of the present utility model. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined in the content of the present utility model can be implemented in other embodiments without departing from the spirit or scope of the content of the present utility model. Therefore, the content of the present utility model will not be limited to these embodiments shown in the content of the present utility model, but rather to the widest scope consistent with the principles and novel features disclosed in the content of the present utility model.

Claims

1. A power-down alarm circuit, characterized in that, Comprising: A power supply control circuit, an alarm driving circuit and an alarm circuit. The power supply control circuit includes a first switching device, a second switching device and a self-locking circuit. The alarm driving circuit includes an oscillator; The first end of the first switching device is electrically connected to a first power supply and is used for being electrically connected to an external key. The second end of the first switching device is electrically connected to the first end of the self-locking circuit. The second switching device is respectively electrically connected to the first power supply and a second power supply. The first end of the self-locking circuit is used for being electrically connected to an external main control circuit. The second end of the self-locking circuit is electrically connected to a third power supply. The third end of the self-locking circuit is electrically connected to the first end of the oscillator. The second end of the oscillator is electrically connected to the alarm circuit. The third end of the oscillator is used for being electrically connected to the main control circuit.

2. The power-off alarm circuit according to claim 1, wherein The self-locking circuit includes a third switching device, a fourth switching device, a first diode and a first resistor; The first end of the third switching device is electrically connected to the third power supply. The second end of the third switching device is respectively electrically connected to the positive electrode of the first diode and the oscillator. The third end of the third switching device is electrically connected to the first end of the fourth switching device. The second end of the fourth switching device is electrically connected to the negative electrode of the first diode and is used for being electrically connected to the main control circuit. The third end of the fourth switching device is grounded. The common connection end of the fourth switching device and the first diode is grounded. The first resistor is electrically connected between the first end and the third end of the third switching device.

3. The power-down alarm circuit according to claim 2, wherein, The power supply control circuit further includes a second diode, a second resistor, a first capacitor and a second capacitor; The positive electrode of the second diode is electrically connected to the first power supply. The negative electrode of the second diode is electrically connected to one end of the second resistor. The other end of the second resistor is electrically connected to the first end of the third switching device. One ends of the first capacitor and the second capacitor are both electrically connected to the other end of the second resistor. The other ends of the first capacitor and the second capacitor are both grounded.

4. The power-off alarm circuit according to claim 1, characterized in that, The alarm driving circuit further includes a fifth switching device and a sixth switching device. The first end of the fifth switching device is used for being electrically connected to the main control circuit. The second end of the fifth switching device is electrically connected to the reset end of the oscillator. The first end of the sixth switching device is electrically connected to the output end of the oscillator. The second end of the sixth switching device is electrically connected to the alarm circuit. The third ends of the fifth switching device and the sixth switching device are both grounded. The reset end and the power supply end of the oscillator are both electrically connected to the self-locking circuit.

5. The power-down alarm circuit according to claim 4, wherein The alarm circuit includes a buzzer, an LED unit, a seventh switching device and a third resistor; The first end of the buzzer is electrically connected to the self-locking circuit. The second end of the buzzer is respectively electrically connected to the second end of the sixth switching device and the first end of the seventh switching device. The second end of the seventh switching device is electrically connected to the third power supply. The third end of the seventh switching device is electrically connected to the LED unit. The third resistor is electrically connected between the first end and the second end of the seventh switching device.

6. The power-off alarm circuit according to claim 5, wherein It further includes an eighth switching device. The first end of the eighth switching device is electrically connected to the first end of the seventh switching device. The second end of the eighth switching device is used to be electrically connected to the main control circuit, and the third end of the eighth switching device is grounded.

7. The power-off alarm circuit according to claim 4, wherein The alarm driving circuit further includes a fourth resistor, a fifth resistor, a sixth resistor and a third capacitor; One end of the fourth resistor is electrically connected to the self-locking circuit, and the other end of the fourth resistor is electrically connected to the discharge end of the oscillator. One end of the fifth resistor is electrically connected to the discharge end of the oscillator, and the other end of the fifth resistor is electrically connected to one end of the third capacitor. The other end of the third capacitor is grounded. The common connection end of the third capacitor and the fifth resistor is respectively electrically connected to the threshold end and the trigger end of the oscillator. The sixth resistor is respectively electrically connected to the output end of the oscillator and the second end of the sixth switching device.

8. The power-down alarm circuit according to claim 2, wherein, The power supply control circuit further includes a seventh resistor, a first filter circuit, a second filter circuit, a third filter circuit and a fourth filter circuit; The first filter circuit is electrically connected between the fourth switching device and the main control circuit. The second filter circuit is electrically connected between the first switching device and the first power supply. The third filter circuit is electrically connected between the first switching device and the key. The fourth filter circuit is electrically connected between the second switching device and the second power supply. One end of the seventh resistor is electrically connected to the first end of the first switching device, and the other end of the seventh resistor is grounded.

9. The power-off alarm circuit according to claim 2, wherein The self-locking circuit further includes an eighth resistor and a ninth resistor. One end of the eighth resistor is respectively electrically connected to the first diode and the second end of the third switching device. One end of the ninth resistor is electrically connected to the negative electrode of the first diode, and the other end of the ninth resistor is grounded.

10. A medical device, characterized in that, It includes the power-off alarm circuit according to any one of claims 1 to 9.

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