Automatic power-off circuit and automatic power-off method thereof

Abstract

An automatic cut-off circuit is coupled between a battery and a load, and is used to automatically cut off a path between the battery and the load after the battery supplies power to the load for a specific period. The automatic cut-off circuit includes a first switch, a first capacitor, a first inversion circuit, a timing circuit, and a logic circuit. The first inversion circuit provides a first signal that is inverse to a potential change of the first capacitor based on the potential change. The timing circuit provides a second signal of the first potential to the logic circuit based on the first signal of the first potential, and adjusts the second signal to a second potential after a specific period. The logic circuit turns on the first switch based on the second signal of the first potential, and turns off the first switch based on the second signal of the second potential.

Description

Technical Field

[0001] This invention relates to an automatic power-off circuit and its automatic power-off method, and more particularly to an automatic power-off circuit and its automatic power-off method suitable for a facial cleansing machine. Background Technology

[0002] With the increasing prevalence of electronic products, more and more household electronic products have emerged, especially with the rapid development of these products. This has led to the development of numerous electronic devices that can replace manual labor, such as, but not limited to, dishwashers, electric toothbrushes, and facial cleansing brushes. Among these, facial cleansing brushes, in addition to replacing manual labor, can deeply cleanse the skin through vibration. Therefore, besides replacing hands, they offer additional benefits, resulting in their growing popularity.

[0003] The deep cleansing function of facial cleansing brushes relies primarily on a motor; however, continuous vibration is not necessary for a deep clean. Specifically, a short period of vibration is usually sufficient for deep cleansing. Excessive or insufficient vibration can lead to over- or under-cleansing. Therefore, existing facial cleansing brushes require manual shutdown to stop the motor after a sufficient period of use. However, users often don't pay attention to the duration of this shutdown, frequently resulting in the aforementioned negative effects. Furthermore, continuous motor operation without proper shutdown fails to provide beneficial skin benefits; therefore, prolonged motor operation wastes electricity and shortens the lifespan of the facial cleansing brush.

[0004] Therefore, how to design an automatic power-off circuit and method suitable for facial cleansing machines, so as to control the motor to stop after running for a short period of time, is a major research topic that the creators of this project intend to conduct. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an automatic power-off circuit suitable for facial cleansing devices, overcoming the limitations of existing technologies. Therefore, the automatic power-off circuit of this invention is coupled between a battery and a load, and is used to automatically disconnect the path between the battery and the load after the battery has supplied power to the load for a specific period. The automatic power-off circuit includes a first switch, a first inverting circuit, a timing circuit, a logic circuit, and a second switch, with the first switch coupled to the battery and the load. The first inverting circuit includes an input terminal and an output terminal; the input terminal is coupled to the battery, the first switch, and a first capacitor, and the first inverting circuit provides a first signal opposite to the potential change based on the potential change of the first capacitor. The timing circuit is coupled to the output terminal of the first inverting circuit, and the logic circuit includes an input terminal and an output terminal. The input terminal of the logic circuit is coupled to the timing circuit, and the output terminal is coupled to the first switch and the first inverting circuit. The second switch includes a first terminal and a second terminal; the first terminal is coupled to the input terminal of the first inverting circuit, and the second terminal is coupled to a second capacitor. The second switch is triggered to conduct, and the second capacitor changes the potential of the first capacitor based on the conduction of the second switch. The timing circuit provides a second signal to the logic circuit based on the first signal being at the first potential, and adjusts the second signal to the second potential after a specific period of time; the logic circuit turns on the first switch based on the second signal at the first potential, and turns off the first switch based on the second signal at the second potential.

[0006] To address the aforementioned problems, this invention provides an automatic power-off method for an automatic power-off circuit, overcoming the limitations of existing technologies. Therefore, the automatic power-off circuit of this invention is coupled between a battery and a load, and includes a first switch, a first capacitor, a first inverting circuit, a timing circuit, and a logic circuit. The automatic power-off method includes the following steps: (a) The first capacitor begins charging from a second potential based on battery connection. (b) The first inverting circuit provides a first signal of the first potential based on the second potential of the first capacitor. (c) The timing circuit provides a second signal of the first potential to the logic circuit based on the first signal being the first potential. (d) The logic circuit turns on the first switch based on the second signal of the first potential. (e) The timing circuit times a specific period, and after the specific period, the timing circuit adjusts the second signal to the second potential. (f) The logic circuit turns off the first switch based on the second signal of the second potential.

[0007] The main objective and effect of this invention is that the automatic power-off circuit short-circuits the path between the battery and the motor for a short period of time (i.e., a specific time period) when the battery is installed in the facial cleansing device or when the user needs to use it, and automatically disconnects the path between the battery and the motor after the time is over, so as to achieve the effect of simultaneously maintaining the cleaning ability of the facial cleansing device and saving battery power consumption.

[0008] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit this invention. Attached Figure Description

[0009] Figure 1 This is a circuit block diagram of the automatic power-off circuit applicable to a facial cleansing machine according to the present invention;

[0010] Figure 2 This is a circuit block diagram of the timing circuit of the present invention;

[0011] Figure 3A This is a detailed circuit block diagram of the first embodiment of the automatic power-off circuit for a facial cleansing machine according to the present invention; and

[0012] Figure 3B This is a detailed circuit block diagram of the second embodiment of the automatic power-off circuit for a facial cleansing machine according to the present invention.

[0013] In the attached figures, the following labels are used:

[0014] 100… batteries

[0015] 200…load

[0016] 300…facial cleansing machine

[0017] 400…External devices

[0018] 1, 1'... Automatic power-off circuit

[0019] Q1…First Switch

[0020] 12, 12'... First Inverting Circuit

[0021] 12A…input terminal

[0022] 12B…output terminal

[0023] C1…First capacitor

[0024] 14, 14'... Timing circuit

[0025] C3…Third capacitor

[0026] A…First End

[0027] B…Second end

[0028] R…resistance

[0029] D…diode

[0030] 16… Logic Circuits

[0031] 16A…input terminal

[0032] 16B…output terminal

[0033] 18…Second Switch

[0034] A…First End

[0035] B…Second end

[0036] C2…Second capacitor

[0037] 20…Connection end

[0038] 22, 22'... Second inverting circuit

[0039] 22A…input terminal

[0040] 22B…output terminal

[0041] 24…charging circuit

[0042] Vdc…DC voltage

[0043] Vin…Input Voltage

[0044] Vc…Transpressure

[0045] Sc1…First Signal

[0046] Sc2…Second signal

[0047] Sc3…Third signal

[0048] Sc… control signal

[0049] St… triggers Detailed Implementation

[0050] The technical content and detailed description of the present invention are explained below with reference to the accompanying drawings:

[0051] Please see Figure 1This is a circuit block diagram of the automatic power-off circuit for a facial cleansing device according to the present invention. The automatic power-off circuit 1 is coupled between the battery 100 and the load 200, which can be the motor of the facial cleansing device 300. The battery 100 provides a DC voltage Vdc to power the motor. When the path between the battery 100 and the motor is short-circuited, the motor receives the DC voltage Vdc and is driven; conversely, the path is broken, causing the motor to stop. The automatic power-off circuit 1 is mainly used to short-circuit the path between the battery 100 and the motor for a short period of time (i.e., a specific time period) when the battery 100 is installed in the facial cleansing device 300 or when the user needs to use it. After the time expires, it automatically disconnects the path between the battery 100 and the motor, thereby improving the cost-effectiveness of the facial cleansing device 300. It is worth mentioning that the cost-effectiveness refers to simultaneously maintaining the cleaning ability of the facial cleansing device and saving battery power consumption. This can increase the lifespan of the facial cleansing device 300.

[0052] Furthermore, the automatic power-off circuit 1 includes a first switch Q1, a first inverting circuit 12, a first capacitor C1, a timing circuit 14, a logic circuit 16, a second switch 18, and a second capacitor C2. The first switch Q1 is coupled between the battery 100 and the load 200 to short-circuit or open-circuit the path between the battery 100 and the load 200 by being controlled to be turned on or off. The first inverting circuit 12 includes an input terminal 12A and an output terminal 12B. The input terminal 12A is coupled to the battery 100, the first switch Q1, and the first capacitor C1. The first inverting circuit 12 provides a first signal Sc1 that is inversely proportional to the potential change of the first capacitor C1 (referring to the change in the stored voltage). The timing circuit 14 is coupled to the output terminal 12B of the first inverting circuit 12 and provides a second signal Sc2 to the logic circuit 16 based on the first signal Sc1 being a first potential (which can be a high potential). Then, the timing circuit 14 automatically times a specific period of time, and after the specific period of time, adjusts the second signal Sc2 from the first potential to the second potential (which can be a low potential).

[0053] Logic circuit 16 includes an input terminal 16A and an output terminal 16B. Input terminal 16A is coupled to timing circuit 14, and output terminal 16B is coupled to the first switch Q1 and the input terminal 12A of the first inverting circuit 12. Logic circuit 16 turns on the first switch Q1 based on a second signal Sc2 at a first potential, and turns off the first switch Q1 based on the second signal Sc2 at a second potential. The first switch Q1 can be a semiconductor switch (e.g., but not limited to a transistor), but is not limited thereto. Second switch 18 includes a first terminal A and a second terminal B. First terminal A is coupled to the input terminal 12A of the first inverting circuit 12, and second terminal B is coupled to the second capacitor C2 and the output terminal 12B of the first inverting circuit 12. Second switch 18 can be a manually controllable switch such as a touch switch or push-button switch. It is mainly used to be turned on based on a manual trigger St, and the second capacitor C2 changes the potential of the first capacitor C1 based on the turn-on of the second switch 18.

[0054] Specifically, the second switch 18 is mainly triggered by a human-induced change in the potential of the first signal Sc1 output by the first inverting circuit 12. After the potential of the first signal Sc1 changes, the timing circuit 14 automatically times a specific period. After the specific period, the timing circuit 14 changes the potential back to the potential when the second switch 18 was not triggered by St, so that the logic circuit 16 can turn the first switch Q1 on / off accordingly. In this way, the automatic power-off circuit 1 can achieve the effect of automatically turning on / off and short-circuiting or disconnecting the path between the battery 100 and the load 200.

[0055] It is worth mentioning that, in one embodiment of the present invention, to avoid confusion, the first potential uniformly refers to a high potential, and the second potential uniformly refers to a low potential, but this is not a limitation. The high or low signal potential is mainly for the various circuits or components to make judgments and perform corresponding controls, and therefore can be adjusted according to the characteristics of the circuit. For example, the logic circuit 16 can conversely turn on the first switch Q1 based on the second signal Sc2 at a low potential (originally a high potential), and turn off the first switch Q1 based on the second signal Sc2 at a high potential (originally a low potential). On the other hand, the first potential and the second potential referred to by each circuit or component can be the same or different. For example, the first potential referred to by the first inverting circuit 12 can be 12V, and the first potential referred to by the logic circuit 16 can be 5V.

[0056] See also Figure 1The automatic power-off circuit 1 further includes a connection terminal 20, a second reverse circuit 22, and a charging circuit 24. The connection terminal 20 is used to couple to an external device 400 (e.g., but not limited to, a charger or other device providing charging power) to receive the input voltage Vin provided by the external device 400. The connection terminal 20 may be, for example, but is not limited to, a USB-type interface. The second reverse circuit 22 includes an input terminal 22A and an output terminal 22B. The input terminal 22A is coupled to the connection terminal 20, and the output terminal 22B is coupled to the input terminal 16A of the logic circuit 16. The second reverse circuit 22 primarily provides a signal indicating whether the external device 400 is connected to the automatic power-off circuit 1. When the external device 400 is connected, the battery 100 must be stopped from supplying power to the load 200. Specifically, the second reverse circuit 22 provides a third signal Sc3, inverse of the input voltage Vin, based on whether the external device 400 is connected, and the logic circuit 16 turns off the first switch Q1 based on the third signal Sc3 (representing that the load is connected) at the second potential. Charging circuit 24 is coupled to connection terminal 20 and battery 100, and is used to convert input voltage Vin to charge battery 100. Charging circuit 24 can be a switching power converter (e.g., but not limited to a buck converter). It is worth noting that, in one embodiment of the present invention, apart from connection terminal 20 and charging circuit 24, the remaining blocks of automatic power-off circuit 1 can be implemented by logic circuits, electronic component circuits, or programmable control. Any components, circuits, or software capable of performing the above functions should be included within the scope of this embodiment.

[0057] Please see Figure 2 This is a circuit block diagram of the timing circuit of the present invention, which can be further referenced. Figure 1The timing circuit 14 includes a third capacitor C3, a resistor R, and a diode D. The third capacitor C3 includes a first terminal A and a second terminal B. The first terminal A of the third capacitor C3 is coupled to the output terminal 12A of the first inverting circuit 12, and the second terminal B of the third capacitor C3 is coupled to the input terminal 16A of the logic circuit 16. The resistor R is coupled to the third capacitor C3 and the ground terminal, and achieves the effect of generating a specific time period through the principle of RC charging and discharging. Specifically, the third capacitor C3 is charged based on the first signal Sc1 being at the first potential, so that a voltage Vc is gradually generated between the first terminal A and the second terminal B of the third capacitor C3. After a specific time period, the voltage Vc generated between the first terminal A and the second terminal B of the third capacitor C3 accumulates sufficiently, so that the potential of the second terminal B becomes the second potential, thereby adjusting the second signal Sc2 provided by the timing circuit 14 to the second potential. Therefore, the time when the voltage Vc is charged to the point that the second signal Sc2 drops to the second potential is the specific time period. For example, suppose the first inverting circuit 12 provides a first potential of 5V. When the third capacitor C3 is not yet charged, 5V can be directly provided to the input terminal 16A of the logic circuit 16. However, when the third capacitor C3 is fully charged, the voltage Vc is, for example, but not limited to, 4V, causing the potential of the second terminal B to become 1V. Thus, due to the charging of the third capacitor C3, the potential of the second terminal B drops from the original 5V to the second potential (i.e., 1V).

[0058] The cathode of diode D is coupled to the second terminal B of the third capacitor C3, and the anode is coupled to ground. Diode D is used to clamp the potential of the second terminal B of the third capacitor C3 to prevent the logic circuit 16 from failing due to a low potential. Specifically, when the third capacitor C3 is fully charged, the first signal Sc1 will change to the second potential for some reason. Therefore, both the first terminal A and the second terminal B of the third capacitor C3 are at the second potential. In this way, the potential of the second terminal B may become negative. If the negative value is too large, exceeding the acceptable input range of the logic circuit 16, it will cause the logic circuit 16 to fail. Therefore, diode D is forward biased in this situation, and the forward bias voltage is approximately 0.7V (depending on the type of diode), so that even if the potential of the second terminal B becomes negative, it will be clamped at -0.7V and not become too low. It is worth mentioning that in one embodiment of the present invention, the timing circuit 14 is not limited to being only powered by... Figure 2 The implementation of the circuit, including any component, circuit, or controller that can automatically change the signal potential after a specific time period, should be included within the scope of this embodiment. For example, but not limited to, a programmable controller can be used to perform the above-mentioned function to provide the specific time period.

[0059] Please see Figure 3A This is a detailed circuit block diagram of the first embodiment of the automatic power-off circuit for a facial cleansing machine according to the present invention, with reference to other diagrams. Figures 1-2In this embodiment, the first inverting circuit 12, the second inverting circuit 22, and the logic circuit 16 can be NAND flash memory, and the first switch Q1 can be a P-channel transistor (p-MOSFET). When the battery 100 is connected, the first capacitor C1 starts charging from the second potential (low potential) based on the connection of the battery 100 (action a). At this time, the first inverting circuit 12 provides a first signal Sc1 of the first potential (i.e., high potential) based on the second potential of the first capacitor C1 (action b). Since the third capacitor C3 of the timing circuit 14 has not yet been charged, the timing circuit 14 provides a second signal Sc2 of the first potential to the logic circuit 16 based on the first signal Sc1 being the first potential (action c), causing the logic circuit 16 to provide a control signal Sc of the second potential based on the second signal Sc2 of the first potential to turn on the first switch Q1 (action d). At this time, the third capacitor C3 starts charging because it receives the first signal Sc1 of the first potential (action e; i.e., the timing circuit 14 starts timing a specific period of time). When the third capacitor C3 is fully charged, it signifies the end of a specific time period. During this specific time period, the timing circuit 14 gradually adjusts the second signal Sc2 from the first potential H to the second potential L. When the second signal Sc2 is at the second potential L, the logic circuit 16 provides a control signal Sc to the first potential H based on the second signal Sc2 at the second potential L, thus turning off the first switch Q1 (action f). Therefore, when the battery 100 is connected to the automatic power-off circuit 1, the motor (i.e., the load 200) will run for a specific time period and then stop.

[0060] After the control signal Sc at the first potential turns off the first switch Q1, the first capacitor C1 is charged to the first potential (action g), causing the first inverting circuit 12 to provide the first signal Sc1 at the second potential based on the first potential of the first capacitor C1 (action h). Therefore, both terminals (A and B) of the third capacitor C3 are pulled to the second potential, and the diode D clamps the potential of the second terminal B to a second potential of -0.7V, causing the timing circuit 14 to maintain the second signal Sc2 at the second potential based on the first signal at the second potential (action i). At this time, the potentials of each component and circuit of the automatic power-off circuit 1 are fixed, so the control signal Sc provided by the logic circuit 16 is fixed at the first potential, maintaining the first switch Q1 in the off state (i.e., steady state).

[0061] Then, when the first switch Q1 is kept in the off state (i.e., not for a specific time period) and the second switch 18 is pressed, the second switch 18 receives trigger St and turns on (action j1). At this time, the first capacitor C1 discharges to the second capacitor C2 based on the conduction of the second switch 18, so the potential originally stored in the first capacitor C1 is instantly changed and drops to the second potential (action k1). When the first capacitor C1 drops to the second potential, it returns to the state of action b above, so the automatic power-off circuit 1 then automatically executes actions c to f in sequence to automatically control the motor to stop. Then, actions g to f are executed again to maintain the first switch Q1 in the off state (i.e., steady state). It is worth mentioning that in one embodiment of the present invention, the capacitance of the second capacitor C2 is more than 5 times the capacitance of the first capacitor C1. Because of this, when the first capacitor C1 is coupled to the second capacitor C2, the first capacitor C1 will be immediately affected by the second capacitor C2 and charge / discharge rapidly, accelerating the response of the first capacitor C1 to each action.

[0062] like Figure 3A As shown, the second terminal B of the second switch 18 is coupled to the output terminal 12B of the first inverting circuit 12, so that the automatic power-off circuit 1 has the function of controlling the fan to stop when the second switch 18 is pressed continuously. Specifically, this circuit structure is in operation during a specific period (i.e., after the second switch 18 is pressed or after the battery 100 is connected, but before the specific period ends), and when the second switch 18 is pressed, the second switch 18 receives a trigger St and is turned on (action j2). At this time, the first signal Sc1 of the first potential provided by the first inverting circuit 12 (i.e., the first signal Sc1 is at the first potential before action b to action h) charges the second capacitor C2 to the first potential (k2). Because the second switch 18 is turned on, the second capacitor C2 charges the first capacitor C1, so regardless of which stage of action b to h is currently in, actions g to i will be executed. Since the second signal Sc2 is at the second potential during action i, the logic circuit 16 turns off the first switch Q1 based on the second signal Sc2 of the second potential (i.e., step f).

[0063] When the automatic power-off circuit 1 needs to charge the battery 100, the external device 400 is connected to the connection terminal 20, causing the automatic power-off circuit 1 to receive the input voltage Vin. Then, the second inverting circuit 22 receives the input voltage Vin based on the connection of the external device 400, and provides a third signal Sc3 of the second potential based on the input voltage Vin (action x; i.e., the third signal Sc3 of the potential reversed by the input voltage Vin). Then, the logic circuit 16 provides a control signal Sc of the first potential based on the third signal Sc3 of the second potential to turn off the first switch Q1 (action y). At this time, the charging circuit 24 also receives the input voltage Vin and converts the input voltage Vin to charge the battery 100 (action z). It is worth mentioning that, in one embodiment of the present invention, Figure 3AThe components (e.g., resistors) and their coupling relationships described in detail are generally for current limiting or voltage regulation purposes and are not the main features of this invention, so they will not be described in detail here.

[0064] Please see Figure 3B This is a detailed circuit block diagram of the second embodiment of the automatic power-off circuit for a facial cleansing machine according to the present invention, with reference to other diagrams. Figures 1-3A The automatic power-off circuit 1' in this embodiment and Figure 3A The difference between the automatic power-off circuit 1 and the automatic power-off circuit 22 is that the first reverse circuit 12' and the second reverse circuit 22' can be reverse circuits (NOT), and the timing circuit 14' can be a controller. Figure 3A The advantage of this circuit structure is that the first inverting circuit 12, the second inverting circuit 22, and the logic circuit 16 all use NAND flash memory, thus allowing implementation with a single NAND flash controller (typically containing 3-4 NAND flash units), saving circuit size and cost. However, the first inverting circuit 12 and the second inverting circuit 22 are actually for inverting functions and can therefore be replaced by NAND flash memory. Furthermore, although the timing circuit 14' can be a controller, it also has an automatic timing function. However, Figure 3A Its circuit structure is simple and its component cost is low, therefore Figure 3A The timing circuit 14 is a preferred embodiment. It is worth mentioning that, in one embodiment of the present invention, although... Figure 3B circuit structure and Figure 3A Slightly different, but their movements are all the same. Figure 3A The similarities are obvious and will not be elaborated upon here. Furthermore, Figure 3A and Figure 3B The circuit structures can be interchanged according to actual needs, and it is not excluded that existing circuits, components or controllers with the same function can be used as replacements.

[0065] However, the above description is only a detailed description and drawings of preferred embodiments of the present invention. The features of the present invention are not limited thereto and are not intended to limit the present invention. The scope of the present invention should be determined by the following claims. All embodiments that are in line with the spirit of the claims and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by those skilled in the art within the field of the present invention can be covered by the following claims.

Claims

1. An automatic power-off circuit, characterized in that, An automatic power-off circuit is coupled between a battery and a load, and is configured to automatically disconnect the path between the battery and the load after the battery has supplied power to the load for a specific period of time. The automatic power-off circuit includes: A first switch, coupling the battery to the load; A first inverting circuit includes an input terminal and an output terminal. The input terminal is coupled to the battery, the first switch and a first capacitor. The first inverting circuit provides a first signal that is inverse to the potential change based on a potential change of the first capacitor. A time-limited circuit is coupled to the output terminal of the first inverting circuit; A logic circuit includes an input terminal and an output terminal, the input terminal being coupled to the timing circuit, and the output terminal being coupled to the first switch and the first inverting circuit; and A second switch includes a first terminal and a second terminal, the first terminal being coupled to the input terminal of the first inverting circuit, and the second terminal being coupled to a second capacitor; the second switch is configured to be turned on based on a trigger, and the second capacitor changes its potential based on the second switch being turned on; The timing circuit provides a second signal to the logic circuit based on the first signal being a first potential, and adjusts the second signal to a second potential after the specific time period; the logic circuit turns on the first switch based on the second signal of the first potential, and turns off the first switch based on the second signal of the second potential.

2. The automatic power-off circuit as described in claim 1, characterized in that, Including: A connection terminal for coupling to an external device to receive an input voltage; and A second inverting circuit includes an input terminal and an output terminal, the input terminal being coupled to the connection terminal, and the output terminal being coupled to the input terminal of the logic circuit; The second inverting circuit provides a third signal that is inverse to the input voltage based on whether the external device is connected or not, and the logic circuit turns off the first switch based on the third signal of the second potential L.

3. The automatic power-off circuit as described in claim 2, characterized in that, Including: A charging circuit is coupled to the connection terminal and the battery, and is used to convert the input voltage to charge the battery.

4. The automatic power-off circuit as described in claim 1, characterized in that, The second terminal of the second switch is coupled to the output terminal of the first reverse circuit and is used to change the potential by the first signal based on the triggering of the second switch during the specific time period.

5. The automatic power-off circuit as described in claim 1, characterized in that, The timing circuit includes: A third capacitor includes a first terminal and a second terminal, the first terminal being coupled to the output terminal of the first inverting circuit, and the second terminal being coupled to the input terminal of the logic circuit; and A resistor is coupled to the third capacitor; The third capacitor is charged based on the first signal being at a first potential, and after a specific period of time, a voltage across the first and second terminals of the third capacitor adjusts the second signal to a second potential.

6. The automatic power-off circuit as described in claim 5, characterized in that, The timing circuit further includes: A diode is coupled to the second terminal of the third capacitor and is used to clamp a potential at the second terminal of the third capacitor.

7. The automatic power-off circuit as described in claim 1, characterized in that, The capacitance of the second capacitor is more than five times that of the first capacitor.

8. The automatic power-off circuit as described in claim 1, characterized in that, The logic circuit is an inverting gate, and the first switch is a P-channel transistor.

9. The automatic power-off circuit as described in claim 1, characterized in that, The automatic power-off circuit is applicable to a facial cleansing machine, and the load is a motor of the facial cleansing machine.

10. An automatic power-off method for an automatic power-off circuit, characterized in that, The automatic power-off circuit is coupled between a battery and a load, and includes a first switch, a first capacitor, a first reverse circuit, a timing circuit, and a logic circuit. The automatic power-off method includes the following steps: (a) The first capacitor begins to be charged by the second potential based on the battery connection; (b) The first reverse circuit provides a first signal of the first potential based on the second potential of the first capacitor; (c) The timing circuit provides a second signal of the first potential to the logic circuit based on the first signal being the first potential; (d) The logic circuit turns on the first switch based on the second signal of the first potential; (e) The timing circuit times a specific period of time, and after the specific period of time, the timing circuit adjusts the second signal to a second potential; and (f) The logic circuit turns off the first switch based on the second signal at the second potential.

11. The automatic power-off method as described in claim 10, characterized in that, It also includes the following steps: (g) The first capacitor is charged to the first potential; (h) The first reverse circuit provides the first signal of the second potential based on the first potential of the first capacitor; and (i) The timing circuit maintains the second signal at the second potential based on the first signal at the second potential.

12. The automatic power-off method as described in claim 11, characterized in that, The automatic power-off circuit further includes a second switch and a second capacitor, and the automatic power-off method further includes the following steps: (j1) If it is not during that specific time period, the second switch is triggered and turned on; (k1) The first capacitor discharges to the second potential based on the conduction of the second switch; and (l1) Repeat steps (b) to (f).

13. The automatic power-off method as described in claim 12, characterized in that, It also includes the following steps: (j2) During that specific time period, the second switch is triggered and turned on; (k2) The first signal at the first potential provided by the first reverse circuit charges the second capacitor to the first potential; and (l2) Repeat steps (g) to (i) and execute step (f).

14. The automatic power-off method as described in claim 10, characterized in that, The automatic power-off circuit further includes a second reverse circuit, and the automatic power-off method further includes the following steps: (x) The second inverting circuit receives an input voltage based on the access of an external device, and provides a third signal of a second potential based on the input voltage; and (y) The logic circuit turns off the first switch based on the third signal of the second potential.

15. The automatic power-off method as described in claim 14, characterized in that, The automatic power-off circuit further includes a charging circuit, and the automatic power-off method further includes the following steps: (z) The charging circuit converts the input voltage to charge the battery.

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