Intelligent access control system and overcurrent automatic shutdown module

Abstract

Disclosed is an intelligent access control system, comprising: an audio module for outputting a doorbell audio signal, a doorbell control module comprising a doorbell switch and a first power supply, an overcurrent automatic shutdown module, the overcurrent automatic shutdown module being connected in series with the doorbell control module across a second power supply, the audio module being connected in parallel with the overcurrent automatic shutdown module, if the doorbell switch is disabled, the second power supply supplies power to the doorbell control module through a first branch in which the overcurrent automatic shutdown module is located, and the voltage applied to the audio module by the second power supply through the first branch makes the audio module inoperable; if the doorbell switch is enabled, the overcurrent automatic shutdown module samples the current of the first branch, if the sampled current reaches a set current threshold, the first branch is triggered to be shut down, so that the doorbell control module is switched from being powered by the second power supply to being powered by the first power supply, and the voltage applied to the audio module by the second power supply makes the audio module work, thereby realizing reliable switching of the internal and external power supplies when the intelligent doorbell function is used.

Description

Technical Field

[0001] This invention relates to the field of smart homes, and in particular, to a smart access control system. Background Technology

[0002] With the development of smart home technology, more and more non-smart access control systems are being replaced by smart access control systems.

[0003] Intelligent access control systems require a continuous power supply to maintain normal operation, which includes both external and internal power sources. These systems typically include functions such as smart doorbells, intercoms, and image capture. In existing intelligent access control systems, the smart doorbell function may experience power outages and restarts during operation due to unreliable switching between external and internal power supplies. Summary of the Invention

[0004] This invention provides an intelligent access control system to achieve reliable switching between external and internal power supplies during the use of the intelligent doorbell function.

[0005] This application provides an intelligent access control system, including: an audio module for outputting doorbell audio signals, a doorbell control module including a doorbell switch and a first power supply, and an overcurrent automatic shutdown module.

[0006] The overcurrent automatic shutdown module and the doorbell control module are connected in series across the two ends of the second power supply, and the audio module is connected in parallel with the overcurrent automatic shutdown module.

[0007] in,

[0008] When the doorbell switch is disabled, the second power supply powers the doorbell control module through the first branch of the overcurrent automatic shutdown module, and the voltage applied by the second power supply to the two ends of the audio module through the first branch makes the audio module not work.

[0009] When the doorbell switch is enabled, the overcurrent automatic shutdown module samples the current of the first branch. When the sampled current reaches a set current threshold, it triggers the shutdown of the first branch. The doorbell control module switches from being powered by the second power supply to being powered by the first power supply, so that the second power supply applies voltage to both ends of the audio module to enable the audio module to work, until the doorbell control module switches from being powered by the first power supply to being powered by the second power supply.

[0010] Preferably, the second power source is an AC power source.

[0011] The overcurrent automatic shutdown module includes: a sampling circuit, a first switching circuit, a rectifier circuit, and a step-down converter circuit;

[0012] The sampling circuit, the first switching circuit, and the doorbell control module are connected in series across the second power supply. The series branch containing the sampling circuit and the first switching circuit is the first branch.

[0013] The audio module is connected in parallel to both ends of the first branch.

[0014] The output voltage from the sampling circuit is rectified by the rectifier circuit and then input to the buck converter circuit. The buck converter circuit converts the input voltage and outputs it to the first switching circuit.

[0015] When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

[0016] Preferably, the second power source is a DC power source.

[0017] The overcurrent automatic shutdown module includes: a sampling circuit, a first switching circuit, and a step-down converter circuit;

[0018] The sampling circuit, the first switching circuit, and the doorbell control module are connected in series across the second power supply. The series branch containing the sampling circuit and the first switching circuit is the first branch.

[0019] The audio module is connected in parallel to both ends of the first branch.

[0020] The output voltage from the sampling circuit is input to the buck converter circuit, which converts the input voltage and outputs it to the first switching circuit.

[0021] When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

[0022] Preferably, the doorbell control module further includes: a power switching circuit and a processor.

[0023] in,

[0024] The processor, in response to an enable signal from the doorbell switch, provides an enable signal for the switching control signal to the power switching circuit; and in response to an enable signal from the doorbell switch, provides an enable signal for the switching control signal to the power switching circuit.

[0025] Under the control of the enable signal of the switching control signal, the power switching circuit switches the second power supply of the doorbell control module to the first power supply; under the control of the de-enable signal of the switching control signal, it switches the first power supply of the doorbell control module to the second power supply.

[0026] Preferably, the power switching circuit includes: a second switching circuit for supplying the second power supply to the doorbell control module, and a third switching circuit for supplying the first power supply to the doorbell control module; the second switching circuit is connected in series with the first branch.

[0027] In response to an enable signal from a doorbell switch, the processor provides an enable signal for a first control signal controlling the second switch circuit and an enable signal for a second control signal controlling the third switch circuit.

[0028] Under the enable signal control of the first control signal, the second switching circuit short-circuits the second power supply provided to the doorbell control module, so that the second power supply voltage is applied to the audio module.

[0029] The third switching circuit supplies the first power supply to the doorbell control module under the control of the enable signal of the second control signal.

[0030] The processor, in response to an enable signal from the doorbell switch, provides an enable signal for the first control signal and an enable signal for the second control signal.

[0031] Under the control of the disabled signal of the first control signal, the second switching circuit supplies the second power to the doorbell control module.

[0032] The third switching circuit turns off the first power supply under the control of the non-enable signal of the second control signal.

[0033] Preferably, the processor further includes: triggering a timer in response to an enable signal from a doorbell switch, and providing an enable signal for the first control signal and an enable signal for the second control signal when the timer reaches a set timer threshold.

[0034] Preferably, the first power source is a battery power source, and the doorbell control module further includes a charging circuit for charging the battery power source when the second power source is provided to the doorbell control module.

[0035] The sampling circuit is a sampling resistor.

[0036] The first switching circuit is a relay switch circuit. The relay switch is connected in series with the sampling resistor. The relay switch is a normally closed switch, and the relay coil is connected to the output terminal of the step-down converter circuit.

[0037] The step-down converter circuit provides a first voltage to the relay coil for relay switching operation when the voltage across the sampling resistor is greater than the voltage threshold, and provides a second voltage to the relay coil to maintain the relay switching in a normal state when the voltage across the sampling resistor is not greater than the voltage threshold.

[0038] The second switching circuit is a thyristor.

[0039] Preferably, the timing sequence of the enable signal of the first control signal and the enable signal of the second control signal satisfies:

[0040] The first switching circuit is disconnected at the first time threshold after the enable signal of the second control signal.

[0041] The enable signal of the first control signal is the second time threshold after the first switching circuit is turned off;

[0042] The timing of the disable signals of the first control signal and the second control signal satisfies the following:

[0043] The first switching circuit is activated at the third time threshold after the inactivation signal of the first control signal.

[0044] The in enable signal of the second control signal is the fourth time threshold after the first switching circuit is turned on;

[0045] The intelligent access control system is an intelligent doorbell, with the doorbell control module located outdoors and the audio module and overcurrent automatic shutdown module located indoors.

[0046] This application provides an overcurrent automatic shutdown module, which is applied to an intelligent access control system with a doorbell function. The intelligent access control system includes: an audio module for outputting doorbell audio signals, and a doorbell control module including a doorbell switch and a first power supply.

[0047] The overcurrent automatic shutdown module and the doorbell control module are connected in series across the two ends of the second power supply, and the audio module is connected in parallel with the overcurrent automatic shutdown module.

[0048] When the doorbell switch is disabled, the second power supply is provided to the doorbell control module through the first branch of the overcurrent automatic shutdown module. The voltage applied to the two ends of the audio module by the second power supply through the first branch makes the audio module not work.

[0049] When the doorbell switch is enabled, the overcurrent automatic shutdown module samples the current of the first branch. When the sampled current reaches a set current threshold, it triggers the shutdown of the first branch, causing the doorbell control module to switch from being powered by the second power supply to being powered by the first power supply. Furthermore, the second power supply applies voltage to both ends of the audio module to enable the audio module to operate, until the doorbell control module switches from being powered by the first power supply to being powered by the second power supply.

[0050] Preferably, the second power source is an AC power source.

[0051] The overcurrent automatic shutdown module includes: a sampling circuit, a first switching circuit, a rectifier circuit, and a step-down converter circuit;

[0052] The sampling circuit, the first switching circuit, and the doorbell control module are connected in series across the second power supply. The series branch containing the sampling circuit and the first switching circuit is the first branch.

[0053] The audio module is connected in parallel to both ends of the first branch.

[0054] The output voltage from the sampling circuit is rectified by the rectifier circuit and then input to the buck converter circuit. The buck converter circuit converts the input voltage and outputs it to the first switching circuit.

[0055] When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

[0056] Preferably, the second power source is a DC power source.

[0057] The overcurrent automatic shutdown module includes: a sampling circuit, a first switching circuit, and a step-down converter circuit;

[0058] The sampling circuit, the first switching circuit, and the doorbell control module are connected in series across the second power supply. The series branch containing the sampling circuit and the first switching circuit is the first branch.

[0059] The audio module is connected in parallel to both ends of the first branch.

[0060] The output voltage from the sampling circuit is input to the buck converter circuit, which then outputs the input voltage to the first switching circuit.

[0061] When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

[0062] Preferably, the sampling circuit is a sampling resistor.

[0063] The first switching circuit is a relay switch circuit. The relay switch is connected in series with the sampling resistor. The relay switch is a normally closed switch, and the relay coil is connected to the output terminal of the step-down converter circuit.

[0064] When the voltage across the sampling resistor is greater than the voltage threshold, the buck converter circuit provides a first voltage to the relay coil for relay switching operation; when the voltage across the sampling resistor is not greater than the voltage threshold, it provides a second voltage to the relay coil for maintaining the relay switch in normal operation.

[0065] This application uses an overcurrent automatic shutdown module to sample the output current of the second power supply. When the current is excessive, it triggers the shutdown of the first branch that supplies power to the doorbell control module via the first branch containing the overcurrent automatic shutdown module. This simultaneously applies the second power supply to the audio module and switches the doorbell control module from the second power supply to the first power supply. This application improves the adaptability of the external power supply voltage of the intelligent access control system and enhances the reliability of switching between external and internal power supplies during the use of the intelligent doorbell function. It also prevents the intelligent access control system from restarting due to power failure, thus improving operational stability. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of an intelligent access control system provided for an embodiment of this application.

[0067] Figure 2 This is a schematic diagram of the circuit functional structure of the smart doorbell according to an embodiment of this application.

[0068] Figure 3 This is a circuit diagram of a doorbell control module.

[0069] Figure 4 This is a timing diagram of control signals from the processor. Detailed Implementation

[0070] To make the objectives, technical means, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings.

[0071] The applicant noted that the specifications and models of internal components in an intelligent access control system need to be significantly adjusted for different input power voltages, making it difficult to make a single device compatible with multiple input power voltage signals. Furthermore, the implementation of the doorbell function in an intelligent access control system is quite complex, requiring it to work in conjunction with the power supply circuit and logic control circuit within the access control system to achieve the ringing operation.

[0072] In view of this, embodiments of this application provide an intelligent access control system. See also Figure 1 As shown, Figure 1 This application provides a schematic diagram of an intelligent access control system. The intelligent access control system includes: an audio module for outputting doorbell audio signals, a doorbell control module including a doorbell switch and a first power supply, and an overcurrent automatic shutdown module.

[0073] The overcurrent automatic shutdown module and the doorbell control module are connected in series across the two ends of the second power supply, and the audio module is connected in parallel with the overcurrent automatic shutdown module.

[0074] in,

[0075] When the doorbell switch is disabled, the second power supply powers the doorbell control module through the first branch of the overcurrent automatic shutdown module, and the second power supply applies voltage to the two ends of the audio module through the first branch, causing the audio module to not work.

[0076] When the doorbell switch is enabled, the overcurrent automatic shutdown module samples the current of the first branch. When the sampled current reaches the set current threshold, the first branch is triggered to shut down, causing the doorbell control module to switch from the second power supply to the first power supply. In addition, the second power supply applies voltage to both ends of the audio module so that the audio module can work, until the doorbell control module switches from the first power supply to the second power supply.

[0077] The first power source is an internal power source, and the second power source is an external input power source.

[0078] The embodiments of this application are applicable to various external input power supply voltages, and switch to internal power supply when the audio module is working and outputting a ringing sound, thereby avoiding power failure and restart.

[0079] To facilitate understanding of the embodiments of this application, a smart doorbell will be used as an example for illustration below. It should be understood that this application is not limited to the smart doorbell itself, and any smart access control system, smart peephole, or other device with doorbell functionality is applicable.

[0080] See Figure 2 As shown, Figure 2 This is a schematic diagram of the circuit functional structure of a smart doorbell according to an embodiment of this application. The smart doorbell includes an indoor section and an outdoor section. The outdoor section includes a doorbell control module, which includes a doorbell switch, a first power supply (internal power supply), a microprocessor, and a power switching circuit for switching between the first power supply and a second power supply (external power supply). The outdoor section may also include an image acquisition device, an intercom device, and other functions. The indoor section includes an audio module for outputting audio signals and an overcurrent automatic shutdown module.

[0081] in,

[0082] The overcurrent automatic shutdown module and the doorbell control module are connected in series across the two ends of the second power supply, while the audio module is connected in parallel with the overcurrent automatic shutdown module.

[0083] If the second power source is an AC power source, the overcurrent automatic shutdown module includes a sampling resistor, a rectifier circuit, a buck converter circuit, and a first switching circuit. The sampling circuit and the switch in the first switching circuit are connected in series and then in parallel with the audio module. The voltage across the sampling resistor is input to the rectifier circuit, and the output voltage of the rectifier circuit is input to the buck converter circuit. After voltage conversion, the output voltage of the buck converter circuit is used to control the first switching circuit.

[0084] If the second power supply is a DC power supply, the overcurrent automatic shutdown module includes a sampling resistor, a buck converter circuit, and a first switching circuit. The sampling circuit and the switch in the first switching circuit are connected in series and then in parallel with the audio module. The voltage across the sampling resistor is input to the buck converter circuit. After voltage conversion, the output voltage of the buck converter circuit is used to control the first switching circuit.

[0085] The first switching circuit can be a relay switch circuit. The output voltage of the buck converter circuit is applied across the relay coil. The relay switch is connected in series with a sampling resistor; this series branch is the first branch. The relay switch is a normally closed switch. The sampling resistor is used to sample the current of the first branch. When the voltage across the sampling resistor is not greater than a set voltage threshold, or when the current sampled by the resistor is not greater than a set current threshold, the voltage across the sampling resistor, after being filtered by a rectifier bridge, drives the buck converter circuit. The second voltage output by the buck converter circuit is applied to the relay coil, and the relay switch remains normally closed. The buck converter circuit can also be a buck circuit.

[0086] The following explanation of the working process of a smart doorbell will be based on the example of AC power supply as the second power source.

[0087] When the doorbell switch is off, because the resistance of the sampling circuit is small and the switch in the first switching circuit is in the on state, the voltage across the audio module, i.e., the voltage across the first branch, is very low, so it will not be activated to ring. Most of the voltage from the second power supply is provided to the doorbell control module, and the smart doorbell can work normally.

[0088] When the doorbell switch in the doorbell control module is enabled—for example, the instant the doorbell switch is turned on, i.e., when the user presses the doorbell switch—the doorbell control module switches from the second power supply to the first power supply and short-circuits the external power supply interface of the doorbell control module, i.e., short-circuiting the second power supply provided to the doorbell control module. When the external power supply interface is short-circuited, the current flowing through the sampling resistor increases instantaneously, and the voltage across the sampling resistor also increases instantaneously. When the voltage across the sampling resistor exceeds a set voltage threshold, or when the current sampled by the resistor exceeds a set current threshold, the voltage across the sampling resistor, after being filtered by the rectifier bridge, drives the buck converter circuit. The first voltage output by the buck converter circuit drives the relay coil, and the relay switch changes from a normally closed state to a normally open state, thereby disconnecting the first branch. After the first branch is disconnected, the second power supply voltage is fully applied to both ends of the audio module, at which point the audio module is activated and rings due to power.

[0089] When the doorbell switch in the doorbell control module is disabled, for example, at the moment the doorbell switch is turned off or at the moment the ringing ends, the doorbell control module disconnects the external power supply port. At this time, the entire second power supply path will be disconnected, there will be no current, the relay switch will also return to the default normally closed state, the power supply of the doorbell control module will switch from the first power supply to the second power supply, and the smart doorbell will return to normal.

[0090] The end time of the ringing is determined by the switching control signal output by the processor in the doorbell control module. For example, when the doorbell switch is turned on, the processor is triggered to start timing. The duration of timing is determined by the duration required for the ringing to continue. When the timing reaches the set timing threshold, the processor outputs the switching control signal.

[0091] The processor responds to an enable signal from the doorbell switch by providing an enable signal for the switching control signal to the power switching circuit; and responds to an enable signal from the doorbell switch by providing an enable signal for the switching control signal to the power switching circuit.

[0092] Under the control of the enable signal of the switching control signal, the power switching circuit switches the second power supply of the doorbell control module to the first power supply; under the control of the de-enable signal of the switching control signal, it switches the first power supply of the doorbell control module to the second power supply.

[0093] See Figure 3 As shown, Figure 3This is a circuit diagram illustrating the function of a doorbell control module. As an example, the power switching circuit in the doorbell control module includes a second switching circuit and a third switching circuit. The second switching circuit essentially provides an external power supply interface for supplying a second power source to the doorbell control module. The second switching circuit is connected in series with the first branch, meaning it is connected in series with the parallel-connected audio module and the overcurrent automatic shutdown module. The second switching circuit includes an optocoupler and a silicon controlled rectifier (SCR). The first control signal for controlling the second switching circuit originates from the processor.

[0094] The third switching circuit is connected to the output terminal of the first power supply and is turned on and off under the control of the second control signal from the processor.

[0095] The first power source in the doorbell control module is a rechargeable battery. The doorbell control module also includes a charging circuit for charging the battery when the second power source of the doorbell control module is in operation.

[0096] The processor, in response to an enable signal from the doorbell switch, provides an enable signal for a first control signal for controlling a second switch circuit and an enable signal for a second control signal for controlling a third switch circuit; in response to an enable signal from the doorbell switch, it provides an enable signal for the first control signal and an enable signal for the second control signal.

[0097] Under the enable signal control of the first control signal, the second switching circuit short-circuits the second power supply provided to the doorbell control module, so that the second power supply voltage is applied to the audio module. Under the de-enable signal control of the first control signal, the second power supply is provided to the doorbell control module. For example, when the optocoupler and the thyristor are turned on, the second power supply input to the doorbell control module is short-circuited; when the optocoupler and the thyristor are turned off, the second power supply is input to the doorbell control module.

[0098] The third switching circuit supplies the first power supply to the doorbell control module under the enable signal of the second control signal, and turns off the first power supply under the disable signal of the second control signal.

[0099] In addition, the processor also responds to the enable signal from the doorbell switch to trigger a timer, and when the timer reaches a set timer threshold, it provides an enable signal for the first control signal and an enable signal for the second control signal.

[0100] The timing of the enable signals for the first and second control signals satisfies the following:

[0101] The first switching circuit is disconnected at a first time threshold after the enable signal of the second control signal, and the enable signal of the first control signal is at a second time threshold after the first switching circuit is disconnected.

[0102] The timing of the disable signals of the first control signal and the second control signal satisfies the following:

[0103] The first switching circuit is turned on at the third time threshold after the first control signal is deactivated, and the second control signal is deactivated at the fourth time threshold after the first switching circuit is turned on.

[0104] As an example, the third switching circuit consists of a pair of switching transistors. Thus, the second control signal includes a third control signal and a fourth control signal. The third control signal is used to control the switching transistor on the output side of the pair, and the fourth control signal is used to control the switching transistor on the input side of the pair.

[0105] See Figure 4 As shown, Figure 4 This is a timing diagram of control signals from the processor. In the left diagram, when the doorbell switch enable signal is input to the processor, it triggers the processor to output the enable signal of the third control signal. After a set time threshold t1, the processor outputs the enable signal of the fourth control signal to switch to the first power supply. After a set time threshold t2, the first switch circuit is turned off. After a set time threshold t3, the processor outputs the enable signal of the first control signal to turn on the thyristor, thereby forming a momentary short-circuit current in the sampling resistor.

[0106] In the diagram on the right, when the doorbell switch off signal is input to the processor, or when the ringing end time is reached, the processor outputs a de-enable signal for the first control signal of the thyristor to control the thyristor to turn off; after the set time threshold t4, the first switching circuit is turned on; after the set time threshold t5, the processor outputs a de-enable signal for the third control signal; after the set time threshold t6, the processor outputs a de-enable signal for the fourth control signal to switch the power supply of the doorbell control module from the first power supply to the second power supply.

[0107] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0108] This application uses an overcurrent automatic shutdown module to automatically shut off the external power supply to the doorbell control module when a sudden increase in the input current of the external power supply is triggered, switching to internal battery power. This enables the internal battery to be powered when the doorbell rings, thus avoiding power failure and restart, improving the reliability of the smart doorbell and enhancing its adaptability to external power supplies. This allows the existing external power supply to be reused during the installation of the smart doorbell.

[0109] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An intelligent access control system, characterized in that, include: An audio module for outputting doorbell audio signals, a doorbell control module including a doorbell switch and a primary power supply, and an overcurrent automatic shutdown module. The overcurrent automatic shutdown module and the doorbell control module are connected in series across the two ends of the second power supply, and the audio module is connected in parallel with the overcurrent automatic shutdown module. When the doorbell switch is disabled, the second power supply powers the doorbell control module through the first branch of the overcurrent automatic shutdown module, and the voltage applied by the second power supply to the two ends of the audio module through the first branch makes the audio module not work. When the doorbell switch is enabled, the overcurrent automatic shutdown module samples the current of the first branch. When the sampled current reaches a set current threshold, it triggers the shutdown of the first branch. Furthermore, the doorbell control module switches from being powered by the second power supply to being powered by the first power supply, so that the second power supply applies voltage to both ends of the audio module to enable the audio module to work, until the doorbell control module switches from being powered by the first power supply to being powered by the second power supply. in, The overcurrent automatic shutdown module includes: a sampling circuit, a first switching circuit, and a step-down converter circuit. The sampling circuit, the first switching circuit, and the doorbell control module are connected in series across the second power supply. The series branch containing the sampling circuit and the first switching circuit is the first branch. The output voltage from the sampling circuit is input to the step-down converter circuit. The step-down converter circuit converts the input voltage and outputs it to the first switching circuit. The doorbell control module further includes a power switching circuit and a processor, wherein the processor, in response to an enable signal from the doorbell switch, provides an enable signal of a switching control signal to the power switching circuit; and in response to an enable signal from the doorbell switch, provides an enable signal of a switching control signal to the power switching circuit; the power switching circuit, under the control of the enable signal of the switching control signal, switches the second power supply of the doorbell control module to the first power supply; and under the control of the enable signal of the switching control signal, switches the first power supply of the doorbell control module to the second power supply.

2. The system as described in claim 1, characterized in that, The second power source is an AC power source. The overcurrent automatic shutdown module also includes: a rectifier circuit; The audio module is connected in parallel to both ends of the first branch. The output voltage from the sampling circuit is rectified by the rectifier circuit and then input to the buck converter circuit. The buck converter circuit converts the input voltage and outputs it to the first switching circuit. When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

3. The system as described in claim 1, characterized in that, The second power source is a DC power source. The audio module is connected in parallel to both ends of the first branch. When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

4. The system as described in claim 1, characterized in that, The power switching circuit includes: a second switching circuit for supplying the second power supply to the doorbell control module, and a third switching circuit for supplying the first power supply to the doorbell control module; the second switching circuit is connected in series with the first branch. In response to an enable signal from a doorbell switch, the processor provides an enable signal for a first control signal controlling the second switch circuit and an enable signal for a second control signal controlling the third switch circuit. Under the enable signal control of the first control signal, the second switching circuit short-circuits the second power supply provided to the doorbell control module, so that the second power supply voltage is applied to the audio module. The third switching circuit supplies the first power supply to the doorbell control module under the control of the enable signal of the second control signal. The processor, in response to an enable signal from the doorbell switch, provides an enable signal for the first control signal and an enable signal for the second control signal. Under the control of the disabled signal of the first control signal, the second switching circuit supplies the second power to the doorbell control module. The third switching circuit turns off the first power supply under the control of the non-enable signal of the second control signal.

5. The system as described in claim 4, characterized in that, The processor further includes: triggering a timer in response to an enable signal from a doorbell switch; and providing an enable signal for the first control signal and an enable signal for the second control signal when the timer reaches a set timer threshold.

6. The system as described in claim 5, characterized in that, The first power source is a battery power source, and the doorbell control module further includes a charging circuit for charging the battery power source when the second power source is provided to the doorbell control module. The sampling circuit is a sampling resistor. The first switching circuit is a relay switch circuit. The relay switch is connected in series with the sampling resistor. The relay switch is a normally closed switch, and the relay coil is connected to the output terminal of the step-down converter circuit. The step-down converter circuit provides a first voltage to the relay coil for relay switching operation when the voltage across the sampling resistor is greater than a voltage threshold, and provides a second voltage to the relay coil to maintain the relay switching in a normal state when the voltage across the sampling resistor is not greater than the voltage threshold. The second switching circuit is a thyristor.

7. The system as described in claim 4, characterized in that, The timing sequence of the enable signal of the first control signal and the enable signal of the second control signal satisfies: The first switching circuit is disconnected at the first time threshold after the enable signal of the second control signal. The enable signal of the first control signal is the second time threshold after the first switching circuit is turned off; The timing of the disable signals of the first control signal and the second control signal satisfies the following: The first switching circuit is activated at the third time threshold after the inactivation signal of the first control signal. The in enable signal of the second control signal is the fourth time threshold after the first switching circuit is turned on; The intelligent access control system is an intelligent doorbell, with the doorbell control module located outdoors and the audio module and overcurrent automatic shutdown module located indoors.

8. An overcurrent automatic shutdown module, characterized in that, This module is used in a smart access control system with a doorbell function. The smart access control system includes: an audio module for outputting doorbell audio signals, and a doorbell control module including a doorbell switch and a first power supply. The overcurrent automatic shutdown module and the doorbell control module are connected in series across the two ends of the second power supply, and the audio module is connected in parallel with the overcurrent automatic shutdown module. When the doorbell switch is disabled, the second power supply is provided to the doorbell control module through the first branch of the overcurrent automatic shutdown module. The voltage applied to the two ends of the audio module by the second power supply through the first branch makes the audio module not work. When the doorbell switch is enabled, the overcurrent automatic shutdown module samples the current of the first branch. When the sampled current reaches a set current threshold, it triggers the shutdown of the first branch, causing the doorbell control module to switch from being powered by the second power supply to being powered by the first power supply. Furthermore, the second power supply applies voltage to both ends of the audio module to enable the audio module to work, until the doorbell control module switches from being powered by the first power supply to being powered by the second power supply. in, The overcurrent automatic shutdown module includes: a sampling circuit, a first switching circuit, and a step-down converter circuit. The sampling circuit, the first switching circuit, and the doorbell control module are connected in series across the second power supply. The series branch containing the sampling circuit and the first switching circuit is the first branch. The output voltage from the sampling circuit is input to the step-down converter circuit. The step-down converter circuit converts the input voltage and outputs it to the first switching circuit. The doorbell control module further includes a power switching circuit and a processor, wherein the processor, in response to an enable signal from the doorbell switch, provides an enable signal of a switching control signal to the power switching circuit; and in response to an enable signal from the doorbell switch, provides an enable signal of a switching control signal to the power switching circuit; the power switching circuit, under the control of the enable signal of the switching control signal, switches the second power supply of the doorbell control module to the first power supply; and under the control of the enable signal of the switching control signal, switches the first power supply of the doorbell control module to the second power supply.

9. The overcurrent automatic shutdown module as described in claim 8, characterized in that, The second power source is an AC power source. The overcurrent automatic shutdown module also includes: a rectifier circuit; The audio module is connected in parallel to both ends of the first branch. The output voltage from the sampling circuit is rectified by the rectifier circuit and then input to the buck converter circuit. The buck converter circuit converts the input voltage and outputs it to the first switching circuit. When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

10. The overcurrent automatic shutdown module as described in claim 8, characterized in that, The second power source is a DC power source. The audio module is connected in parallel to both ends of the first branch. When the output voltage from the buck converter circuit is applied, the first switching circuit shuts off the first branch, so that the voltage across the first branch is applied to the two ends of the audio module. When the output voltage from the buck converter circuit is not applied, the first switching circuit connects the first branch.

11. The overcurrent automatic shutdown module as described in claim 8, characterized in that, The sampling circuit is a sampling resistor. The first switching circuit is a relay switch circuit. The relay switch is connected in series with the sampling resistor. The relay switch is a normally closed switch, and the relay coil is connected to the output terminal of the step-down converter circuit. When the voltage across the sampling resistor is greater than a voltage threshold, the buck converter circuit provides a first voltage to the relay coil for relay switching operation; when the voltage across the sampling resistor is not greater than the voltage threshold, it provides a second voltage to the relay coil for maintaining the relay switch in normal operation.

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