Transmitting circuit and security check door

Abstract

The invention relates to a transmitting circuit and a security door, and the transmitting circuit comprises at least one transmitting module and a coil of the security door. The transmitting module comprises a pre-driving circuit and a synchronous rectification controller; the pre-driving circuit is connected with the synchronous rectification controller and is used for preprocessing the input signal to obtain a PWM driving signal; the synchronous rectification controller is integrated with overheat protection, is connected with a coil of the security door, and is used for providing overheat protection and outputting a stable emission signal under a PWM driving signal; the coil is caused to generate a physical magnetic field in space based on the transmit signal. According to the synchronous rectification controller, the problems that in the prior art, overload burning is prone to occurring due to lack of a protection circuit, and the size is large due to a discrete construction scheme are solved, overheating protection is provided through overheating protection integrated in the synchronous rectification controller, and the size of the whole circuit is reduced through an integrated circuit.

Description

Technical Field

[0001] The present application relates to the technical field of low-frequency magnetic field space construction for security inspection doors, and in particular to a transmitting circuit and a security inspection door. Background Art

[0002] A security gate is a security inspection device used to detect whether a person or object is carrying specific prohibited items. It is generally placed in passages where people or items need to pass through, such as airports, stations, courts, important event venues and other areas with dense population and high security requirements. When a person or item passes through the security gate, it can quickly and non-invasively check whether there is a potential security threat. It includes a transmitting circuit and a receiving circuit; a passage area for pedestrians and / or items to pass through is provided between the transmitting circuit and the receiving circuit. Among them, the transmitting circuit is an important part of the security gate. The current solution is to use discrete MOS tubes, diodes and other components to build a power circuit; its disadvantages are: the lack of a protection circuit is prone to overload and burnout, and the discrete construction solution is large in size.

[0003] There is a lack of protection circuit in related technologies, which makes it easy to overload and burn out, and the discrete construction solution is large in size. No effective solution has been proposed yet. Summary of the invention

[0004] In this embodiment, a transmitting circuit and a security door are provided to solve the problems in the related art of lack of protection circuits that are prone to overload and burnout, and the large size of discrete construction solutions.

[0005] In a first aspect, a transmitting circuit is provided in this embodiment, comprising: at least one transmitting module and a coil of a security door; The transmitting module includes a pre-driving circuit and a synchronous rectification controller; The pre-driving circuit is connected to the synchronous rectification controller and is used to pre-process the input signal to obtain a PWM driving signal; The synchronous rectification controller is integrated with overheat protection and is connected to the coil of the security door to provide overheat protection and output a stable transmission signal under the PWM drive signal; so that the coil generates a physical magnetic field in space based on the transmission signal.

[0006] In some of the embodiments, the transmitting module further includes an electromagnetic interference elimination circuit; The electromagnetic interference elimination circuit is arranged between the synchronous rectification controller and the coil, and is used to eliminate the electromagnetic interference of the transmission signal, so that the coil generates a physical magnetic field in space based on the eliminated transmission signal.

[0007] In some of the embodiments, the electromagnetic interference elimination circuit includes a resistor R1 and an inductor L1; The resistor R1 and the inductor L1 are connected in parallel to form an RLC parallel unit.

[0008] In some embodiments, the synchronous rectification controller is a synchronous rectification pressure reducing controller; the synchronous rectification pressure reducing controller includes a PWM and protection logic control unit, a power MOS tube and a driving unit; The PWM and protection logic control unit is connected to the driving unit through the power MOS tube, and is used to provide overheat protection, and under the PWM driving signal, controls the operation of the power MOS tube and outputs the transmission signal; The driving unit is connected to the PWM and protection logic control unit and the power MOS tube respectively, and is used to adjust the PWM driving signal according to the transmission signal.

[0009] In some of the embodiments, the transmitting circuit is a single-frequency transmitting circuit; The single-frequency transmitting circuit includes a transmitting module and the coil of the security door connected to the transmitting module.

[0010] In some of the embodiments, the transmitting circuit is a dual-frequency transmitting circuit; The dual-frequency transmitting circuit includes two transmitting modules and the coil of the security door respectively connected to the two transmitting modules.

[0011] In some embodiments, the two transmitting modules in the dual-frequency transmitting circuit respectively generate a first transmitting signal and a second transmitting signal; the first transmitting signal and the second transmitting signal have different frequencies; The coil constructs a dual-frequency physical magnetic field in space under the first transmitting signal and the second transmitting signal.

[0012] In some of the embodiments, the transmitting circuit is a three-frequency transmitting circuit; The three-frequency transmitting circuit includes three transmitting modules and the coils of the security door respectively connected to the three transmitting modules.

[0013] In some embodiments, the three transmitting modules in the three-frequency transmitting circuit respectively generate a first transmitting signal, a second transmitting signal and a third transmitting signal; the frequencies of the first transmitting signal, the second transmitting signal and the third transmitting signal are different; The coil constructs a three-frequency physical magnetic field in space under the first transmitting signal, the second transmitting signal and the third transmitting signal.

[0014] In a second aspect, a security door is provided in this embodiment, comprising a receiving circuit and a transmitting circuit as described in the first aspect above; The receiving circuit is used to generate an induction signal of the physical magnetic field.

[0015] Compared with the related art, the transmitting circuit and security door provided in this embodiment, wherein the transmitting circuit includes at least one transmitting module and a coil of the security door; the transmitting module includes a pre-driving circuit and a synchronous rectification controller; the pre-driving circuit is connected to the synchronous rectification controller, and is used to pre-process the input signal to obtain a PWM driving signal; the synchronous rectification controller is integrated with overheating protection, and is connected to the coil of the security door to provide overheating protection, and output a stable transmitting signal under the PWM driving signal; the coil generates a physical magnetic field in space based on the transmitting signal, which solves the problem in the related art that the protection circuit is easy to overload and burn, and the discrete construction solution is large in size, and uses the overheating protection integrated in the synchronous rectification controller to provide overheating protection, and adopts an integrated circuit to achieve the reduction of the volume of the overall circuit.

[0016] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 is a structural block diagram of a transmitting circuit provided in an embodiment of the present application; Figure 2 is a structural block diagram of a transmitting module provided in an embodiment of the present application; Figure 3 is a structural block diagram of an electromagnetic interference elimination circuit provided by an embodiment of the present application; Figure 4 is a circuit diagram of a dual-frequency transmitting circuit provided in an embodiment of the present application; Figure 5 It is a structural block diagram of a three-frequency transmitting circuit provided in one embodiment of the present application.

[0018] In the figure: 100, transmitting module; 110, pre-driving circuit; 120, synchronous rectification controller; 130, electromagnetic interference elimination circuit; 200, coil. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the contents disclosed in the present application, some changes such as design, manufacturing or production based on the technical contents disclosed in the present application are only conventional technical means, and should not be understood as insufficient contents disclosed in the present application.

[0020] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0021] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. In this application, when an element is referred to as "provided on" another element, it can be directly provided on the other element or there can also be a centered element. When an element is considered to be "provided on" another element, it can be directly provided on the other element or there can be a centered element at the same time. When an element is considered to be "fixed on" another element, it can be directly fixed on the other element or there can be a centered element at the same time. The terms "first", "second", "third" and the like involved in this application are merely used to distinguish similar objects and do not represent a specific ordering of objects. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0022] See also Figure 1 , This embodiment provides a transmitting circuit, including: at least one transmitting module 100 and a coil 200 of a security door; The transmitting module 100 includes a pre-driving circuit 110 and a synchronous rectification controller 120; The pre-driving circuit 110 is connected to the synchronous rectification controller 120 and is used to pre-process the input signal to obtain a PWM driving signal; The synchronous rectification controller 120 is integrated with overheat protection and is connected to the coil 200 of the security door to provide overheat protection and output a stable transmission signal under a PWM drive signal; the coil 200 generates a physical magnetic field in space based on the transmission signal.

[0023] Specifically, the transmitting circuit includes at least one transmitting module 100 and a coil 200 of the security door. Each transmitting module 100 can generate a stable transmitting signal of its own frequency under the drive of the PWM driving signal, so that the coil 200 generates a physical magnetic field of different frequencies in the space based on the transmitting signal. The space here refers to the physical space. For example: the security door has a security inspection channel; then the space can be considered as the security inspection channel. In this embodiment, the number of transmitting modules 100 is not limited. The combination of different transmitting modules 100 can realize the combination of physical magnetic fields of different frequencies, so that it is suitable for different application fields.

[0024] Among them, the pre-drive circuit 110 pre-processes the input signal before it is input into the synchronous rectification controller 120. Its purpose is to amplify, filter, level convert and other operations on the input signal to meet the requirements of the subsequent circuit for the signal. Among them, the specific choice of pre-processing can be determined by the application scenario. For example: the power of the input signal is low and cannot directly drive the subsequent load or circuit; then the pre-processing needs to amplify the input signal to enhance its driving ability, and then obtain a PWM drive signal that meets the requirements. That is to say, the transmitting module 100 of this embodiment can also control the volume of the overall device in the application scenario suitable for high-power. Preferably, the pre-drive circuit 110 can be a dual-power bus transceiver, which is not limited.

[0025] Among them, the synchronous rectification controller 120 is mainly used to output the transmission signal under the PWM driving signal; and has PWM control, and can adopt pulse width modulation (PWM) technology, according to the feedback of the output transmission signal, adjust the duty cycle of the PWM signal, and then control the relevant components in the synchronous rectification controller 120 (which can be the conduction time of the main switch tube and the synchronous rectification tube) to maintain the stability of the output transmission signal. And at least overheating protection is integrated in the synchronous rectification controller 120; overheating protection is used to provide overheating protection; for example: it can detect the temperature of the coil 200, and when the temperature of the coil 200 reaches the temperature threshold, the synchronous rectification controller 120 stops outputting the transmission signal. In this embodiment, the specific implementation method of overheating protection is not limited. Among them, the synchronous rectification controller 120 can be a voltage-type synchronous rectification controller, a current-type synchronous rectification controller, etc., and there is no limitation on this.

[0026] In the related art, a security gate is a security inspection device used to detect whether a person or object is carrying specific prohibited items. It is generally placed at passages where people or objects need to pass through, such as airports, stations, courts, important event venues and other areas with dense population and high security requirements. When a person or object passes through the security gate, it can quickly and non-invasively check whether there is a potential security threat. It includes a transmitting circuit and a receiving circuit; a passage area for pedestrians and / or objects to pass through is provided between the transmitting circuit and the receiving circuit. Among them, the transmitting circuit is an important component of the security gate. The current solution is to use discrete MOS tubes, diodes and other components to build a power circuit; its disadvantages are: the lack of a protection circuit is prone to overload and burnout, and the discrete construction solution is large in size. The transmitting circuit of the present application includes at least one transmitting module 100 and a coil 200 of a security door; the transmitting module 100 includes a pre-driving circuit 110 and a synchronous rectification controller 120; the pre-driving circuit 110 is connected to the synchronous rectification controller 120, and is used to pre-process the input signal to obtain a PWM driving signal; the synchronous rectification controller 120 is integrated with an overheating protection, and is connected to the coil 200 of the security door to provide overheating protection, and output a transmitting signal under the PWM driving signal; the coil 200 generates a physical magnetic field in space based on the transmitting signal, which solves the problem in the related art that the protection circuit is easy to overload and burn, and the discrete construction solution is large in size, and uses the overheating protection integrated in the synchronous rectification controller 120 to provide overheating protection, and adopts an integrated circuit to achieve a reduction in the size of the overall circuit.

[0027] The following is a detailed description of each of the above components: In some of the embodiments, Figure 2 As shown, the transmitting module 100 further includes an electromagnetic interference elimination circuit 130; The electromagnetic interference elimination circuit 130 is disposed between the synchronous rectification controller 120 and the coil 200 , and is used to eliminate electromagnetic interference of the transmission signal, so that the coil 200 generates a physical magnetic field in space based on the eliminated transmission signal.

[0028] In this embodiment, on the basis of the pre-drive circuit 110 and the synchronous rectification controller 120, an electromagnetic interference elimination circuit 130 is also included. The electromagnetic interference elimination circuit 130 is an electronic circuit for suppressing or eliminating electromagnetic interference (EMI); it may include inductance elements, capacitance elements and other elements; wherein, the inductance elements include differential mode inductance and common mode inductance. The differential mode inductance is connected between the positive and negative poles of the power supply to prevent the propagation of differential mode noise and act as a low-pass filter. The common mode inductance can be a symmetrically wound two-wire inductance placed between the positive and negative poles of the input end of the power supply to suppress common mode interference signals. The capacitance elements mainly include X capacitors (differential mode capacitors) and Y capacitors (common mode capacitors). The X capacitor is connected between the positive and negative poles of the power supply to filter differential mode interference signals. Its capacity is generally large, but it requires a high withstand voltage. The Y capacitor is connected between the positive and negative poles of the power supply and the ground, and is mainly used to eliminate common mode interference signals. Other components may be varistors, magnetic beads and other components. Varistors can respond instantly when a circuit encounters overvoltage or surge, clamping the excess voltage to a safe level, and also play a certain role in suppressing high-frequency transient interference. Magnetic beads can be used to absorb high-frequency noise and present a higher impedance in the high-frequency band, thereby effectively suppressing high-frequency electromagnetic interference.

[0029] Through this embodiment, the high-frequency harmonic components in the transmission signal output by the synchronous rectification controller 120 are consumed, and interference is reduced, so as to adapt to normal operation in an environment where electromagnetic interference is stored.

[0030] In some of the embodiments, Figure 3 As shown, the electromagnetic interference elimination circuit 130 includes a resistor R1 and an inductor L1; The resistor R1 and the inductor L1 are connected in parallel to form an RLC parallel unit.

[0031] Specifically, the electromagnetic interference elimination circuit 130 includes a resistor R1 and an inductor L1 connected in parallel, which form an RLC parallel unit. The RLC parallel unit can suppress the high-frequency component by about 80% (i.e., eliminate 80% of the high-frequency component), thereby reducing the risk of electromagnetic radiation.

[0032] Through this embodiment, the overall structure of the transmitting circuit can be simplified, the size of the device can be further reduced, and the risk of electromagnetic radiation can be reduced.

[0033] In some embodiments, the synchronous rectification controller is a synchronous rectification pressure reducing controller; the synchronous rectification pressure reducing controller includes a PWM and protection logic control unit, a power MOS tube and a driving unit; The PWM and protection logic control unit is connected to the driving unit through the power MOS tube to provide overheat protection, and controls the operation of the power MOS tube under the PWM driving signal to output the transmission signal; The driving unit is connected to the PWM and protection logic control unit and the power MOS tube respectively, and is used to adjust the PWM driving signal according to the transmission signal.

[0034] Specifically, the synchronous rectification controller is a synchronous rectification pressure reducing controller; the synchronous rectification pressure reducing controller includes a PWM and protection logic control unit, a power MOS tube and a driving unit. Among them, the power MOS tube includes an upper power MOS tube and a lower power MOS tube. Under the control of the PWM and protection logic control unit, the upper power MOS tube and the lower power MOS tube are turned on or off to output a transmission signal. The driving unit adjusts the PWM driving signal according to the transmission signal so that the transmission signal is output stably.

[0035] Among them, the PWM and protection logic control unit includes a peripheral circuit and a logic control chip; it integrates overheat protection, coil 200 load current zero-crossing detection and overcurrent protection. Among them, the overheat protection is used to prevent the temperature of the coil 200 from exceeding the temperature threshold. The coil 200 load current zero-crossing detection is used to prevent the coil 200 current from flowing back to the power supply when the upper power MOS tube is turned off, causing damage to the previous circuit. The zero-crossing detection is combined with other actions to protect the upper power MOS tube. After the upper power MOS tube is turned off, the lower power MOS tube will be turned off only when the coil 200 current is detected to be 0; among them, the overcurrent protection coil 200 prevents excessive current from flowing into the coil 200, causing damage to the subsequent circuit. In other embodiments, the synchronous rectifier pressure reducing controller can be a product chip, which is not limited to this.

[0036] Through this embodiment, the synchronous rectification controller circuit is simplified while integrating various circuit protections; and has the advantages of high efficiency, low heat generation, small overall size, and high operational reliability.

[0037] It should be noted that, through the combination of different numbers of transmitting modules 100, various frequency transmitting circuits can be flexibly implemented, as described below: In some of the embodiments, the transmitting circuit is a single-frequency transmitting circuit; The single-frequency transmitting circuit includes a transmitting module 100 and a coil 200 of a security door connected to the transmitting module 100 .

[0038] Specifically, a transmitting module 100 and a coil 200 of a security door connected to the transmitting module 100 are used to realize a single-frequency transmitting circuit; the single-frequency transmitting circuit is suitable for a single-frequency security door application, so that the single-frequency transmitting circuit also has the advantages of high efficiency, low heat generation, small overall size, and high operational reliability.

[0039] In this embodiment, in addition to the coil 200 of the security door, the overall occupied area of ​​the transmitting circuit (including the pre-driving circuit, the synchronous rectification controller and the electromagnetic interference elimination circuit) is about 14mm×22mm. Compared with the traditional discrete solution (the area is generally 50mm×80mm), the area is optimized to about 8% of the traditional solution. It can be seen that the overall circuit volume can be simplified.

[0040] In some of the embodiments, the transmitting circuit is a dual-frequency transmitting circuit; The dual-frequency transmitting circuit includes two transmitting modules 100 and a coil 200 of a security door respectively connected to the two transmitting modules 100 .

[0041] Specifically, Figure 4 As shown, two transmitting modules 100 and coils 200 of the security door respectively connected to the two transmitting modules 100 are used to realize a dual-frequency transmitting circuit; it is suitable for the application of dual-frequency security doors, so that the dual-frequency transmitting circuit also has the advantages of high efficiency, low heat generation, small overall size and high operational reliability.

[0042] In some of the embodiments, the two transmitting modules 100 in the dual-frequency transmitting circuit respectively generate a first transmitting signal and a second transmitting signal; the first transmitting signal and the second transmitting signal have different frequencies; The coil 200 constructs a dual-frequency physical magnetic field in space under the first transmitting signal and the second transmitting signal.

[0043] Specifically, the dual-frequency transmitting circuit has an additional transmitting module 100 with different frequencies compared to the single-frequency transmitting circuit. Different PWM driving signals can control the two transmitting modules 100 to generate a first transmitting signal and a second transmitting signal with different frequencies. The coil 200 constructs a dual-frequency physical magnetic field in space under the first transmitting signal and the second transmitting signal. The dual-frequency physical magnetic field can be applied to the dual-frequency transmitting solutions of the classification door and the mobile phone door, which is highly flexible and widely applicable.

[0044] In some of the embodiments, the transmitting circuit is a three-frequency transmitting circuit; The three-frequency transmitting circuit includes three transmitting modules 100 and coils 200 of the security door respectively connected to the three transmitting modules 100.

[0045] Specifically, Figure 5 As shown, three transmitting modules 100 and coils 200 of security doors respectively connected to the three transmitting modules 100 are used to realize a three-frequency transmitting circuit; it is suitable for the application of three-frequency security doors, so that the three-frequency transmitting circuit also has the advantages of high efficiency, low heat generation, small overall size and high operating reliability.

[0046] In some embodiments, the three transmitting modules 100 in the three-frequency transmitting circuit respectively generate a first transmitting signal, a second transmitting signal and a third transmitting signal; the frequencies of the first transmitting signal, the second transmitting signal and the third transmitting signal are different; The coil 200 constructs a three-frequency physical magnetic field in space under the first transmitting signal, the second transmitting signal and the third transmitting signal.

[0047] Specifically, the three-frequency transmitting circuit adds a transmitting module 100 with a different frequency compared to the dual-frequency transmitting circuit. Different PWM driving signals can control the three transmitting modules 100 to generate a first transmitting signal, a second transmitting signal and a third transmitting signal with different frequencies. The coil 200 constructs a three-frequency physical magnetic field in space under the first transmitting signal, the second transmitting signal and the third transmitting signal, making this embodiment highly flexible and widely applicable.

[0048] It should be noted that the above modules can be functional modules or program modules, and can be implemented by software or hardware. For modules implemented by hardware, the above modules can be located in the same processor; or the above modules can be located in different processors in any combination.

[0049] In addition, in combination with the transmitting circuit provided in the above embodiment, a security door can also be provided in this embodiment. The security door includes a receiving circuit and the transmitting circuit of any one of the above embodiments; the receiving circuit is used to generate an induction signal of the physical magnetic field.

[0050] The above-mentioned security door solves the problem in related technologies that the protection circuit is lacking and prone to overload and burning, and the discrete construction solution is large in size. Overheat protection is provided by using the overheat protection integrated in the synchronous rectification controller, and an integrated circuit is used to reduce the size of the overall circuit.

[0051] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementation modes, and will not be repeated in this embodiment.

[0052] It should be understood that the specific embodiments described herein are only used to explain the application, rather than to limit it. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of this application.

[0053] Obviously, the drawings are only some examples or embodiments of the present application. For ordinary technicians in the field, the present application can also be applied to other similar situations based on these drawings without creative work. In addition, it is understandable that although the work done in this development process may be complicated and lengthy, for ordinary technicians in the field, certain changes in design, manufacturing or production based on the technical content disclosed in this application are only conventional technical means and should not be regarded as insufficient content disclosed in this application.

[0054] The term "embodiment" in this application refers to a specific feature, structure or characteristic described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various locations in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is clearly or implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0055] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. A transmitting circuit, characterized in that: include: At least one transmitting module and a coil for a security door; The transmitting module includes a pre-driving circuit and a synchronous rectification controller; The pre-driving circuit is connected to the synchronous rectification controller and is used to pre-process the input signal to obtain a PWM driving signal; The synchronous rectification controller is integrated with overheat protection and is connected to the coil of the security door to provide overheat protection and output a stable transmission signal under the PWM drive signal; so that the coil generates a physical magnetic field in space based on the transmission signal.

2. The transmitting circuit according to claim 1, characterized in that: The transmitting module also includes an electromagnetic interference elimination circuit; The electromagnetic interference elimination circuit is arranged between the synchronous rectification controller and the coil, and is used to eliminate the electromagnetic interference of the transmission signal, so that the coil generates a physical magnetic field in space based on the eliminated transmission signal.

3. The transmitting circuit according to claim 2, characterized in that: The electromagnetic interference elimination circuit includes a resistor R1 and an inductor L1; The resistor R1 and the inductor L1 are connected in parallel to form an RLC parallel unit.

4. The transmitting circuit according to claim 1, characterized in that: The synchronous rectification controller is a synchronous rectification pressure reducing controller; the synchronous rectification pressure reducing controller comprises a PWM and protection logic control unit, a power MOS tube and a driving unit; The PWM and protection logic control unit is connected to the driving unit through the power MOS tube, and is used to provide overheat protection, and under the PWM driving signal, controls the operation of the power MOS tube and outputs the transmission signal; The driving unit is connected to the PWM and protection logic control unit and the power MOS tube respectively, and is used to adjust the PWM driving signal according to the transmission signal.

5. The transmitting circuit according to claim 1, characterized in that: The transmitting circuit is a single-frequency transmitting circuit; The single-frequency transmitting circuit includes a transmitting module and the coil of the security door connected to the transmitting module.

6. The transmitting circuit according to claim 1, characterized in that: The transmitting circuit is a dual-frequency transmitting circuit; The dual-frequency transmitting circuit includes two transmitting modules and the coil of the security door respectively connected to the two transmitting modules.

7. The transmitting circuit according to claim 6, characterized in that: The two transmitting modules in the dual-frequency transmitting circuit generate a first transmitting signal and a second transmitting signal respectively; the first transmitting signal and the second transmitting signal have different frequencies; The coil constructs a dual-frequency physical magnetic field in space under the first transmitting signal and the second transmitting signal.

8. The transmitting circuit according to claim 1, characterized in that: The transmitting circuit is a three-frequency transmitting circuit; The three-frequency transmitting circuit includes three transmitting modules and the coils of the security door respectively connected to the three transmitting modules.

9. The transmitting circuit according to claim 8, characterized in that: The three transmitting modules in the three-frequency transmitting circuit respectively generate a first transmitting signal, a second transmitting signal and a third transmitting signal; the frequencies of the first transmitting signal, the second transmitting signal and the third transmitting signal are different; The coil constructs a three-frequency physical magnetic field in space under the first transmitting signal, the second transmitting signal and the third transmitting signal.

10. A security door, characterized in that: A transmitting circuit comprising a receiving circuit and a transmitting circuit according to any one of claims 1 to 9; The receiving circuit is used to generate an induction signal of the physical magnetic field.

Images