A dual-frequency detection circuit and a dual-frequency security inspection door

Abstract

The present invention relates to a dual-frequency detection circuit and a dual-frequency security inspection door, comprising: a central processing unit, a high-frequency and low-frequency signal generating module, a sensing module, a receiving circuit, and a signal processing circuit; the high-frequency and low-frequency signal generating module is connected to the central processing unit, receives the frequency signal output by the central processing unit and generates high-frequency and low-frequency signals according to the frequency signal, the sensing module is respectively connected to the high-frequency and low-frequency signal generating module and the receiving circuit, generates sensing signals to the receiving circuit according to the high-frequency and low-frequency signals, the receiving circuit receives the sensing signals, picks up and performs primary processing on the sensing signals and transmits them to the signal processing circuit, the signal processing circuit is connected to the receiving circuit, processes the signals output by the signal processing circuit and transmits them to the central processing unit, and the central processing unit outputs an action control signal according to the signals transmitted by the signal processing circuit. The present invention can realize simultaneous detection of high-frequency and low-frequency signals, can detect ferromagnetic and non-ferromagnetic metals, and has high detection sensitivity and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of security inspection, and more specifically, to a dual-frequency detection circuit and a dual-frequency security inspection door. Background Art

[0002] With the development of the economy and the improvement of people's living standards, people's awareness of safety prevention has been continuously enhanced, and the requirements for their own safety and the safety of the surrounding environment are also increasing, which will inevitably increase the demand for security inspection doors; moreover, the application fields of security inspection doors will continue to expand. Whether it is special fields that require security inspection doors or ordinary public places that also need to use security inspection doors, therefore, the demand for security inspection doors will increase significantly.

[0003] At present on the market, metal detection security inspection doors basically adopt a single-frequency detection method, and there are usually the following problems:

[0004] A. The detection types are single. Due to the correlation between metal detection sensitivity and working frequency, the single-frequency working method can only detect a certain type of metal substance with relatively high precision. For example, the detection precision of low-frequency signals for ferromagnetic metals is relatively high, while the detection precision for non-ferromagnetic metals (such as stainless steel) is relatively poor. At present, the domestically self-designed metal detectors mainly adopt single-frequency detection, including analog and digital types, and the detection types are all very single.

[0005] B. The detection precision is relatively low. At present, the technology of domestic metal detectors is relatively backward, and there are few with the function of "online detection". Even if they have the function of "online detection", they are only connected to a single-chip microcomputer, and the data processing ability is limited. Therefore, the overall detection precision is still not high. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a dual-frequency detection circuit and a dual-frequency security inspection door in view of the above-mentioned defects of the prior art.

[0007] The technical solution adopted by the present invention to solve its technical problems is to construct a dual-frequency detection circuit, including: a central processing unit, a high and low frequency signal generation module, an induction module, a receiving circuit, and a signal processing circuit;

[0008] The high and low frequency signal generation module is connected to the central processing unit, receives the frequency signal output by the central processing unit, and generates high and low frequency signals according to the frequency signal. The induction module is respectively connected to the high and low frequency signal generation module and the receiving circuit, generates an induction signal according to the high and low frequency signals and transmits it to the receiving circuit. The receiving circuit receives the induction signal, picks up and performs primary processing on the induction signal, and then transmits it to the signal processing circuit. The signal processing circuit is connected to the receiving circuit, processes the signal output by the signal processing circuit, and then transmits it to the central processing unit. The central processing unit outputs an action control signal according to the signal transmitted by the signal processing circuit.

[0009] Wherein, it further includes: a power amplification module connected to the high and low frequency signal generation module, which amplifies the high and low frequency signals output by the high and low frequency signal generation module.

[0010] Wherein, the high and low frequency signal generation module includes: a high frequency signal generation circuit and a low frequency signal generation circuit;

[0011] The high frequency signal generation circuit is connected to the central processing unit, receives the first frequency signal output by the central processing unit, and generates a high frequency signal according to the first frequency signal;

[0012] The low frequency signal generation circuit is connected to the central processing unit, receives the second frequency signal output by the central processing unit, and generates a low frequency signal according to the second frequency signal.

[0013] Wherein, the power amplification module includes: a high frequency power amplification circuit and a low frequency power amplification circuit;

[0014] The high frequency power amplification circuit is connected to the high frequency signal generation circuit, receives the high frequency signal, amplifies the high frequency signal, and then outputs the amplified high frequency signal to the induction module;

[0015] The low frequency power amplification circuit is connected to the low frequency signal generation circuit, receives the low frequency signal, amplifies the low frequency signal, and then outputs the amplified low frequency signal to the induction module.

[0016] Wherein, the signal processing circuit includes: an amplitude increasing circuit;

[0017] The amplitude increasing circuit is connected to the receiving circuit, receives the induction signal output by the receiving circuit, and performs secondary amplification on the induction signal output by the receiving circuit, and then outputs an amplified signal.

[0018] Wherein, the signal processing circuit further includes: a filtering module connected to the amplitude increasing circuit;

[0019] The filtering module receives the amplified signal output by the amplitude increasing circuit, and after filtering the amplified signal, outputs a filtered signal.

[0020] Wherein, the filtering module includes: a first band-pass filter and a second band-pass filter;

[0021] The first band-pass filter is connected to the amplitude increasing circuit, receives the amplified signal output by the amplitude increasing circuit, and after filtering the amplified signal, outputs a first filtered signal;

[0022] The second band-pass filter is connected to the amplitude increasing circuit, receives the amplified signal output by the amplitude increasing circuit, and after filtering the amplified signal, outputs a second filtered signal.

[0023] Wherein, the first band-pass filter and the second band-pass filter operate in different frequency bands.

[0024] Wherein, the signal processing circuit further includes: a detection module connected to the filtering module, receiving the filtered signal output by the filtering module, and performing detection processing on the filtered signal.

[0025] Wherein, the detection module includes: a first detector and a second detector;

[0026] The first detector is connected to the first band-pass filter, receives the first filtered signal output by the first band-pass filter, and after performing detection processing on the first filtered signal, outputs a first detection signal;

[0027] The second detector is connected to the second band-pass filter, receives the second filtered signal output by the second band-pass filter, and after performing detection processing on the second filtered signal, outputs a second detection signal.

[0028] Wherein, the frequency band of the first detector is different from the frequency band of the second detector.

[0029] Wherein, the signal processing circuit further includes: an analog-to-digital conversion circuit connected to the detection module;

[0030] The analog-to-digital conversion circuit receives the detection signal output by the detection module, and after performing analog-to-digital conversion on the detection signal, outputs a digital signal to the central processing unit.

[0031] Wherein, the induction module includes: a transmitting module and a receiving module;

[0032] The transmitting module is connected to the high-frequency signal generation circuit and the low-frequency signal generation circuit, receives the high-frequency signal output by the high-frequency signal generation circuit and the low-frequency signal output by the low-frequency signal generation circuit, and superimposes the high-frequency signal and the low-frequency signal to generate a superimposed signal;

[0033] When the transmitting module generates a superimposed signal, the receiving module generates the induction signal according to the superimposed signal.

[0034] Wherein, the transmitting module includes at least one transmitting circuit, and each transmitting circuit includes: a first transmitting coil for receiving the high-frequency signal and a second transmitting coil for receiving the low-frequency signal; the first transmitting coil and the second transmitting coil superimpose the high-frequency signal and the low-frequency signal and then output a superimposed signal;

[0035] The receiving module includes at least one receiving coil corresponding to the transmitting circuit; each receiving is correspondingly arranged with a transmitting circuit; the receiving coil generates the induction signal according to the superimposed signal.

[0036] Wherein, it further includes: an action circuit connected to the central processor, receiving the action control signal output by the central processor and performing actions according to the action control signal.

[0037] The present invention further provides a dual-frequency security inspection door, including the above-mentioned dual-frequency detection circuit.

[0038] Implementing the dual-frequency detection circuit and the dual-frequency security inspection door of the present invention has the following beneficial effects: including: a central processor, a high-low frequency signal generation module, an induction module, a receiving circuit, and a signal processing circuit; the high-low frequency signal generation module is connected to the central processor, receives the frequency signal output by the central processor and generates high-low frequency signals according to the frequency signal, the induction module is respectively connected to the high-low frequency signal generation module and the receiving circuit, generates an induction signal to the receiving circuit according to the high-low frequency signals, the receiving circuit receives the induction signal, picks up and performs primary processing on the induction signal and then transmits it to the signal processing circuit, the signal processing circuit is connected to the receiving circuit, processes the signal output by the signal processing circuit and then transmits it to the central processor, and the central processor outputs an action control signal according to the signal transmitted by the signal processing circuit. The present invention can realize simultaneous detection of high-low frequency signals, can detect ferromagnetic and non-ferromagnetic metals, and has high detection sensitivity and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The following will further illustrate the present invention in conjunction with the drawings. In the drawings:

[0040] Figure 1 is a schematic structural diagram of Embodiment 1 of the dual-frequency detection circuit of the present invention;

[0041] Figure 2 It is a schematic structural diagram of the second embodiment of the dual-frequency detection circuit of the present invention;

[0042] Figure 3 It is a schematic structural diagram of the induction module of the present invention;

[0043] Figure 4 It is a circuit diagram of the high-frequency signal generation circuit or the low-frequency signal generation circuit of the present invention. Detailed implementation manners

[0044] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation manners of the present invention will now be described in detail with reference to the accompanying drawings.

[0045] Refer to Figure 1 , Figure 1 It is a schematic structural diagram of the first embodiment of the dual-frequency detection circuit provided by the present invention.

[0046] As Figure 1 shown, the dual-frequency detection circuit may include: a central processor 11, a high-low frequency signal generation module 12, an induction module 14, a receiving circuit 15, and a signal processing circuit 16.

[0047] The high-low frequency signal generation module 12 is connected to the central processor 11, receives the frequency signal output by the central processor 11, and generates high-low frequency signals according to the frequency signal. The induction module 14 is respectively connected to the high-low frequency signal generation module 12 and the receiving circuit 15, generates an induction signal according to the high-low frequency signals and transmits it to the receiving circuit 15. The receiving circuit 15 receives the induction signal, picks up and performs primary processing on the induction signal, and then transmits it to the signal processing circuit 16. The signal processing circuit 16 is connected to the receiving circuit 15, processes the signal output by the signal processing circuit 16, and then transmits it to the central processor 11. The central processor 11 outputs an action control signal according to the signal transmitted by the signal processing circuit 16.

[0048] Further, as Figure 1 shown, the dual-frequency detection circuit further includes: a power amplification module 13 connected to the high-low frequency signal generation module 12, which amplifies the high-low frequency signals output by the high-low frequency signal generation module 12.

[0049] Specifically, in this dual-frequency detection circuit, the central processing unit 11 can output frequency signals of different frequencies to the high-low frequency signal generation module 12. After the high-low frequency signal generation module 12 processes the frequency signals output by the central processing unit 11, it outputs corresponding high-low frequency signals (including high-frequency signals and low-frequency signals). The generated high-frequency signals and low-frequency signals are transmitted to the induction module 14, and the induction module 14 superimposes and processes the high-frequency signals and low-frequency signals to generate corresponding induction signals to the receiving circuit 15. After the receiving circuit 15 picks up and performs primary processing on the induction signals, they are then transmitted to the signal processing circuit 16, and then processed by the signal processing circuit 16 and returned to the central processing unit 11. The central processing circuit completes the detection based on the signals returned by the signal processing circuit 16, thereby realizing the simultaneous detection of high-frequency signals and low-frequency signals. Further, due to the correlation between the detection sensitivity and the frequency, low-frequency signals are more likely to detect ferromagnetic metals, and high-frequency signals are more likely to detect non-ferromagnetic metals. Therefore, different types of metal substances can be detected simultaneously with high precision through this dual-frequency detection circuit.

[0050] Reference Figure 2 , Figure 2 FIG. is a schematic structural diagram of Embodiment 2 of the dual-frequency detection circuit provided by the present invention.

[0051] As Figure 2 shown, the high-low frequency signal generation module 12 includes: a high-frequency signal generation circuit 121 and a low-frequency signal generation circuit 122.

[0052] Among them, the high-frequency signal generation circuit 121 is connected to the central processing unit 11, receives the first frequency signal output by the central processing unit 11, and generates a high-frequency signal according to the first frequency signal; the low-frequency signal generation circuit 122 is connected to the central processing unit 11, receives the second frequency signal output by the central processing unit 11, and generates a low-frequency signal according to the second frequency signal.

[0053] In some embodiments, both the first frequency signal and the second frequency signal are square wave signals. Further, the first frequency signal and the second frequency signal are square wave signals of different frequencies.

[0054] Further, in some embodiments, both the high-frequency signal generation circuit 121 and the low-frequency signal generation circuit 122 can be implemented by using the Figure 4 circuit shown.

[0055] As Figure 4 shown, both the high-frequency signal generation circuit 121 and the low-frequency signal generation circuit 122 can include: a pulse generator, a MOS transistor Q, a resistor R, a diode D, a transformer T, a capacitor C, and a transmitting coil L.

[0056] Specifically, as Figure 4As shown, the output terminal of the pulse generator is connected to the gate of MOS transistor Q. The source of MOS transistor Q is grounded. The drain of MOS transistor Q is connected to the first end of resistor R. The second end of resistor R is connected to the cathode of diode D. The anode of diode D is connected to the first end of the primary winding of transformer T. The second end of the primary winding of transformer T is connected to VCC. The first end of the secondary winding of transformer T is connected to the first end of capacitor C. The second end of the secondary winding of transformer T and the second end of capacitor C are grounded. The transmitting coil L is connected in parallel with capacitor C.

[0057] As Figure 4 shown, the current in the secondary side of transformer T is proportional to the conduction current Id of the field effect transistor. Through frequency selection by the LC resonance circuit, a large-amplitude excitation voltage is applied to the excitation coil, thereby meeting the power transmission requirements.

[0058] In some embodiments, the power amplification module 13 includes: a high-frequency power amplification circuit 131 and a low-frequency power amplification circuit 132.

[0059] The high-frequency power amplification circuit 131 is connected to the high-frequency signal generation circuit 121, receives the high-frequency signal, amplifies the high-frequency signal, and then outputs the amplified high-frequency signal to the induction module 14.

[0060] The low-frequency power amplification circuit 132 is connected to the low-frequency signal generation circuit 122, receives the low-frequency signal, amplifies the low-frequency signal, and then outputs the amplified low-frequency signal to the induction module 14.

[0061] In some embodiments, both the high-frequency power amplification circuit 131 and the low-frequency power amplification circuit 132 can be implemented by existing conventional power amplification circuits, and the present invention does not make specific limitations.

[0062] In some embodiments, the receiving circuit 15 can be composed of a band-pass filter formed by an operational amplifier and corresponding capacitors and resistors, which can perform primary pickup and amplification on the induction signal generated by the induction module 14.

[0063] As Figure 2 shown, in some embodiments, the signal processing circuit 16 includes: an amplitude increase circuit 161.

[0064] The amplitude increase circuit 161 is connected to the receiving circuit 15, receives the induction signal output by the receiving circuit 15, and performs secondary amplification on the induction signal output by the receiving circuit 15, and then outputs an amplified signal.

[0065] Optionally, the amplitude increase circuit 161 is a secondary amplification circuit, which can perform secondary amplification on the signal output by the receiving circuit 15, thereby realizing the amplification of the signal amplitude.

[0066] Further, the signal processing circuit 16 further includes: a filtering module 162 connected to the amplification circuit 161. The filtering module 162 receives the amplified signal output by the amplification circuit 161, filters the amplified signal, and outputs a filtered signal.

[0067] As Figure 2 shown, in some embodiments, the filtering module 162 includes: a first band-pass filter 1621 and a second band-pass filter 1622.

[0068] The first band-pass filter 1621 is connected to the amplification circuit 161, receives the amplified signal output by the amplification circuit 161, filters the amplified signal, and outputs a first filtered signal; the second band-pass filter 1622 is connected to the amplification circuit 161, receives the amplified signal output by the amplification circuit 161, filters the amplified signal, and outputs a second filtered signal.

[0069] In some embodiments, both the first band-pass filter 1621 and the second band-pass filter 1622 can be composed of an operational amplifier and capacitance resistors to amplify signals within a specified frequency range.

[0070] Further, in some embodiments, the first band-pass filter 1621 and the second band-pass filter 1622 operate in different frequency bands, so as to achieve filtering and amplification in different frequency bands.

[0071] Further, as Figure 1 shown, the signal processing circuit 16 further includes: a detection module 163 connected to the filtering module 162, receiving the filtered signal output by the filtering module 162, and performing detection processing on the filtered signal.

[0072] Optionally, as shown, the detection module 163 includes: a first detector 1631 and a second detector 1632.

[0073] The first detector 1631 is connected to the first band-pass filter 1621, receives the first filtered signal output by the first band-pass filter 1621, performs detection processing on the first filtered signal, and outputs a first detection signal; the second detector 1632 is connected to the second band-pass filter 1622, receives the second filtered signal output by the second band-pass filter 1622, performs detection processing on the second filtered signal, and outputs a second detection signal.

[0074] In some embodiments, the frequency band of the first detector 1631 is different from that of the second detector 1632. Further, the first detector 1631 and the second detector 1632 are phase-sensitive detectors with different frequency bands. Among them, both the first detector 1631 and the second detector 1632 can utilize the fact that the reference signal frequency is related to the input signal frequency and not related to noise, so as to extract useful signals from strong noise and improve the detection accuracy.

[0075] Further, in some embodiments, the signal processing circuit 16 further includes: an analog-to-digital conversion circuit 164 connected to the detection module 163; the analog-to-digital conversion circuit 164 receives the detection signal output by the detection module 163, performs analog-to-digital conversion on the detection signal, and then outputs a digital signal to the central processor 11.

[0076] Optionally, the analog-to-digital conversion circuit 164 can be implemented by a conventional analog-to-digital converter, or the corresponding pins of the A / D function of the central processor 11 can be used to implement the conversion of analog signals to digital signals.

[0077] In some embodiments, the induction module 14 includes: a transmission module 141 and a reception module 142.

[0078] The transmission module 141 is connected to the high-frequency signal generation circuit 121 and the low-frequency signal generation circuit 122, receives the high-frequency signal output by the high-frequency signal generation circuit 121 and the low-frequency signal output by the low-frequency signal generation circuit 122, and performs superposition processing on the high-frequency signal and the low-frequency signal to generate a superimposed signal; when the transmission module 141 generates a superimposed signal, the reception module 142 generates an induction signal according to the superimposed signal.

[0079] Optionally, in some embodiments, the transmission module 141 includes at least one transmission circuit, and each transmission circuit includes: a first transmission coil for receiving a high-frequency signal and a second transmission coil for receiving a low-frequency signal; the first transmission coil and the second transmission coil perform superposition processing on the high-frequency signal and the low-frequency signal and then output a superimposed signal.

[0080] The reception module 142 includes at least one reception coil arranged corresponding to the transmission circuit; each reception coil is arranged corresponding to a transmission circuit; the reception coil generates an induction signal according to the superimposed signal.

[0081] As Figure 3 shown, the transmission circuit can be arranged on one side, and the reception coil can be arranged on the other side. Among them, each transmission circuit corresponds to one reception coil, that is, the horizontal position of one reception coil corresponds to two transmission coils, as Figure 3As shown, the transmitting circuit 1 corresponds to the receiving coil 1, the transmitting circuit 2 corresponds to the receiving coil 2, ……, and the transmitting circuit N corresponds to the receiving coil N. Among them, the transmitting circuit 1, the transmitting circuit 2, ……, the transmitting circuit N can be set in one security door or separately set in N security doors. That is, the transmitting circuit 1 and the receiving coil 1 can be set in the No. 1 security door (area 1), the transmitting circuit 2 and the receiving coil 2 can be set in the No. 2 security door (area 2), ……, the transmitting circuit N and the receiving coil N are set in the No. N security door (area N). Among them, two transmitting coils in each transmitting circuit are respectively applied with transmitting signals of different frequencies, high and low.

[0082] As Figure 3 shown, the high-frequency signal is applied to the first transmitting coil, and the low-frequency signal is applied to the second transmitting coil. After being superimposed by the first transmitting coil and the second transmitting coil, a corresponding induced signal is generated by the receiving coil. After being filtered by the receiving circuit 15, the amplitude-increasing circuit 161, the first band-pass filter 1621, and the second band-pass filter 1622, the induced signal is then subjected to detection processing by the first detector 1631 and the second detector 1632. Since different types of metals are sensitive to detection signals of different frequencies, they will be respectively reflected in detectors of different frequencies, thereby realizing the detection of metals.

[0083] Further, in some embodiments, the dual-frequency detection circuit further includes: an action circuit 17 connected to the central processing unit 11, receiving the action control signal output by the central processing unit 11, and performing actions according to the action control signal.

[0084] Optionally, in some embodiments, the action circuit 17 may include: an alarm circuit, including but not limited to an audible and visual alarm, a buzzer, an indicator light, etc. Among them, the action control signal output by the central processing unit 11 can be a switch signal or an audio signal.

[0085] Further, in some embodiments, the present invention also provides a dual-frequency security door, which may include the dual-frequency detection circuit of the embodiments of the present invention. Among them, the transmitting circuit is set on one side door of the security door, and the receiving circuit 15 is set on the other side door of the security door.

[0086] By setting the dual-frequency detection circuit, simultaneous detection of low-frequency signals and high-frequency signals can be realized. Ferromagnetic metals can be detected by using low-frequency signals, and non-ferromagnetic metals can be detected by using high-frequency signals, thereby achieving the purpose of security detection, greatly improving the detection accuracy of the security door, and having strong anti-interference ability.

[0087] The above embodiments are only used to illustrate the technical concept and features of the present invention. The purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and shall not limit the protection scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the claims of the present invention shall fall within the scope covered by the claims of the present invention.

Claims

1. A dual-frequency detection circuit, characterized in that: include: Central processing unit, high and low frequency signal generating module, sensing module, receiving circuit, and signal processing circuit; The high and low frequency signal generating module is connected to the central processing unit, receives the frequency signal output by the central processing unit and generates high and low frequency signals according to the frequency signal; the sensing module is respectively connected to the high and low frequency signal generating module and the receiving circuit, generates sensing signals to the receiving circuit according to the high and low frequency signals; the receiving circuit receives the sensing signals, picks up and performs primary processing on the sensing signals, and then transmits them to the signal processing circuit; the signal processing circuit is connected to the receiving circuit, processes the signals output by the signal processing circuit, and then transmits them to the central processing unit; the central processing unit outputs an action control signal according to the signals transmitted by the signal processing circuit; The dual-frequency detection circuit further includes: a power amplification module connected to the high- and low-frequency signal generation module and amplifying the high- and low-frequency signals output by the high- and low-frequency signal generation module; The high and low frequency signal generating module comprises: a high frequency signal generating circuit and a low frequency signal generating circuit; The high-frequency signal generating circuit is connected to the central processing unit, receives a first frequency signal output by the central processing unit, and generates a high-frequency signal according to the first frequency signal; The low-frequency signal generating circuit is connected to the central processing unit, receives the second frequency signal output by the central processing unit, and generates a low-frequency signal according to the second frequency signal; The sensing module includes: a transmitting module and a receiving module; The transmitting module is connected to the high-frequency signal generating circuit and the low-frequency signal generating circuit, receives the high-frequency signal output by the high-frequency signal generating circuit and the low-frequency signal output by the low-frequency signal generating circuit, and performs superposition processing on the high-frequency signal and the low-frequency signal to generate a superposition signal; When the transmitting module generates the superposition signal, the receiving module generates the sensing signal according to the superposition signal; The transmitting module includes at least one transmitting circuit, each of which includes: a first transmitting coil for receiving the high-frequency signal and a second transmitting coil for receiving the low-frequency signal; the first transmitting coil and the second transmitting coil perform superposition processing on the high-frequency signal and the low-frequency signal and then output a superposition signal; The receiving module includes at least one receiving coil arranged corresponding to the transmitting circuit; each receiving coil is arranged corresponding to one transmitting circuit; each transmitting circuit is arranged corresponding to one receiving coil; the receiving coil generates the induction signal according to the superimposed signal, the transmitting circuit is arranged on one side, and the receiving coil is arranged on the other side.

2. The dual-frequency detection circuit according to claim 1, characterized in that: The power amplification module includes: a high-frequency power amplification circuit and a low-frequency power amplification circuit; The high-frequency power amplifier circuit is connected to the high-frequency signal generating circuit, receives the high-frequency signal, amplifies the high-frequency signal, and then outputs the amplified high-frequency signal to the sensing module; The low-frequency power amplifier circuit is connected to the low-frequency signal generating circuit, receives the low-frequency signal, amplifies the low-frequency signal, and then outputs the amplified low-frequency signal to the sensing module.

3. The dual-frequency detection circuit according to claim 1, characterized in that: The signal processing circuit comprises: an amplifier circuit; The amplifier circuit is connected to the receiving circuit, receives the sensing signal output by the receiving circuit, performs secondary amplification on the sensing signal output by the receiving circuit, and outputs an amplified signal.

4. The dual-frequency detection circuit according to claim 3, characterized in that: The signal processing circuit further includes: a filtering module connected to the amplifier circuit; The filtering module receives the amplified signal output by the amplifier circuit, performs filtering on the amplified signal, and then outputs a filtered signal.

5. The dual-frequency detection circuit according to claim 4, characterized in that: The filtering module includes: a first band-pass filter and a second band-pass filter; The first bandpass filter is connected to the amplifier circuit, receives the amplified signal output by the amplifier circuit, and outputs a first filtered signal after filtering the amplified signal; The second bandpass filter is connected to the amplifier circuit, receives the amplified signal output by the amplifier circuit, and outputs a second filtered signal after filtering the amplified signal.

6. The dual-frequency detection circuit according to claim 5, characterized in that: The first bandpass filter and the second bandpass filter operate in different frequency bands.

7. The dual-frequency detection circuit according to claim 5, characterized in that: The signal processing circuit further includes: a detection module connected to the filtering module, receiving the filtering signal output by the filtering module, and performing detection processing on the filtering signal.

8. The dual-frequency detection circuit according to claim 7, characterized in that: The detection module includes: a first detector and a second detector; The first detector is connected to the first bandpass filter, receives a first filtered signal output by the first bandpass filter, performs detection processing on the first filtered signal, and outputs a first detection signal; The second detector is connected to the second band-pass filter, receives the second filtered signal output by the second band-pass filter, performs detection processing on the second filtered signal, and then outputs a second detected signal.

9. The dual-frequency detection circuit according to claim 8, characterized in that: The frequency band of the first detector is different from the frequency band of the second detector.

10. The dual-frequency detection circuit according to claim 8, characterized in that: The signal processing circuit further comprises: an analog-to-digital conversion circuit connected to the detection module; The analog-to-digital conversion circuit receives the detection signal output by the detection module, performs analog-to-digital conversion on the detection signal, and then outputs a digital signal to the central processing unit.

11. The dual-frequency detection circuit according to any one of claims 1 to 10, characterized in that: Also includes: An action circuit is connected to the central processing unit, receives an action control signal output by the central processing unit, and performs an action according to the action control signal.

12. A dual-frequency security door, characterized in that: The invention comprises the dual-frequency detection circuit as described in any one of claims 1 to 11.

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