Radio frequency card reader circuit

Abstract

The embodiment of the utility model discloses a radio frequency card reader circuit. The circuit comprises a proximity detector, a microprocessor, a driving circuit, a radio frequency processing circuit and an indicating lamp circuit, and the microprocessor is respectively connected with the proximity detector, the driving circuit, the radio frequency processing circuit and the indicating lamp circuit. Whether a radio frequency card is close to the card reader or not is detected through the proximity detector, and when no radio frequency card is close to the card reader, the microprocessor, the driving circuit, the radio frequency processing circuit and the indicator lamp circuit are in a dormant state, so that the power consumption of the card reader is reduced; when a radio frequency card approaches the card reader, the approach detector sends a wake-up signal to the microprocessor so that the microprocessor is switched from a dormant state to a working state, and identity verification of the radio frequency card is realized. By adopting the scheme, the power consumption of the card reader can be greatly reduced, the battery life is prolonged, and the stability of the access control system is guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of access control electronic circuit technology, specifically to an radio frequency card reader circuit. Background Technology

[0002] Card readers are core devices in access control systems, undertaking the crucial task of identity verification. However, existing card readers in access control systems often suffer from excessive power consumption, reducing battery life. Furthermore, excessive power consumption can generate significant heat, affecting the stability of the entire access control system. Utility Model Content

[0003] In view of the above problems, the present invention provides an embodiment of an RF card reader circuit that overcomes or at least partially solves the above problems.

[0004] According to one aspect of the present invention, an RFID reader circuit is provided, comprising: a proximity detector, a microprocessor, a driving circuit, an RFID processing circuit, and an indicator light circuit; wherein the microprocessor is connected to the proximity detector, the driving circuit, the RFID processing circuit, and the indicator light circuit respectively.

[0005] The proximity detector includes an infrared transmitter, an infrared receiver, an infrared processing circuit, and a comparison circuit. The infrared receiver is connected to the infrared processing circuit, the infrared processing circuit is connected to the comparison circuit, and the comparison circuit is connected to the microprocessor. The infrared transmitter is used to emit infrared signals, the infrared receiver is used to receive infrared reflected signals, the infrared processing circuit is used to process the infrared reflected signals to obtain a proximity detection signal, and the comparison circuit is used to compare the signal strength of the proximity detection signal with a preset threshold. When the signal strength of the proximity detection signal is greater than the preset threshold, a wake-up signal is sent to the microprocessor.

[0006] After receiving the wake-up signal, the microprocessor starts the drive circuit; the radio frequency processing circuit processes the received card identity signal and transmits the processed card identity signal to the microprocessor; the microprocessor processes the card identity signal to obtain card identity information, and turns on the indicator light circuit when the card identity information matches the preset identity information.

[0007] In one optional implementation, the comparison circuit sends a sleep signal to the microprocessor when the signal strength of the proximity detection signal is less than or equal to a preset threshold, and the microprocessor shuts down the drive circuit after receiving the sleep signal.

[0008] In one alternative implementation, the infrared transmitter, infrared receiver, infrared processing circuit, and comparison circuit are integrated into the proximity detection chip U1.

[0009] In one optional implementation, the proximity detection chip U1 includes an interface P1, which is connected to a microprocessor; the interface P1 includes an interrupt pin, a clock pin, and a data pin.

[0010] In one optional implementation, the microprocessor includes a timer circuit, which resets the timer circuit after receiving a wake-up signal; the timer circuit outputs a timing end signal when the timing reaches a preset duration, and the microprocessor shuts down the drive circuit after receiving the timing end signal.

[0011] In one optional embodiment, the driving circuit includes: resistor R19, transistor Q1, transistor Q2, coil COIL1, coil COIL2, and capacitor C15;

[0012] The first terminal of resistor R19 is connected to the microprocessor, and the second terminal of resistor R19 is connected to the gates of transistors Q1 and Q2. The drain of transistor Q1 is connected to a 3.3V voltage, and the source of transistor Q1 is connected to the source of transistor Q2 and the coil COIL1. The drain of transistor Q2 is grounded. The coil COIL2 is connected to capacitor C15.

[0013] In one optional embodiment, the radio frequency processing circuit includes: a filtering circuit, an amplification circuit, and a shaping circuit;

[0014] The output of the filter circuit is connected to the input of the amplifier circuit, and the output of the amplifier circuit is connected to the input of the shaping circuit.

[0015] In one optional embodiment, the filter circuit includes: diode D1, resistor R10, resistor R7, capacitor C6, capacitor C7, and capacitor C5.

[0016] The amplifier circuit includes: amplifier U1A, amplifier U1B, amplifier U1C, resistor R4, resistor R5, resistor R6, resistor R8, resistor R9, resistor R11, resistor R12, capacitor C3, capacitor C4, capacitor C8, capacitor C9, and capacitor C10.

[0017] The shaping circuit includes: comparator U1D and resistor R2.

[0018] In one optional embodiment, the positive terminal of diode D1 is connected to coil COIL2; the negative terminal of diode is connected to the first terminal of resistor R10, the first terminal of resistor R7, and the first terminal of capacitor C6; the second terminal of resistor R10 is grounded; the second terminals of capacitor C6 and capacitor C7 are grounded; the second terminal of resistor R7 is connected to the first terminal of capacitor C7 and the first terminal of capacitor C5; the second terminal of capacitor C5 is connected to the first terminal of resistor R8.

[0019] The second terminal of resistor R8 is connected to the inverting input terminal of amplifier U1C, the first terminal of resistor R12, and the first terminal of capacitor C10; the second terminal of resistor R12 is connected to the second terminal of capacitor C10, the output terminal of amplifier U1C, and the first terminal of resistor R6.

[0020] The second terminal of resistor R6 is connected to the first terminals of capacitor C4 and capacitor C8; the second terminal of capacitor C4 is connected to the first terminal of resistor R11 and the inverting input terminal of amplifier U1B; the output terminal of amplifier U1B is connected to the first terminal of resistor R5, the second terminal of resistor R11, and the second terminal of capacitor C8.

[0021] The second terminal of resistor R5 is connected to the first terminal of capacitor C9 and the first terminal of capacitor C3; the second terminal of capacitor C3 is connected to the first terminal of resistor R9 and the inverting input terminal of amplifier U1A; the output terminal of amplifier U1A is connected to the first terminal of resistor R4, the second terminal of resistor R9, and the second terminal of capacitor C9.

[0022] The second terminal of resistor R4 is connected to the first terminal of resistor R2 and the non-inverting input of comparator U1D; the output of comparator U1D is connected to the microprocessor.

[0023] The non-inverting input terminals of amplifiers U1A, U1B, and U1C, as well as the inverting input terminal of comparator U1D, are connected to a 2.5V voltage.

[0024] In one optional implementation, the indicator circuit includes: a light-emitting diode D2 and a resistor R29;

[0025] In this circuit, the positive terminal of LED D2 is connected to a 3.3V voltage, the negative terminal of LED D2 is connected to the first terminal of resistor R29, and the second terminal of resistor R29 is connected to the microprocessor.

[0026] The RFID card reader circuit provided in this application uses a proximity detector to detect whether an RFID card is approaching the reader. When no RFID card is near the reader, the microprocessor, drive circuit, RFID processing circuit, and indicator light circuit are all in sleep mode, thereby reducing the reader's power consumption. When an RFID card approaches the reader, the proximity detector sends a wake-up signal to the microprocessor, causing the microprocessor to switch from sleep mode to working mode. This then activates the drive circuit and triggers the RFID processing circuit to enter working mode, enabling the verification of the RFID card's identity. Finally, after successful identity verification, the indicator light circuit is activated to indicate successful identity verification through indicator light. Using the RFID card reader circuit provided in this application significantly reduces reader power consumption, extends battery life, and ensures the stability of the access control system.

[0027] The above description is merely an overview of the technical solutions of the present utility model embodiments. In order to better understand the technical means of the present utility model embodiments and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present utility model embodiments more obvious and understandable, the following are specific implementation methods of the present utility model embodiments. Attached Figure Description

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0029] Figure 1 A schematic diagram of an RFID card reader circuit provided in an embodiment of this application is shown;

[0030] Figure 2 A schematic diagram of a proximity detection chip U1 provided in an embodiment of this application is shown;

[0031] Figure 3 A schematic diagram of a microprocessor provided in an embodiment of this application is shown;

[0032] Figure 4 This illustration shows a schematic diagram of an interface provided in an embodiment of this application;

[0033] Figure 5 A schematic diagram of a driving circuit provided in an embodiment of this application is shown;

[0034] Figure 6 A schematic diagram of a radio frequency processing circuit provided in an embodiment of this application is shown;

[0035] Figure 7 A schematic diagram of an indicator light circuit provided in an embodiment of this application is shown;

[0036] Figure 8 A schematic diagram of a power module provided in an embodiment of this application is shown. Detailed Implementation

[0037] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0038] Figure 1A schematic diagram of an RFID card reader circuit according to an embodiment of this application is shown. The card reader circuit provided in this embodiment can be applied to access control systems.

[0039] Specifically, such as Figure 1 As shown, the card reader circuit includes: a proximity detector 10, a microprocessor 20, a driver circuit 30, a radio frequency processing circuit 40, and an indicator light circuit 50. The microprocessor 20 is connected to the proximity detector 10, the driver circuit 30, the radio frequency processing circuit 40, and the indicator light circuit 50.

[0040] The proximity detector 10 is used to emit infrared signals and receive infrared reflection signals. After processing the infrared reflection signals, a proximity detection signal is obtained, and then a wake-up signal is sent to the microprocessor 20 when the signal strength of the proximity detection signal is greater than a preset threshold.

[0041] Specifically, the proximity detector 10 includes an infrared transmitter 11, an infrared receiver 12, an infrared processing circuit 13, and a comparison circuit 14. The infrared receiver 12 is connected to the infrared processing circuit 13, the infrared processing circuit 13 is connected to the comparison circuit 14, and the comparison circuit 14 is connected to the microprocessor 20. The infrared transmitter 11 transmits infrared signals, the infrared receiver 12 receives reflected infrared signals, the infrared processing circuit 13 processes the reflected infrared signals to obtain a proximity detection signal, and the comparison circuit 14 compares the signal strength of the proximity detection signal with a preset threshold. When the signal strength of the proximity detection signal exceeds the preset threshold, a wake-up signal is sent to the microprocessor 20.

[0042] In the specific implementation process, the infrared transmitter 11 emits infrared light (infrared signal). The infrared light is reflected when it encounters an obstacle, and the infrared receiver 12 receives the reflected infrared signal. Since the intensity of the reflected infrared signal varies depending on the distance of the obstacle, the intensity of the reflected infrared signal received by the infrared receiver 12 also varies depending on the location of the obstacle in front of the infrared transmitter 11. The infrared receiver 12 provides the reflected infrared signal to the infrared processing circuit 13, which performs filtering, analog-to-digital conversion, and other processing on the reflected infrared signal to generate a proximity detection signal. The proximity detection signal is further transmitted to the comparison circuit 14 for comparison with a preset threshold. When the signal strength of the proximity detection signal is higher than the preset threshold, the comparison circuit outputs a wake-up signal, such as a high-level signal, to the microprocessor 20; when the signal strength of the proximity detection signal is equal to or lower than the preset threshold, the comparison circuit outputs a low-level signal, and the microprocessor 20 does not receive the wake-up signal.

[0043] Upon receiving the wake-up signal, the microprocessor 20 indicates that an RFID card is approaching the card reader, thus switching from sleep mode to working mode. It then activates the drive circuit 30 to generate a carrier signal of the corresponding frequency band (e.g., a 125kHz carrier signal), which is transmitted outward through the antenna coil.

[0044] When the RFID card approaches the reader coil, the RFID card chip is activated by the electromagnetic field of the carrier signal emitted by the reader antenna. This activates the card identification signal, which is then encoded, modulated, and transmitted as an RFID signal. This card identification signal is received by the reader antenna coil and transmitted to the RFID processing circuit 40. The RFID processing circuit 40 processes the received card identification signal and transmits the processed signal to the microprocessor 20.

[0045] The microprocessor 20 processes the card identity signal to obtain the card identity information, and activates the indicator light circuit 50 when the card identity information matches the preset identity information, thereby indicating that the current identity verification is successful.

[0046] Therefore, the RFID reader in this embodiment includes a working state and a sleep state. In the sleep state, only the proximity detector 10 is turned on to detect whether an RFID card is approaching, while the drive circuit 30 is turned off. That is, in the sleep state, the drive circuit 30 does not transmit carrier signals outward through the antenna, and the RFID processing circuit 40 does not receive card identity signals. Consequently, the RFID processing circuit 40 is also in a sleep state, and the microprocessor 20 does not process card identity signals. After receiving the wake-up signal sent by the proximity detector 10, the RFID reader switches from the sleep state to the working state. In the working state, the drive circuit 30 transmits carrier signals outward through the antenna, causing the passive RFID card to be sensed. The RFID card then transmits its identity signal. After the reader antenna receives the card identity signal, the RFID processing circuit 40 starts processing the card identity signal. The microprocessor 20 then starts recognizing and verifying the card identity, and activates the indicator light circuit 50 if the identity verification is successful.

[0047] Therefore, the RFID card reader circuit provided in this application embodiment detects whether an RFID card is near the card reader using a proximity detector. When no RFID card is near the card reader, the microprocessor, drive circuit, RFID processing circuit, and indicator light circuit are all in a sleep state, thereby reducing the card reader's power consumption. When an RFID card is near the card reader, the proximity detector sends a wake-up signal to the microprocessor, causing the microprocessor to switch from sleep state to working state, thereby activating the drive circuit and triggering the RFID processing circuit to enter working state, realizing the identity verification of the RFID card. Finally, after successful identity verification, the indicator light circuit is activated to indicate successful identity verification through indicator light. Using the RFID card reader circuit provided in this application embodiment can significantly reduce card reader power consumption, extend battery life, and ensure the stability of the access control system.

[0048] In one optional implementation, the infrared processing circuit 13 in the proximity detector may include a filtering circuit, an amplification circuit, and an analog-to-digital converter circuit, etc. The filtering circuit is used to filter the infrared reflected signal, the amplification circuit is used to amplify the signal, and the analog-to-digital converter circuit is used to convert the analog signal into a digital signal. The comparison circuit 14 may specifically be a comparator, etc.

[0049] In one optional implementation, when the signal strength of the proximity detection signal is less than or equal to a preset threshold, the comparison circuit 14 sends a sleep signal to the microprocessor 20. After receiving the sleep signal, the microprocessor 20 shuts down the drive circuit 30, so that the card reader enters sleep mode again to reduce power consumption.

[0050] Specifically, the infrared transmitter 11, infrared receiver 12, infrared processing circuit 13, and comparator circuit 14 can be integrated into the proximity detection chip U1 to reduce the size and weight of the card reader. Furthermore, other components in the card reader can be lightweight and miniaturized to further reduce the size and weight of the card reader.

[0051] refer to Figure 2 The proximity detection chip U1 can employ an integrated optical sensor such as the APDS_9930. The proximity detection chip U1 operates on a 3.3V voltage and includes interrupt pins, clock pins, and data pins. For example, the interrupt pin APDS_9930_INT can be used to transmit sleep and / or wake-up signals; the clock pin APDS_9930_SCL is used to transmit a synchronization clock signal; and the data pin APDS_9930_SDA is used for bidirectional data transmission between the proximity detection chip U1 and the microprocessor 20, such as sensor configuration data.

[0052] In an optional embodiment, the microprocessor 20 may further include a timer circuit that outputs a timeout end signal after a preset duration has elapsed since the timer started. In this embodiment, the microprocessor 20 resets the timer circuit after receiving a wake-up signal from the proximity detector 10, causing the timer circuit to restart timing. After the timer circuit outputs the timeout end signal, the microprocessor 20 receives the timeout end signal and shuts down the drive circuit 30, thereby causing the RFID reader to re-enter sleep mode.

[0053] Specifically, the microprocessor 20 can employ Figure 3 The structure shown. (As illustrated) Figure 3 As shown, the microprocessor 20 can be chip U2, specifically CH32V003F4P6. Pin 10 of chip U2 is connected to the clock pin APDS_9930_SCL of chip U1; pin 11 of chip U2 is connected to the data pin APDS_9930_SDA of chip U1; and pin 5 of chip U2 is connected to the interrupt pin APDS_9930_INT of chip U1. Pin 20 of chip U2 is connected to the driver circuit 30; and pin 15 of chip U2 is connected to the radio frequency processing circuit 40.

[0054] refer to Figure 4 The proximity detection chip U1 includes an interface P1, which is connected to the microprocessor 20. Interface P1 includes an interrupt pin APDS_9930_INT, a clock pin APDS_9930_SCL, a data pin APDS_9930_SDA, and a 3.3V voltage source. A resistor R40 is connected in series between the APDS_9930_INT pin and the 3.3V voltage source, a resistor R41 is connected in series between the APDS_9930_SCL pin and the 3.3V voltage source, and a resistor R42 is connected in series between the APDS_9930_SDA pin and the 3.3V voltage source. Microprocessor 20 (chip U2) includes interface P2, which includes a GLED pin, a CLK OUT pin, and a HID DATA pin. The GLED pin is connected to indicator light circuit 50, the CLK OUT pin is connected to driver circuit 30, and the HID DATA pin is connected to RF processing circuit 40. Microprocessor 20 also includes connector JP1, which includes a 3.3V power supply pin, a SWIO pin, and a ground pin. Furthermore, microprocessor 20 includes VCC pin, UTX pin, URX pin, MCU INT pin, and GND pin. The GLED pin, CLK OUT pin, and COIL2 can also be integrated into interface P4. This RF card reader uses a universal interface and protocol to adapt to different RF cards (such as 125kHz low-frequency cards), improving its flexibility and versatility in different application scenarios.

[0055] In one alternative implementation, refer to Figure 5 The driving circuit 30 includes: a resistor R19, a transistor Q1, a transistor Q2, a coil COIL1, a coil COIL2, and a capacitor C15; the first end of the resistor R19 is connected to the microprocessor 20, and the second end of the resistor R19 is connected to the gate of transistor Q1 and the gate of transistor Q2; the drain of transistor Q1 is connected to a 3.3V voltage, and the source of transistor Q1 is connected to the source of transistor Q2 and the coil COIL1; the drain of transistor Q2 is grounded; the coil COIL2 is connected to the first end of the capacitor C15, and the second end of the capacitor C15 is grounded.

[0056] In one optional embodiment, the radio frequency processing circuit 40 includes a filter circuit, an amplifier circuit, and a shaping circuit; wherein the input terminal of the filter circuit is connected to the coil COIL2, the output terminal of the filter circuit is connected to the input terminal of the amplifier circuit, and the output terminal of the amplifier circuit is connected to the input terminal of the shaping circuit. The filter circuit is used to filter signal noise, the amplifier circuit is used to amplify the signal, and the rectifier circuit is used to convert the signal into a preset square wave signal.

[0057] Specifically, refer to Figure 6 The filtering circuit includes: diode D1, resistor R10, resistor R7, capacitor C6, capacitor C7, and capacitor C5; the amplification circuit includes: amplifier U1A, amplifier U1B, amplifier U1C, resistor R4, resistor R5, resistor R6, resistor R8, resistor R9, resistor R11, resistor R12, capacitor C3, capacitor C4, capacitor C8, capacitor C9, and capacitor C10; the shaping circuit includes: comparator U1D and resistor R2.

[0058] In this configuration, the positive terminal of diode D1 is connected to coil COIL2; the negative terminal of diode D1 is connected to the first terminals of resistors R10 and R7, and the first terminal of capacitor C6; the second terminal of resistor R10 is grounded; the second terminals of capacitors C6 and C7 are grounded; the second terminal of resistor R7 is connected to the first terminals of capacitors C7 and C5; the second terminal of capacitor C5 is connected to the first terminal of resistor R8; the second terminal of resistor R8 is connected to the inverting input terminal of amplifier U1C, the first terminal of resistor R12, and the first terminal of capacitor C10; the second terminal of resistor R12 is connected to the second terminal of capacitor C10, the output terminal of amplifier U1C, and the first terminal of resistor R6; the second terminal of resistor R6 is connected to the first terminals of capacitors C4 and C8; the second terminal of capacitor C4 is connected to the first terminal of resistor R11 and the inverting input terminal of amplifier U1B. The output of amplifier U1B is connected to the first terminal of resistor R5, the second terminal of resistor R11, and the second terminal of capacitor C8; the second terminal of resistor R5 is connected to the first terminals of capacitors C9 and C3; the second terminal of capacitor C3 is connected to the first terminal of resistor R9 and the inverting input of amplifier U1A; the output of amplifier U1A is connected to the first terminal of resistor R4, the second terminal of resistor R9, and the second terminal of capacitor C9; the second terminal of resistor R4 is connected to the first terminal of resistor R2 and the non-inverting input of comparator U1D; the output of comparator U1D is connected to the microprocessor; the non-inverting inputs of amplifiers U1A, U1B, and U1C, and the inverting input of comparator U1D are connected to a 2.5V voltage, which is obtained by dividing a 3.3V voltage through resistor R1. Figure 6 The circuit structure shown can improve the recognition distance and stability of the RFID reader.

[0059] In one alternative implementation, refer to Figure 7 The indicator light circuit 50 includes a light-emitting diode (LED) D2 and a resistor R29. The positive terminal of LED D2 is connected to a 3.3V voltage, and the negative terminal of LED D2 is connected to the first terminal of resistor R29. The second terminal of resistor R29 is connected to the microprocessor 20. When the microprocessor 20 determines that the card's identity information matches the preset identity information, the indicator light circuit 50 is activated, causing LED D2 to light up to indicate successful identity verification.

[0060] In one alternative implementation, refer to Figure 8 The RFID card reader provided in this application embodiment also includes a power module, which provides power to other modules in the RFID card reader. Specifically, as... Figure 8As shown, the input port IN of power chip U3 is connected to VCC, the first terminal of capacitor C11, the first terminal of capacitor C14, and the first terminal of resistor R27; the SHDN pin of power chip U3 is connected to the second terminal of resistor R27; the second terminals of capacitors C11 and C14 are grounded; the output terminal of chip U3 is connected to a 3.3V voltage. Additionally, VCC33OUT is connected to the drain of transistor Q3, the gate of transistor Q3 is connected to the second terminals of resistors R14 and R13, the first terminal of resistor R13 is connected to a 3.3V voltage, and resistor R14 is connected to the MCU VCCOUT pin of microprocessor 20.

[0061] It should be noted that relational terms such as "first" and "second" in this utility model are only used to distinguish one entity or operation from another entity or operation, and do not represent any actual relationship or order between the entities or operations.

[0062] The illustrations provided in this utility model are only schematic representations of the basic concept of this utility model. The illustrations only show the components related to this utility model and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0063] The term "connection" in this invention includes both direct and indirect connections, such as connections made through active devices, passive devices, or electrical conduction media; it may also include connections made by other active or passive devices that are known to those skilled in the art and can achieve the same or similar functional purpose, such as connections made through switches, follower circuits, or other circuits or components.

[0064] The description and application of this utility model herein are illustrative and not intended to limit the scope of the utility model to the above embodiments. The effects or advantages involved in the embodiments may not be manifested in the embodiments due to various factors, and the description of effects or advantages is not intended to limit the embodiments. Variations and modifications of the embodiments disclosed herein are possible, and various substitutions and equivalents of the components in the embodiments are well known to those skilled in the art. It should be clear to those skilled in the art that this utility model can be implemented in other forms, structures, arrangements, proportions, and with other components, materials, and parts without departing from the spirit or essential characteristics of this utility model. Other variations and modifications can be made to the embodiments disclosed herein without departing from the scope and spirit of this utility model.

Claims

1. A radio frequency card reader circuit, comprising: include: The system includes a proximity detector, a microprocessor, a drive circuit, a radio frequency processing circuit, and an indicator light circuit; wherein the microprocessor is connected to the proximity detector, the drive circuit, the radio frequency processing circuit, and the indicator light circuit respectively. The proximity detector includes an infrared transmitter, an infrared receiver, an infrared processing circuit, and a comparison circuit. The infrared receiver is connected to the infrared processing circuit, the infrared processing circuit is connected to the comparison circuit, and the comparison circuit is connected to the microprocessor. The infrared transmitter is used to emit infrared signals, the infrared receiver is used to receive infrared reflected signals, the infrared processing circuit is used to process the infrared reflected signals to obtain a proximity detection signal, and the comparison circuit is used to compare the signal strength of the proximity detection signal with a preset threshold. When the signal strength of the proximity detection signal is greater than the preset threshold, a wake-up signal is sent to the microprocessor. After receiving the wake-up signal, the microprocessor starts the drive circuit; the radio frequency processing circuit processes the received card identity signal and transmits the processed card identity signal to the microprocessor; the microprocessor processes the card identity signal to obtain card identity information, and turns on the indicator light circuit when the card identity information matches the preset identity information.

2. The radio frequency card reader circuit of claim 1, wherein, When the signal strength of the detection signal is less than or equal to a preset threshold, the comparison circuit sends a sleep signal to the microprocessor. Upon receiving the sleep signal, the microprocessor shuts down the drive circuit.

3. The radio frequency card reader circuit of claim 2, wherein, The infrared transmitter, infrared receiver, infrared processing circuit, and comparison circuit are integrated into the proximity detection chip U1.

4. The radio frequency card reader circuit of claim 3, wherein, The proximity detection chip U1 includes an interface P1, which is connected to a microprocessor; the interface P1 includes an interrupt pin, a clock pin, and a data pin.

5. The radio frequency card reader circuit of claim 1, wherein, The microprocessor includes a timer circuit. After receiving a wake-up signal, the microprocessor resets the timer circuit. When the timer reaches a preset duration, the timer circuit outputs a timing end signal. After receiving the timing end signal, the microprocessor shuts down the drive circuit.

6. The radio frequency card reader circuit of any of claims 1-5, wherein, The driving circuit includes: resistor R19, transistor Q1, transistor Q2, coil COIL1, coil COIL2, and capacitor C15; The first terminal of resistor R19 is connected to the microprocessor, and the second terminal of resistor R19 is connected to the gates of transistors Q1 and Q2. The drain of transistor Q1 is connected to a 3.3V voltage, and the source of transistor Q1 is connected to the source of transistor Q2 and the coil COIL1. The drain of transistor Q2 is grounded. The coil COIL2 is connected to capacitor C15.

7. The radio frequency card reader circuit of any of claims 1-5, wherein, The radio frequency processing circuit includes: a filter circuit, an amplifier circuit, and a shaping circuit; The output of the filter circuit is connected to the input of the amplifier circuit, and the output of the amplifier circuit is connected to the input of the shaping circuit.

8. The radio frequency card reader circuit of claim 7, wherein, The filter circuit includes: diode D1, resistor R10, resistor R7, capacitor C6, capacitor C7, and capacitor C5; The amplifier circuit includes: amplifier U1A, amplifier U1B, amplifier U1C, resistor R4, resistor R5, resistor R6, resistor R8, resistor R9, resistor R11, resistor R12, capacitor C3, capacitor C4, capacitor C8, capacitor C9, and capacitor C10. The shaping circuit includes: comparator U1D and resistor R2.

9. The radio frequency card reader circuit according to claim 8, characterized in that, Diode D1's anode is connected to coil COIL2; diode's cathode is connected to the first terminal of resistor R10, the first terminal of resistor R7, and the first terminal of capacitor C6; the second terminal of resistor R10 is grounded; capacitors C6 and C7's second terminals are grounded; the second terminal of resistor R7 is connected to the first terminal of capacitor C7 and the first terminal of capacitor C5; the second terminal of capacitor C5 is connected to the first terminal of resistor R8. The second terminal of resistor R8 is connected to the inverting input terminal of amplifier U1C, the first terminal of resistor R12, and the first terminal of capacitor C10; the second terminal of resistor R12 is connected to the second terminal of capacitor C10, the output terminal of amplifier U1C, and the first terminal of resistor R6. The second terminal of resistor R6 is connected to the first terminals of capacitor C4 and capacitor C8; the second terminal of capacitor C4 is connected to the first terminal of resistor R11 and the inverting input terminal of amplifier U1B; the output terminal of amplifier U1B is connected to the first terminal of resistor R5, the second terminal of resistor R11, and the second terminal of capacitor C8. The second terminal of resistor R5 is connected to the first terminal of capacitor C9 and the first terminal of capacitor C3; the second terminal of capacitor C3 is connected to the first terminal of resistor R9 and the inverting input terminal of amplifier U1A; the output terminal of amplifier U1A is connected to the first terminal of resistor R4, the second terminal of resistor R9, and the second terminal of capacitor C9. The second terminal of resistor R4 is connected to the first terminal of resistor R2 and the non-inverting input of comparator U1D; the output of comparator U1D is connected to the microprocessor. The non-inverting input terminals of amplifiers U1A, U1B, and U1C, as well as the inverting input terminal of comparator U1D, are connected to a 2.5V voltage.

10. The radio frequency card reader circuit of any one of claims 1-5, wherein, The indicator light circuit includes: a light-emitting diode D2 and a resistor R29; In this circuit, the positive terminal of LED D2 is connected to a 3.3V voltage, the negative terminal of LED D2 is connected to the first terminal of resistor R29, and the second terminal of resistor R29 is connected to the microprocessor.

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