An EMI interference prevention structure of a tablet computer charging cabinet

Abstract

The utility model discloses a kind of EMI interference prevention structures of tablet computer charging cabinet, including charging cabinet body, multiple side-by-side distribution charging placement grooves are provided on charging cabinet body, the same side of each charging placement groove is provided with inclined support partition, wireless transmitting circuit is provided in support partition, and wireless transmitting circuit is electrically connected with main control board being arranged in the inside of charging cabinet body;Multiple charging base, mounting groove for installing tablet computer is provided on charging base, charging head is provided in mounting groove, and charging head is matched with the charging port of tablet computer, wireless receiving circuit is provided in charging base, and wireless receiving circuit is electrically connected with charging head.The utility model realizes for multiple tablet computer charging, improves charging convenience and use efficiency, and overall structure is compact, satisfies the use demand of miniaturization.

Description

Technical Field

[0001] This utility model relates to the field of electronic product charging technology, specifically to an EMI interference prevention structure for a tablet computer charging cabinet. Background Technology

[0002] Tablet computers are increasingly used in modern electronic devices, and tablet charging cabinets are widely used to facilitate centralized charging management. However, electromagnetic interference (EMI) is a problem during the operation of tablet charging cabinets.

[0003] Tablet charging cabinets typically contain a main control board and multiple wireless transmission circuits. When these circuits operate simultaneously, they continuously generate electromagnetic signals of a certain frequency and intensity. The superposition of these signals can interfere with the power supply of the main control board, leading to excessive conducted interference and radiation. Conducted interference may cause power input instability, affecting the normal operation of the input rectifier and filter circuits; excessive radiation may adversely affect surrounding electronic devices and reduce the electromagnetic compatibility of the entire charging cabinet. Utility Model Content

[0004] In order to overcome the problem of excessive conducted interference and radiation caused by the simultaneous operation of multiple wireless transmission circuits in the existing technology of tablet charging, this utility model provides an EMI interference prevention structure for tablet charging cabinet.

[0005] The technical solution of this utility model is as follows:

[0006] An EMI interference prevention structure for a tablet computer charging cabinet includes a charging cabinet body with an AC input terminal for connecting to an external power source. A main control board and a TX board are disposed within the charging cabinet body. Multiple wireless transmission circuits are disposed on the TX board. The main control board is electrically connected to the AC input terminal and the multiple wireless transmission circuits. One end of the AC input terminal connected to the main control board is covered with conductive cloth, and the conductive cloth is grounded.

[0007] In a preferred embodiment of this utility model, the conductive cloth is made of copper foil.

[0008] In a preferred embodiment of this utility model, the main control board is provided with an input rectifier and filter circuit, a transformer, an output rectifier and filter circuit, and a multi-channel BUCK power supply circuit. The AC input terminal is electrically connected to the input terminal of the input rectifier and filter circuit. The output terminal of the input rectifier and filter circuit is electrically connected to the primary winding of the transformer. The secondary winding of the transformer is electrically connected to the input terminal of the output rectifier and filter circuit. The output terminal of the output rectifier and filter circuit is electrically connected to multiple wireless transmission circuits through the multiple BUCK power supply circuits, and the BUCK power supply circuits correspond one-to-one with the wireless transmission circuits.

[0009] In a preferred embodiment of this utility model, the BUCK power supply circuit includes a power management chip U4, capacitors EC6, EC9, C11, C13, C30, C35, resistors R21, R28, R29, R30, R58, and inductor L3. The BST pin of the power management chip U4 is connected sequentially through resistor R29 and capacitor C11 to the SW pin of the power management chip U4, one end of resistor R58, and one end of inductor L3. The other end of resistor R58 is connected through capacitor C30 to the negative terminal of capacitor EC9, one end of resistor R30, and ground. The other end of resistor R30 is connected to... The CS pin of the power management chip U4 is electrically connected. The other end of the inductor L3 is electrically connected to the positive terminal of the capacitor EC9, one end of the resistor R28, and the corresponding wireless transmission circuit. The VIN pin of the power management chip U4 is electrically connected to the output terminal of the output rectifier filter circuit, the positive terminal of the capacitor EC9, and one end of the capacitor C35. The FB pin of the power management chip U4 is electrically connected to one end of the resistor R21, one end of the capacitor C13, and the other end of the resistor R28. The negative terminal of the capacitor EC9, the other end of the capacitor C35, the other end of the resistor R21, the other end of the capacitor C13, and the GND pin of the power management chip U4 are all grounded.

[0010] As a preferred embodiment of this utility model, the power management chip U4 is model number LYF82031.

[0011] As a preferred embodiment of this utility model, the transformer is a flyback transformer, and the transformer model is IW3627.

[0012] As a preferred embodiment of this utility model, the main control board is further provided with an RC snubber circuit, and the AC input terminal is electrically connected to the input terminal of the input rectifier filter circuit through the RC snubber circuit.

[0013] As a preferred embodiment of this utility model, the wireless transmitting circuit includes a wireless transmitting chip and a wireless transmitting coil. The wireless transmitting chip is electrically connected to the input terminal of the wireless transmitting coil and the output terminal of a corresponding BUCK power supply circuit.

[0014] As a preferred embodiment of this utility model, the wireless transmitting circuit further includes a charging indicator light, and the wireless transmitting chip is electrically connected to the charging indicator light.

[0015] In a preferred embodiment of this invention, all the grounding points of the wireless transmitting circuits are connected to the same point.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] 1. By wrapping the end of the AC input terminal connected to the input rectifier and filter circuit with conductive cloth and grounding the conductive cloth, a shielding layer can be formed. The shielding layer can block the electromagnetic signals generated by the wireless transmission circuit, preventing them from entering the connection part between the AC input terminal and the input rectifier and filter circuit, thereby reducing the impact of electromagnetic interference on the power supply. At the same time, through grounding, the conductive cloth introduces the induced electromagnetic interference signals to the ground, avoiding the propagation and accumulation of interference signals in the circuit, which helps to stabilize the power supply input, reduce noise and fluctuations in the power supply, and ensure that the input rectifier and filter circuit can work normally.

[0018] 2. By adding a BUCK power supply circuit to each wireless transmission circuit on the main control board, the working state of each wireless transmission circuit is relatively independent, reducing the interference signal strength of each wireless transmission circuit and reducing mutual signal interference. This enables multiple wireless transmission circuits to work stably and normally, effectively solving the crosstalk and mutual inductance problems between multiple wireless transmission circuits, and further preventing electromagnetic signal interference from the TX board to the main control board.

[0019] 3. By connecting all the grounding points of the wireless transmission circuits to the same point, the intensity of the specific frequency signal generated by the wireless transmission coils of all the wireless transmission circuits in the circuit loop can be minimized. This can further prevent the fixed frequency signal generated by the wireless transmission coils from interfering with the main control board (i.e., EMI interference), thereby avoiding conducted interference and radiation exceeding the standard on the main control board, ensuring the normal operation of the main control board and the electromagnetic compatibility of the entire system. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is an internal schematic diagram of the EMI interference prevention structure of a tablet computer charging cabinet in one embodiment of this utility model.

[0022] Figure 2 This is a schematic diagram of the EMI interference prevention structure of a tablet computer charging cabinet in one embodiment of this utility model;

[0023] Figure 3 This is a circuit diagram of the BUCK power supply circuit in one embodiment of this utility model;

[0024] Figure 4 This is a schematic diagram of the EMI interference prevention structure of a tablet computer charging cabinet in another embodiment of this utility model;

[0025] Figure 5 This is a schematic block diagram of the wireless transmission circuit in one embodiment of the present invention;

[0026] Figure 6 This is a circuit diagram of a wireless transmitting chip in one embodiment of this utility model.

[0027] In the diagram,

[0028] 1. Charging cabinet body; 2. AC input terminal; 3. Main control board; 31. Input rectifier and filter circuit; 32. Transformer; 33. Output rectifier and filter circuit; 34. BUCK power supply circuit; 35. RC absorption circuit; 4. TX board; 41. Wireless transmission circuit; 411. Wireless transmission coil; 412. Wireless transmission chip; 413. Charging indicator light; 5. Conductive cloth. Detailed Implementation

[0029] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that similar reference numerals and letters in the following drawings indicate similar items; therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. It is also declared that the embodiments described below are only for explaining this utility model and are not intended to limit this utility model.

[0030] It should be noted that the terms "installation," "setting," "connection," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly defined. Indications of orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used in the application's product, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0031] Please see Figure 1 This utility model provides an EMI interference prevention structure for a tablet computer charging cabinet, including a charging cabinet body 1. The charging cabinet body 1 has an AC input terminal 2 for connecting to an external power source. Inside the charging cabinet body 1 are a main control board 3 and a TX board 4. The TX board 4 has multiple wireless transmission circuits 41. The main control board 3 is electrically connected to both the AC input terminal 2 and the multiple wireless transmission circuits 41. One end of the AC input terminal 2 connected to the main control board 3 is wrapped with a conductive cloth 5, and the conductive cloth 5 is grounded. Since the multiple wireless transmission circuits 41 continuously generate electromagnetic signals of a certain frequency and intensity when operating simultaneously, the superposition of these signals can interfere with the power supply of the main control board 3, leading to excessive conducted interference and radiation. This embodiment, by wrapping the end of the AC input terminal 2 connected to the main control board 3 with the conductive cloth 5 and grounding the conductive cloth 5, forms a shielding layer. This shielding layer blocks the electromagnetic signals generated by the wireless transmission circuits 41, preventing them from entering the connection between the AC input terminal 2 and the main control board 3, thereby reducing the impact of electromagnetic interference on the power supply. By grounding, the conductive cloth 5 introduces the induced electromagnetic interference signal into the ground, avoiding the propagation and accumulation of interference signals in the circuit, which helps to stabilize the power input, reduce noise and fluctuations in the power supply, and ensure that the input rectifier and filter circuit 31 can work normally.

[0032] Please see Figure 2In one embodiment, the main control board 3 is provided with an input rectifier and filter circuit 31, a transformer 32, an output rectifier and filter circuit 33, and a multi-channel BUCK power supply circuit 34. The AC input terminal 2 is electrically connected to the input terminal of the input rectifier and filter circuit 31. The output terminal of the input rectifier and filter circuit 31 is electrically connected to the primary winding of the transformer 32. The secondary winding of the transformer 32 is electrically connected to the input terminal of the output rectifier and filter circuit 33. The output terminal of the output rectifier and filter circuit 33 is electrically connected to a multi-channel wireless transmission circuit 41 through the multi-channel BUCK power supply circuit 34. The BUCK power supply circuit 34 corresponds one-to-one with the wireless transmission circuit 41. During wireless charging, the charging coils generate electromagnetic signals. If the coil spacing is too small, the electromagnetic signals generated by different charging coils are prone to mutual interference, affecting the charging effect and even causing charging failure. This makes it impossible to achieve miniaturization in actual multi-channel wireless charging designs. Therefore, in this embodiment, a BUCK power supply circuit 34 is added to each wireless transmitting circuit 41 on the main control board 3. Each BUCK power supply circuit 34 can independently provide a stable power supply to its corresponding wireless transmitting circuit 41, making the working state of each wireless transmitting circuit 41 relatively independent, reducing the interference signal strength of each wireless transmitting circuit 41, reducing mutual signal interference, and enabling multiple wireless transmitting circuits 41 to work stably and normally. This effectively solves the crosstalk and mutual inductance problems between multiple wireless transmitting circuits 41, and further avoids electromagnetic signal interference from the TX board 4 to the main control board 3. Through comparative testing, the interference signal strength of the BUCK power supply circuit 34 without independent power supply is about 200mV, while the interference signal strength of the BUCK power supply circuit 34 with independent power supply is reduced to 40mV. When designing multi-channel wireless charging, this invention eliminates the need to reserve excessive space to avoid interference, allowing for a more compact and miniaturized charging cabinet structure.

[0033] In one embodiment, to effectively reduce electromagnetic interference, the grounding points of all wireless transmitting circuits 41 are connected to the same point. This arrangement minimizes the intensity of the specific frequency signals generated by the wireless transmitting coils 411 of all wireless transmitting circuits 41 in the circuit loop. This further prevents the fixed-frequency signals generated by the wireless transmitting coils 411 from interfering with the main control board 3 (i.e., EMI interference), thereby avoiding conducted interference and excessive radiation on the main control board 3, ensuring the normal operation of the main control board 3 and the electromagnetic compatibility of the entire system.

[0034] Please see Figure 3In one embodiment, the BUCK power supply circuit 34 includes a power management chip U4, capacitors EC6, EC9, C11, C13, C30, and C35, resistors R21, R28, R29, R30, and R58, and an inductor L3. The BST pin of the power management chip U4 is connected to the SW pin of the power management chip U4, one end of resistor R58, and one end of inductor L3 via resistor R29 and capacitor C11. The other end of resistor R58 is connected to the negative terminal of capacitor EC9, one end of resistor R30, and ground via capacitor C30. The other end of resistor R30... The CS pin of the power management chip U4 is electrically connected to the power supply circuit. The other end of the inductor L3 is electrically connected to the positive terminal of capacitor EC9, one end of resistor R28, and the corresponding wireless transmission circuit 41. The VIN pin of the power management chip U4 is electrically connected to the output terminal of the output rectifier filter circuit 33, the positive terminal of capacitor EC9, and one end of capacitor C35. The FB pin of the power management chip U4 is electrically connected to one end of resistor R21, one end of capacitor C13, and the other end of resistor R28. The negative terminal of capacitor EC9, the other end of capacitor C35, the other end of resistor R21, the other end of capacitor C13, and the GND pin of the power management chip U4 are all grounded. The BUCK power supply circuit 34 outputs 15V and has an output current of 1.33A; the transformer 32 outputs 20V and has an output current of 6A.

[0035] In the aforementioned BUCK power supply circuit 34, the power management chip U4 and surrounding components such as capacitors, resistors, and inductors, together with the BUCK power supply circuit 34, convert the 20V voltage output from the transformer 32 into a 15V voltage suitable for the wireless transmission circuit 41. This allows the wireless transmission circuit 41 to operate under a suitable voltage environment, ensuring its stable performance and reliability. The voltage divider circuit composed of resistors R21 and R28 connected to the FB pin of the power management chip U4 can monitor the output voltage in real time and adjust the chip's operating state according to the feedback signal, thereby maintaining a stable output voltage. When the load changes or the input voltage fluctuates, it ensures that the output voltage remains at 15V, providing a stable power supply for the wireless transmission circuit 41. Capacitors EC6, EC9, C11, C13, C30, and C35 act as filters and energy storage components in the circuit, smoothing voltage fluctuations, reducing ripple and noise in the power supply, and providing a cleaner power source for the circuit. Resistor R30 serves as a current sensing resistor and is connected to the CS pin of the power management chip U4. When the current in the circuit is too high, the CS pin detects the voltage change and the chip will take corresponding protection measures, such as reducing the output power or shutting down the circuit, thereby avoiding component damage caused by overcurrent and improving the safety and reliability of the circuit.

[0036] In one specific embodiment, the power management chip U4 is model LYF82031. The LYF82031 chip has high conversion efficiency, which can efficiently convert the input electrical energy into voltage and current suitable for use by the wireless transmission circuit 41. It can precisely control the output voltage and current and integrates a variety of protection functions, such as overcurrent protection, overvoltage protection, undervoltage protection and overheat protection.

[0037] In one specific embodiment, transformer 32 is a flyback transformer, model IW3627. The flyback transformer IW3627 can adapt to a wide input voltage range, has good electrical isolation, high energy conversion efficiency, and stable output characteristics.

[0038] Please see Figure 4 In one embodiment, the main control board 3 is also equipped with an RC absorption circuit 35, and the AC input terminal 2 is electrically connected to the input terminal of the input rectifier filter circuit 31 through the RC absorption circuit 35. The RC absorption circuit 35 consists of a resistor (R) and a capacitor (C). The RC absorption circuit 35 has a certain filtering effect on the electromagnetic interference signal generated by the wireless transmission circuit 41. The capacitor has a small impedance to the electromagnetic interference signal, which can bypass the electromagnetic interference signal to ground, while the resistor can limit the current and prevent excessive current from damaging the circuit. In this way, the RC absorption circuit 35 can further reduce the electromagnetic interference signal in the power input, improve the purity of the power supply, and reduce the impact of EMI interference on the anti-EMI interference structure of the entire tablet computer charging cabinet. Secondly, when the AC input terminal 2 is connected to the power supply, a momentary surge voltage may occur, which may damage or interfere with the input rectifier filter circuit 31. When the surge voltage occurs, the RC absorption circuit 35 can absorb the surge energy through the charging of the capacitor and the current limiting effect of the resistor, reduce the amplitude of the surge voltage, and protect the input rectifier filter circuit 31 from damage.

[0039] It should be noted that since the input rectifier filter circuit 31, transformer 32, output rectifier filter circuit 33 and RC absorption circuit 35 are existing technologies well known to those skilled in the art, this utility model has not made any improvements to them, so their specific circuit structures and working principles will not be described in detail.

[0040] Please see Figure 5In one embodiment, the wireless transmitting circuit 41 includes a wireless transmitting coil 411 and a wireless transmitting chip 412. The wireless transmitting chip 412 is electrically connected to the input terminal of the wireless transmitting coil 411 and the output terminal of a corresponding BUCK power supply circuit 34. The wireless transmitting chip 412, in conjunction with the wireless transmitting coil 411, converts the electrical energy provided by the BUCK power supply circuit 34 into electromagnetic signals for transmission, thereby achieving wireless charging. By connecting to the corresponding BUCK power supply circuit 34, a stable power supply is ensured for the wireless transmitting circuit 41, enabling the wireless transmitting coil 411 to continuously and stably transmit electromagnetic signals, providing energy to the wireless receiving circuit within the charging base, and thus charging the tablet computer.

[0041] Furthermore, the wireless transmitting circuit 41 also includes a charging indicator light 413. The wireless transmitting chip 412 is electrically connected to the charging indicator light 413, and the charging indicator light 413 is located on the outside of a corresponding charging slot. The charging indicator light 413 can reflect the working status of the wireless transmitting circuit 41 in real time. When the wireless transmitting circuit 41 is working normally and transmitting electromagnetic signals to the charging base, the charging indicator light 413 lights up, allowing the user to intuitively see that the corresponding charging slot is charging the tablet computer inside the charging base. This provides the user with a clear indication of the charging status, making it convenient for the user to understand whether the tablet computer is charging normally and whether charging is complete.

[0042] Please see Figure 6 In one specific embodiment, the wireless transmitter chip 412 is model MT5811. The MT5811 chip has good compatibility with other circuit components (such as the wireless transmitter coil 411, the BUCK power supply circuit 34, etc.), can operate stably in the working environment of the charging cabinet, reduce the occurrence of failures caused by chip performance problems, and improve the reliability of the entire wireless charging system.

[0043] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

[0044] The present utility model patent has been described above with reference to the accompanying drawings. Obviously, the implementation of the present utility model patent is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present utility model patent, or the direct application of the inventive concept and technical solution of the present utility model patent to other occasions without modification, are all within the protection scope of the present utility model.

Claims

1. An EMI interference prevention structure for a tablet computer charging cabinet, characterized in that, The device includes a charging cabinet body, which has an AC input terminal for connecting to an external power source. The charging cabinet body contains a main control board and a TX board. The TX board has multiple wireless transmission circuits. The main control board is electrically connected to the AC input terminal and the multiple wireless transmission circuits. The end of the AC input terminal connected to the main control board is covered with conductive cloth, and the conductive cloth is grounded.

2. The EMI interference prevention structure of the tablet charging cabinet according to claim 1, characterized in that, The conductive cloth is made of copper foil.

3. The EMI interference prevention structure of the tablet charging cabinet according to claim 1, characterized in that, The main control board is equipped with an input rectifier and filter circuit, a transformer, an output rectifier and filter circuit, and a multi-channel BUCK power supply circuit. The AC input terminal is electrically connected to the input terminal of the input rectifier and filter circuit. The output terminal of the input rectifier and filter circuit is electrically connected to the primary winding of the transformer. The secondary winding of the transformer is electrically connected to the input terminal of the output rectifier and filter circuit. The output terminal of the output rectifier and filter circuit is electrically connected to multiple wireless transmission circuits through the multiple BUCK power supply circuits. Each BUCK power supply circuit corresponds to one wireless transmission circuit.

4. The EMI interference prevention structure of the tablet charging cabinet according to claim 3, characterized in that, The BUCK power supply circuit includes a power management chip U4, capacitors EC6, EC9, C11, C13, C30, and C35, resistors R21, R28, R29, R30, and R58, and an inductor L3. The BST pin of the power management chip U4 is connected sequentially through resistor R29 and capacitor C11 to the SW pin of the power management chip U4, one end of resistor R58, and one end of inductor L3. The other end of resistor R58 is connected through capacitor C30 to the negative terminal of capacitor EC9, one end of resistor R30, and ground. The other end of resistor R30 is connected to the power management chip... The CS pin of U4 is electrically connected. The other end of the inductor L3 is electrically connected to the positive terminal of the capacitor EC9, one end of the resistor R28, and the corresponding wireless transmission circuit. The VIN pin of the power management chip U4 is electrically connected to the output terminal of the output rectifier filter circuit, the positive terminal of the capacitor EC9, and one end of the capacitor C35. The FB pin of the power management chip U4 is electrically connected to one end of the resistor R21, one end of the capacitor C13, and the other end of the resistor R28. The negative terminal of the capacitor EC9, the other end of the capacitor C35, the other end of the resistor R21, the other end of the capacitor C13, and the GND pin of the power management chip U4 are all grounded.

5. The EMI interference prevention structure of the tablet charging cabinet according to claim 4, characterized in that, The power management chip U4 is model number LYF82031.

6. The EMI interference prevention structure of the tablet charging cabinet according to claim 4, characterized in that, The transformer is a flyback transformer.

7. The EMI interference prevention structure of the tablet charging cabinet according to claim 3, characterized in that, The main control board is also equipped with an RC snubber circuit, and the AC input terminal is electrically connected to the input terminal of the input rectifier filter circuit through the RC snubber circuit.

8. The EMI interference prevention structure of the tablet charging cabinet according to claim 3, characterized in that, The wireless transmitting circuit includes a wireless transmitting chip and a wireless transmitting coil. The wireless transmitting chip is electrically connected to the input terminal of the wireless transmitting coil and the output terminal of a corresponding BUCK power supply circuit.

9. The EMI interference prevention structure of the tablet charging cabinet according to claim 8, characterized in that, The wireless transmitting circuit also includes a charging indicator light, and the wireless transmitting chip is electrically connected to the charging indicator light.

10. The EMI interference prevention structure of the tablet charging cabinet according to claim 1, characterized in that, All the grounding points of the wireless transmission circuits are connected to the same point.

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