Shielded discharge tube assembly with filtering function

Abstract

The utility model discloses a shielding type discharge tube subassembly with filter function, including shell and the discharge tube of being placed in the shell still include printed board and filter capacitor, the shell includes metal base and metal cover, and the upper end surface of metal base is equipped with annular recess and installs the conductive rubber ring in this annular recess, and printed board installs in metal base, and the discharge tube and two filter capacitors install on printed board, and four insertion pins are installed on metal base through four insulating bushings respectively, and two insertion pins are connected with one end of two filter capacitors and two input ends of discharge tube respectively, and the other end of two filter capacitors is connected with metal base, and the other two insertion pins are connected with two output ends of discharge tube respectively. The utility model has good signal shielding effect, reduces the risk of internal coupling and radiation emission overproof, and can provide the release path of interference current rapidly at the moment of discharge tube triggering, improves the stability under the conduction emission test.

Description

Technical Field

[0001] This utility model relates to a discharge tube assembly, and more particularly to a shielded discharge tube assembly with filtering function. Background Technology

[0002] A gas discharge tube (GDT) is a high-voltage protection component that uses the ionization characteristics of inert gas or semiconductors to protect circuits. It is mainly used in communication systems, power equipment, and electronic instruments for lightning strike and instantaneous overvoltage protection at the input terminals. Under normal conditions, it maintains high impedance. When an overvoltage occurs in the circuit, the gas or semiconductor material inside it quickly ionizes and conducts, forming a low-impedance path to discharge the surge current, thereby clamping the voltage at a safe level. After the overvoltage disappears, it automatically returns to the high impedance state.

[0003] In practical applications, discharge tubes are generally integrated with other electronic components as an electrical assembly. When electromagnetic protection and noise interference are required, filtering and radiation protection are usually implemented within the entire electrical assembly. However, this approach has significant drawbacks in certain specific applications. For example, in the design of traditional ignition devices, electromagnetic compatibility (EMC) pretreatment of the internal discharge tube is often neglected. This leads to excessive conduction and radiation emissions during EMC testing due to the strong interference generated by the high-voltage discharge of the discharge tube. Furthermore, the discharge tube itself is prone to accidental ignition during electrostatic discharge testing. The traditional solution is to ignore the EMC issue of the discharge tube in the design. The solution is often to add a filter circuit to the power input of the overall ignition device to suppress noise interference from the discharge tube. This suppression method is simplistic, prone to coupling within the product, and ineffective in reducing radiation emissions. Moreover, without any protective measures, a short circuit failure of the discharge tube can have a significant impact on the entire system.

[0004] In addition, traditional discharge tube products lack protection against short circuit faults and high voltage static electricity, posing safety hazards. Utility Model Content

[0005] The purpose of this invention is to provide a shielded discharge tube assembly with filtering function that can prevent electromagnetic radiation and interference from stray waves in order to solve the above problems.

[0006] This utility model achieves the above objectives through the following technical solutions: A shielded discharge tube assembly with filtering function includes a housing and a discharge tube placed inside the housing, as well as a printed circuit board and filter capacitors. The housing includes a metal base with an inner cavity and an open upper end, and a metal cover plate mounted on the upper end of the metal base. The upper surface of the metal base has an annular groove, and a conductive rubber ring is installed in the annular groove. The upper surface of the conductive rubber ring is in close contact with the lower surface of the metal cover plate. The printed circuit board is mounted inside the metal base, and the discharge tube and two filter capacitors are mounted on the printed circuit board. Four pins are installed on the metal base through four insulating sleeves. Two of the pins, serving as the input terminals of the discharge tube assembly, are connected to one end of the two filter capacitors and the two input terminals of the discharge tube, respectively. The other ends of the two filter capacitors are connected to the metal base. The other two pins, serving as the output terminals of the discharge tube assembly, are connected to the two output terminals of the discharge tube, respectively.

[0007] Preferably, in order to achieve short-circuit protection, the shielded discharge tube assembly with filtering function further includes a thermistor, which is connected in series between the pin that serves as the positive terminal of the discharge tube assembly and the corresponding input terminal of the discharge tube.

[0008] Preferably, in order to achieve high-voltage electrostatic protection, the shielded discharge tube assembly with filtering function further includes a TVS diode, the two ends of which are respectively connected to the two input terminals of the discharge tube.

[0009] Preferably, in order to facilitate the positioning of the printed circuit board and to facilitate quick insertion onto the circuit board in application, the four vertical pins are respectively installed on the base plate of the metal base near the four corners, and the horizontal printed circuit board is provided with mounting through holes near the four corners, and the four insulating sleeves pass through the four mounting through holes respectively.

[0010] Preferably, to achieve better filtering effect, the filtering capacitor is a Y capacitor.

[0011] Preferably, in order to achieve a reliable connection between the metal cover plate and the metal base, the metal cover plate and the metal base are welded together or connected by screws.

[0012] The beneficial effects of this utility model are as follows: This invention employs a metal base and a metal shell, tightly connected by a conductive rubber ring, providing excellent signal shielding and efficient electromagnetic radiation protection. The metal base's proximity to the ground shortens the grounding loop, reducing the risk of internal coupling and excessive radiated emissions. Simultaneously, two filter capacitors filter the input, quickly providing a release path for interference current at the moment of discharge tube triggering, reducing noise current entering subsequent circuits and improving stability under conducted emission testing. A thermistor is connected in series at one input of the discharge tube. Under normal conditions, the thermistor exhibits low resistance, not affecting the original circuit characteristics. When the discharge tube experiences a short circuit failure leading to a sharp increase in current, the thermistor heats up, causing its resistance to rise rapidly, thus limiting the current to a very low level and protecting downstream circuits and components. By installing a TVS diode between the two input terminals of the discharge tube, the TVS diode is in reverse cutoff state under normal circuit operating voltage, exhibiting high impedance characteristics and having almost no impact on the circuit. When transient high voltages such as electrostatic pulses appear in the circuit, as long as the voltage exceeds the breakdown voltage of the TVS diode, its PN junction rapidly undergoes avalanche breakdown, becoming a low impedance state, clamping the voltage across its terminals to a relatively safe predetermined level, thereby ensuring that downstream devices and systems are not affected by high voltage pulses and will not malfunction. By installing pins at the four corners of the base plate of the metal base and achieving insulation through insulating sleeves, and with the four insulating sleeves passing through the four mounting through holes of the printed circuit board, not only is the airtight insulation performance of the pins under high temperature and high pressure conditions guaranteed, but it can also prevent short circuits between the pin solder joints and the metal base, ensuring the reliability and stability of the entire component during long-term operation. Attached Figure Description

[0013] Figure 1 This is a perspective view of the shielded discharge tube assembly with filtering function described in this utility model before assembly. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings: like Figure 1As shown, the shielded discharge tube assembly with filtering function of this utility model includes a shell and a discharge tube 5 placed inside the shell, as well as a printed circuit board 6 and filter capacitors 2. The shell includes a metal base 10 with an inner cavity and an open upper end, and a metal cover plate 1 installed on the upper end of the metal base 10. The upper surface of the metal base 10 is provided with an annular groove and a conductive rubber ring 11 is installed in the annular groove. The upper surface of the conductive rubber ring 11 is in close contact with the lower surface of the metal cover plate 1. The printed circuit board 6 is installed inside the metal base 10, and the discharge tube 5 and two filter capacitors 2 are installed on the printed circuit board 6. Four pins 8 are installed on the metal base 10 through four insulating sleeves 9. Two pins 8, which are the input ends of the discharge tube assembly, are connected to one end of the two filter capacitors 2 and the two input ends of the discharge tube 5, respectively. The other ends of the two filter capacitors 2 are connected to the metal base 10. The other two pins 8, which are the output ends of the discharge tube assembly, are connected to the two output ends of the discharge tube 5, respectively.

[0015] like Figure 1 As shown, this utility model also discloses the following more optimized specific structures: To achieve short-circuit protection, the shielded discharge tube assembly with filtering function also includes a thermistor 3, which is connected in series between the pin 9, which serves as the positive terminal of the discharge tube assembly, and the corresponding input terminal of the discharge tube 5.

[0016] To achieve high-voltage electrostatic protection, the shielded discharge tube assembly with filtering function also includes a TVS diode 4, with the two ends of the TVS diode 4 connected to the two input ends of the discharge tube 5, respectively.

[0017] To facilitate the positioning of the printed circuit board 6 and its quick insertion into the circuit board (not shown in the figure) during application, four vertical pins 8 are respectively installed on the base plate of the metal base 10 near the four corners. A vertical through hole is provided at this position, and an insulating sleeve 9 is placed in the vertical through hole and in close contact with its hole wall. The pins 8 pass through the corresponding insulating sleeve 9 and are in close contact with its inner wall. The horizontal printed circuit board 6 is provided with mounting through holes 7 near the four corners, and the four insulating sleeves 9 pass through the four mounting through holes 7 respectively.

[0018] To achieve better filtering results, filter capacitor 2 is a Y capacitor.

[0019] Preferably, in order to achieve a reliable connection between the metal cover plate 1 and the metal base 10, the metal cover plate 1 and the metal base 10 are welded together (or connected by screws).

[0020] like Figure 1As shown, during use, this discharge tube assembly is installed on the circuit board of the relevant equipment, and connected to the corresponding power supply positive and negative terminals and the input terminals of the corresponding electronic components through four pins 8 respectively. During normal operation, the positive and negative terminals of the input terminals are filtered by two filter capacitors 2, which can quickly provide a release path for interference current at the moment of triggering of the discharge tube 5, reduce the noise current entering the subsequent circuit, and improve the stability under conducted emission test. At the same time, the metal shell composed of the metal base 10 and the metal cover plate has a good signal shielding effect, realizing an efficient anti-electromagnetic radiation function. When the discharge tube 5 fails due to a short circuit and the current increases sharply, the thermistor 3 heats up and the resistance value rises sharply, thereby limiting the current to a very small level and realizing the protection function of the downstream circuit and devices. When transient high voltage such as electrostatic pulse appears in the circuit, as long as the voltage exceeds the breakdown voltage of the TVS diode 4, its PN junction will quickly undergo avalanche breakdown and become a low impedance state, which will clamp the voltage across its two ends to a relatively safe predetermined level, thereby ensuring that the downstream devices and systems will not be affected by the high voltage pulse and fail.

[0021] Note: Since only the metal base 10 and the metal cover 1 are visible after product assembly, this structure consists of... Figure 1 Therefore, the assembled 3D model is not included in the accompanying diagram of the instruction manual.

[0022] The above embodiments are merely preferred embodiments of this utility model and are not intended to limit the technical solutions of this utility model. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of this utility model patent.

Claims

1. A shielded discharge tube assembly with filtering function, comprising a housing and a discharge tube disposed within the housing, characterized in that: It also includes a printed circuit board and filter capacitors. The housing includes a metal base with an inner cavity and an open top, and a metal cover plate mounted on the upper end of the metal base. The upper surface of the metal base has an annular groove, and a conductive rubber ring is installed in the annular groove. The upper surface of the conductive rubber ring is in close contact with the lower surface of the metal cover plate. The printed circuit board is mounted inside the metal base. The discharge tube and the two filter capacitors are mounted on the printed circuit board. Four pins are mounted on the metal base through four insulating sleeves. Two of the pins, which serve as the input ends of the discharge tube assembly, are connected to one end of the two filter capacitors and the two input ends of the discharge tube, respectively. The other ends of the two filter capacitors are connected to the metal base. The other two pins, which serve as the output ends of the discharge tube assembly, are connected to the two output ends of the discharge tube, respectively.

2. The shielded discharge tube assembly with filtering function according to claim 1, characterized in that: The shielded discharge tube assembly with filtering function also includes a thermistor, which is connected in series between the pin, which serves as the positive terminal of the discharge tube assembly, and the corresponding input terminal of the discharge tube.

3. The shielded discharge tube assembly with filtering function according to claim 2, characterized in that: The shielded discharge tube assembly with filtering function also includes a TVS diode, the two ends of which are respectively connected to the two input terminals of the discharge tube.

4. The shielded discharge tube assembly with filtering function according to any one of claims 1-3, characterized in that: The four vertical pins are respectively installed on the base plate of the metal base near the four corners, and the horizontal printed circuit board is provided with mounting through holes near the four corners, and the four insulating sleeves pass through the four mounting through holes respectively.

5. The shielded discharge tube assembly with filtering function according to any one of claims 1-3, characterized in that: The filter capacitor is a Y capacitor.

6. The shielded discharge tube assembly with filtering function according to any one of claims 1-3, characterized in that: The metal cover plate is welded to the metal base or connected by screws.

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