CN110944138A - Device for preventing cable television set top box HDMI from catching fire - Google Patents

Abstract

The invention provides equipment for preventing a cable set top box HDMI from catching fire, which realizes the isolation of a cable network signal ground and a television set top box protective ground by adding a set top box built-in antenna isolator and prevents the function of overheating and firing of a set top box HDMI output port caused by instant leakage current brought by ground potential difference. The built-in antenna isolator adopts a plurality of high-voltage patch capacitors for signal ground isolation, and a plurality of isolation capacitors are connected in parallel and then connected in series between a signal ground and a protective ground. The antenna isolator is added in the signal transmission link, so that the cable television network signal is necessarily attenuated, and therefore, the insertion loss of the antenna isolator is smaller and better, and a mode of connecting a plurality of isolation capacitors in parallel is usually adopted to reduce the grounding impedance and reduce the insertion loss. The invention adopts the built-in antenna isolator, and can avoid the safety problem caused by neglected installation of the antenna isolator.

Description

Device for preventing cable television set top box HDMI from catching fire

Technical Field

The invention relates to the technical field of communication, in particular to a device for preventing an HDMI (high-definition multimedia interface) of a cable set top box from catching fire.

Background

The cable digital TV set-top box is a cable TV signal receiving and converting device, which modulates, decodes and restores the compressed and coded and modulated digital TV signal and outputs high-quality audio and video programs through a TV set. With the popularization of high-definition televisions, more and more set top boxes adopt the HDMI as an audio/video transmission port.

Due to instant current leakage caused by the ground potential difference between a signal ground in a cable network signal transmission link and a user household equipment protection ground, the HDMI output port of the set top box is overheated and fires. According to the requirements of GB 8898 plus 2011 standard, after an isolator is added between a coaxial socket of a cable network antenna and a protective grounding circuit, the fire hazard is eliminated, and suggestions are provided for the design and safe use of a cable digital television set top box product. In actual use, the functions of GB 8898 plus 2011 standard and the isolator are unknown to users, the cable network signal ground is directly connected with the protection ground of the television set top box easily in neglected installation or even discarded, and the functions cannot be effectively played, so that the HDMI of the set top box is ignited without any isolation measures, and the personal and property safety of the users is influenced.

In order to avoid the situation, a solution is to provide an antenna isolator in the cable tv set-top box, so as to isolate the cable network signal ground from the tv set-top box protective ground, and prevent the instant leakage current caused by the ground potential difference between the cable network signal ground and the tv set-top box from causing the overheating of the HDMI output port of the set-top box and causing fire.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a device for preventing the HDMI of the cable television set top box from catching fire.

The invention provides a device for preventing the HDMI of a cable set top box from catching fire, which comprises: the antenna isolator is mounted on the set-top box.

Preferably, the antenna isolator is installed in a manner including an external antenna isolator and an internal antenna isolator.

Preferably, the built-in antenna isolator adopts a plurality of high-voltage patch capacitors which are connected in parallel and then connected in series between a signal ground and a protective ground for signal isolation.

Preferably, the capacitance of the antenna isolator is 1100-2100 pF, the ground voltage difference is less than 150V, and the withstand voltage of the capacitor is 600V-1 kV.

Preferably, the antenna isolator meets the requirements of insulation resistance and dielectric strength, and simultaneously meets the requirements of insertion loss and transmission loss.

Preferably, the insulation resistance of the antenna isolator is greater than 10M omega, and the dielectric strength is 1 kV.

Preferably, the antenna isolator insertion loss is below 1dB, and the transmission loss is below-8 dB.

Preferably, the insertion loss is reduced by connecting a plurality of isolation capacitors in parallel, so that the ground impedance is reduced and the insertion loss is reduced.

Compared with the prior art, the invention has the following beneficial effects: the antenna isolator is used for isolating a wired network signal ground from a user protection ground and generally comprises an external ground and an internal ground. The external antenna isolator is suitable for a cable television set top box or a television product without the internal antenna isolator, and the price is relatively high; in addition, the user generally does not know that the function of the user is easy to miss the clothes and even discard, and the user cannot effectively play a role. And the built-in antenna isolator is adopted, so that the safety problem caused by neglected installation of the antenna isolator by a user can be avoided.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic diagram of a wired network signal transmission circuit

FIG. 2 is a diagram of a conventional wired network signal transmission link

FIG. 3 is a diagram of a wired network signal transmission link according to the present invention

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

According to the requirements of GB 8898 plus 2011 standard, after an isolator is added between a coaxial socket of a cable network antenna and a protective grounding circuit, the fire hazard is eliminated, and suggestions are provided for the design and safe use of a cable digital television set top box product.

The invention aims to provide a convenient and safe method for designing an HDMI anti-ignition of a cable television set top box for a common user by aiming at an external antenna isolator used at present.

The invention provides a device for preventing the HDMI of a cable set top box from catching fire, which comprises: the antenna isolator is mounted on the set-top box.

Specifically, the antenna isolator mounting manner includes an external antenna isolator and an internal antenna isolator. The external antenna isolator is suitable for a cable television set top box or a television product without the built-in antenna isolator;

specifically, the built-in antenna isolator adopts a plurality of high-voltage patch capacitors which are connected in parallel and then connected in series between a signal ground and a protective ground for signal isolation.

Specifically, the transmission frequency of the cable television signal is 110M-872M, the capacitance of the antenna isolator is 1100-2100 pF, the ground voltage difference is less than 150V, and the withstand voltage of the capacitor is 600V-1 kV.

Specifically, the antenna isolator meets the requirements of insulation resistance and dielectric strength, and simultaneously meets the requirements of insertion loss and transmission loss.

Specifically, according to the GB 8898-2011 standard, the insulation resistance of the isolator should be greater than 2M Ω, and the withstand voltage of the isolation capacitor is greater than 500V. The antenna isolator after the design improvement of the set-top box is verified by tests, the insulation resistance of the antenna isolator is larger than 10M omega, the dielectric strength is 1kV, and the requirements of GB 8898-.

Specifically, insertion loss and reflection loss: the addition of an antenna isolator to the signal transmission link inevitably attenuates the cable television network signal. The smaller the insertion loss of the antenna isolator, the better;

in addition, as the impedance matching requirement of the radio frequency circuit is high, the design of the PCB layout and the isolation capacitor needs to meet the requirement of radio frequency input reflection loss, and the reflection loss of GY/T241-2009 technical requirement and measurement method of the high-definition cable digital television set top box requires to be lower than-8 dB.

Specifically, the antenna isolator insertion loss is below 1 dB.

Specifically, the insertion loss is reduced by connecting a plurality of isolation capacitors in parallel, so that the ground impedance is reduced, and the insertion loss is reduced.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims (7)

1. The utility model provides a realize that cable STB HDMI prevents equipment that catches fire which characterized in that includes: the antenna isolator is installed on the set-top box in a mode of comprising an external antenna isolator and an internal antenna isolator.

2. The device for realizing HDMI fire prevention of a cable set-top box according to claim 1, wherein the built-in antenna isolator adopts a plurality of high voltage patch capacitors connected in parallel and then connected in series between a signal ground and a protection ground for signal isolation.

3. The device for realizing HDMI fire prevention of the cable set-top box according to claim 1, wherein the capacitance of the antenna isolator is 1100-2100 pF, the ground voltage difference is less than 150V, and the withstand voltage of the capacitor is 600V-1 kV.

4. The device for realizing HDMI fire prevention of a cable set-top box according to claim 1, wherein the antenna isolator meets the requirements of insulation resistance and dielectric strength, and meets the requirements of insertion loss and transmission loss.

5. The device for realizing HDMI fire prevention of a cable set-top box according to claim 4, wherein the insulation resistance of the antenna isolator is greater than 10M Ω, and the dielectric strength is 1 kV.

6. The device for realizing HDMI fire prevention of a cable set-top box according to claim 4, wherein the insertion loss of the antenna isolator is lower than 1dB, and the transmission loss is lower than-8 dB.

7. The device of claim 6, wherein the insertion loss is reduced by connecting a plurality of isolation capacitors in parallel, thereby reducing the ground impedance and the insertion loss.

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