Subway vehicle LCD display screen signal transmission circuit and device

Abstract

The utility model provides a subway vehicle LCD display screen signal transmission circuit and device, and relates to the technical field of vehicle-mounted screens. The circuit comprises a signal input terminal, a signal output terminal, a first differential amplification unit, a second differential amplification unit, a relay unit, a signal processing unit, a video signal output unit and an audio signal output unit. The signal input terminal receives video and audio signals. When the relay is switched on, the video signal is directly forwarded to the output terminal; and when the circuit is disconnected, the signal is amplified by the double-differential amplification unit and then is forwarded. In addition, after being amplified by the first differential amplification unit, the video signal is processed by the signal processing unit and then sent to the video output unit. The audio signal is directly played by the audio output unit, and the size of the audio signal is regulated and controlled by the signal processing unit. According to the technical scheme, the anti-interference capability of display screen signals transmitted among a plurality of LCD display screens can be improved.

Description

Technical Field

[0001] This application relates to the technical field of vehicle-mounted screens. Specifically, it relates to a circuit and device for signal transmission of an LCD display screen in a subway vehicle. Background Technique

[0002] The signal transmission circuit of the LCD display screen in a subway vehicle, as a core component of the internal information display system of the subway vehicle, undertakes the important task of efficiently and stably transmitting external video and audio signals to multiple LCD display screens inside the subway vehicle for display and playback. Currently, most of the signal transmission circuits of LCD display screens in subway vehicles adopt the methods of direct transmission or simple amplification processing. After the video signal is connected through the input terminal, it is either directly transmitted to the display screen or transmitted after passing through a simple amplification circuit.

[0003] However, these existing methods of direct transmission or simple amplification processing lack an effective anti-interference mechanism, are prone to problems such as signal loss or quality degradation, have limited anti-interference ability and poor stability, and cannot well ensure the transmission of signals between multiple LCD display screens. Utility Model Content

[0004] To solve the above problems, this application provides a circuit and device for signal transmission of an LCD display screen in a subway vehicle, which can enhance the anti-interference ability of the display screen signal during transmission between multiple LCD display screens.

[0005] This application is implemented as follows:

[0006] In a first aspect, this application provides a circuit for signal transmission of an LCD display screen in a subway vehicle, which includes a signal input terminal, a signal output terminal, a first differential amplification unit, a second differential amplification unit, a relay unit, a signal processing unit, a video signal output unit, and an audio signal output unit. The signal input terminal is used to access video signals and audio signals. One end of the output loop of the relay unit is connected to the signal input terminal, and the other end is connected to the signal output terminal; among them, when the output loop of the relay unit is connected, the video signal accessed through the signal input terminal is directly transmitted to the signal output terminal for video signal forwarding; when the output loop of the relay unit is disconnected, the video signal accessed through the signal input terminal is first transmitted to the first differential amplification unit for amplification, and then amplified by the second differential amplification unit and transmitted to the signal output terminal for video signal forwarding. The video signal accessed through the signal input terminal is also amplified by the first differential amplification unit and then transmitted to the signal processing unit for signal processing and then transmitted to the video signal output unit. The audio signal accessed through the signal input terminal is output through the audio signal output unit, and the magnitude of the output audio signal is adjusted by the signal processing unit.

[0007] In some implementations, the circuit further includes an audio amplification unit. The signal input terminal and the signal processing unit are respectively connected to the input end of the audio amplification unit, and the output end of the audio amplification unit is connected to the audio signal output unit.

[0008] In some implementations, the circuit further includes a first TVS protection unit and a second TVS protection unit; the signal input terminal is connected to the first differential amplification unit through the first TVS protection unit, the second differential amplification unit is connected to the signal output terminal through the second TVS protection unit, and the first TVS protection unit is further connected to the output loop of the relay unit.

[0009] In some implementations, the circuit further includes a power supply unit, which is used to provide operating voltages for the first differential amplification unit, the second differential amplification unit, the relay unit, the signal processing unit, the video signal output unit, and the audio signal output unit.

[0010] In some implementations, the relay unit includes at least one normally closed relay. When power is supplied to the input loop of the normally closed relay, the video signal input through the signal input terminal is first transmitted to the first differential amplification unit for amplification, and then amplified by the second differential amplification unit and transmitted to the signal output terminal for video signal forwarding; when there is no power supply to the input loop of the normally closed relay, the video signal input through the signal input terminal is directly transmitted to the signal output terminal for video signal forwarding.

[0011] In some implementations, the first differential amplification unit includes a differential amplifier chip of the EL5375IUZ or EL4543IUZ model.

[0012] In some implementations, the second differential amplification unit includes a differential amplifier chip of the EL5375IUZ or EL4543IUZ model.

[0013] In some implementations, the signal processing unit includes an MCU control chip of the NT68168BFG model.

[0014] In a second aspect, the present application provides a device for signal transmission of an LCD display screen of a subway vehicle, which includes a circuit for signal transmission of an LCD display screen of a subway vehicle as described in any one of the first aspects.

[0015] Compared with the prior art, the present application has at least the following advantages or beneficial effects:

[0016] By optimizing the circuit topology, this application allows direct transmission of video signals when signal quality is good, reducing unnecessary processing steps. When signal quality is poor, two-stage differential amplification is used for transmission, effectively suppressing noise and improving the signal's anti-interference ability. Furthermore, the audio signal output size can be dynamically adjusted based on ambient noise or passenger needs to ensure audio playback quality. In other words, by optimizing the circuit topology, this application achieves fine processing and flexible control of video and audio signals, ensuring the anti-interference ability of video signals transmitted between multiple LCD screens while reducing unnecessary processing steps and improving transmission efficiency and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a structural diagram of an embodiment of a circuit for signal transmission on an LCD display screen of a subway vehicle according to the present application;

[0019] Figure 2 This is a structural diagram of another embodiment of a circuit for signal transmission on an LCD display screen of a subway vehicle according to the present application;

[0020] Figure 3 This is a structural diagram of another embodiment of a circuit for signal transmission on an LCD display screen of a subway vehicle according to the present application;

[0021] Figure 4 This is a schematic diagram of the circuit principle of the signal input terminal and the signal output terminal in one embodiment of a signal transmission circuit for an LCD display screen on a subway vehicle of the present application;

[0022] Figure 5 This is a schematic diagram of the circuit principle of a relay unit in an embodiment of a circuit for signal transmission on an LCD display screen of a subway vehicle according to the present application;

[0023] Figure 6 This is a schematic diagram of the circuit principle of the first TVS protection unit in an embodiment of a signal transmission circuit for an LCD display screen on a subway vehicle of the present application;

[0024] Figure 7 This is a schematic diagram of the circuit principle of the first differential amplifier unit in an embodiment of a circuit for signal transmission of an LCD display screen on a subway vehicle of the present application;

[0025] Figure 8Schematic diagram of the circuit principle of the second differential amplification unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0026] Figure 9 Schematic diagram of the circuit principle of the second TVS protection unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0027] Figure 10 Schematic diagram of the circuit principle of the signal processing unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0028] Figure 11 Schematic diagram of the circuit principle of the audio amplification unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0029] Figure 12 Schematic diagram of the circuit principle of the video signal output unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0030] Figure 13 Schematic diagram of the circuit principle of the serial port unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0031] Figure 14A Schematic diagram of the circuit principle of the first voltage stabilization part of the power supply unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0032] Figure 14B Schematic diagram of the circuit principle of the second voltage stabilization part and the flash storage part of the power supply unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application;

[0033] Figure 14C Schematic diagram of the circuit principle of the power management chip part of the power supply unit in an embodiment of the circuit for signal transmission of the LCD display screen of a subway vehicle in this application. Detailed implementation manners

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are some, rather than all, of the embodiments of this application. Usually, the components of the embodiments of this application described and illustrated herein can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0036] Embodiment:

[0037] The following will make a detailed description of some embodiments of the present application in conjunction with the drawings. Without conflict, the following various embodiments and the various features in the embodiments can be combined with each other.

[0038] Please refer to Figure 1 This circuit for signal transmission of an LCD display screen of a subway vehicle includes a signal input terminal, a signal output terminal, a first differential amplification unit, a second differential amplification unit, a relay unit, a signal processing unit, a video signal output unit, and an audio signal output unit. The signal input terminal is used to access video signals and audio signals. One end of the output loop of the relay unit is connected to the signal input terminal, and the other end is connected to the signal output terminal. Among them, when the output loop of the relay unit is turned on, the video signal accessed through the signal input terminal is directly transmitted to the signal output terminal for video signal forwarding. When the output loop of the relay unit is turned off, the video signal accessed through the signal input terminal is first transmitted to the first differential amplification unit for amplification, and then amplified by the second differential amplification unit and transmitted to the signal output terminal for video signal forwarding. The video signal accessed through the signal input terminal is also amplified by the first differential amplification unit and then transmitted to the signal processing unit for signal processing and then transmitted to the video signal output unit. The audio signal accessed through the signal input terminal is output through the audio signal output unit, and the magnitude of the output audio signal is adjusted by the signal processing unit.

[0039] It should be noted that due to the complex electromagnetic environment inside the subway vehicle, the directly transmitted video signal is easily interfered with, resulting in a decline in picture quality and affecting the viewing experience of passengers. However, if the video signal is good but still transmitted after passing through a simple amplification circuit, it may cause unnecessary processing of the signal. That is to say, the existing processing method of directly transmitting the video signal to the display screen or transmitting it after passing through a simple amplification circuit after accessing through the input terminal cannot flexibly process the video signal, and the signal stability is poor.

[0040] However, in the above embodiment, by selectively turning on and off the relay unit, the switching between the direct transmission and differential amplification transmission of the video signal is achieved. As Figure 2As shown, when forwarding the accessed video signal to the next LCD display screen, there are two cases. One is when the signal quality is good, the relay unit is turned on, and the video signal is directly transmitted to the next LCD display screen through the forwarding loop 1, reducing unnecessary processing links and improving the signal transmission efficiency. The other is when the signal quality is poor, the relay unit is turned off, and the video signal is transmitted to the next LCD display screen after being amplified by two-stage differential amplification units through the forwarding loop 2, effectively enhancing the anti-interference ability of the signal and improving the signal stability. Among them, when the accessed video signal is output to the current LCD display screen, it is first amplified by the first differential amplification unit and then processed by the signal processing unit (mainly the conventional coding and output processing of the video signal, and at the same time, the existing self-checking algorithm can be used to control the retransmission of error data and prevent the loss of video signals) and then can be transmitted to the current LCD display screen. It should be noted that the quality of the signal can be judged manually, and then by turning on / off the power supply of the input loop of the relay unit, the switching between the direct transmission and differential amplification transmission of the video signal can be realized. It is also possible to use the processor to analyze the quality of the video signal.

[0041] At the same time, this application uses two-stage differential amplification units (the first and second differential units) to amplify the video signal. Compared with a single amplification circuit, it can provide a greater gain. At the same time, the first differential amplification unit and the second differential amplification unit can also effectively suppress the common-mode noise, further improving the signal-to-noise ratio of the signal and ensuring the clarity and integrity of the video signal during the transmission process.

[0042] In addition, the output size of the audio signal in the prior art is usually fixed and cannot be dynamically adjusted according to the ambient noise or the needs of passengers. However, this application can adjust the audio signal through the signal processing unit, and can dynamically adjust the output size of the audio signal according to the ambient noise level or the auditory needs of passengers, ensuring the clarity and comfort of the audio playback.

[0043] In short, in this application, when the signal quality is good, the video signal is directly transmitted, reducing unnecessary processing links. When the signal quality is poor, through two-stage differential amplification transmission, the noise is effectively suppressed and the anti-interference ability of the signal is improved. And the output size of the audio signal can be dynamically adjusted according to the ambient noise or the needs of passengers, ensuring the audio playback effect. That is to say, this application realizes the fine processing and flexible control of the video signal and the audio signal by optimizing the circuit topology structure, which can not only ensure the anti-interference ability of the video signal during transmission between multiple LCD display screens, but also reduce unnecessary processing links and improve the transmission efficiency and quality.

[0044] Please refer to Figure 2, in some embodiments of the present application, the circuit further includes an audio amplification unit, the signal input terminal and the signal processing unit are respectively connected to the input end of the audio amplification unit, and the output end of the audio amplification unit is connected to the audio signal output unit.

[0045] In the above embodiment, the transmission loop of the audio signal is further optimized, and an audio amplification unit is added. Specifically, the input ends of the audio amplification unit are respectively connected to the signal input terminal and the signal processing unit, and its output end is connected to the audio signal output unit. Such a design enables the audio signal to be appropriately amplified during transmission, thereby ensuring the clarity and loudness of audio playback. By preprocessing the audio signal through the signal processing unit, such as volume adjustment, sound quality optimization, etc., and then amplifying it through the audio amplification unit and finally outputting it to the passengers, the auditory experience of the passengers can be further improved. This improvement not only enhances the transmission effect of the audio signal, but also makes the entire circuit system more complete and better able to meet the requirements of the in-vehicle information display system of subway vehicles.

[0046] Please refer to Figure 3 , in some embodiments of the present application, the circuit further includes a first TVS protection unit and a second TVS protection unit; the signal input terminal is connected to the first differential amplification unit through the first TVS protection unit, the second differential amplification unit is connected to the signal output terminal through the second TVS protection unit, and the first TVS protection unit is further connected to the output loop of the relay unit.

[0047] In the above embodiment, the safety of the circuit is further enhanced by adding a first TVS (Transient Voltage Suppressor) protection unit and a second TVS protection unit. Specifically, the signal input terminal is first connected to the first differential amplification unit through the first TVS protection unit. Such a design can suppress transient overvoltage at the signal input end and protect the subsequent circuit from damage. At the same time, the first TVS protection unit is also connected to the output loop of the relay unit to ensure effective protection of the circuit when the relay unit switches states.

[0048] On the other hand, the output of the second differential amplification unit is connected to the signal output terminal through the second TVS protection unit, which can suppress transient overvoltage at the signal output end again to further ensure the stability and safety of the output signal.

[0049] In summary, by adding these two TVS protection units, the present application can effectively prevent circuit failures caused by transient overvoltage, improving the reliability and stability of the entire circuit. This improvement not only enhances the protection ability of the circuit but also makes the operation of the in-vehicle information display system of subway vehicles safer and more reliable.

[0050] In some embodiments of the present application, the circuit further includes a power supply unit, which is used to provide operating voltages for the first differential amplification unit, the second differential amplification unit, the relay unit, the signal processing unit, the video signal output unit, and the audio signal output unit. By pre-setting a power supply unit instead of connecting to an external power supply, the stability and reliability of the entire circuit can be ensured. After all, a stable power supply is particularly important for the differential amplification unit, which can ensure that the video signal will not be distorted due to voltage fluctuations during the amplification process. At the same time, for key components such as the relay unit and the signal processing unit, a stable power supply is also the basis for their normal operation.

[0051] In some embodiments of the present application, the relay unit includes at least one normally closed relay. When the input circuit of the normally closed relay is powered, the video signal input through the signal input terminal is first transmitted to the first differential amplification unit for amplification, and then amplified by the second differential amplification unit and transmitted to the signal output terminal for video signal forwarding. When the input circuit of the normally closed relay is not powered, the video signal input through the signal input terminal is directly transmitted to the signal output terminal for video signal forwarding.

[0052] It should be noted that in order to avoid the influence of the failure or damage of the current circuit on the transmission of video signals to the next LCD display screen, it is necessary to ensure that the video signal can still be forwarded to the next LCD display screen when the current circuit fails. In the above embodiments, by using a normally closed relay to set up the relay unit, this requirement can be achieved. Thus, the fault tolerance of the circuit is improved, ensuring that the video signal can still be transmitted in case of a failure, and also reducing the risk of the decline in the passenger experience caused by circuit failures.

[0053] Among them, the normally closed relay is closed by default (i.e., when there is no applied voltage), which means that current or signal can pass through it. When an applied voltage acts on the relay (usually to change its state), it will open. However, in case of power failure or failure of the relay unit resulting in no power supply to the input circuit, the relay will remain closed. Thus, when there is power supply to the input circuit of the normally closed relay (usually indicating normal operation of the system), the relay will open, and at this time, the video signal will be amplified by two-stage differential amplification units and then transmitted to the signal output terminal to ensure signal quality and stability. If the power supply unit fails or the relay unit loses power supply for some reason, the normally closed relay will remain closed. In this case, the video signal input through the signal input terminal will directly bypass the differential amplification unit and be directly transmitted to the signal output terminal through the closed relay contact. This design ensures that even if the current circuit fails, the video signal can continue to be transmitted through another path, thus avoiding the impact on the next LCD display screen.

[0054] In some embodiments of the present application, the first differential amplification unit includes a differential amplifier chip of model EL5375IUZ or EL4543IUZ. Similarly, in some embodiments of the present application, the second differential amplification unit may also include a differential amplifier chip of model EL5375IUZ or EL4543IUZ.

[0055] It should be noted that EL5375IUZ is a three-channel differential amplifier chip with a gain-bandwidth product of up to 200MHz. Its input bias current and input offset voltage are both maintained at a low level, which helps to reduce signal distortion. And EL4543IUZ is a differential amplifier chip with a bandwidth of 350MHz and a slew rate of 1000V / μs, which can be perfectly applicable to the processing and forwarding of high-speed video signals in the present application. In the in-vehicle information display system of subway vehicles, the transmission quality and stability of video signals are crucial. Using EL5375IUZ or EL4543IUZ as the differential amplifier chip of the first differential amplification unit and / or the second differential amplification unit can significantly improve the anti-interference ability and transmission distance of video signals. The differential amplification technology itself can effectively suppress common-mode noise, and the high bandwidth and high speed of these two chips further ensure the integrity and clarity of the signal during transmission.

[0056] In some embodiments of the present application, the signal processing unit includes an MCU control chip of model NT68168BFG.

[0057] In the above embodiments, the MCU of the NT68168BFG model has high-precision ADC and DAC peripheral interfaces, which can accurately collect and process analog signals. This helps to improve the accuracy and precision of the signal processing unit, thus ensuring the stability and reliability of the system. At the same time, this MCU has rich built-in peripheral interfaces and expandable memory, which can support a variety of signal processing and control tasks. This enables the signal processing unit to better adapt to various complex application scenarios and improves the flexibility and scalability of the system.

[0058] Among them, in the signal processing unit, the NT68168BFG plays a crucial role. It is responsible for receiving, processing, and transmitting signals to achieve precise control of the entire system. Specifically, through its built-in peripheral interfaces such as ADC (Analog-to-Digital Converter) and DAC (Digital-to-Analog Converter), this MCU can collect and process analog signals in real time and convert them into digital signals for further processing. At the same time, it can also communicate with other circuit components through interfaces such as GPIO (General-Purpose Input / Output Port) to control external devices.

[0059] In addition, the NT68168BFG also has powerful algorithm calculation and control capabilities. It can process signals such as filtering, amplification, and modulation according to preset algorithms and parameters, so as to achieve precise control of the signals. This ability enables the signal processing unit to better adapt to various complex application scenarios and improves the overall performance of the system.

[0060] The embodiment of this application also provides a device for signal transmission of the LCD display screen of a subway vehicle, which includes a circuit for signal transmission of the LCD display screen of a subway vehicle as described above. By encapsulating the circuit with signal transmission of the LCD display screen of a subway vehicle into a housing, a device for signal transmission of the LCD display screen of a subway vehicle can be made, which is conducive to users' use and is convenient and fast.

[0061] To enable those skilled in the art to more intuitively understand this application, a specific example will be given here for illustration.

[0062] In this example, as Figure 4 shown, the serial port socket CON12 and the terminal block CN16 constitute the signal input terminals, while the serial port socket CON14 and the terminal block CN17 constitute the signal output terminals. Among them, the signal input terminal part also includes the capacitor C42 and the fuse A21, and the signal input terminal part also includes the capacitor C34 and the fuse A20. As Figure 5 shown, in this example, the relay unit includes 3 signal relays of the model G6J-2P-Y-4.5V, as well as a matching common-mode inductor. As Figure 6As shown, the first TVS protection unit in this example includes two electrostatic protection tubes (U44 and U45) of the AZC099-04S.R7G model, as well as capacitor C66 and capacitor C67. As Figure 7 As shown, the first differential amplification unit in this example includes a differential amplifier chip U48 of the EL5375IUZ model and its peripheral circuit, which mainly includes a series of inductors, capacitors and resistors. As Figure 8 As shown, the second differential amplification unit in this example includes a differential amplifier chip U3 of the EL4543IUZ model, capacitor C60 and multiple resistors (resistor R9, resistor R10, resistor R12, resistor R13, resistor R16 and resistor R17). As Figure 9 As shown, the second TVS protection unit in this example includes two electrostatic protection tubes (U46 and U47) of the AZC099-04S.R7G model, as well as capacitor C58 and capacitor C59. As Figure 10 As shown, the signal processing unit in this example includes an MCU chip U5 of the NT68168BFG model and its peripheral circuit, which mainly includes capacitors, resistors and crystal oscillators. As Figure 11 As shown, the audio amplification unit in this example includes an audio power amplification chip U35 of the NS4268 model and its peripheral circuit, which mainly includes capacitors, resistors and a terminal block CN11. As Figure 12 As shown, the video signal output unit in this example includes terminal block CN8, triode Q2, triode Q3, resistor R7, resistor R32, resistor R33 and capacitor C18. As Figure 13 As shown, the serial port unit in this example includes terminal block CN5, terminal block CN14 and terminal block CN14 and their respective peripheral circuits. As Figure 14A 、 14B As shown in 14C, the unit part in this example includes a first voltage regulation part, a second voltage regulation part, a flash storage part and a power management chip part. Among them, the first voltage regulation part is mainly composed of a linear voltage regulator chip U2 of the LC1117CLTR33 model, terminal block CON10 and terminal block CN. The second voltage regulation part is composed of a switching voltage regulator chip U50 of the LM2F662M model, resistor A6, capacitor E23, capacitor C41 and capacitor E21. The flash storage part is composed of a flash memory of the GD25Q41BTIG model, capacitor C19 and resistor R24. The power management chip part is composed of a power management chip U1 of the FR9888SPGTR model and its peripheral circuit, and the peripheral circuit includes resistor R2, resistor R3, resistor R4, resistor R, resistor R1, capacitor C3, capacitor C4, capacitor C27, capacitor C14, capacitor E54, capacitor E55, inductor L24.

[0063] In this example, the video signal is controlled by three signal relays of model G6J-2P-Y-4.5V, and different forwarding loops are determined by whether power is supplied ( Figure 1 the forwarding loop 1 and forwarding loop 2 in

[0064] When power is supplied: The video signal is input through the serial port socket CON12, transmitted by the signal relay of model G6J-2P-Y-4.5V, and then processed by the differential amplifier chip U48 after passing through the inductor L61, inductor L62, inductor L63, resistor R100, resistor R103, resistor R104, resistor R107, resistor R108, resistor R111. After passing through resistor R59, resistor R66, resistor R73, inductor L1, inductor L2, inductor A19, and then through the differential amplifier chip U3, it is output from the serial port socket CON14 through resistor R9, resistor R10, resistor R12, resistor R13, resistor R16, resistor R17. The audio signal is input through the serial port socket CON12 and directly output from the serial port socket CON14.

[0065] When power is not supplied: The video signal is input through the serial port socket CON12, transmitted by the signal relay of model G6J-2P-Y-4.5V, and then directly output from the serial port socket CON14. The audio signal is input through the serial port socket CON12 and directly output from the serial port socket CON14.

[0066] When transmitting the video signal to the current LCD display, the signal processed by the differential amplifier chip U48 passes through resistor R38, resistor R40, resistor R41, resistor R43, capacitor C24, capacitor C26, capacitor C28, capacitor C30, and then is output from the interface of the 2*15P terminal block CN8 after being processed by the MCU chip U5. The audio signal input from the serial port socket CON12 is amplified and processed by the audio power amplifier chip U35 through capacitor C16 and then output from the interface of the terminal block CN11.

[0067] For those skilled in the art, it is obvious that this application is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of this application, this application can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of this application is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in this application. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. A circuit for signal transmission of a subway vehicle LCD display screen, characterized in that: The circuit includes a signal input terminal, a signal output terminal, a first differential amplification unit, a second differential amplification unit, a relay unit, a signal processing unit, a video signal output unit, and an audio signal output unit; The signal input terminal is used to receive video signals and audio signals, and one end of the output circuit of the relay unit is connected to the signal input terminal, and the other end is connected to the signal output terminal; wherein, when the output circuit of the relay unit is connected, the video signal received through the signal input terminal is directly transmitted to the signal output terminal for video signal forwarding; when the output circuit of the relay unit is disconnected, the video signal received through the signal input terminal is first transmitted to the first differential amplifier unit for amplification, and then amplified by the second differential amplifier unit and transmitted to the signal output terminal for video signal forwarding; The video signal input through the signal input terminal is amplified by the first differential amplifier unit, and then transmitted to the signal processing unit for signal processing and then transmitted to the video signal output unit; The audio signal input through the signal input terminal is output through the audio signal output unit, and the size of the output audio signal is adjusted by the signal processing unit.

2. The circuit according to claim 1, wherein: The circuit further includes an audio amplifying unit, a signal input terminal and a signal processing unit are respectively connected to the input end of the audio amplifying unit, and an output end of the audio amplifying unit is connected to the audio signal output unit.

3. The circuit according to claim 1 or 2, characterized in that The circuit also includes a first TVS protection unit and a second TVS protection unit; the signal input terminal is connected to the first differential amplifier unit through the first TVS protection unit, the second differential amplifier unit is connected to the signal output terminal through the second TVS protection unit, and the first TVS protection unit is also connected to the output circuit of the relay unit.

4. The circuit according to claim 1, wherein: The circuit further includes a power supply unit configured to provide an operating voltage to the first differential amplification unit, the second differential amplification unit, the relay unit, the signal processing unit, the video signal output unit, and the audio signal output unit.

5. The circuit according to claim 1, wherein: The relay unit includes at least one normally closed relay. When the input circuit of the normally closed relay is powered, the video signal connected through the signal input terminal is first transmitted to the first differential amplifier unit for amplification, and then amplified by the second differential amplifier unit and transmitted to the signal output terminal for video signal forwarding; when the input circuit of the normally closed relay is not powered, the video signal connected through the signal input terminal is directly transmitted to the signal output terminal for video signal forwarding.

6. The circuit according to claim 1, wherein: The first differential amplifier unit includes a differential amplifier chip of EL5375IUZ or EL4543IUZ model.

7. The circuit according to claim 1, wherein: The second differential amplifier unit includes a differential amplifier chip of EL5375IUZ or EL4543IUZ model.

8. The circuit according to claim 1, wherein: The signal processing unit includes an NT68168BFG MCU control chip.

9. A device for transmitting signals on a subway vehicle LCD display screen, characterized in that: The invention comprises a circuit for transmitting signals of an LCD display screen of a subway vehicle as described in any one of claims 1 to 8.

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