Subway vehicle LCD display screen signal transmission circuit and device

Abstract

The invention 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] The present application relates to the technical field of vehicle-mounted screens, and in particular to a circuit and device for transmitting signals of an LCD display screen on a subway vehicle. Background Art

[0002] The signal transmission circuit of the subway vehicle LCD display screen, as the core component of the subway vehicle internal information display system, 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. At present, the signal transmission circuit of the subway vehicle LCD display screen mostly adopts 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 a simple amplification circuit.

[0003] However, the existing direct transmission or simple amplification processing methods lack effective anti-interference mechanisms and are prone to signal loss or quality degradation. They have limited anti-interference capabilities and poor stability, and cannot effectively guarantee signal transmission between multiple LCD screens. Summary of the invention

[0004] In order to solve the above problems, the present application provides a circuit and device for signal transmission of a subway vehicle LCD display screen, which can improve the anti-interference ability of display screen signals transmitted between multiple LCD screens.

[0005] This application is implemented as follows:

[0006] In the first aspect, the present application provides a signal transmission circuit for a subway vehicle LCD display screen, which includes a signal input terminal, a signal output terminal, a first differential amplifier unit, a second differential amplifier 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 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 accessed 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 accessed 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 accessed through the signal input terminal is also 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 accessed 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.

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

[0009] In some implementations, the circuit further includes a power supply unit for providing 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.

[0010] In some implementations, 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.

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

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

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

[0014] In a second aspect, the present application provides a device for transmitting signals on an LCD display screen of a subway vehicle, which includes a circuit for transmitting signals on 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 invention has at least the following advantages or beneficial effects:

[0016] This application optimizes the circuit topology so that when the signal quality is good, the video signal can be transmitted directly to reduce unnecessary processing links. When the signal quality is poor, the two-stage differential amplification transmission can effectively suppress noise and improve the signal's anti-interference ability. And the audio signal output size can be dynamically adjusted according to environmental noise or passenger needs to ensure the audio playback effect. In other words, this application achieves fine processing and flexible control of video and audio signals by optimizing the circuit topology, which can not only ensure the anti-interference ability of video signals transmitted between multiple LCD screens, but also reduce unnecessary processing links and improve 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 drawings required for use in the embodiments will be briefly introduced below. 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 related drawings can be obtained based on these drawings without paying creative work.

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

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

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

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

[0025] Figure 8This is a schematic diagram of the circuit principle of the second differential amplifier unit in an embodiment of a circuit for signal transmission of a subway vehicle LCD display screen in the present application;

[0026] Fig. 9 This is a schematic diagram of the circuit principle of the second TVS protection unit in an embodiment of a circuit for signal transmission of a subway vehicle LCD display screen in the present application;

[0027] Fig.10 This is a schematic diagram of the circuit principle of a signal processing unit in an embodiment of a circuit for signal transmission of a subway vehicle LCD display screen in the present application;

[0028] Fig.11 This is a schematic diagram of the circuit principle of an audio amplifier unit in an embodiment of a circuit for signal transmission of a subway vehicle LCD display screen in the present application;

[0029] Fig.12 This is a schematic diagram of the circuit principle of a video signal output unit in an embodiment of a signal transmission circuit for an LCD display screen of a subway vehicle of the present application;

[0030] Fig.13 This is a schematic diagram of the circuit principle of the serial port unit in an embodiment of a circuit for signal transmission of a subway vehicle LCD display screen in the present application;

[0031] Fig.14A This is a schematic diagram of the circuit principle of the first voltage stabilizing part of the power supply unit in an embodiment of a signal transmission circuit for an LCD display screen of a subway vehicle of the present application;

[0032] Fig. 14B This is a schematic diagram of the circuit principle of the second voltage stabilizing part and the flash storage part of the power supply unit in an embodiment of a signal transmission circuit for an LCD display screen of a subway vehicle of the present application;

[0033] Fig. 14C This is a schematic diagram of the circuit principle of the power management chip part of the power supply unit in an embodiment of a circuit for signal transmission of an LCD display screen of a subway vehicle of the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here 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 accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0036] Example:

[0037] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0038] Please refer to Figure 1 , a signal transmission circuit for a subway vehicle LCD display screen includes a signal input terminal, a signal output terminal, a first differential amplifier unit, a second differential amplifier 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 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 accessed 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 accessed 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 accessed through the signal input terminal is also 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 accessed 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.

[0039] It should be noted that due to the complex electromagnetic environment inside the subway vehicle, the directly transmitted video signal is easily interfered, resulting in a decrease in picture quality and affecting the viewing experience of passengers. However, if the video signal is good, it is still transmitted after a simple amplification circuit, which may cause unnecessary signal processing. In other words, the existing video signal is either directly transmitted to the display screen after being connected through the input terminal, or transmitted after a simple amplification circuit. The processing method cannot flexibly process the video signal, and the signal stability is poor.

[0040] However, in the above embodiment, the switching between direct transmission of the video signal and differential amplification transmission is achieved by selectively connecting and disconnecting the relay unit. Figure 2As shown, when forwarding the accessed video signal to the next LCD display screen, there are two situations. One is that 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, which reduces unnecessary processing links and improves the efficiency of signal transmission; the other is that when the signal quality is poor, the relay unit is disconnected, and the video signal is amplified by the two-stage differential amplifier unit through the forwarding loop 2 before being transmitted to the next LCD display screen, which effectively enhances the anti-interference ability of the signal and improves the stability of the signal. Among them, when the accessed video signal is output to the current LCD display screen, it is first amplified by the first differential amplifier unit, and then processed by the signal processing unit (mainly the conventional encoding and output processing of the video signal, and the existing self-checking algorithm can be used to control the retransmission of erroneous data and prevent the packet loss of the video signal) before being transmitted to the current LCD display screen. It should be noted that the quality of the signal can be manually judged, and then the power supply of the input loop of the relay unit is turned on / off, so as to realize the switching between the direct transmission of the video signal and the differential amplification transmission. The processor can also be used to analyze the quality of the video signal.

[0041] At the same time, the present application adopts a two-stage differential amplifier unit (the first and second differential units) to amplify the video signal, which can provide a greater gain than a single amplifier circuit. At the same time, the first differential amplifier unit and the second differential amplifier unit can also effectively suppress common-mode noise, further improving the signal-to-noise ratio of the signal, and ensuring the clarity and integrity of the video signal during transmission.

[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 passenger needs. However, the present application adjusts 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 the passengers, thereby ensuring the clarity and comfort of the audio playback.

[0043] In short, when the signal quality is good, the present application directly transmits the video signal to reduce unnecessary processing links. When the signal quality is poor, it transmits through two-stage differential amplification to effectively suppress noise and improve the signal's anti-interference ability. And the audio signal output size can be dynamically adjusted according to environmental noise or passenger needs to ensure the audio playback effect. In other words, the present application achieves fine processing and flexible control of video and audio signals by optimizing the circuit topology, which can not only ensure the anti-interference ability of video signals transmitted between multiple LCD screens, but also reduce unnecessary processing links and improve transmission efficiency and quality.

[0044] Please refer to Figure 2In some embodiments of the present application, the circuit also includes an audio amplifying unit, the signal input terminal and the signal processing unit are respectively connected to the input end of the audio amplifying unit, and the output end of the audio amplifying 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 end of the audio amplification unit is respectively connected to the signal input terminal and the signal processing unit, and the output end is connected to the audio signal output unit. Such a design enables the audio signal to be properly amplified during the transmission process, thereby ensuring the clarity and loudness of the audio playback. The audio signal is pre-processed by the signal processing unit, such as volume adjustment, sound quality optimization, etc., and then amplified by the audio amplification unit, and finally output to the passengers, which can further enhance the passengers' auditory experience. This improvement not only enhances the transmission effect of the audio signal, but also makes the entire circuit system more perfect, which can better meet the needs of the internal information display system of the subway vehicle.

[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 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.

[0047] In the above embodiment, the safety of the circuit is further improved 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 amplifier 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 circuit of the relay unit to ensure that the circuit can be effectively protected when the relay unit switches state.

[0048] On the other hand, the output of the second differential amplifier unit is connected to the signal output terminal through the second TVS protection unit, so that the transient overvoltage can be suppressed again at the signal output end, further ensuring the stability and safety of the output signal.

[0049] In short, by adding these two TVS protection units, the present application can effectively prevent circuit failures caused by transient overvoltages and improve the reliability and stability of the entire circuit. This improvement not only enhances the protection capability of the circuit, but also makes the operation of the subway vehicle internal information display system 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 an operating voltage for the first differential amplifier unit, the second differential amplifier unit, the relay unit, the signal processing unit, the video signal output unit, and the audio signal output unit. By presetting a power supply unit in advance instead of connecting to an external power supply, the stability and reliability of the entire circuit can be guaranteed. After all, a stable power supply is particularly important for the differential amplifier 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 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.

[0052] It should be noted that in order to prevent the failure or damage of the current circuit from affecting the transmission of the video signal of the next LCD display screen, it is necessary to ensure that the video signal can be forwarded to the next LCD display screen when the current circuit fails. In the above embodiment, this requirement can be achieved by setting the relay unit using a normally closed relay. This improves the fault tolerance of the circuit, ensures that the video signal can still be transmitted in the event of a failure, and also reduces the risk of reduced passenger experience due to circuit failure.

[0053] Among them, the normally closed relay is closed by default (i.e. when there is no external voltage), which means that current or signal can pass through it. When an external voltage is applied to the relay (usually to change its state), it will open. However, when the input circuit is not powered due to a power failure or a relay unit failure, the relay will remain closed. In this way, when the input circuit of the normally closed relay is powered (usually indicating that the system is working properly), the relay will open, and the video signal will be amplified by the two-stage differential amplifier unit and then transmitted to the signal output terminal to ensure signal quality and stability. If the power unit fails or the relay unit loses power for some reason, the normally closed relay will remain closed. In this case, the video signal connected through the signal input terminal will directly bypass the differential amplifier unit and be directly transmitted to the signal output terminal through the closed relay contacts. This design ensures that even if the current circuit fails, the video signal can continue to be transmitted through another path, thereby avoiding the impact on the next LCD display.

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

[0055] It should be noted that the EL5375IUZ is a three-channel differential amplifier chip with a gain-bandwidth product of up to 200MHz. Its input bias current and input bias voltage are both kept at a low level, which helps to reduce signal distortion. The EL4543IUZ is a differential amplifier chip with a bandwidth of 350MHz and a slew rate of 1000V / μs, which is perfectly suitable for the processing and forwarding of high-speed video signals in this application. In the internal 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 amplifier unit and / or the second differential amplifier unit can significantly improve the anti-interference ability and transmission distance of the video signal. 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 the NT68168BFG model.

[0057] In the above embodiment, the NT68168BFG model MCU has high-precision ADC and DAC peripheral interfaces, which can realize accurate acquisition and processing of analog signals. This helps to improve the precision and accuracy of the signal processing unit, thereby ensuring the stability and reliability of the system. At the same time, the MCU has built-in rich 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 improve the flexibility and scalability of the system.

[0058] Among them, in the signal processing unit, NT68168BFG plays a vital role. It is responsible for receiving, processing and transmitting signals to achieve precise control of the entire system. Specifically, the MCU can collect and process analog signals in real time through its built-in ADC (analog-to-digital converter) and DAC (digital-to-analog converter) and other peripheral interfaces, 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 input and output port) to achieve control of external devices.

[0059] In addition, NT68168BFG also has powerful algorithm calculation and control capabilities. It can filter, amplify, modulate and process signals according to preset algorithms and parameters, thereby achieving precise control of signals. This capability enables the signal processing unit to better adapt to various complex application scenarios and improve the overall performance of the system.

[0060] The embodiment of the present application also provides a device for transmitting signals on a subway vehicle LCD display screen, which includes a circuit for transmitting signals on a subway vehicle LCD display screen as described above. The device can be made into a device for transmitting signals on a subway vehicle LCD display screen by encapsulating the circuit for transmitting signals on a subway vehicle LCD display screen into a housing, thereby facilitating the user to use the device conveniently and quickly.

[0061] In order to enable those skilled in the art to understand the present application more intuitively, a specific example will be used here to illustrate.

[0062] In this example, if Figure 4 As shown, the serial port socket CON12 and the terminal block CN16 constitute the signal input terminal, while the serial port socket CON14 and the terminal block CN17 constitute the signal output terminal. The signal input terminal part also includes a capacitor C42 and a fuse A21, and the signal output terminal part also includes a capacitor C34 and a fuse A20. Figure 5 As shown in the figure, the relay unit in this example includes three signal relays of model G6J-2P-Y-4.5V and matching common mode inductors. Figure 6As shown, the first TVS protection unit in this example includes two AZC099-04S.R7G electrostatic protection tubes (U44 and U45), and capacitors C66 and C67. Figure 7 As shown, the first differential amplifier 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. Figure 8 As shown, the second differential amplifier unit in this example includes a differential amplifier chip U3 of the EL4543IUZ model, a capacitor C60, and a plurality of resistors (resistor R9, resistor R10, resistor R12, resistor R13, resistor R16, and resistor R17). Fig. 9 As shown, the second TVS protection unit in this example includes two AZC099-04S.R7G electrostatic protection tubes (U46 and U47), as well as capacitors C58 and C59. Fig.10 As shown, the signal processing unit in this example includes an MCU chip U5 of the NT68168BFG model and its peripheral circuits, which mainly include capacitors, resistors and crystal oscillators. Fig.11 As shown, the audio amplifier unit in this example includes an audio power amplifier chip U35 of the NS4268 model and its peripheral circuit, which mainly includes capacitors, resistors and a terminal block CN11. Fig.12 As shown, the video signal output unit in this example includes a terminal block CN8, a transistor Q2, a transistor Q3, a resistor R7, a resistor R32, a resistor R33 and a capacitor C18. Fig.13 As shown, the serial port unit in this example includes a terminal block CN5, a terminal block CN14 and a terminal block CN14 and their corresponding peripheral circuits. Fig.14A , 14B As shown in Figure 14C, the unit part in this example includes a first voltage stabilizing part, a second voltage stabilizing part, a flash storage part and a power management chip part. Among them, the first voltage stabilizing part is mainly composed of a linear voltage regulator chip U2 of the LC1117CLTR33 model, a terminal block CON10 and a terminal block CN. The second voltage stabilizing part is composed of a switching voltage stabilizing chip U50 of the LM2662M model, a resistor A6, a capacitor E23, a capacitor C41 and a capacitor E21. The flash storage part is composed of a flash memory of the GD25Q41BTIG model, a capacitor C19 and a resistor R24. The power management chip part is composed of a power management chip U1 of the FR9888SPGTR model and its peripheral circuit, which includes a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R1, a capacitor C3, a capacitor C4, a capacitor C27, a capacitor C14, a capacitor E54, a capacitor E55 and an 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 circuits are determined by whether power is supplied ( Figure 1 Forwarding loop 1 and forwarding loop 2 in it).

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

[0065] When no power is supplied: the video signal is input from the serial port socket CON12, and is directly output from the serial port socket CON14 after being transmitted by the signal relay of G6J-2P-Y-4.5V. The audio signal is input from the serial port socket CON12 and is directly output from the serial port socket CON14.

[0066] When the video signal is transmitted 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 is processed by the MCU chip U5 before being output from the 2*15P terminal block CN8 interface. The audio signal input from the serial port socket CON12 passes through capacitor C16, is amplified by the audio power amplifier chip U35, and is output from the terminal block CN11 interface.

[0067] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A subway vehicle LCD display signal transmission circuit, 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 access the video signal and the audio signal, 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 accessed 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 accessed through the signal input terminal is firstly 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 also 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, characterized in that The circuit further comprises an audio amplifying unit, a signal input terminal and a signal processing unit are respectively connected to an 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, characterized in that The circuit further includes a power supply unit for providing 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, characterized in that 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, characterized in that The first differential amplifier unit includes a differential amplifier chip of EL5375IUZ or EL4543IUZ model.

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

8. The circuit according to claim 1, characterized in that The signal processing unit includes an MCU control chip of the NT68168BFG model.

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 a subway vehicle LCD display screen as described in any one of claims 1 to 8.

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