Technical Analysis of Two Technologies for HDMI Interface Connectors

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HDMI interface connectors are widely used at present, especially under the market trend of integrated Internet TV and home appliance ecological chains. According to Guoguang Group, they are applied to high-definition TV set-top boxes, DVD players, personal computers, video game consoles, integrated amplifiers, digital audio equipment and televisions. HDMI interfaces can be classified into three types: Type A, Type B and Type C. Each type of interface consists of a socket for equipment terminals and a plug for cable terminals.

According to data platforms, HDMI interface connectors are convenient to use, as a single cable can transmit both audio and video signals. Is this statement true?

Based on user feedback, many users who are new to HDMI interfaces believe that the so-called "all-in-one HD cable" can transmit both audio and video signals at the same time. However, after connecting a computer to an LCD TV via an HDMI port, they find that the TV has no sound.

Why does this happen?

ELINKcar, an HDMI connector manufacturer, analyzes that audio and video signals of most computers are independent and output separately. Video signals are output from the computer's graphics card or integrated graphics card on the motherboard, while audio needs to be output from the sound card or integrated sound card on the motherboard. Therefore, even if the graphics card is equipped with an HDMI or DVI interface, it only transmits video signals without audio. Users need an additional audio output to hear matching sound.

When purchasing an LCD TV and planning to connect it to a computer via HDMI or DVI conversion, consumers should check in advance whether the product has a dedicated audio input interface reserved for the HDMI port. If not, speakers will be required for the computer's audio output.

Lianka Automotive Electronics has learned that some claim HDMI supports hot-plugging while others hold the opposite view. The following explains this from several technical principles.

The 19th pin of the HDMI female connector is a shortened pin, known as the Hot Plug Detect (HPD) pin. When unplugging the HDMI cable, this pin disconnects first. The HDMI circuit then detects the disconnection and notifies the input/output devices to stop working, enabling hot-plugging. The principle relies on different pin lengths to achieve hot-plugging, which is somewhat similar to that of USB. A USB interface has four gold fingers inside, with the two longer ones for power supply, ensuring priority power supply during plugging and unplugging, followed by data exchange, thus protecting device data during hot-plugging.

In addition to supporting hot-plugging, HDMI interface devices also feature "plug-and-play", which has greatly promoted the popularity of HDMI devices. As a connector manufacturer, Guoguang Group shares the technical applications of various interface connectors.