This content comes from the following networks. Hope it helps.
/article/88/171/2008/2008102014723.html
HDMI interface types According to the difference in electrical structure and physical shape, HDMI interfaces can be divided into Type?A?, Type? B, ?Type?C three types. Each type of interface consists of a socket for the device side and a plug for the wire side. They are driven by 5V low voltage and have an impedance of 100 ohms. All three types of plugs can provide reliable TMDS connections. Type A is a standard 19-pin HDMI interface and has the highest penetration rate. Type B interface is slightly larger in size, but has 29 pins and can provide dual TMDS transmission channels, so it supports Higher data transfer rates and Dual-Link? DVI connectivity. The Type C interface has the same performance as the Type A interface, but is smaller in size and is more suitable for compact portable devices.
Physical specifications of Type?A
TYPE?A is the most common interface form. The Type?A HDMI socket is in a flat "D" shape, wide at the top and narrow at the bottom. There is a metal shielding layer with a thickness of 0.5 mm on the outside of the interface to prevent various interference signals from the outside world. Among them, the inner diameter of the socket used for the equipment end is 14 mm at its widest and 4.55 mm high. The 19 pins are arranged in two layers in the center. Each pin is 0.45mm wide and 4.1mm long.
The outer diameter of the Type A plug is 13.9 mm at its widest point and 4.45 mm high. The pins inside are arranged in a ring. The HDMI standard stipulates that the errors in these dimensions should be controlled within a fairly small range (around 0.05 mm) to ensure good contact. ?
Taking Type?A as an example, the definitions of each HDMI pin are as follows:
Physical specifications of Type?B
Physical structure of Type B HDMI interface Compared with the A-type interface, the basic shape has not changed much, it is all "D" type. However, the maximum width of the socket end reaches 21.3 mm, which is a full circle larger than the 14 mm of Type A.
Correspondingly, the size of the plug end of the B-type interface has also changed. See the figure below for details.
Type?B type interface
Type?C interface physical specifications
Type?C?-Type?A converter
These three HDMI interfaces are not fully compatible, which means that type A head cannot be connected to type B head through an adapter device, and type B head cannot be converted to type C head. However, since type A head and The C-type heads are only different in physical size, and they can be compatible through conversion equipment.
The conversion between HDMI and DVI is a physical conversion. Because it uses the same TMDS transmission mechanism as DVI, HDMI has very strong compatibility with the DVI interface. There are also many HDMI-DVI adapter products on the market, which are very suitable for old equipment without HDMI. The HDMI-DVI adapter is essentially a physical conversion tool between the two connectors. It only involves the shape, size and pin definition of the interface, and there is no change in the circuit part. The HDMI standard also takes into account the issue of compatibility with DVI devices: as long as the HDMI device detects that the signal sent by the other party does not contain the special control data (VSDB signal) specified in the HDMI standard, it is specifically used for two devices to confirm each other's identity. ), the other party will be regarded as a DVI device and the transmission specification will be switched to the DVI format, thereby ensuring good compatibility.