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An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals. The connectors are also sometimes casually referred to as A/V jacks. The name "RCA" derives from the Radio Corporation of America, which introduced the design by the early 1940s for internal connection of the pickup to the chassis in home radio-phonograph consoles. It was originally a low-cost, simple design, intended only for mating and disconnection when servicing the console. Refinement came with later designs, although they remained compatible. RCA connectors began to replace the older quarter-inch phone connectors for many other applications in the consumer audio world when component high-fidelity systems started becoming popular in the 1950s. However, quarter-inch phone connectors are still common in professional audio, while miniature phone connectors (3.5 mm) have become predominant in personal stereo systems. The connection's plug is called an RCA plug or phono plug, for "phonograph." The name "phono plug" is sometimes confused with a "phone plug" which may refer to a quarter-inch "phone plug" - Tip/Sleeve (TS) or Tip/Ring/Sleeve (TRS) connector - or to a 4P4C connector used for a telephone (which is often, though incorrectly, called "RJ9", "RJ10", or "RJ22"). ==Uses== In the most normal use, cables have a standard plug on each end, consisting of a central male connector, surrounded by a ring. The ring is often segmented for flexibility. Devices mount the socket (female jack), consisting of a central hole with a ring of metal around it. The ring is slightly smaller in diameter and longer than the ring on the plug, allowing the plug's ring to fit tightly over it. The jack has a small area between the outer and inner rings which is filled with an insulator, typically plastic (very early versions, or those made for use as RF connectors used ceramic). As with many other connectors, the RCA has been adopted for other uses than originally intended, including as a power connector, an RF connector, and occasionally as a connector for loudspeaker cables. Its use as a connector for composite video signals is extremely common, but provides poor impedance matching. RCA connectors and cable are also commonly used to carry S/PDIF-formatted digital audio, with plugs colored orange to differentiate them from other typical connections. Connections are made by pushing the cable's plug into the female jack on the device. The signal-carrying pin protrudes from the plug, and often comes into contact with the socket before the grounded rings meet, resulting in loud hum or buzz if the audio components are powered while making connections. Continuous noise can occur if the plug partially falls out of the jack, breaking ground connection but not the signal. Some variants of the plug, especially cheaper versions, also give very poor grip and contact between the ground sheaths due to their lack of flexibility. They are often color-coded, yellow for composite video, red for the right audio channel, and white or black for the left channel of stereo audio. This trio (or pair) of jacks can be found on the back of almost all audio and video equipment. One or more sets are often found on the front panel of modern TV sets to facilitate connection of camcorders, other portable video sources and video game consoles. Although nearly all connectors, including analog and S/PDIF audio as well as composite and component video, can use identical 75 Ω cables, sales of special-purpose cables for each use have proliferated. Varying cable quality means that a cheap line-level audio cable might not successfully transfer component video or digital audio signals due to impedance mismatch and poor shielding quality (causing signal-to-noise ratio to be too low). For digital audio, cables should meet the S/PDIF specification as defined by the international standard IEC 60958-3 for assured performance. The male plug has a center pin which is 3.175 mm (1/8 inch) in diameter, and is surrounded by an outer shell which is 8.25 mm (1/3 inch) in diameter. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「RCA connector」の詳細全文を読む スポンサード リンク
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