Pattern buffer
From Memory Alpha, the free Star Trek reference.
The pattern buffer is a key component of the transporter system. The buffer is used to temporarily store the matter stream, following dematerialization, but prior to sending the stream to its target. This is done because of the relative motion of transporter and target. By temporarily storing the matter stream, the Doppler compensators have the time to adjust the targeting scanners.
A matter stream cannot be stored indefinitely in the buffer; after 420 seconds, the stored pattern will degrade and the object will be lost. The only known record of a person surviving in a buffer longer than the expected figure was Captain Montgomery Scott on board the USS Jenolan. Following the Jenolan's crash-landing on a Dyson sphere, Scott, with the help of Matt Franklin, was able to store his pattern in the buffer for 75 years. This was achieved by disabling the rematerialization subroutine, connecting the phase inducers to the emitter array, bypassing the override, and locking the buffer into a continuous diagnostic cycle. Although Captain Scott's pattern suffered less than 0.003% degradation, and was successfully recovered by Geordi La Forge of the USS Enterprise-D in 2369, Franklin was irretrievable, as one of the inducers had failed, causing a 53% degradation in his pattern. (TNG: "Relics")
In 2152, diamagnetic storms saturated with polaric energy were encountered on a planet visited by the crew of the first starship Enterprise. The storms interfered with the operation of the ship's transporter, resulting in Hoshi Sato being trapped in its pattern buffer for 8.3 seconds while Malcolm Reed worked to reintegrate the matter stream. (ENT: "Vanishing Point")
On Galaxy-class starships the pattern buffer is located immediately beneath the transporter pad.
When weapons were beamed to a rebel camp on Krios from a cargo transporter of the Enterprise-D in 2367, Miles O'Brien asked Geordi La Forge if he could check the reliability of the pattern buffers. (TNG: "The Mind's Eye")
When Jadzia Dax decided to stay on planet Meridian in 2371, the transporter buffer of the USS Defiant was used to bring her quantum matrix in sync with that of the Meridians. (DS9: "Meridian")
Starships can also transfer patterns from one pattern buffer to another by "locking on" to the target buffer and energizing. (VOY: "Future's End, Part II")
To eliminate the medical condition called transporter psychosis, Federation transporters are equipped with multiplex pattern buffers. (TNG: "Realm of Fear")
The transporter buffer of an Intrepid-class starship performs a version of a microcellular scan every time it is used. (VOY: "Favorite Son")
Cardassian transporter systems were still equipped with active feed pattern buffers in 2367, considered outdated by Starfleet. (TNG: "The Wounded")
In 2374, the crew of Voyager overloaded the ship's pattern buffers attempting to transport deuterium from beneath the surface of a Y-class planet. (VOY: "Demon")
