Optical disc of light. An early optical disc system existed in 1935, named . An early analog optical disc used for video recording was invented by David Paul Gregg in 1958 and patented in the US in 1961 and 1969. This form of optical disc was a very early form of the DVD (). It is of special interest that , filed 1989, issued 1990, generated royalty income for Pioneer Corporation's DVA until 2007 —then encompassing the CD, DVD, and Blu-ray systems. In the early 1960s, the Music Corporation of America bought Gregg's patents and his company, Gauss Electrophysics. American inventor James
Optical disc drive maximum speed (56× for CDs or around 18× in the case of DVDs) at which drives can operate. Current optical drives use either a "tray-loading" mechanism, where the disc is loaded onto a motorized or manually operated tray, or a "slot-loading" mechanism, where the disc is slid into a slot and drawn in by motorized rollers. With both types of mechanism, if a CD or DVD is left in the drive after the computer is turned off, the disc cannot be ejected using the normal eject mechanism of the drive. However, tray-loading drives account for this situation by providing a