In computing, an optical disc drive is a disc drive that reads or writes data to or from optical discs using electromagnetic waves or laser light that are in or close to the visible light spectrum. Recent drives, sometimes known as burners or writers (because they physically burn the organic dye on write-once CD-R, DVD-R, and BD-R LTH discs), can read and write data to and from discs, in contrast to older drives that can only read data from certain discs. Common optical media that can be read and recorded by these drives include compact discs, DVDs, and Blu-ray discs.
History
The 12-inch Laservision video disc was the first laser disc, and it was presented in 1972. An analogue format, similar to that of a video cassette, was used to store the video signal. A 5-inch audio compact disc (CD) in a read-only format developed by Sony and Philips in 1975 was the first optical disc to be recorded digitally.
In 1983, Sony, Kokusai Denshin Denwa (KDDI), and Matsushita (Panasonic) announced the creation of the first erasable optical disc drives. In 1987, Sony finally unveiled the first 5-inch optical disc drive that could be erased and written to again, with dual-sided discs that could store 325 MB each side.
Sony introduced the MiniDisc format in September 1992, which was intended to combine the convenience of a cassette size with the audio fidelity of CDs.80 minutes of audio can be stored in the usual capacity. Sony unveiled an enhanced Hi-MD format in January 2004 that included a 1 GB (48 hours of audio) capacity boost.
Sony introduced the first Blu-ray prototype in October 2000, and on April 10, 2003, the first commercial recording device hit the market. TDK revealed in January 2005 that they had created “Durabis,” an ultra-hard yet incredibly thin polymer coating, for Blu-ray discs. This was a key technical advancement since consumers wanted better protection than DVD for bare discs to prevent damage and scratching. Technically speaking, Blu-ray Disc also needed a thinner layer due to the ‘blue’ laser’s’ lower wavelength and narrower beam. Midway through June 2006, the Samsung BD-P1000 became the first BD-ROM player to be distributed. Sony and MGM launched the first Blu-ray Disc titles on June 20, 2006.
With the introduction of low-cost, tough, quick, and high-capacity USB drives and video on demand over the internet, computer manufacturers started to discontinue installing built-in optical disc drives on their computers in the middle of the 2010s. In laptops, the absence of an optical drive enables the use of larger batteries or circuit boards that are less dense and require fewer layers, which lowers production costs and reduces weight and thickness. Additionally, makers of computer cases started to stop supplying 5-by-14-inch slots for mounting optical disc drives. However, it’s still possible to buy brand-new optical disc drives. Hitachi, LG Electronics, Toshiba, Samsung Electronics, Sony, NEC, Lite-On, Philips, Pioneer Corporation, Plextor, Panasonic, Yamaha Corporation, and Kenwood are notable optical disc drive OEMs.
Types of DVD
The majority of optical disc drives on the market as of 2023 are DVD-ROM and BD-ROM drives, which read and write to those formats as well as supporting CD, CD-R, and CD-ROM discs. Compact disc drives are no longer produced separately from audio equipment. Although read-only DVD and Blu-ray drives are produced, they are less prevalent in the consumer market and are primarily used in media players and game consoles. Due to cost-cutting and weight-saving measures during the past ten years, laptop computers no longer come with optical disc drives, necessitating the purchase of external optical drives by customers.
With factory-pressed read-only media (ROM), pits and lands are generated in the plastic disc by pressing a thermoplastic resin into a nickel stamper that was made by plating a glass “master” with raised “bumps” on a flat surface. The phase of the reflected beam is changed with reference to the incoming beam because the depth of the pits is around 1/4 to 1/60 of the laser’s wavelength. This causes mutual destructive interference and lowers the intensity of the reflected beam. Photodiodes use this as a source of information to produce electrical impulses that correspond.
By laser-selectively heating (burning) specific regions of an organic dye layer, an optical disc recorder encodes (also known as burns, as the dye layer is permanently burned) data into a recordable CD-R, DVD-R, DVD+R, or BD-R disc (referred to as a blank).
This alters the dye’s reflectivity and produces readable markings like pits and landings on pressed discs. The technique is permanent for recordable discs, and the media may only be written to once. The writing laser is far more potent than the reading laser, which typically has a maximum power of 5 mW. Around 2.5 volts is the operating voltage for DVD lasers.
A laser’s power must grow proportionately to the writing speed because the faster the writing, the less time it needs to heat a point on the media. Although some lasers have been operated up to 400 mW before the diode fails, DVD burner lasers typically peak at around 200 mW, either in continuous wave or bursts.
The recording layer of rewritable CD-RW, DVD-RW, DVD+RW, DVD-RAM, or BD-RE media is heated by a laser to melt a crystalline metal alloy. The material can either be kept in an amorphous state or allowed to melt back into crystalline form depending on the amount of power used, allowing for the creation of marks with different levels of reflectivity.
Although double-sided media can be utilized, accessing the data on the other side requires physically turning the media over, which makes using a regular drive difficult.
Two independent data layers are separated by a semi-reflective layer in double-layer or dual-layer (DL) media. Both layers are reachable from the same side, however switching the laser’s focus requires the optics. Traditional single-layer (SL) writable media are made with a spiral groove that is sculpted into the protective polycarbonate layer (rather than the data recording layer) to lead and coordinate the speed of the recording head. The components of a double-layered writable medium are as follows: a first data layer, a first polycarbonate layer with a shallow groove, a first semi-reflective layer, a second (spacer) polycarbonate layer with a deeper groove, and a second data layer. In contrast to the second groove spiral, which begins on the outside edge and moves inside, the first groove spiral typically begins on the inner edge and moves outside.
Drives created by Zen Technology and Sony use several laser beams operating simultaneously to read and write discs at speeds that are faster than those feasible with a single laser beam. The disc’s potential for wobbling at high rotating speeds, where CDs become unreadable above 25,000 RPM and Blu-rays can only be written to beyond 5,000 RPMs, is the reason for the constraint of a single laser beam. By increasing the rotational speed of the disc, which reads more pits in less time, increasing the data rate, faster drives spin the disc at higher rates, which is the only option to enhance read and write speeds with a single laser beam without changing the pit length of the disc. Additionally, CDs of poor quality or broken discs may explode at lower speeds and at 27,500 RPMs, seriously damaging the area around the disc.
Appliances and Functionality of DVD
Optical disc drives are a crucial component of stand-alone devices like CD players, DVD players, Blu-ray disc players, DVD recorders, as well as some desktop video game consoles like the Sony PlayStation 4, Microsoft Xbox One, Nintendo Wii U, Sony PlayStation 5, and Xbox Series X, as well as older consoles like the Sony PlayStation 3 and Xbox 360, and some portable video game consoles like the Sony PlayStation Portable (using proprietary, now-discontinued UMDs). Additionally, they are frequently used in computers to record discs for archival and data exchange reasons as well as to read discs that contain software and other media.
The 1.44 MB capacity of floppy disc drives has been rendered obsolete because optical media, which are inexpensive and have a much higher capacity to accommodate massive data, are now the norm for computers and a lot of consumer electronics. Where read/write capability is required, high-capacity, tiny, and affordable USB flash devices are acceptable.
A standard DVD holds 4.7 gigabytes, but there are higher-capacity formats like multi-layer Blu-ray Discs that are available. Disc recording is limited to storing files that can be played on consumer appliances (movies, music, etc.), relatively small volumes of data for local use, and data for distribution, but only on a small scale. Mass-producing many identical discs by pressing (replication) is less expensive and faster than individual recording (duplication).
Drives with mechanical tray loading (desktop computer drives) include an indentation in the tray to support 8-centimeter-diameter discs. However, it can only be applied to horizontal processes. Slot-loading drives, which are widely seen in game consoles and vehicle radios, would be able to recognise discs that are 8 centimetres in diameter and automatically centre the disc.
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