22-10-2010, 04:10 PM
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compact disc
History
The compact disc is a spin-off of the Laserdisc technology. Philips publicly demonstrated a prototype of an optical digital audio disc at a press conference called "Philips Introduce Compact Disc"[2] in Eindhoven, The Netherlands on March 8, 1979.Three years earlier, Sony first publicly demonstrated an optical digital audio disc in September 1976. In September 1978, they demonstrated an optical digital audio disc with a 150 minute playing time, and with specifications of 44,056 Hz sampling rate, 16-bit linear resolution, cross-interleaved error correction code, that were similar to those of the Compact Disc introduced in 1982. Technical details of Sony's digital audio disc were presented during the 62nd AES Convention, held on March 13-16, 1979 in Brussels.
Later that year, Sony and Philips Consumer Electronics (Philips) set up a joint task force of engineers to design a new digital audio disc. The task force, led by prominent members Kees Schouhamer Immink and Toshitada Doi , progressed the research into laser technology and optical discs that had been started independently by Philips and Sony in 1977 and 1975, respectively.After a year of experimentation and discussion, the taskforce produced the Red Book, the Compact Disc standard. Philips contributed the general manufacturing process, based on video Laserdisc technology. Philips also contributed Eight-to-Fourteen Modulation which offers both a long playing time and a high resilience against disc defects such as scratches and fingerprints, while Sony contributed the error-correction method, . The Compact Disc Story,told by a former member of the taskforce, gives background information on the many technical decisions made, including the choice of the sampling frequency, playing time, and disc diameter. The taskforce consisted of around four to eight persons, though according to Philips, the compact disc was thus "invented collectively by a large group of people working as a team.
