It might seem self-evident today, but in the early 1970s it was anything but obvious that a new audio technology—one totally incompatible with existing vinyl records—would have a chance of succeeding in the marketplace. Nevertheless, back then a team of researchers and engineers at N.V. Philips’ Gloeilampenfabrieken, in Eindhoven, the Netherlands, took the first steps toward creating what we now all know as the compact disc. In recognition of that achievement, an IEEE Milestone in Electrical Engineering and Computing is scheduled to be dedicated at a ceremony in Eindhoven on 6 March 2009—30 years after the technology was first demonstrated to the international press. IEEE milestones honor significant achievements in electrical, electronic, and computer engineering that demonstrate technological innovation and excellence for the benefit of humanity.
Engineers today might find it hard to believe that when Lou F. Ottens, technical director of Philips’s Audio Products Division, set his company on the path to the CD in 1972, he did not envision a digital device. Signals were to be impressed on the disc surface as continuously variable—that is, analog—microscopic elevations on a metalized plastic carrier, and read out with a gas laser. The advantages over conventional technology were twofold: It was contactless, so it eliminated disc wear, and if lasers were used to imprint the discs, the microscopic elevations could be made quite narrow, leading to long playing times and small disc size.
CONQUERING DEFECTS The first experimental analog audio long-play (ALP) discs were based on the same optical technology used earlier by Philips in its video long-play (VLP) system. Because the audio signal was registered onto the disc surfaces in an analog fashion, microscopic faults in those surfaces caused the same sort of crackling noise that affected ordinary LP records. The only way to prevent the scratches and other imperfections on the disc from affecting the quality of the reproduced sound was to switch from analog to digital registration.
The digital technology was developed in a cooperative effort involving engineers from the audio group and researchers from IEEE Fellow J.B. Hans Peek’s Distribution Systems and Fundamental Aspects group at the Nat. Lab., Philips’s world-class research laboratory. “Nat. Lab.” derives from the Dutch Natuurkundig Laboratorium, or physics laboratory.
A key step in the development of the CD, suggested by Lorend Vries, a member of Peek’s group, was to add error correction to the analog-to-digital conversion of the audio signal. That not only corrected most of the errors caused by unavoidable defects on the disc surface, but also gave excellent noise immunity. The merging of optical VLP technology with digital signal processing was the key innovation that made the CD possible.
While that new technology was being developed, advances in other fields—semiconductor lasers, aspherical lenses, increasingly dense integrated circuits, and disc technology—solved many of the remaining problems. In particular, they made possible a compact player as well as a compact disc.
Physically, the IEEE milestone is a plaque, which is to be unveiled at the High Tech Campus in Eindhoven. The inscription on the plaque reads:
COMPACT DISC AUDIO PLAYER, 1979
On 8 March 1979, N.V. Philips’ Gloeilampenfabrieken demonstrated for the international press a Compact Disc Audio Player. The demonstration showed that it is possible by using digital optical recording and play back to reproduce audio signals with superb stereo quality. This research at Philips established the technical standard of digital optical recording systems.
INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS