CD player in 1970. Following litigation, Sony and Philips licensed Russell's patents (then held by a Canadian company, Optical Recording Corp.) in the 1980s. The Compact Disc is an evolution of LaserDisc technology, where a focused laser beam is used that enables the high information density required for high-quality digital audio signals. Prototypes were developed by Philips and Sony independently in the late 1970s. In 1979, Sony and Philips set up a joint task force of engineers to design a new digital audio disc. After a year of experimentation and discussion, the "Red Book" CD-DA standard was published in 1980. After their
Philips CD-i best software required the MPEG upgrade card. By mid-1996 the U.S. market for CD-i software had dried up and Philips had given up on releasing titles there, but continued to publish CD-i games in Europe, where the console still held some popularity. With the home market exhausted, Philips tried with some success to position the technology as a solution for kiosk applications and industrial multimedia. In addition to consumer models, professional and development players were sold by Philips Interactive Media Systems and their VARs. Philips marketed several CD-i player models. There also exist a number of hard-to-categorize models, such as