Sony Corporation (Sony Electronics Corporation until 1 April 2021) is the electronics business unit of the Sony Group. It primarily conducts research and development (R&D), planning, designing, manufacturing and marketing for electronics products. Sony Global Manufacturing & Operations Corporation (SGMO) is a wholly-owned subsidiary of Sony Corporation and responsible for managing manufacturing operations both in Japan and overseas, through its own factories as well as third party contract manufacturers. Audio In 1979, Sony released the world's first portable music player, the Walkman, bundled with the MDL-3L2 headphones. This line fostered a fundamental change in music listening habits by allowing people to carry music with them and listen to music through lightweight headphones. Originally used to refer to portable audio cassette players, the Walkman brand has been widely adopted by the company to encompass its portable digital audio and video players as well as a line of former Sony Ericsson mobile phones. In the case of optical disc players, the Discman brand was used until the late 1990s. In 1999 Sony's first portable digital audio players were introduced; one was a player using Memory Stick flash storage created by the Walkman division, and the other was a smaller pen-sized player with embedded flash storage created by the Vaio division; both accompanied with Sony's OpenMG copyright protection technology and PC software for music transfer. Sony continue to develop Walkman digital audio players. Sony is a major audio products manufacturer and one of the active noise control technology leaders. Video Sony produced the TV8-301, the world's first all-transistor television, in 1959. In 1968, the company introduced the Trinitron brand name for its lines of aperture grille cathode ray tube televisions and afterwards computer monitors. Sony stopped production of Trinitron for most markets, but continued producing sets for markets such as Pakistan, Bangladesh and China. Sony discontinued its series of Trinitron computer monitors in 2005. The company discontinued the last Trinitron-based television set in the US in early 2007. The end of Trinitron marked the end of Sony's analog television sets and monitors. Sony used the LCD WEGA name for its LCD TVs until summer 2005. The company then introduced the BRAVIA name. BRAVIA is an in-house brand owned by Sony which produces high-definition LCD televisions, projection TVs and front projectors, home cinemas and the BRAVIA home theatre range. All Sony high-definition flat-panel LCD televisions in North America have carried the logo for BRAVIA