Video High Density (VHD) was an analogue videodisc format, marketed predominantly in Japan by JVC. It was first demonstrated in 1978 and eventually released in Japan in 1983.
VHD discs are 25 cm in diameter, and stored in a caddy like the the RCA SelectaVision system, which is inserted into the player and then withdrawn. VHD stores 60 minutes of video per side, so needs to be removed and turned over.
Like the RCA system, the signal is recorded on the discs as variations in capacitance, a conductive coating on the disc itself forming part of a resonant circuit. A diamond stylus reads the signal, though unlike CED there are no actual grooves—the stylus follows the tracks electronically, like a compact disc. Naturally this means less wear, though there is still physical contact (unlike LaserDisc) so some wear would still occur.
By the time of its launch in 1983, both LaserDisc and SelectaVision were suffering the onslaught of VHS and Betamax. JVC opted not to release VHD as a consumer product in the US, but in the UK Thorn EMI committed to the system and in 1981 invested in a factory at Swindon to press disks and developed a catalogue of ‘interactive’ titles to support a planned launch in 1984. However, it cancelled the investment in late 1983. VHD remained on the market in the UK primarily as an educational and training tool, usually linked to a computer, but attracted few customers.
A stereoscopic system was sold in Japan, achieving the 3D effect by using double-speed discs with alternate-eye images and LCS glasses to pass the correct view to each eye.
VHD was essentially defunct after 1986.