Room 7c exhibit 3
 
JVC HD-7900 VHD player
   
 
 
 
FORMAT: VHD  
 
DATE: 1983

PRICE: $?
[2005: $?]

44x37x12cm


  
 
This is another foreign interloper, a Japanese VHD machine from Victor - or JVC as we know them. VHD stands for Video High Density, and there was also AHD, for high quality audio disks. The capacitive recording system was similar to CED / SelectaVision, but VHD was more sophisticated, and allowed full interactivity like LaserDisc or modern DVDs.
VHD disks don't have grooves; the diamond stylus was flat and followed the tracks electronically, like a CD or DVD. Although this was more complex, it made trick-play functions less prone to damaging the disc - though since the stylus was still in contact with the surface of the disc, a small amount of wear would still have occurred.

As with CED, a sleeve or caddy was used to protect the discs from casual wear and prying fingers.
The discs contained two frames per revolution, which was a good compromise between quality and capacity, but which naturally meant that a real "freeze frame" was not possible - any difference between the two frames would appear as jitter. Discs which contained still-frame "picture catalogues" recorded the same frame twice, to get a perfect still - at the cost of reduced capacity.
They're smaller than CED disks, 25cm as opposed to 30. The reduced size (and weight!) make them significantly more convenient and easier to handle than the rival system.



CED (right) and VHD caddies
One of the many unique features of VHD was that the system was always designed to be multi-standard - any disc could be played and watched on any TV system. So, an american NTSC disc could be played on a UK player, and watched on a UK PAL TV. (You have to wonder if the same artificial "region crippling" used on DVD would have been applied!)
When you turn the machine on, the machine prepares itself for playing and opens the door covering the disk slot. The caddy is inserted and withdrawn, leaving the disk inside the machine. Removing the caddy triggers the machine to lower the disk onto the turntable, and it's ready to go.
This machine has very few controls, basically just play and stop buttons - all the trick-play and interactive controls are on the remote. A couple of sliders control the audio levels and alternate channel selection (at least I think so - the labels are in Japanese) and there are also sockets for headphones and even a microphone - Karaoke, anyone?

Like CED, the stylus was easily accessible for changing, via a lid on the top of the machine.
Inside, the machine is pretty similar to a CED player, with the stylus unit on a moving trolley (the grey box, shown here in its "parked" position at the top of the picture). A brush under the unit cleans the stylus every time it's parked.

A complicated system of interlocking pins, clips and levers opens the caddy (which involves unlocking it and pulling the two sides apart), removes the end-cover and grips the edge of the disk while the caddy is withdrawn, then a raised centre boss holds the disk in the centre and lowers it onto the turntable.
These complicated mechanical systems must have been prone to failures and jams, and could even have stranded a disk in the machine. The modern tray-loading approach is far better, even if it does expose the disk to the elements!
The VHD / AHD format was first demonstrated in 1978, and eventually released in Japan in April 1983. By this time, both LD and CED were suffering from poor sales, and despite the usual promises and pre-release hype, VHD was never released as a consumer product outside Japan - not even making it to the US.

Elvis on VHD
Some Elvis fanatics will collect VHD and CED disks,
even though they can't actually play them!
In Japan itself the main use for VHD was in Karaoke machines - the players had a control interface, which could be connected to a computer via a separate control unit. This also allowed the discs to be used as interactive training material, where the progress through the disc was optional at each step, so that the user could navigate through it according to choice. These features were also used for interactive "Anime" films, which were popular in Japan (and for which these machines are still used, apparently).

In the UK, as in the US, VHD was never launched as a consumer product. But a PAL version was made, for commercial demonstration and diagnostic uses. One application was an engine fault-finding system, where the user would navigate through the material until they found images and information on fixing the problem. It's also possible that PAL karaoke machines were made.

One final variant was available, at least in Japan: 3D! Two parallel images were recorded, on alternate frames, and the discs played at double-speed. LCD glasses were connected to the player, and each lens was opened and closed in synch with the images, so that each eye got a different image and the viewer saw 3D. As for the Anime discs, these systems are still collectible in their own right.