A diverse range of technologies are available to display high-definition content, but what are they and which should you chose?
- HD Display Technologies
- Flat-Screen and Flat-panel Televisions
The two display technologies you may well have heard about and which are by far the most popular are:
- LCD (Liquid Crystal Display)
- Plasma also known as PDP (Plasma Display Panel)
There are of course other ways to display high-definition content including:
- Rear Projection
- CRT (Cathode Ray Tube)
- ...and many more...
One of the big two above, LCD stands for Liquid Crystal Display, a technology that has existed for many years in devices like digital watches but has only recently begun to be used for displays as technologies have improved.
LCDs are lit from behind and use liquid crystals sandwiched between two glass plates to block or emit this light to form an image.
Read more about LCD displays
The other most common display technology for HD screens, Plasma Display Panel (PDP) is usually abbreviated to plasma.
As with LCD two glass sheets are used in a sandwich but a plasma display uses small capsules of gas that emit light when an electrical charge is applied to them.
Read more about plasma displays
Rear-projection was, and to a lesser extent still is, used in very large screen televisions. More common in the US that Europe, this older technology has been improved recently using Digital Light Projection (DLP) technology, however displays are bulkier than LCDs and plasmas, but can offer a cost effective large screen display.
Where a cinema projector usually projects on to the front of a reflective screen, rear-projection TVs work on a similar principle but project on to the back of a translucent screen, often using mirrors and lenses to achieve a sensible size enclosure.
Just like the projector found in a cinema high-definition projectors are available offering the possibility of very large images projected on to a separate screen.
As with rear-projection televisions modern projectors have benefited from DLP technology that uses movable microscopic mirrors on a semiconductor chip to reflect or deflect a light source to product an image. High-definition projectors are expensive but can project very large images on to compact screens or other flat surfaces.
It is hard to find a new HD-capable Cathode Ray Tube (CRT) television today but they did exist in the past, based on the higher resolution (than standard-definition television) tubes used for computer displays.
Both these terms are well on the way to be becoming synonymous with high-definition television, however it's important to note that the two are not the same and neither automatically implies a particular screen will support HD content.
The term 'flat screen' simply means that the physical surface of the display is flat, but beyond that it doesn't tell you much else. The term originally arose to distinguish newer 'tube' televisions that featured a flatter or flat screen compared to the older visibly curved screens. It has since been applied to any display technology that features a flat screen, which could include LCDs, plasmas, rear-projection and flat-screen CRTs.
'Flat Pannel' is another broad term used to describe the technologies that allow a much thinner and lighter display compared to the bulky, boxy cathode ray tube displays of the past. Most frequently this means LCD and plasma displays but the term can equally be applied to OLEDs (Organic Light Emitting Diode) often used in smaller screens, and upcoming technologies such as the various types of emissive display.
Both terms are commonly (mis)used to broadly refer to LCDs and plasma displays since these are by the far the most commonly available of all the technologies listed above.