Plasma panels
Introduction to flat panel displays
Electronic displays have been around almost since the electron was first discovered in 1897. Scientists and engineers have developed a very wide range of electronic display technologies and today, the choice has never been wider.
For years, the most common display technology has been the cathode ray tube or CRT. In the last few years, around 115 million new CRT computer monitors and 130 million new television sets based on CRT technology have been sold annually throughout the world. CRTs have been produced in large volumes for over 50 years and consequently, manufacturers have developed very efficient processes and enjoy great economies of scale. This means that CRT technology delivers a good performance at relatively low cost.
But now there are newer, slimmer, lighter and more versatile products that are true alternatives to the traditional CRT device. Currently, the most popular technologies are:
Plasma display panel, PDP. Liquid crystal display, LCD. Digital light processing, DLP.
There are other technologies that are being developed such as organic light-emitting diodes (OLED), field emissive displays and surface- conduction electron-emitter displays (SED).
The CRT is a well tried and tested technology and remains the standard for standard definition picture quality. Nonetheless, flat panel displays (FPDs) have a number of advantages that makes them more desirable than the CRT. These advantages are:
● Fully flat display.
● Large screen formats.
● Thin (40 mm) – suitable for wall hanging.
● Small in size – occupying less desk space.
● Fully digital internal operation.
● Light weight – 1/6th of CRT.
● Unaffected by magnetic fields.
● Fully flicker-free operation.
● Larger viewing area – a 15″ flat panel gives the same viewable screen as a 17″ CRT.
● High resolution.
On the other hand, flat panels have disadvantages, but these are differ- ent depending on the type of FPD under consideration. In general, how- ever, FPDs are more complex, more expensive, have restricted viewing angle and use more power than the comparable conventional CRT display.
Viewing angle
Traditional CRT displays may be viewed at virtually any angle without degradation in colour or brightness. The same cannot be said of flat panel displays FPDs. FPDs are specified with a ‘viewing angle’ defined as the angle (horizontal and vertical) from which the display can be correctly seen without discolouring or brightness degradation. Most FDPs have a viewing angle of 160°V and H. That means that a picture may be viewed at 80° (160°/2) from a line drawn vertically from the centre of the screen. Given that at 90° the viewer is facing the edge of panel, such a viewing angle is a very tall order. Some manufacturers claim a viewing angle as high as 170°. That being said, a viewer may find that images at the extreme ends of the specified viewing angle do not provide comfortable viewing or good picture quality.