I love CRTs – Fact.

Why?

Is it because they heat my room and give the central heating a rest? No.

Is it because they allow me to fill space that would otherwise be used for unnecessary items? No.

Is it because they trap and attract dust, lightening my workload with the duster? No

Is it because they consume more power and assist me to help my chosen electricity company to increase its’ profits? No.

The reason is that there is no picture equal to a CRT picture.

That is a fact. There is no comparable picture from any flat-screen TFT (Thin Film Transistor (Or LED)) monitor ever built which is able to rival the uniqueness and completeness of the picture on an old CRT (Cathode Ray Tube) monitor.

Simplified Technical Information

The cathode ray tube is exactly what it says on the tin: Basically it’s a tube which has a widened out end with a screen on it, with a thermionic valve at the other end producing three rays of electrons. These electron-rays are propelled along the tube from the valve end, electromagnetically steered by the frame and line coils attached externally around the thin neck of the tube which you normally don’t get to see from the outside of the monitor, and targeted onto many groups of three different tiny dots of reactive phosphor on the inside of the screen; producing light with either a red, green, or blue wavelength. Red, blue, and green are the three primary colours from which all other colours are made up: Yellow, for instance, is just an intense green. White is a mixture of all three colours on proportion to one another. Each cluster of three phosphor dots is being hit by all three electron beams, one beam hitting each dot, many times a second in a process known as scanning: The electromagnetic coils affixed to the tube inside the monitor steer the electron beams to hit the first set of dots; the “red” beam always hits the “red” dot; which is made of a phosphor which emits red light when it is hit by an electron beam, and likewise with the “green” and “blue” beams. (The beams themselves have no colour; in fact they’re invisible. They travel as minutely thin particle-beams within the vacuum (Lack of air molecules that is, rather than a Hoover.) inside the tube until they strike a phosphor dot on the screen, producing light accordingly.) After hitting the first cluster of dots the beam is fired at the second set of dots…and so on at incredible speed; so fast in fact that the human eye doesn’t perceive it, but rather sees a complete picture. After the entire screen has been covered and all the clusters have been hit the process happens again. The number of times per second this process happens is the screen’s “refresh rate”, and is controlled from the computer’s  graphics chip, with a relevant GUI (Graphical User Interface) in Windows operating the chip’s settings by means of Direct X – Which provides an interface between the Windows operating system itself and the components of the computer.

(If you use a CRT monitor and the screen appears to flicker; try setting the refresh rate frequency to at least 80Hz: Anything less tends to cause eye-strain from a CRT monitor.)

Why Better?

So that’s very roughly how it works; but why does it produce a better picture? The gun electrodes of each of the sections of the valve producing the three electron-rays can have their electrical potential varied to a greater extent, more easily, and faster, than each individual transistor in a TFT monitor. Since the same electrical terminal’s electrical potential affects the entire picture in a CRT, rather than each individual transistor’s electrical potential, as in a TFT, this doesn’t necessitate the relevant circuitry to work at such a high speed in the case of a CRT, thus giving less chance of error due to lack of responsiveness of given components: For instance if the first, third, fifth… cluster was required to be a bright pixel and the second, fourth, sixth… cluster was required to be a dim pixel, a CRT monitor would simply increase the voltage on the gun-anode as the electron beams fired at the first cluster, then decrease the gun-anode’s voltage on the second cluster, and so on… A TFT monitor, however, first has to digitally address the first set of transistors corresponding to the first pixel and increase their voltage, then digitally address the second set of transistors corresponding to the second pixel and decrease their voltage…and so on: Therefore the digital circuitry in the TFT monitor has to work many times faster than the analogue circuitry on the CRT monitor. Quite obviously technology has found a way around this problem to a certain extent by using complex algorithms and digital matrices, as well as the increased switching frequencies of individual transistors on a silicon wafer; but still overall CRTs are better and can reproduce better and more colours as a result.

The Conundrum

That’s the technical bit covered very basically although not at all thoroughly: It gives you a very rough idea of what’s going on. The real conundrum, however, is in relation to the human eye and the claimed colour reproduction statistics of TFT vs. CRT monitors: According to statistics; a decent TFT monitor is capable of accurately reproducing 24 million colours; whereas a CRT monitor is capable of accurately reproducing 32 million colours. Seeing as the human eye, according to scientists, is only capable of perceiving 24 million colours, it should follow that a CRT monitor, by all logic, should appear to give no better picture than a TFT monitor. However this is clearly not the case; therefore someone somewhere is cooking the books; as the figures just don’t add up.

This is where I jump off and leave you with the conundrum. (I didn’t state I’d solve it myself anywhere did I?) The question is, bearing in mind the figures I’ve just presented, why is a CRT picture still so much better than a TFT picture? If you have any ideas then your comments are invited.

Would anyone like to provide any enlightenment?

 ©KKomp 2008