CRT Televisions

With this being said, I start the discussion with introducing different generations of television sets and the technology incorporated in each of them; at the end of this introduction, a post will be dedicated to comparing all of them and a small buyer's guide would be in order.

CRT (Cathode Ray Tube) Televisions
These televisions use an electron gun (a source of electrons) and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen. Colour CRTs employ three separate electron guns that share some electrodes for all three beams (see picture).

The resolution on these televisions depends on the “dot pitch” (see picture). Health concerns include use of high-voltage (32 kilo volts for colour televisions), electromagnetic fields (Very Low Frequency), ionizing radiation (emitting a small amount of X-ray), toxicity (proper recycling is required), and flicker (relatively low refresh rate causes headaches).

The screen is scanned with the ray gun repeatedly and the image is refreshed 60 times per second. There are two types of scan available: progressive and interlaced. In progressive scanning, the whole picture is created in one scan (usually 480 lines); in interlaced scanning, the entire screen is refreshed in two phases. In phase one, half of the lines (even numbered) are refreshed and in phase two, the other half (odd numbered) are refreshed. Progressive scanning introduces less flicker compared to interlaced scanning.