Overview

A CRT (Cathode Ray Tube) is an established technology that’s been around for a very long time. Tube based TVs were the norm before microdisplays such as LCD, DLP, and LCoS hit the market. The illustration below details the inner components of a CRT based TV.

CRTs consist of a large vacuum tube with a glass screen on one end, and electron beams on the other. The glass screen is coated with phosphors that produce light when excited by an electron beam. A shadow mask is used to make sure the beam hits the exact correct spot. The beam rapidly scans a line horizontally from top to bottom producing an image. To make a color image, CRT-based rear-projection TVs use three electron guns (red, green, and blue). Keep in mind that there are no fixed pixels in rear projection CRT TVs. The horizontally scanning beam makes CRTs an analog device, and all digital video signals (HDMI, DVI) will have to be converted to analog.

Production Update

Upside

• Top notch in blacks
• Great contrast ratio
• Least expensive technology
• Great picture quality

Downside

• Big and heavy
• Low brightness levels
• Reflections
• No native resolution
• Convergence issues – over time, tubes become misaligned reducing sharpness and picture quality
• Burn in problems – watch out for 4:3 image’s black-bars or a HTPC
• Analog conversion of digital video signals introduces sampling noise into the picture.

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