What is a CRT Monitor?

What is a CRT Monitor?

In the 20th century, inventors, scientists, doctors and others have successfully combined different types of electronic technology to produce remarkable appliances for enjoyment and for business tools. One piece of equipment that fits into this category is the cathode ray tube.

When you view a television program or see crisp images on some computer monitors you may be looking at a CRT display. In recent years this type of monitor or TV screen has been replaced by monitors and television sets using liquid crystal display or plasma technology. CRT monitors and TV sets are much larger – wider and deeper, consequently taking up a lot more space.

How Does It Do That?

The CRT unit creates the image you see using lines of very small dots of various colors. In newer LCD or plasma displays the image is created by pixels. Basically, the more dots or pixels per square inch of monitor or TV screen the sharper the picture. The large surface of the screen we see images on gradually narrows toward the back where there is a cathode (charged filament) in a vacuum. This filament sends electrons into the vacuum inside the tube.

Since these electrons carry a negative charge they attract to anodes (positive charge) that reduce the beam of particles into three beams. These beams contact the screen, which has a phosphor coating that will glow when contacted by the beams. Images are constructed of three basic colors. The beams are narrowed and guided by coils either horizontally or vertically.

Fast Motion

In order to have an image that is clear enough for television viewing or computer monitor use, these beams must work across the phosphor-coated screen very quickly. Different designs cover the screen almost continuously with the speed depending on what is called a refresh rate. If this rate isn’t high enough (well above 60 Hz) we see inconsistent images. People of older generations who experienced CRT television and CRT computer monitors know about “flicker” on the screen.

Of course, the images we see on a CRT screen will be much crisper if there are enough dots per square inch of screen. This is measured by a method called dot pitch. A CRT computer monitor often didn’t have the refined technology to produce clear, sharp images. In fact, if the dot pitch was too low even text on a word document might be “fuzzy.”
The key to a quality CRT monitor or television screen is the proper design of the vacuum tube and the components that direct the beam onto the screen. If all the pieces are working well together, viewers see a clear picture. For the first decade or so of home-computer use CRT monitors were the only types of viewing screen available. They have largely been replaced with flat-screen technology such as LCD and plasma. For some situations, a CRT monitor is still preferred because of response time. They are often faster than even the best LCD monitor, especially for full-motion video in computer games.