What a CRT monitor is

A CRT monitor (cathode ray tube) is an older display technology that uses a beam of electrons to paint images on a glass screen coated with phosphor. The beam scans across the screen line by line, left to right and top to bottom, refreshing the image dozens of times per second. When you look at the screen, you see a stable picture, but it is actually being redrawn constantly.

CRT monitors were the standard for computers and televisions from the 1950s through the early 2000s. Most homes and offices have replaced them with flat-panel displays — LCD, LED, or OLED screens — which work by lighting up individual pixels rather than scanning a beam. But CRT technology still exists in some specialized settings, and understanding how it works helps explain why flat-panel monitors became the default choice.

Key Takeaways

  • CRT monitors use an electron beam that scans the screen to create an image, while modern flat-panel monitors light up individual pixels all at once.
  • CRT screens are large and heavy because they need depth to accommodate the electron gun and scanning mechanism inside the tube.
  • CRT monitors produce less eye strain for some users because the constant refresh creates a softer flicker than older LCD technology, though modern displays have largely solved this problem.
  • Most CRT monitors are no longer manufactured, but they remain in use in some professional settings like graphic design and retro gaming because of their color accuracy and response time.

How the electron beam creates an image

Inside a CRT monitor is an electron gun — a heated filament that releases electrons. These electrons are accelerated and focused into a thin beam, then steered by magnetic coils that bend the beam left and right (horizontal scan) and up and down (vertical scan). The beam travels across the screen in a pattern called a raster: it starts at the top left, moves right across the first line, jumps back to the left, moves down one line, and repeats until it reaches the bottom of the screen.

The front of the screen is coated with phosphor, a material that glows when struck by electrons. The brightness of the glow depends on the strength of the beam. By varying the beam's intensity as it scans, the monitor can create different brightness levels at each point on the screen. The beam completes a full scan of the entire screen dozens of times per second — typically 60 to 85 times, depending on the monitor's refresh rate.

This constant rescanning is why CRT monitors need to refresh so frequently. If the refresh rate drops too low, the image appears to flicker noticeably because the phosphor's glow fades between scans. A refresh rate of 60 Hz means the entire screen is redrawn 60 times per second, which is fast enough that most people do not perceive flicker.

Why CRT monitors are large and heavy

The physical size of a CRT monitor is determined by the distance the electron beam must travel. The electron gun sits at the back of the tube, and the beam has to travel in a straight line to the front of the screen. For a 17-inch monitor (measured diagonally across the screen), the tube itself might be 16 to 18 inches deep. For a 21-inch monitor, the depth could exceed 20 inches.

This depth requirement made CRT monitors impractical for modern workspaces where desk space is limited. A flat-panel monitor with the same screen size is only 1 to 3 inches thick. The weight also became a problem: a 21-inch CRT monitor could weigh 60 to 80 pounds, while a modern flat-panel monitor of the same size weighs 5 to 10 pounds.

Color and image quality in CRT displays

CRT monitors produce color by using three electron guns — one for red, one for green, and one for blue — that scan the screen simultaneously. The screen is covered with a pattern of red, green, and blue phosphor dots or stripes. When all three beams hit the same spot at full strength, the phosphors glow and blend together to create white light. By varying the intensity of each beam independently, the monitor can produce any color in the visible spectrum.

One reason CRT monitors remained popular in professional settings is their color accuracy and response time. The phosphor glows when ready when struck by the electron beam and fades gradually afterward, creating smooth color transitions. Modern LCD monitors can match or exceed CRT color accuracy, but older LCD technology had visible delays between when a pixel was told to change color and when it actually changed — a problem called response time lag. For graphic designers and video editors, CRT monitors offered predictable, accurate color without the lag.

Flicker and eye strain considerations

CRT monitors produce a visible flicker at low refresh rates because the phosphor's glow fades between scans. At 60 Hz, some people notice flicker and experience eye strain after extended use. At 75 Hz or higher, flicker becomes imperceptible to most users. This is why CRT monitors were often set to 85 Hz or higher when used for long work sessions.

Paradoxically, this constant refresh can feel easier on the eyes than the static image on an older LCD monitor. Early flat-panel technology had a dimmer, more static appearance that some users found more fatiguing. Modern LCD and LED monitors have much higher refresh rates (120 Hz to 360 Hz in gaming displays) and better color uniformity, so this advantage has largely disappeared. Today, eye strain from monitor use is more often related to screen brightness, viewing distance, and how long you use the monitor without a break — factors that explore equally to any display type.

Where CRT monitors are still used

CRT monitors are no longer manufactured by major display companies, but they remain in use in specific contexts. Retro gaming communities prefer CRT monitors because older video games were designed for the scanning beam's behavior, and the image quality on original hardware is noticeably better on a CRT than on a flat-panel display. Some arcade cabinets still use CRT monitors because replacement parts are available and the technology is proven.

A small number of professional graphic designers and video editors continue to use CRT monitors for color-critical work, though this is becoming rare as modern LCD technology has improved. Some medical imaging workstations and industrial control systems still rely on CRT displays because they were built around that technology and replacement would be expensive.

If you encounter a CRT monitor in a thrift store or online marketplace and are considering it for retro gaming or nostalgia, be aware that CRT monitors can develop problems over time. The electron gun can weaken, the capacitors inside can fail, and the tube itself can develop internal arcing. A monitor that has been in storage for years may not work reliably without repair.

CRT versus modern flat-panel displays

The shift from CRT to flat-panel technology happened because flat panels solved the size and weight problem while offering comparable or better image quality. A flat-panel monitor uses a grid of liquid crystal cells (LCD) or light-emitting diodes (LED, OLED) that can be switched on and off independently. The entire image is displayed at once, not scanned line by line. This allows for much thinner, lighter displays that take up less desk space.

Flat-panel monitors also use less power than CRT monitors — a typical 24-inch LCD monitor uses 20 to 40 watts, while a 21-inch CRT monitor used 80 to 120 watts. They produce less heat and do not emit the same level of electromagnetic radiation. For most users, the practical advantages of flat-panel displays far outweigh any image quality differences.

Frequently Asked Questions

Can I still buy a new CRT monitor?

No, major manufacturers stopped producing CRT monitors around 2010. You can find used CRT monitors through thrift stores, online marketplaces, and specialty retro gaming communities, but availability and condition vary widely. Before buying a used CRT monitor, check that it powers on and displays an image without visible distortion or discoloration.

Is a CRT monitor safer than a flat-panel monitor?

CRT monitors emit a small amount of electromagnetic radiation and X-rays, but at levels well below safety limits set by regulatory agencies. Modern flat-panel monitors are not known to pose radiation risks. For general health and safety, the differences between CRT and flat-panel monitors are negligible. Eye strain and posture are more important factors in monitor safety for either type.

Why do old video games look better on a CRT monitor?

Older video games were designed with CRT scanning in mind. The electron beam's behavior created natural anti-aliasing and softened the edges of pixels, making low-resolution graphics appear smoother. On a flat-panel monitor, the same games show sharp, blocky pixels because each pixel is displayed as a discrete square. Some retro gaming enthusiasts use special software filters to approximate the CRT look on modern displays.

What should I do with an old CRT monitor I no longer use?

CRT monitors contain lead and other materials that require special handling for disposal. Do not throw a CRT monitor in the trash. Contact your local waste management facility or electronics recycling program to find out where to take it. Many communities have e-waste collection events, and some retailers accept old electronics for recycling when you buy a replacement.

Do CRT monitors cause more eye strain than LCD monitors?

At high refresh rates (75 Hz and above), CRT monitors do not cause more eye strain than modern LCD monitors. At lower refresh rates, the visible flicker can be fatiguing. Modern LCD and LED monitors have largely eliminated this problem through higher refresh rates and better color uniformity. Eye strain is more often related to screen brightness, viewing distance, and how long you use the monitor without breaks.