What Is a Cathode Ray Tube?
The cathode ray tube has been around since the late 1800s, but cathode ray tube televisions have only been commercially available since the 1930s. As technological advances are made, more cathode ray tubes are ending up waiting for disposal.
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Identification
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Cathode ray tubes (CRT) are found in older televisions and computer monitors. These screens of televisions and monitors are lined with phosphorus dots on the inside which illuminates when struck with electrons from the cathode, which is a heated filament.
How It Works
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The cathode in CRTs is sealed in a vacuum that helps the negatively charged electrons toward a focusing anode which is positively charged. They then get pulled toward an accelerating anode. In addition to the accelerating anode, the sides of the tube help move the electrons toward the viewing screen because they are coated with conductive resin. The tighter the dots of phosphorus are, the better the screen resolution is.
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Getting the Signal Right
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When a CRT receives a signal, it uses metal steering coils to steer the electrons magnetically to produce the correct picture. These steering coils are usually made out of copper.
Warning
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Cathode ray tubes contain heavy metals, such as lead and copper. They also contain brominated flame retardants. They are typically managed as universal waste under the U.S. Environmental Protection Agency's Resource Recovery and Conservation Act of 1976.
Recycling
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Many states have set up programs for recycling CRTs and televisions to keep dangerous chemicals and metals out of landfills and incinerators. Several states have even banned them from landfill or incinerators completely. Check with your municipality's Department of Environment or Natural Resources for options.
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References
Resources
- Photo Credit Courtesy of Leipnizkeks on Wikimedia Commons
