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video camera A video camera is a camera used for electronic motion picture acquisition, initially developed by the television industry but now common in other applications as well. The earliest video cameras were those of John Logie Baird, based on the electromechanical Nipkow disk and used by the BBC in experimental broadcasts through the 1930s. All-electronic designs based on the cathode ray tube, such as Vladimir Zworykin's Iconoscope and Philo T. Farnsworth's Image dissector, supplanted the Baird system by the 1940s and remained in wide use until the 1980s, when cameras based on solid-state image sensors such as CCDs (and later CMOS active pixel sensors) eliminated common problems with tube technologies such as burn-in and made digital video workflow practical. Video cameras are used primarily in two modes. The first, characteristic of much early television, is what might be called a live broadcast, where the camera feeds real time images directly to a screen for immediate observation; in addition to live television production, such usage is characteristic of security, military/tactical, and industrial operations where surreptitious or remote viewing is required. The second is to have the images recorded to a storage device for archiving or further processing; videotape is traditional for this purpose, but optical disc media, hard disk, and flash memory are all used as well. Recorded video is used not only in television and film production, but also surveillance and monitoring tasks where unattended recording of a situation is required for later analysis. Modern video cameras have numerous designs and uses, not all of which resemble the early television cameras. Professional video cameras, such as those used in television and sometimes film production; these may be studio-based or mobile. Such cameras generally offer extremely fine-grained manual control for the camera operator, often to the exclusion of automated operation. Camcorders, which combine a camera and a VCR or other recording device in one unit; these are mobile, and are widely used for television production, home movies, electronic news gathering (including citizen journalism), and similar applications. Closed-circuit television cameras, generally used for security, surveillance, and/or monitoring purposes. Such cameras are designed to be small, easily hidden, and able to operate unattended; those used in industrial or scientific settings are often meant for use in environments that are normally inaccessible or uncomfortable for humans, and are therefore hardened for such hostile environments (e.g. radiation, high heat, or toxic chemical exposure). Webcams can be considered a type of CCTV camera. Digital cameras which convert the signal directly to a digital output; such cameras are often extremely small, even smaller than CCTV security cameras, and are often used as webcams or optimized for still-camera use. These cameras are sometimes incorporated directly into computer or communications hardware, particularly mobile phones, PDAs, and some models of laptop computer. Larger video cameras (especially camcorders and CCTV cameras) can also be used as webcams or for other digital input, though such units may need to pass their output through an analog-to-digital converter in order to store the output or send it to a wider network. Special systems, like those used for scientific research, e.g. on board a satellite or a spaceprobe, or in artificial intelligence and robotics research. Such cameras are often tuned for non-visible light such as infrared (for night vision and heat sensing) or X-ray (for medical and astronomical use). wikivideo camera
monitor disposal Computer monitors may contain toxic phosphors within the glass envelope. The glass envelopes of modern CRTs may be made from heavily leaded glass, which represent an environmental hazard. Indirectly heated vacuum tubes (including CRTs) use barium compounds and other reactive materials in the construction of the cathode and getter assemblies; normally this material will be converted into oxides upon exposure to the air, but care should be taken to avoid contact with the inside of all broken tubes.
In some jurisdictions, discarded CRTs are regarded as toxic waste. In October 2001, the United States Environmental Protection Agency created rules stating that CRTs must be brought to special recycling places. In November 2002, the EPA began fining companies that disposed of CRTs through landfills or incineration. Regulatory agencies, local and statewide, monitor the disposal of CRTs and other computer equipment. monitor disposal is hard
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