page_title: Technology of television
section_title: Display technology
hierarchical_section_title: Technology of television / Display technology
context_page_description: The technology of television has evolved since its early days using a mechanical system invented by Paul Gottlieb Nipkow in 1884. Every television system works on the scanning principle first implemented in the rotating disk scanner of Nipkow. This turns a two-dimensional image into a time series of signals that represent the brightness and color of each resolvable element of the picture. By repeating a two-dimensional image quickly enough, the impression of motion can be transmitted as well. For the receiving apparatus to reconstruct the image, synchronization information is included in the signal to allow proper placement of each line within the image and to identify when a complete image has been transmitted and a new image is to follow.
  While mechanically-scanned systems were experimentally used, television as a mass medium was made practical by the development of electronic camera tubes and displays. By the turn of the 20th century, it was technically feasible to replace the analog signals for television broadcasting with digital signals. Many television viewers no longer use an antenna to receive over-the-air broadcasts, instead relying on cable television systems.
context_section_description: There are now several kinds of video displays used in modern TV sets:
  CRT (cathode-ray tube): Up until the first decade of the 21st century, the most common screens were direct-view CRTs for up to roughly 100 cm (40 inch) (in 4:3 ratio) and 115 cm (45 inch) (in 16:9 ratio) diagonals.   A typical NTSC broadcast signal's visible portion has an equivalent resolution of 449 x 483 rectangular pixels.
  Rear Projection (RPTV) displays can be made in large sizes, (254 cm (100 inch) and beyond), and use projection technology. Three types of projection systems are used in projection TVs: CRT-based, LCD-based, and DLP (reflective micromirror chip) -based, D-ILA and LCOS-based. Projection television has been commercially available since the 1970s, but at that time could not match the image sharpness of the CRT.
  A variation is a video projector, using similar technology, which projects onto a screen.  This is often referred to as "front projection".
  Flat-panel display (LCD or plasma): Flat panels television sets use active matrix LCD or plasma display technology. Flat panel LCDs and plasma displays are as little as 25.4 mm thick and can be hung on a wall like a picture or put over a pedestal. Some models can also be used as computer monitors.
  LED (light-emitting diode) arrays (not to be confused with the LED backlighting used behind some LCD panels consequently advertised as "LED") became the favored technology for large outdoor video and stadium screens after the advent of very bright LEDs and the matrix driver electronics for them. They make possible ultra-large flat panel video displays that other technologies are currently not able to match in performance.
  OLED (organic light-emitting diode) technology is currently (2019) used in high end smartphone screens and televisions. Unlike LCD panels, OLED screens are viewable from extreme angles, are free from pixel lag, and offer a very high contrast ratio comparable to CRT displays, with very deep blacks. They can be extremely thin and lightweight and can, at least in prototype, be made flexible enough to roll up when not in use.
  Each has its pros and cons. Front projection and plasma displays have a wide viewing angle (nearly 180 degrees) so they may be best for a home theater with a wide seating arrangement. Rear projection screens do not perform well in daylight or well-lit rooms and so are only suitable for darker viewing areas.
caption: Digital video equipment in an edit suite
exif: {"Image ImageDescription": "", "Image Make": "DV3300", "Image Model": "DV3300", "Image Orientation": "Horizontal (normal)", "Image XResolution": "96", "Image YResolution": "96", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "DV3300", "Image DateTime": "2005:06:29 13:15:13", "Image YCbCrPositioning": "Co-sited", "Image Copyright": "Copyright 5,2003", "Image ExifOffset": "359", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail Orientation": "Horizontal (normal)", "Thumbnail XResolution": "1", "Thumbnail YResolution": "1", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1434", "Thumbnail JPEGInterchangeFormatLength": "7057", "EXIF ExposureTime": "1923769/16777216", "EXIF FNumber": "0/0", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "100", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2005:06:29 13:15:13", "EXIF DateTimeDigitized": "2005:06:29 13:15:13", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "103261/65536", "EXIF ShutterSpeedValue": "25/8", "EXIF ApertureValue": "3", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "3", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1000", "EXIF ExifImageLength": "750", "EXIF RelatedSoundFile": "", "EXIF ExposureIndex": "1", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF DigitalZoomRatio": "0/0", "EXIF FocalLengthIn35mmFilm": "0", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "1298"}