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{{Unreferenced stub|auto=yes|date=December 2009}} {{refimporove|date=January 2011}}
'''Electric eye''' is a somewhat dated term used to describe an opto-electronic means of sensing something, most commonly a ] of some type. An example is the ] system used on ]s that use a light transmitter and receiver at the bottom of the door to prevent closing if there is any obstruction in the way that breaks the light beam. '''Electric eye''' describes a ] used for detecting obstruction of a light beam. An example is the ] system used on ]s that use a light transmitter and receiver at the bottom of the door to prevent closing if there is any obstruction in the way that breaks the light beam. The device does not provide an image; only presence of light is detectable. Visible light may be used, but ] radiation conceals the operation of the device and typically is used in modern systems. Originally systems used lamps powered by DC or the line frequency, but modern photodetector systems use an infrared ] modulated at a few kilohertz, which allows the detector to reject stray light and improves range and sensitivity of the device.


In the frequently played "Proper Modulation" ] from the ], Stern's father, a ], describes "the electric eye" as "a green type of... tube." He is apparently describing a "]" (used as a recording level indicator on some tape recorders), rather than an electric eye.


==Examples== ==Examples==
'''Highway vehicle counter''' '''Highway vehicle counter'''
* In the 1930s a primitive electric eye vehicle counter was introduced in the US using two IR lamps set apart so that only cars and not pedestrians would be counted. <ref> </ref> * In the 1930s an electric eye vehicle counter was introduced in the US using two IR lamps set apart so that only cars and not pedestrians would be counted. <ref> </ref>
'''First compact commercial unit''' '''First compact commercial unit'''
* Also, a compact type of electric eye was offered in 1931 that was enclosed in a small steel case and much easier to install compared to older models. <ref> </ref> * Also, a compact type of electric eye was offered in 1931 that was enclosed in a small steel case and much easier to install compared to older models. <ref> </ref>
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'''Business alarm system''' '''Business alarm system'''
* In 1931 an electric eye that used invisible UV wave length was offered to businesses in need of a 24 hour alarm system. <ref> </ref> * In 1931 an electric eye that used invisible UV wave length was offered to businesses in need of a 24 hour alarm system. <ref> </ref>


{{Empty section|date=July 2010}}


==See also== ==See also==

Revision as of 14:29, 25 January 2011

For other uses, see Electric eye (disambiguation).

Template:Refimporove Electric eye describes a photodetector used for detecting obstruction of a light beam. An example is the Door#Door-related accidents system used on garage door openers that use a light transmitter and receiver at the bottom of the door to prevent closing if there is any obstruction in the way that breaks the light beam. The device does not provide an image; only presence of light is detectable. Visible light may be used, but infrared radiation conceals the operation of the device and typically is used in modern systems. Originally systems used lamps powered by DC or the line frequency, but modern photodetector systems use an infrared LED modulated at a few kilohertz, which allows the detector to reject stray light and improves range and sensitivity of the device.


Examples

Highway vehicle counter

  • In the 1930s an electric eye vehicle counter was introduced in the US using two IR lamps set apart so that only cars and not pedestrians would be counted.

First compact commercial unit

  • Also, a compact type of electric eye was offered in 1931 that was enclosed in a small steel case and much easier to install compared to older models.

Automatic wrapping wachines

  • In the 1930s an electric eye apparatus was developed to help a wrapping machine, wrap 82 boxes a minute.

Automatic door opener

  • In 1931 General Electric tested the first automatic door openers now popular in hospitals. They called their electric eye, the Magic Eye.

Business alarm system

  • In 1931 an electric eye that used invisible UV wave length was offered to businesses in need of a 24 hour alarm system.

See also

Reference and Notes

  1. "Autos Are Counted By Electric Eye", January 1937, Popular Science
  2. "Electric Eye And Relay Set Combined In Cabinet", March 1931, Popular Mechanics
  3. "Electric Eye is Robot Guard For Wrapping Machine", February 1931, Popular Mechanics
  4. "Door That Opens Itself Is Boon To Waitresses", February 1931, Popular Mechanics
  5. "UV Ray Electric Eye Alarm, February 1931

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