Monoscope

Source: Wikipedia, the free encyclopedia.
For the portable telescope, see Spotting scope.
Indian Head test pattern
was generated by a monoscope.
A monoscope
Early Cinema Television (UK) monoscope advertisement

A monoscope was a special form of

technologically obsolete
by the 1980s.

Design

The monoscope was similar in construction to a

video
output of the tube.

This signal reproduced an accurate still image of the target, so the monoscope was used to produce still images such as test patterns and station logo cards. For example, the classic

Indian Head test card
as used by many television stations in North America, was often produced using a monoscope.

Usage

The target is Test Card G in this example

Monoscopes were available with a wide variety of standard patterns and messages, and could be ordered with a custom image such as a station logo. Monoscope "cameras" were widely used to produce test cards, station logos, special signals for test purposes and standard announcements like "Please stand by" and "normal service will be resumed....".[1] They had many advantages over using a live camera pointed at a card; an expensive camera was not tied up, they were always ready, and were never misframed or out of focus. Indeed, monoscopes were often used to calibrate the live cameras, by comparing the monoscope image and the live camera image of the same test pattern.

Part of a character generator target with numbers and symbols

Pointing an electronic camera at the same stationary monochrome caption for a long period of time could result in the image becoming burnt onto the camera tube's target — and even onto the phosphor of a monitor displaying it in extreme cases.

Monoscopes were used as

solid state
TV test pattern signal generators.

See also

  • Test card, the updated, coloured version of monoscopes.

References

  1. ^ "Photographic image" (JPG). Tvcameramuseum.org. Retrieved 30 June 2022.
  2. ^ "4560 Custom-built, 2" diameter, Electrostatic-Focus, Electrostatic-Deflection Monoscope Tubes For Use As Alphanumeric Character Generators data sheet" (PDF). RCA Electronic Components. May 1969. Retrieved 27 September 2017.
  3. ^ "CK1414 Symbolray character generating cathode ray tube data sheet" (PDF). Raytheon Company components division, industrial components operation. 15 April 1966. Retrieved 29 July 2017.
  4. ^ "Symbolray™ application note" (PDF). Raytheon Company components division, industrial components operation. Retrieved 27 September 2017.
  5. Compagnie Française Thomson-Houston
    division tubes electroniques, Paris (France). January 1968. Retrieved 27 September 2017.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Monoscope&oldid=1123308145"