Monoscope

Monoscope
The Indian Head test pattern
A Monoscope
Early Cinema Television (UK) monoscope advertisement

A monoscope was a special form of cathode ray tube that was used to generate, rather than display, a video signal. Each tube was only capable of generating a single video signal, hence the name. This kind of test card generation system was technologically obsolete by the 1980, but served many private and state broadcasters faithfully since its early use in the 1950s.

Contents

Design

Essentially similar in construction to an ordinary CRT, the monoscope contained a formed metal target in place of the phosphor coating at its "screen" end and as the electron beam scanned the target, a varying electrical signal was produced.

This signal reproduced an accurate image of the target and so could be used to produce test patterns and the like. For example, the classic Indian Head test card shown on the right was often produced using a monoscope.

Usage

Monoscope "cameras" were widely used to produce test cards, Station Logos, special signals for test purposes and of course announcements, like "normal service will be resumed....". They had many advantages over the use of a more expensive live camera, they were always ready, and were never misframed or out of focus.

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.

The target is Test Card G in this example

The monoscope declined in popularity during the 1960s due to its inability to generate a colour test card.

See also

  • Test card, the updated, coloured version of monoscopes.
  • Images of test cards

References


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Look at other dictionaries:

  • monoscope — monoskopas statusas T sritis radioelektronika atitikmenys: angl. monoscope vok. Monoskop, n rus. моноскоп, m pranc. monoscope, m …   Radioelektronikos terminų žodynas

  • monoscope — /mon euh skohp /, n. a cathode ray tube that provides a signal of a fixed pattern for testing television equipment. [1935 40; MONO + SCOPE] * * * …   Universalium

  • monoscope — mono·scope …   English syllables

  • monoscope — ˈ ̷ ̷ ̷ ̷+ˌskōp noun Etymology: mon + scope : a cathode ray tube designed to produce for test purposes a video signal of a stationary pattern which has been printed in black foil ink on the aluminum coated signal plate and sealed in the tube …   Useful english dictionary

  • Indian Head test card — The Indian Head Test Card was a black and white television test pattern which was introduced in 1939 by RCA of Harrison, New Jersey as a part of the RCA TK 1 Monoscope. 20th century television later became so important socially that this purely… …   Wikipedia

  • monoscop — MONOSCÓP, monoscoape, s.n. Tub cu fascicul electronic, folosit în televiziune pentru generarea unui semnal de imagine corespunzător unei imagini fixe. – Din fr. monoscope. Trimis de LauraGellner, 04.06.2004. Sursa: DEX 98  monoscóp s. n. (sil.… …   Dicționar Român

  • Cathode ray tube — Cutaway rendering of a color CRT: 1. Three Electron guns (for red, green, and blue phosphor dots) 2. Electron beams 3. Focusing coils 4. Deflection coils 5. Anode connection 6. Mask for separating beams for red,… …   Wikipedia

  • Monoskop — monoskopas statusas T sritis radioelektronika atitikmenys: angl. monoscope vok. Monoskop, n rus. моноскоп, m pranc. monoscope, m …   Radioelektronikos terminų žodynas

  • monoskopas — statusas T sritis radioelektronika atitikmenys: angl. monoscope vok. Monoskop, n rus. моноскоп, m pranc. monoscope, m …   Radioelektronikos terminų žodynas

  • моноскоп — monoskopas statusas T sritis radioelektronika atitikmenys: angl. monoscope vok. Monoskop, n rus. моноскоп, m pranc. monoscope, m …   Radioelektronikos terminų žodynas

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