Los cinescopios son tubos de rayos catódicos (TRC) destinados a la reproducción de imágenes en aparatos de TV. Estos tubos se fabrican en diversos tamaños según el tipo de aparato de TV y operan siempre por el mismo principio. En la figura 1 tenemos una vista en corte de un tubo de este tipo.


 

 

 

 

Para la emisión de los electrones existe en la parte posterior del tubo denominada "cañón" un cátodo el cual debe ser calentado por un filamento. Tenemos después una rejilla de control que permite controlar la cantidad de electrones emitidos lo que corresponde al brillo o luminosidad de la imagen final.

El electrodo siguiente tiene por objetivo enfocar el haz de electrones emitidos por el cátodo de modo a impedir su dispersión. El ánodo de alta tensión tiene por objetivo acelerar los electrones que son emitidos por el cátodo. La imagen se reproduce cuando el haz de electrones se centra en un mamparo recubierto con material fosforescente. El impacto de los electrones libera energía en la forma de luz visible.

Para que la imagen se forme en su totalidad, el haz de electrones debe "barrer" toda la pantalla rápidamente. Esto es logrado por su desviación a través de placas colocadas en el propio tubo y también por la acción de campos magnéticos externos producidos por bobinas colocadas en el cuello del tubo.

En estas placas y bobinas se aplican a las tensiones y corrientes responsables de la reproducción de la imagen. Para el caso de un tubo de TV en color, el sistema es diferente sólo en lo que se refiere a los haces de electrones que son tres, como muestra la figura 2. En esta tenemos un corte de un tubo para TV en color con su principio de " funcionamiento, observándose que todos los colores posibles se obtienen de la combinación de tres fundamentales.


| Haga click en la imagen para ampliar |

 

 

 

1 - Cátodos

3 - 3 haces de electrones

4 - pantalla

5 - Tríadas en los colores RGB

 

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