Slit mask

A slit mask is a variant of the shadow mask in color picture tubes .

Detail from a slit mask, view from the front

In contrast to the shadow mask, the holes in the slit mask are elliptical or slit-shaped. As in the case of the strip mask, the phosphor layers lie next to one another and are hit by electrons from different directions through the mask. This makes it possible to ensure that only the luminous layer of one color is excited by the associated electron beam.

The aim of the development of the slit mask was to combine the advantages of the shadow mask and the strip mask. The figure below left shows a macro image of a white picture surface of a so-called black matrix picture tube. In the diagram at the bottom right, the fluorescent colored strips are shown in color for better illustration, but regardless of their color, they consist of an almost white powder.

Inferior slit mask picture tubes, like shadow masks, tend to doming - a bulging of the mask caused by thermal expansion that leads to color defects.

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  Macro shot of a white section of a black matrix picture tube

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  Schematic representation of the color formation matching the picture on the left (angle and mask spacing not to scale)

See also

• Manufacture of pinhole and slit masks
• Structure of color picture tubes - see cathode ray tube
• Image generation in a color picture tube

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Web links

• Explanation with graphics at at-mix.de
• Article with pictures at tom's hardware
• Technical basics of color display on monitors ( memento from September 15, 2003 in the Internet Archive ) at the Humboldt University in Berlin