Abstract: A piezoelectric device, comprising a number of polarizable ceramic plates 1 which are stacked with intermediate metal plates which serve as electrodes. The stack is subjected to a large amount of preload by a preloading element having a relatively flat spring-force characteristic over the piezoelectric operating range of the device which is formed by a cylindrical housing having two sets of parallel pairs of slots 7, 10, rotationally displaced by 90 degrees, the preloading force being applied to the stack by threaded end plugs 4 and 5. The ceramic plates are polarized only after assembly and preloading.

Abstract: The bridges between apertures located at the edge of the shadow mask of a color display tube are made at least 20% wider than the others. The width of the bridges increases linearly from row to row from the center to the edge of the mask whereby a continuously varying brightness distribution is obtained. The reproduction mask used in the fabrication of such a shadow mask can be made photographically by exposing photosensitive material through a pattern of bridges, rotating the pattern and repeating the exposure.

Abstract: An exposure device for the manufacture of cathode-ray tubes for displaying colored pictures comprises an elongate light source shaped so that the amount of light radiated by said light source increases linearly from zero at the ends of the light source to a maximum at the center of the light source, so that a triangular light profile is obtained. The device may be used to manufacture cathode-ray tubes wherein the display screen is composed of triplets of phosphor lines of very constant width.

Abstract: The bridges between apertures located at the edge of the shadow mask of a color display tube are made at least 20% wider than the others. The width of the bridges increases linearly from row to row from the center to the edge of the mask whereby a continuously varying brightness distribution is obtained. The reproduction mask used in the fabrication of such a shadow mask can be made photographically by exposing photosensitive material through a pattern of bridges, rotating the pattern and repeating the exposure.

Abstract: An exposure device for the manufacture of display screens of color television display tubes is disclosed comprising a filter of non-uniform transmittance which includes a transparent plate provided with a large number of parallel opaque linear regions. The transmission of the filter is varied by varying the width of the linear regions.