Abstract: The invention relates to a method of producing a screen (6) having a striped structure of electroluminescent material on a display window (3) of a color display tube (1). In present day color display tubes (1), this screen (6) is produced using a photochemical process for exposing a photosensitive material which is applied to the display window (3). Normally, the exposure device used for this process comprises two lenses, a first lens (28) for correcting the rotation of the image of the elongated light source (22) and a second lens (27) for taking care that the landing position of the light on the display window (3) will be representative of the landing position of the electron beams (7), (8), (9) in the color display tube (1) when it is operated. Unfortunately, the prior art system has the disadvantage that the line-growth factor is not constant over the entire screen (6).

Abstract: A photosensitive layer of or for a cathode ray tube is illuminated by means of a laser illumination arrangement. The laser illumination arrangement comprises a homogenizer which serves to reduce the coherence of the laser beam.

Abstract: In the manufacturing process of colour display tubes with a dotted screen pattern, to form the screen (11), a segmented lens (3) is used for exposing the display window (4) in order to apply a structure of a black matrix layer and a layer with electroluminescent material to it. Principally, a segmented lens (3) gives rise to a phenomenon that is called facet marking; this is a result of the fact that the images of consecutive facets (12) of the lens on the screen (11) are disjunct or partly overlap, giving dark lines (42) or bright lines (44). In present day colour display tubes—especially for use as computer monitors—it is getting more and more important to reduce facet marking as far as possible. It is proposed to manufacture the segmented lens (3) according to a new process in which the mould (30) for the manufacture of said segmented lens is significantly changed.

Abstract: A photosensitive layer of or for a cathode ray tube is illuminated by means of a laser illumination arrangement. The laser illumination arrangement comprises a homogenizer which serves to reduce the coherence of the laser beam.