| 摘要 |
<p>777,868. Colour television tubes. CHROMATIC TELEVISION LABORATORIES, Inc. Dec. 22, 1954 [Dec. 22, 1953], No. 36999/54. Class 39(1). Colour balance is achieved in a television tube with colour control grids and a display screen having strips of three different phosphors emitting the three component colours of white light, by making those phosphor strips centred behind the interspaces of the grid elements wider at their ends than at their central portions with reciprocal variations in the width of the other phosphor strips. Behind the wires 15, 15<1> of a deflection control grid are positioned the green phosphor strips 27 flanked by red and blue strips 29, 31. The centrally-positioned green strips are wider at the ends as shown in an exaggerated form in Fig. 2. The screen is constructed by machining metal masks to shape and moving them step by step across the surface from which a master pattern is to be produced, e.g. a silk screen or a photographic plate Alternatively, a photographic plate or a fluorescent screen is placed in a demountable tube with a deflection grid in the position of the multicolour screen. With the appropriate voltages on the grid, the photographic plate is exposed by the electron beam ; or the fluorescent plate is photographed and stencils prepared from the negatives so obtained. The green band may be adjusted in size to give correct colour balance. The mathematical formulae for the calculation of the strip widths are given in the Specification. Specification 721,523 is referred to.</p> |
