| 摘要 |
<p>1427649 Colour television tube PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 23 July 1974 [26 July 1973] 32539/74 Heading H1D In a three-gun colour TV tube (Fig. 1, not shown) with apertured shadow mask and luminescent screen 7, the three phosphor dots 24, 25, 26 luminescing red, green, blue respectively when bombarded by electrons from the respective guns are made smaller than their electron impact zones 27, 28, 29 (negative tolerance). The whole of the screen is coated with a thin reflective electron-permeable Al film 30, initially vapour-deposited over an acrylate skin which is later removed by heat. Ambient light will then be reflected specularly through face plate 2 by the inter-dot areas, reducing the loss of contrast. The film also increases the forward emission of light from the edges of the dots. If the phosphor areas are elongated strips, negative tolerance is ensured by making the phosphor strips narrower than their electron impact zones.</p> |
