| 摘要 |
<p>766,052. Embossing. GRETENER, E. April 7, 1955 [April 9, 1954], No. 10322/55. Class 100(2) [Also in Group XX] A reflecting projection screen is made of a number of embossed strips 4, Fig. 1 each strip being produced from metal foil with a highly reflective surface by embossing it with a stamping die which extends across the entire width of the strip, the strip being advanced between successive strokes of the die so that successive embossments are adjacent. The embossment consists of a series of concave rectangular depressions the curvature across the width being greater than that along the length. One, or as many as three rows of depressions may be stamped at each stroke, the strip being advanced a corresponding distance between strokes. For accurate screens one row only is stamped at each stroke as shown in Fig. 3. The embossing die 21 co-operates with an anvil 23 and holding down members 25, .26 are provided on each side co-operating with lower members 27, 28. The holding down members prevent distortion of the strip during the stamping process and do not engage the strip with sufficient pressure to emboss it. A screen as shown in Fig. 3 reflects light at right angles to the screen surface but it may be desired to have the light reflected at an angle to the screen surface. In this case as shown in Fig. 4 the members 27, 28 are arranged one below and one above the level of the anvil 23 so that during the embossing stroke a step is formed on one side of the depression as shown in Fig. 4a. The light is now reflected at an angle 33 to the surface of the screen 31. If it is desired that this angle should change across the width of the screen, the holding members are gradually adjusted in height as the strip advances. Specification 766,051 [Group XX] is referred to.</p> |
