| 摘要 |
546,718. Tickets. LANG, M. March 3, 1941, No. 2830. [Classes 16 and 73] To prevent the forgery of tickets and the like, their surfaces are provided with continuous, even, regular, smooth grooves or ribs. The grooves or ribs may be parallel or diagonal or form squares, and present sharper well-defined edges and clear outlines. The ribbing may be effected with or after the printing and by interdependent mechanisms. The rollers used may be in sections to vary the positions of the grooves and free spaces. |
