AUDITORIUM BOARD RULING METHOD Russian patent published in 2001 - IPC

FIELD: manufacture of auditorium boards for writing information with chalk. SUBSTANCE: method involves removing covering from auditorium board having steel sheet, undercoat and covering, by laser beam to depth less than covering thickness; applying lines in at least two parallel rows. Lines are made discrete, for instance in the form of dots deepened into covering. Dots in adjacent rows may be arranged in opposed relation or in staggered arrangement. Lines are visually exposed only upon chalking of board. Upon dry sweeping of board, lines do not disappear, and disappear upon removal of information by wet cleaning method. Method allows auditorium boards to be prevented from damage in the process of ruling. Besides, lines are temporarily removed. EFFECT: increased efficiency and improved quality of board. 5 dwg