BLACKBOARD

摘要

The black board is intended for use at schools and universities. It has a simplified construction and may be cleaned very effectively, which improves hygienic conditions. It includes a frame (1) with two rolls (4), around which is stretched a flexible endless tape (5), actuated by a motor-reductor group (7). The bottom roll (4) is enveloped by a bath (10) with a cleaning liquid. The bath (10) has a borne wiping cylinder, consisting of a shaft (11) with an attached to it wiping sponge (12) with a profile of irregular hexagon, formed by three short operable walls and three long non-operable walls. It also has a fixator (13) for situating the wiping sponge (12) in various positions toward the endless tape (5). The washing liquid contains water with solved in it citric acid and a conservant. The top front end of the bath (10) is affixed motively to a cleaning plate (14).