Showing papers on "Blackboard (design pattern) published in 1981"
Patent•
23 Oct 1981
TL;DR: A blackboard cleaning device consisting of a sponge eraser pad, a filter covered with fabric, and a turbine fan driven by an electric motor is used to create a suction force whereby chalk powder or particles are collected on the surface of the fabric to accumulate in a lower transparent chamber as mentioned in this paper.
Abstract: A blackboard cleaning device comprises a sponge eraser pad 21, a filter 31 covered with fabric 32, and a turbine fan 422 driven by an electric motor to create a suction force whereby chalk powder or particles are collected on the surface of the fabric to be accumulated in a lower transparent chamber 14
10 citations
Patent•
19 Feb 1981
TL;DR: In this article, a blackboard and demonstration board are mounted on a stand, the board being in two or more parts (2,3) hinging together, e.g. with the aid of a strip.
Abstract: The blackboard and demonstration board is mounted on a stand, the board being in two or more parts (2,3) hinging together, e.g. with the aid of a strip. The stand comprises several components (6) fitted one inside the other, their length being the same as that of the board parts, and one or more components are fixed detachably to the latter, extending across the hinge line (10). The board parts can be of the same size, while the stand can be three-legged, two parts of it being detachable from the board parts and securing them in the unfolded position while the third is detachably inserted in one of them and at an angle to it.
1 citations