Straightedge supporting device for rail type drawing instrument
US4070758A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 9, 1976 |
| Grant date | Jan 31, 1978 |
| Priority date | — |
| Expiry date | Dec 9, 1996 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB43L13/02
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A straightedge supporting device for rail type drawing instrument which has a cross rail capable of being manually shifted in a desired direction on a drawing board while remaining in a predetermined orientation, a head supported by a longitudinal rail on the drawing board, a ruler mounting plate mounted on the head for rotation in a plane parallel to the surface of the drawing board, a fixing element for detachably fixing the ruler mounting plate to the head and disengaging it therefrom, and a straightedge mounted on the ruler mounting plate. The improved straightedge supporting device operates such that when the drawing board is tilted and the straightedge is not fixed to the head, a turning force is applied to the ruler mounting plate in the opposite direction to the turning moment which tends to cause the straightedge to swing downwardly along the surface of the drawing board due to its own weight, so that the straightedge remains in a stable static condition on the inclined drawing board at a desired angle to the head.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.