Student's multi-function protractor
US4791733A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 22, 1987 |
| Grant date | Dec 20, 1988 |
| Priority date | — |
| Expiry date | Jul 22, 2007 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB43L13/08
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
A student's multi-function protractor for conveniently drawing different geometric figures including a transparent middle plate which fits on the retainment space between an upper base and a lower base. The middle plate is rotatable in the retainment space. The circumferential edge with the middle plate of the upper base has a 360 degree scale. In addition, the middle plate has a plurality of parallel grooves which are scattered on one side from the central point for providing direct drawings. By accompanied with the grooves, scales and the indication elements on the middle plate, the protractor of this invention is used to easily draw different geometric figures.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.