Photo-optical keyboard having light attenuating means
US4379968A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 24, 1980 |
| Grant date | Apr 12, 1983 |
| Priority date | — |
| Expiry date | Dec 24, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/969
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
The invention relates to photo-optical detection by coded aperture in which photo-optical keyboard apparatus includes a pattern arrangement of keys in rows and columns wherein each row is provided with a light source or generator optically couplable to a light receiver or receptor and including individual key stems each of which is provided with a light transfer attenuating, limiting or constricting element each element being arranged to pass or restrict a percentage of the light from source to receptor, key to key, by column to row effective to indicate the precise key position or location as a result of the actuation or depression of any key in the pattern arrangement. By electrically multiplexing the light signals a minimum circuit complex is required.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.