Geographical chronological device
US5917778A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 1997 |
| Grant date | Jun 29, 1999 |
| Priority date | — |
| Expiry date | Sep 25, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04B19/22
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A geographical chronological device which simultaneously indicates the time in multiple cities or countries, and displays fluctuations in day or night in a geographic location. The earth clock has a semi-transparent world map depicting a polar planetary projection of the world from the north or south pole. An adjustable shadow disk is disposed adjacent to and partly visible through the semi-transparent world map. The shadow disk has a periphery with time indicia disposed about the periphery. The adjustable shadow disk has an adjustable dark portion to indicate night and an adjustable light portion to indicate day. The dark and light portions adjust to indicate relatively greater or lesser night and day according to the change in seasons. A clock movement provides relative movement between the semi-transparent world map and the adjustable shadow disk.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.