Clock synchronization circuit for control of traffic signals
US4472714A · kind A · utility
11Cited by
5References
8Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jan 21, 1983 |
| Grant date | Sep 18, 1984 |
| Priority date | — |
| Expiry date | Jan 21, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08G1/07
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A device used in the control of automobile traffic signal systems for maintaining a local time reference during periods when the a.c. power is interrupted. An accurate oscillator such as a crystal controlled oscillator is used to provide a local time reference during power interruptions. The device maintains a local clock in synchronism with the a.c. power when the power is present and maintains the time reference in synchronism with the crystal oscillator during those periods when the a.c. power is absent. Pulse trains at different rates generated in synchronism with the oscillator are combined to achieve these objects.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.