Device for measuring time lapse after turn off of power source and method thereof
US5500834A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 29, 1994 |
| Grant date | Mar 19, 1996 |
| Priority date | — |
| Expiry date | Aug 29, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04F10/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
While the electric power source is turned on, capacitor 1 is charged to a voltage EO by a direct current constant voltage supplier through transistor 4. When the electric power is disconnected, transistor 4 is switched off to discharge capacitor 1 through resistor R1. When the power source is turned on, the voltage of capacitor 1 is read by A/D converter to be produced and stored in CPU 12 memory. Then transistor 4 is switched on to charge capacitor 1 to the voltage EO. Then transistor 4 is switched off and transistor 5 is switched on to discharge capacitor 1 through resistor R2 and a counter stars. When the voltage of capacitor 1 reduces to the same voltage stored in the memory, transistor 5 is switched off to stop the counter and to obtain the counted value t2. Then transistor 4 is switched on to prepare for the next operation. The time lapse t1 after the power source being turned off is obtained by a formula (R1/R2).times.t2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.