Apparatus and method for determining a time that a system's main power was inactive
US5410581A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 2, 1994 |
| Grant date | Apr 25, 1995 |
| Priority date | — |
| Expiry date | May 2, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C3/04
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An apparatus and method for determining a time that a system's main power was inactive includes a counter circuit (171) for accumulating transitions of a clock signal (149) while the system's main power (117) is inactive. Preferably, another circuit (159, 125) determines a periodicity of the clock signal (149) after the system's main power (117) transitions active. Then a computational circuit, preferably a microcontroller (129), determines the time (183) that the system's main power (117) was inactive dependent on a number of transitions of the clock signal (149) accumulated by the counter circuit (171) when the system's main power (119) was inactive and the determined periodicity of the clock signal (149) after the system's main power (117) transitions active. Preferably, this apparatus and method are used in a vehicle to determine how long a time that an engine is turned off and to modify an engine control strategy dependent on that determined time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.