Battery operated computer having improved battery gauge and system for measuring battery charge
US5341503A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 1992 |
| Grant date | Aug 23, 1994 |
| Priority date | — |
| Expiry date | Apr 16, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/382
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A digitizer tablet computer has a host processor connected to a service processor which, in turn, is connected to a digitizer controller and to a power subsystem microcontroller. A battery supplies the primary power for operating the computer but the computer is also connectable to an external source of DC power to charge the battery and to operate the computer when it is not running on battery power. The service processor includes a battery gauge the contents of which indicate how much power is left in the battery and how much time remains at the current rate of power consumption before the power runs out. The amount of remaining power in the gauge is determined by keeping track of power consumed, power added, and power lost during off periods. The use of the second derivative of a voltage versus time discharge curve creates a point from which relative accurate estimates can be made of how much longer the computer can be operated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.