Charging method and device

Details Charging method and device Charging method and device

2000-01-12

2001-01-02

Riley, Shawn (Department: 2838)

Electricity: battery or capacitor charging or discharging

Battery or cell charging

Pulsed

C320S162000

Utility Patent

active

06169388

ABSTRACT:

BACKGROUND OF THE INVENTION
With the proliferation of cellular phones, there has been pressure to improve the battery power capability to supply these devices. The efficacy of these phones relies on mobility and such mobility requires efficient battery power. From the start the batteries used have been rechargeable, prompting significant development in the structure of rechargeable batteries. Under normal conditions, the charging of such batteries is accomplished by circuitry built into the control microprocessor of the cellular phone. In order to operate, however, the controller requires a minimum voltage level from the batteries. A problem therefore arises when the battery charge is depleted below these minimum levels.
It is a purpose of this invention to provide an improved charging system for depleted batteries.
One of the prior art solutions to this charging problem is shown schematically in FIG.
1
. In this instance, a start up module is added to the controller circuit to provide a limited initial constant current charge at a low current for example from 100 ma to 180 ma. This charging current is allowed to build the battery voltage to a level which will support the operation of the main controller. The controller will then take over, switching off the start-up charging module and allowing the battery to charge in a more rapid conventional manner.
In the start up mode at which the controller
2
is disabled, the start up current must be limited in order avoid excessive power loss. The power loss is caused by the need to dissipate the voltage drop from the charger voltage to the battery voltage. In view of the limited charge current, the start up mode requires an unacceptably long period of time to reach the operative voltage of the controller
2
.
It is a purpose of this invention to provide a quicker start up charging mechanism which operates with lower power consumption.
SUMMARY OF THE INVENTION
In this invention, the start up charging circuitry is replaced by a new and unique low power start up module. The start up module of this invention consists of a pulse generator which is used to cycle the conventional charging circuit. In the start up mode, the controller charging circuit is disabled because of insufficient voltage from the battery. In this invention the charging switch is controlled by the start up module when the battery power is below the threshold of the controller. The start up module generates a pulse chain which cycles the charging switch and thereby turns the standard charging circuit on and off. In this manner a relatively rapid and efficient initial charging of a dead or substantially depleted battery is obtained. A comparator senses the battery voltage, enables the controller charging cycle, and disables the start up charging cycle when the operational threshold voltage for the controller is obtained.


REFERENCES:
patent: 5446364 (1995-08-01), Naskali
patent: 5625274 (1997-04-01), Naskali
patent: 5648711 (1997-07-01), Hakkarainen
patent: 5760568 (1998-06-01), Naskali
patent: 5821735 (1998-10-01), Scharff

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