Electrical transmission or interconnection systems – Switching systems – Condition responsive
Reexamination Certificate
1998-10-21
2001-02-20
Fleming, Fritz (Department: 2836)
Electrical transmission or interconnection systems
Switching systems
Condition responsive
C307S039000, C307S140000, C340S636210
Reexamination Certificate
active
06191505
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention claims priority from Japanese Patent Application No. 9-288467 filed Oct. 21, 1997, which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a control device for a power source unit of a device such as a portable terminal, etc., which includes a battery as a power source thereof.
2. Description of Related Art
In a conventional portable terminal, a voltage detection circuit of a battery is connected to a microprocessor of the portable terminal and the microprocessor controls a power source of the terminal to turn on/off the power source. In such case, there is a possibility of a malfunction of a load due to abnormal operation of the power source unit when the control of the power source unit by the microprocessor fails.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an on/off control device of a power source unit capable of preventing a malfunction of a load due to abnormal operation of the power source unit from occurring.
In order to achieve the above object, an on/off control device of a power source unit according to an embodiment of the present invention comprises an on/off signal generator circuit for generating an on/off signal for on/off controlling the power source unit which supplies a battery voltage to a load, a voltage detection circuit for detecting the battery voltage and determining whether or not the voltage is within a tolerable input voltage range of the power source unit and an on/off signal transmitter circuit for transmitting the on/off signal to the power source unit when the battery voltage is within the tolerable input voltage range of the power source unit and transmitting an off signal to the power source unit when the battery voltage is out of the tolerable input voltage range of the power source unit.
According to another aspect of the present invention, an on/off control device of power source unit comprises an on/off signal generator circuit which generates on/off signals for on/off controlling a plurality of power source units which supply a battery voltage to respective loads, a plurality of voltage detection circuits provided for the respective power source units, each voltage detection circuit detecting the battery voltage and determining whether or not the battery voltage is within a tolerable input voltage range of the corresponding power source unit and on/off signal transmitter circuits provided for the respective power source units, each on/off signal transmitter transmitting the on/off signal to the corresponding power source unit when the battery voltage is within the tolerable input voltage range of the corresponding power source unit and transmitting an off signal to the corresponding power source unit when the battery voltage is out of the tolerable input voltage of the corresponding power source unit.
According to the present invention, the battery voltage that is within the tolerable input voltage range of the power source unit is detected to on/off control the power source unit such that the power source unit is reliably turned off when the battery voltage is lowered.
The voltage detection circuit detects the battery voltage and, when the battery voltage is within the tolerable input voltage range of the power source unit, the on/off signal transmitter circuit allows the on/off signal generator circuit to send the on/off signal to the power source unit. When the battery voltage becomes smaller than the tolerable input voltage range of the power source unit due to an increase of power consumption of the load, the off signal is sent from the on/off signal transmitter circuit to the power source unit regardless of the on/off signal from the on/off signal generator circuit.
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Fleming Fritz
Foley & Lardner
NEC Corporation
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