Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2000-11-13
2002-11-26
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
C320S128000
Reexamination Certificate
active
06486635
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a monitor signal output circuit for outputting a monitor signal to monitor a voltage of a battery, a battery pack having a monitor signal output function, a battery voltage monitor circuit for monitoring a voltage of a battery in accordance with a monitor signal, a battery system and an apparatus each having a battery and a monitoring function for a voltage of the battery, a battery voltage monitor method for monitoring a voltage of a battery, and a battery voltage monitor program storage medium storing therein a program for a battery voltage monitor.
2. Description of the Related Art
Many of portable type of electronic apparatuses such as a note type of personal computer and the like are loaded with a battery for apparatuses.
In case of an apparatus which is operated on a desk, or in the event that a portable type of apparatus such as a note type of personal computer is operated on a desk, there is no need to consider such a matter that a supply of electric power for operating those types of apparatus operated by electric power from a commercial power supply through an AC adapter is interrupted. On the other hand, in case of an apparatus operative upon receipt of supply of electric power from a battery, there is a need for a user always to be aware of a residue of the battery. Particularly, in case of an information processing apparatus such as a notebook-sized personal computer and the like, there is a possibility that when the residue of the battery becomes zero (or the battery died), all of partially completed data will be erased. Accordingly, there is a need for a user to be aware of a state of consumption of the battery and to save the partially completed data onto a non-volatile storage medium such as a hard disk before the residue of the battery becomes zero.
For the purpose of preventing troubles involved in a situation that the residue of the battery becomes zero, the conventional notebook-sized personal computer and the like incorporates thereinto a system for monitoring the residue of the battery.
FIG. 11
shows a battery system having a battery residue monitor function.
A battery system
10
comprises a battery pack
20
and a battery voltage monitor section
30
. The battery system
10
is incorporated into a notebook-sized personal computer
40
. The battery pack
20
is connected with the battery voltage monitor section
30
in such a manner that a selection signal input terminal
20
a
of the battery pack
20
, a battery voltage output terminal
20
b
of the battery pack
20
, a power supply terminal
20
c
of the battery pack
20
and a ground terminal
20
d
of the battery pack
20
are connected with a selection signal output terminal
30
a
of the battery voltage monitor section
30
, a battery voltage input terminal
30
b
of the battery voltage monitor section
30
, a power supply terminal
30
c
of the battery voltage monitor section
30
and a ground terminal
30
d
of the battery voltage monitor section
30
, respectively.
The battery voltage monitor section
30
shown in
FIG. 11
comprises a DC-DC converter circuit
31
and a microcomputer
32
operative upon receipt of a supply of an electric power of 5.0 V from the DC-DC converter circuit
31
.
The microcomputer
32
transmits a selection signal for optionally selecting any one; of three batteries S
1
, S
2
, and S
3
, which are connected in series within the battery pack
20
, via the selection signal output terminal
30
a
of the battery voltage monitor section
30
and the selection signal input terminal
20
a
of the battery pack
20
to a battery protection circuit
21
of the battery pack
20
. The battery protection circuit
21
transmits in accordance with the selection signal a monitor signal representative of a voltage of the battery selected by the selection signal via the battery voltage output terminal
20
b
of the battery pack
20
and the battery voltage input terminal
30
b
of the battery voltage monitor section
30
to the microcomputer
32
. The microcomputer
32
converts the transmitted battery voltage into a digital signal to recognize the battery voltage in form of a digital value, so that the residue of the battery is recognized from the battery voltage.
The battery pack
20
shown in
FIG. 11
is provided with two FETs (FET
1
and FET
2
). The batteries S
1
, S
2
, and S
3
are each a chargeable battery, for example, a lithium-ion battery. FET
1
of the two FETs turns off, when a voltage of the batteries S
1
, S
2
, and S
3
goes down to the lower limit, and thereby preventing an over discharge of the batteries S
1
, S
2
, and S
3
. FET
2
turns off when the batteries S
1
, S
2
, and S
3
are completely charged and further charged, and thereby preventing an over-charge of the batteries S
1
, S
2
, and S
3
.
FIG. 12
is a view showing an internal structure of the battery protection circuit of the battery pack
20
shown in FIG.
11
. However, here, the prevention of the over discharge and the over charge of the batteries is not a main subject matter, and thus a circuit structure of the prevention of the over discharge and the over charge of the batteries and the associated description will be omitted.
The battery protection circuit
21
has: a selection signal input terminal
21
a
for inputting a selection signal; a monitor signal output terminal
21
b
for outputting a monitor signal representative of a voltage of a battery; a node connection terminal
21
c
connected to one end (a plus electrode of S
1
) of a plurality (three) of batteries S
1
, S
2
and S
3
connected in series; a node connection terminal
21
d
connected to a connecting point of two batteries S
1
and S
2
; a node connection terminal
21
e
connected to a connecting point of two batteries S
2
and S
3
; and a node connection terminal
21
f
connected to another, end (a minus electrode of S
3
) of the batteries S
1
, S
2
and S
3
connected in series. Both ends of the plurality (three) of batteries connected in series and the connecting points of the battery-to-battery are referred to as a ‘node’.
The battery protection circuit
21
comprises three differential amplifiers AMP
1
, AMP
2
, and AMP
3
, and a multiplexer MPX. The three differential amplifiers AMP
1
, AMP
2
, and AMP
3
are for inputting two nodes
21
c
and
21
d
, two nodes
21
d
and
21
e
, and two nodes
21
e
and
21
f
, respectively. Outputs of the three differential amplifiers AMP
1
, AMP
2
, and AMP
3
are fed to the multiplexer MPX. The multiplexer MPX selects one of the three inputs in accordance with the selection signal entered through the selection signal input terminal
21
a
and outputs the selected one through the monitor signal output terminal
21
b.
The microcomputer
32
shown in
FIG. 11
sequentially outputs the selection signal to optionally select the batteries S
1
, S
2
and S
3
, and receives through an AD conversion the monitor signal representative of the associated voltages of the batteries S
1
, S
2
and S
3
, and thus it is possible to know the voltages of the batteries S
1
, S
2
and S
3
.
FIG. 13
is a graph showing a relation between a discharge time (a horizontal axis) and a battery voltage (a vertical axis) of a lithium-ion battery.
FIG. 14
is a graph showing a relation between a battery voltage (a vertical axis) and a battery residue (a horizontal axis) of a lithium-ion battery.
As shown in
FIG. 13
, when a battery is used, a voltage of the battery is gradually lowered. When the voltage of the battery is monitored, as shown in
FIG. 14
, it is possible to know the residue of the battery from the voltage of the battery.
According to the microcomputer
32
, it is possible to take measures to meet the situation that the battery is not usable, in such a manner that the microcomputer
32
detects the respective voltages of the batteries S
1
, S
2
and S
3
to know the residue of the batteries, so that the microcomputer
32
informs of the residue a user of the notebook-sized personal computer
40
, and when the residue
Matsuda Kouichi
Ozawa Hidekiyo
Saeki Mitsuo
Shigeaki Nakazawa
Armstrong Westerman & Hattori, LLP.
Fujitsu Limited
Luk Lawrence
Tso Edward H.
LandOfFree
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