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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spare battery unit which is chargeable
so as to supply an electric power to battery-driven machines such as a
notebook type personal computer and, more particularly, to an adapter for
an external battery and a battery system including such an adapter.
2. Description of the Related Art
Various battery-driven machines which utilize a chargeable battery as their
power source have become widespread.
An example of such machines is a notebook type personal computer. A
notebook type personal computer is advantageous in that it is portable
because it is driven by a battery removably installed in the interior of
the machine without the need for connection with the mains power. Before
the power of the battery is consumed, the battery is charged by a charger,
thereby maintaining the function of the battery.
A conventional battery will now be explained with reference to FIG. 3.
A personal computer 1 is provided therewithin with an internal battery 2
which is removable and chargeable, and the electric power of the battery 2
is utilized for various operations. When the internal battery 2 is
charged, a predetermined DC is supplied from a DCIN terminal 3 and
introduced to the internal battery 2 so as to charge it.
For this purpose, the DCIN terminal 3 is connected to a DC cable 4, and the
DC cable 4 is connected to a plug 6 through an AC adapter/charger 5.
The AC power (usually AC 100 to 240 V) from the plug 6 is converted into a
predetermined DC power (e.g., DC 12 V) by the AC adapter/charger, and
input to the DCIN terminal 3 of the personal computer 1 through the DC
cable 4, thereby charging the internal battery 2.
In this way, by charging the internal battery 2 with a predetermined
frequency, it is possible to maintain the power of the internal battery 2
and to drive the personal computer by utilizing the power.
However, since the capacity of the internal battery 2 is limited, the
computer can be operated for about 2 hours at most without recharging the
internal battery. Although it is possible to prolong the duration of
continuous use of the computer by increasing the capacity of the internal
battery 2, since the weight of the personal computer 1 is thereby
increased, there is a limit to increases in the capacity of the internal
battery 2.
In order to permit continuous use of the computer for a long time use
without charging while maintaining the light weight of the personal
computer 1, a battery identical to the internal battery 2 may be provided
as a spare battery which replaces the internal battery 2 after a
predetermined time has passed.
However, during the period when the batteries are being changed, the power
supply to the personal computer 1 is zero, so that the data and the like
which are stored in a RAM or the like of the personal computer 1 are lost.
To prevent this, a battery for backing up the RAM is provided in the
personal computer 1 separately from the internal battery 2 so as to save
the data and the like in a memory such as a magnetic disk which can store
the data before the power supply to the personal computer is cut off for
the purpose of exchanging the batteries.
This is, however, also disadvantageous in that the system for providing the
backup battery within the personal computer 1 requires an additional
device, which occupies a considerable space in the personal computer 1,
increases the weight of the computer and leads to an increase in cost.
Especially, since the backup battery is not operated for any significant
period of time, it is inefficient to provide it within the personal
computer 1.
In addition, it is troublesome for the user to save the data and the like
in a magnetic disk or the like before exchanging the batteries and to
restore the data after they are exchanged.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to eliminate the
above-described problems in the related art and to provide an adapter for
an external battery and a battery system which are capable of efficiently
utilizing an external battery.
To achieve this aim, an adapter for an external battery according to the
present invention comprises: a battery connector for connecting the
adapter to an external battery which is chargeable; an external device
connector including a power output terminal which is connected to the
battery connector so as to output the power from the external battery, and
a power input terminal for receiving a current for charging the external
battery; an output diode which is provided in a current path between the
power output terminal and the battery connector so as to apply a current
from the external battery to the power output terminal; and a charging
diode which is provided between the power input terminal and the battery
connector so as to apply a current from the power input terminal to the
external battery.
A battery system according to the present invention comprises:
an adapter for an external battery; and
a computer including a power input terminal for receiving a power to be
supplied to a load, a charging current receiving means for receiving a
current for charging an internal battery, and a diode disposed in a
current path for supplying the current from the internal battery to the
load so as to check a reverse flow;
the power output terminal of the adapter for an external battery being
connected to the power input terminal of the computer so as to enable a
power to be supplied from the external battery to the computer; and
the power input terminal of the adapter for an external battery being
connected to the power output terminal of a charger so as to enable the
external battery to be charged.
According to the present invention, it is possible to output the power of
the external battery from the power output terminal and to receive the
charged power of the external battery from the input terminal by
connecting the adapter for an external battery to the external battery.
By connecting the adapter for an external battery to the charger, it is
possible to charge the external battery.
It is also possible to supply the power of the external battery to the
machine by connecting the adapter for an external battery to the computer.
The above and other objects, features and advantages of the present
invention will become clear from the following description of the
preferred embodiment thereof, taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the external appearance of an embodiment of
an adapter for an external battery and a battery system, showing three
connection modes of the adapter with a charger and a computer;
FIG. 2 is a circuit diagram of the power circuitry within the adapter for
an external battery, the charger and the computer shown in FIG. 1; and
FIG. 3 is an explanatory view of a conventional adapter in the state of
charging a battery within a computer.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows an embodiment of an adapter for an external battery according
to the present invention and an external battery which is connected to the
adapter. The connection between the adapter, a charger and a computer can
be established by one cable in three modes by switching, as shown in FIG.
1.
In FIG. 1, an external battery 7 is chargeable and it is formed into a
portable battery power pack. For example, a battery MBC-18NBAT, produced
by Sanyo Electric Co., Ltd. is preferred.
In order to connect the external battery 7 to a charger or a computer, an
adapter 9 for an external battery which is characteristic of the present
invention is provided. The adapter 9 incorporates diodes for selectively
restricting the connection circuits and the current paths, as will be
described later. The adapter 9 is also provided with a connector for
electrically connecting the adapter 9 to the battery 7 and another
connector for electrically connecting the adapter 9 to an external charger
or a computer, as will be described later. In FIG. 1, an external device
connector is represented by the numeral 10.
The external battery 7 shown in FIG. 1 constitutes an auxiliary power
source with respect to a portable notebook type computer. Power is
supplied from the external battery 7 to a notebook type computer 24
through a cable 32 via the adapter 9. The notebook type computer 24 is,
for example, a portable computer of MBC-18NB series, produced by Sanyo
Electric Co., Ltd. An internal battery for normally supplying power to the
computer is provided within the computer 24. The adapter 9 of the present
invention allows the external battery 7 to effectively cooperate with the
internal battery.
A charger 13 is provided so as to selectively charge either the external
battery 7 or the internal battery provided within the computer 24 through
the common cable 32. The charger 13 receives AC power from a mains power
source through a plug 5, rectifies the AC power current and lowers the
voltage thereof. Thereafter, the charger 13 supplies current to the
external battery 7, or to the internal battery within the computer 24 or
the group of devices through the cable 32 as a charging or driving
current.
As will be described later, according to the present invention, since the
adapter 9 for an external battery has a characteristic connecting
structure and characteristic current paths, it is possible to connect the
adapter 9 to the computer 24 and the charger 13 in three different
charging or power supply modes by using the common cable 32. As is clear
from FIG. 1, the common cable 32 has two four-terminal 31a and 31b, each
at a respective end thereof.
FIG. 2 shows the power circuitry of the adapter 9 having a structure
characteristic of the present invention, the charger 13 and the notebook
type computer 24.
The external battery 7 is a chargeable battery which has the same ability
as the internal battery for supplying power necessary for driving the
personal computer. The external battery 7 is connected to the adapter 9
for an external battery through the battery connector 8 of the adapter 9.
The positive pole of the external battery 7 is connected to the
positive-pole terminal 8a of the battery connector 8, and the negative
pole of the external battery 7 is connected to the negative-pole terminal
8b of the battery connector 8.
The adapter 9 for an external battery has an external device connector 10,
and the connector 10 has four terminals 10a to 10d. The first terminal 10a
and the second terminal 10b are connected to the positive-pole terminal 8a
of the connector 8 through a diode 11 for checking the inflow of a current
and a diode 12 for checking the outflow of a current, respectively. The
third terminal 10c (through terminal) is connected to the negative-pole
terminal (common terminal) 8b, and the fourth terminal 10d is open.
If a load is connected between the first terminal 10aand the third terminal
10c, power is supplied from the external battery 7 to the load through the
diode 11. On the other hand, if the second terminal 10b and the third
terminal 10c are connected to a DC supply source, it is possible to charge
the external battery 7 through the diode 12.
In FIG. 2, the charger 13 is composed of an AC adapter 13a for AC/DC
conversion and a charge controller 13b for controlling the output DC
power. The AC adapter 13 includes a rectifier 14 which is connected to the
plug 5, a capacitor 15 for smoothing the output of the rectifier 14 and a
voltage-drop transformer 16 for lowering the smoothed DC voltage. A
switching transistor 17 supplies a predetermined control signal to the
primary coil of the voltage-drop transistor 16, and a diode 18 and a
capacitor 19 are used to obtain a predetermined DC power at the output of
the secondary coil of the voltage-drop transformer 16.
The AC power (usually AC 100/110 V) supplied from the plug 5 is therefore
output as a predetermined DC power which is determined by the ON/OFF of
the switching transistor 17. In other words, the smaller the duty ratio of
the pulsating control signal which controls the ON/OFF of the switching
transistor 17, the smaller the output power of the transistor 17, so that
it is possible to control the output power by the ON/OFF control of the
switching transistor 17.
The charge controller 13b is composed of a changeover switch 20, a
connector 23 having four terminals 23a to 23d, a controller 22 and a
resistor 21 for pulling up the potential of the line connecting the
terminal 23d and the controller 22. The input terminal of the changeover
switch 20 is connected to the DC power output terminal of the AC adapter
13a, while one output terminal is connected to the terminal 23a of the
connector 23 and the other output terminal is connected to the terminal
23b. The DC output from the AC adapter 13a is therefore output from either
the terminal 23a or the terminal 23b in accordance with the switching
operation of the changeover switch 20.
As will be described later, when the charger 13 is connected to the
computer 24, it is possible to determine whether the power of the charger
13 should drive directly each device of the computer 24 or charge the
internal battery.
The controller 22 controls the switching operation of the changeover switch
20 and the ON/OFF operation of the switching transistor 17 in the AC
adapter 13a in accordance with the signal supplied from the computer 24 to
the controller 22 through the terminal 23d.
In other words, when the controller 22 judges from the signal input from
the computer 24 to the terminal 23d that the personal computer 24 is being
operated, the controller 22 connects the changeover switch 20 to the
terminal 23a and so controls the ON/OFF operation of the switching
transistor 17 that power having a predetermined voltage is output from the
terminal 23a. As a result, the computer 24 is driven by the charger 13.
On the other hand, when the controller 22 judges from the signal input from
the computer 24 to the terminal 23d that the personal computer 24 is in an
inoperative state, the controller 22 connects the changeover switch 20 to
the terminal 23b and so controls the ON/OFF operation of the switching
transistor 17 that power having a constant current is output from the
terminal 23b. As a result, the internal battery within the computer 24 is
charged.
The terminal 23c is connected to the grounding side of the voltage-drop
transformed 16 of the AC adapter 13a.
The personal computer 24 includes a removable internal battery 25, a load
26 for conducting various operations of the personal computer, and a
connector 27 having four terminals 27a to 27d for connecting the computer
24 to an external device. The positive pole of the internal battery 25 and
the terminal 27a are connected to the load 26 such as CPU, memory,
display, hard disk drive and floppy disk drive through a power switch 28,
so that it is possible to supply the power from the internal battery 25 or
the terminal 27a to the load 26. A diode 29 for preventing a current from
flowing to the internal battery 25 is provided between the internal
battery 25 and the path connecting the power switch 28 and the terminal
27a. All the currents from the terminal 27a are therefore used to drive
the computer 24 and the internal battery 25 is inhibited from being
charged.
Thus, in the present invention, while the charger 13 is driving the
computer 24, the driving of the computer 24 at a constant voltage is not
impaired by the current for charging the internal battery 25.
The terminal 27b is connected to the positive pole of the internal battery
25 through a diode 30, thereby enabling the internal battery 25 to be
charged by the current supplied from the charger 13 through the terminal
27b.
At this time, the charger 13 outputs a constant current and charges the
internal battery 25 by a constant current in accordance with the charged
state of the internal battery 25.
A power ON/OFF detection signal is output from the load 26 to the terminal
27d, and the information about which charging mode should be selected is
output from the terminal 27d. The terminal 27c is a grounding terminal (0
V common terminal).
As described above, according to the present invention, the adapter 9 for
an external battery, the charger 13 and the personal computer 24 have the
common four-terminal connectors 10, 23 and 27, respectively. It is
therefore possible to connect each other by the DC cable 32 having the
four-terminal connectors 31a, 31b at the respective ends in a desired
mode, as shown in FIG. 1.
The adapter of the present invention and the charger and the computer which
are connected to the adapter have the above-described power circuitry.
Three charging and driving modes of the computer using the adapter 9 of
the present invention will be explained in the following.
Mode A (the computer 24 is driven and the internal battery 25 is charged by
the charger 13).
In this mode, the computer 24 is connected to the charger 13 by the cable
32. In the mode A, a mode is further selected from two different power
supply modes depending upon whether or not the computer 24 is being
operated.
In a first mode, the computer 24 is being operated. The charger 13 detects
the operative state of the computer 24 and supplies power having a
constant voltage to the computer 24.
In a second mode, the computer 24 is in an inoperative state, and the
computer 24 requires the charger 13 to supply power having a constant
current for charging the internal battery 25.
When the charger 13 is connected to the personal computer 24 by the DC
cable 32, the load 26 outputs an operative state detection signal of [H]
or [L] from the terminal 27d in accordance with the state of the power
switch 28. For example, when the power switch 28 is ON, the load 26
outputs a signal of [L] which requires the supply of an operating current
to the load 26. On the other hand, when the power switch 28 is OFF, the
load 26 outputs a signal of [H] which requires the internal battery 25 to
be charged.
The detection signal of [H] or [L] is supplied to the controller 22 through
the terminal 23d of the charge controller 13b. The controller 22 operates
the transistor 17 and the switch 20 in accordance with the detection
signal. If the detection signal indicates the demand for an operating
current when the power switch 28 is ON (i.e, a detection signal of [L]),
the controller 22 switches the connection of the changeover switch 20 from
the terminal 23b to the terminal 23a, controls the switching transistor 17
so as to output a constant voltage and outputs power with a constant
voltage from the terminal 23a. The personal computer 24 receives the
constant voltage from the terminal 27a, and the load 26 is operated by the
power of the constant voltage.
On the other hand, if the detection signal obtained at the terminal 23d
indicates the demand for a charging current when the power switch 28 is
OFF (i.e, a detection signal of [H]), the controller 22 switches the
connection of the changeover switch 20 from the terminal 23a to the
terminal 23b, controls the switching transistor 17 so as to output a
constant current and outputs power with a constant current from the
terminal 23b. Since the power with a constant current is supplied to the
personal computer 24 from the terminal 27b, it is supplied to the internal
battery 25 through the diode 30, thereby charging the internal battery 25.
Mode B (the external battery 7 is charged by the charger 13)
In the mode B, charging power is supplied from the charger 13 to the
battery 7 in order to fully charge the external battery 7. The adapter 9
of the present invention is used for charging. The charger 13 outputs
power having a constant current for charging the external battery 7. When
the charger 13 is connected to the adapter 9 for an external battery by
the DC cable 32, which is used in common in each mode, since the terminal
10d of the adapter 9 for an external battery is open, the level of the
signal obtained at the terminal 23d becomes [H] by virtue of the pull-up
resistor 21. The controller 22 judges that there is a demand for charging,
switches the connection of the switch 20 from the terminal 23a to the
terminal 23b, and simultaneously supplies a constant current control
signal to the switching transistor 17. A constant current is therefore
output from the terminal 23b. A constant current is thus obtained at the
terminal 10b of the adapter 9 for an external battery, and it is supplied
to the external battery 7 through the diode 12, thereby charging the
external battery 7.
Mode C (the computer 24 is driven by the external battery 7)
In the mode C, the power of the external battery 7 is directly supplied to
the load 26 of the computer 24 through the adapter 9, and the external
battery 7 is used either in place of or in cooperation with the internal
battery 25. In the mode C, it is possible to directly supply the power of
the external battery 7 to the load 26 without the need for removing the
internal battery 25 from the computer 24. It is also possible to remove
the internal battery 25 from the computer 24 for charging the internal
battery 25 during this auxiliary power supply. The backing up of the
memory for data is therefore dispensed with, which is necessary at the
time of exchanging the live batteries in the prior art.
When the adapter 9 for an external battery is connected to the personal
computer 24 by the DC cable 32, the current from the external battery 7 is
supplied to the terminal 27a of the personal computer 24 through the diode
11 and the terminal 10a. The power is therefore supplied to the load 26
through the power switch 28, and the load 26 operates by the power of the
external battery 7.
At this time, the power of the internal battery 25 within the personal
computer 24 is also supplied to the load 26 through the diode 29 and the
power switch 28. It is therefore possible to operate the personal computer
24 by utilizing the power from both external battery 7 and internal
battery 25. If each of the external battery 7 and the internal battery 25
has a capacity for continuous use for 2 hours, this embodiment allows the
personal computer 24 to be continuously used for 4 hours, which is the sum
of the capacities of the batteries 7 and 25. In a general notebook type
personal computer, if it is usable for 4 consecutive hours, there is
almost no trouble in ordinary use. If the external battery 7 and the
adapter 9 for an external battery are carried together with the personal
computer 24, sufficiently continuous use of the personal computer 24 is
possible without charging.
As described above, according to the present invention, since each member
is connected by the DC cable 32 which has connectors 31 at the respective
ends, the system is simplified.
If the internal battery 25 is removed while power is supplied from the
external battery 7, since the power from the external battery 7 is
supplied to the personal computer 24, the data in load 26 such as a RAM or
the like are not lost. It is therefore possible to change the internal
batteries 25 without the need for the backing-up operation.
If a plurality of batteries are carried and the internal batteries 25 are
exchanged while the external battery 7 is connected to the personal
computer 24, it is possible to further prolong the time enabling the
continuous use of the computer 24. It is also possible to alleviate
problems at the time of exchanging the deteriorated internal battery.
In this embodiment, the charger 13 switches between the adapter mode and
the charging mode in accordance with the detection signal from the
personal computer 24 in the mode A. Alternatively, it is possible to
provide a manual switch for switching modes in the charger 13. In this
case, the number of terminals at both ends of the connectors may be
reduced to 3, and a 3-pin DC cable may be used.
As described above, according to an adapter for an external battery and a
battery system of the present invention, it is possible both to charge an
external battery and to supply power from the external battery by
utilizing one adapter for an external battery, so that efficient use of
the external battery is enabled. It is also possible without increasing
the weight of the personal computer to prolong the time enabling the
continuous use of the computer without charging.
While there has been described what is at present considered to be a
preferred embodiment of the invention, it will be understood that various
modifications may be made thereto, and it is intended that the appended
claims cover all such modifications as fall within the true spirit and
scope of the invention.
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