Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – With discharge of cells or batteries
Reexamination Certificate
2001-12-14
2003-09-09
Patel, Rajnikant B. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
With discharge of cells or batteries
C363S020000
Reexamination Certificate
active
06617826
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 90114489, filed Jun. 14, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to a charging device, and more specifically relates to a charging device suitable for a rechargeable battery of a portable device.
2. Description of Related Art
Digital electronic products have brought more convenient life for human beings as they have been highly developed. Furthermore, high developments of a variety of portable digital devices, such as a mobile phone, a notebook computer (notebook) or a personal digital assistance (PDA), considerably increase convenient life and work efficiency for human beings. As for the notebook, due to its portability, the power supplied to the notebook depends on a special battery installed therein. Therefore, it is very important that the power of the battery is continuously and stably supplied to the notebook for maintaining normal operations of the notebook. Accordingly, charging ability and charging time are important criteria for evaluating a notebook.
FIG. 1
shows a block diagram for a system block
100
of a conventional notebook. As shown, The conventional system block
100
is coupled to an external power source
102
, and the system block
100
comprises a charging device
103
and a main function device
104
. The charging device
103
utilizes the external power source
102
to charge a rechargeable battery
106
. The charging device
103
comprises a current detecting device
108
for detecting a charging current fed into the rechargeable battery and then outputting a charging current signal according to the detected charging current.
FIG. 2
shows a block diagram of the current detecting device
108
. The current detecting device
108
consists of a current detecting resistor
202
and a current to voltage convert circuit
204
, which connection is as shown in FIG.
2
. When the charging device
103
begins to charge rechargeable battery
106
, the charging current flows through the current detecting resistor
202
and a voltage drop occurs over the current detecting resistor
202
. As the charging current becomes larger, the voltage drop increases, too. Therefore, by means of the current detecting resistor
202
, the current to voltage convert circuit
204
is able to detect the charging current and then outputs a proper voltage according to the detected charging current. The outputted voltage is defined as the charging current signal, representing the magnitude of the charging current.
Referring to
FIG. 1
again, the charging current signal from the current detecting device
108
is fed to a current error amplifier
110
. The current error amplifier
110
is coupled to the current detecting device
108
for receiving the charging current signal from the current detecting device
108
and a predetermined charging current signal Cs of the charging device. The current error amplifier
110
compares the detected and predetermined charging current signals for setting and adjusting the charging state of the charging device
103
. A DC-DC converter power stage
112
is coupled to the current error amplifier
110
for adjusting the charging current inputted to the current detecting device
108
according to a charging current adjustment signal, thereby the charging state of the charging device
103
can be adjusted. Additionally, the voltage of the rechargeable battery
106
is also feedback to a voltage error amplifier
114
. The voltage error amplifier
114
receives a charging voltage signal of the rechargeable battery
106
and a predetermined charging voltage signal Vs of the charging device
103
, and then accordingly generates a charging voltage adjustment signal to the DC-DC converter power stage
112
. The DC-DC converter power stage
112
receives the charging current adjustment signal from the current error amplifier
110
and the voltage adjustment signal from the voltage error amplifier
114
to adjust the charging power. In other words, the charging device
103
can adjust and determine the charging condition during charging the rechargeable battery
106
according to the charging current inputted to the rechargeable battery
106
and the charging voltage of the rechargeable battery
106
itself.
FIGS.
3
A~
3
C show timing diagrams that the charging voltage and the charging current are varied with time when the charging device
103
charges the rechargeable battery with a full rated current. Assuming an initial charging voltage Vi of the rechargeable battery
106
, the initial charging voltage Vi is smaller than a full rated voltage Vf of the rechargeable battery
106
. The charging device
103
determines the full rated voltage Vf of the rechargeable battery
106
according to the predetermined charging voltage signal previously inputted to the voltage error amplifier
114
. When the charging process begins, both of the charging current adjustment signal from the current error amplifier
110
and the charging voltage adjustment signal from the voltage error amplifier
114
are inputted to the DC-DC converter power stage
112
, in which both adjustment signals are represented by their voltages. Because the voltage Vi of the recharging battery
106
is smaller than its full rated voltage Vf, the charging voltage adjustment signal outputted from the voltage error amplifier
114
is smaller than the charging current adjustment signal outputted from the current error amplifier
110
. Accordingly, the DC-DC converter power stage
112
adjusts the charging state based upon the received charging current adjustment signal, and then the charging device
103
charges the rechargeable battery
106
with a full rated current Is. The full rated current Is is determined by the charging device
103
according to a predetermined charging current signal previously inputted to the current error amplifier
110
. For example, as shown in
FIG. 3A
, the full rated current Is
3
is inputted to the rechargeable battery
106
.
Referring to
FIG. 3A
, as the charging time increases, the voltage of the rechargeable battery
106
increases. The voltage level of the charging voltage adjustment signal increases as the voltage of the rechargeable battery
106
increases, but is still smaller than the voltage level of the charging current adjustment signal outputted from the current error amplifier
110
. Therefore, the DC-DC converter power stage
112
adjusts the charging state according to the received charging current adjustment signal such that the charging current is maintained at the fall rated current Is
3
preset by the charging device
103
.
For example, as shown in
FIG. 3A
, when the charging process proceeds to time t
3
, the charging voltage of the rechargeable battery
106
is equal to the predetermined full rated voltage Vf of the rechargeable battery
106
. Thereafter, the voltage level of the charging voltage adjustment signal outputted from the voltage error amplifier
114
is larger than the voltage level of the charging current adjustment signal outputted from the current error amplifier
110
. The DC-DC converter power stage
112
adjusts the charging state according to the received charging voltage adjustment signal. Then, the charging current for the rechargeable battery
106
decreases as the time increases. Furthermore, the voltage of the rechargeable battery is maintained at the full rated voltage Vf.
As the foregoing description, the full rated current Is inputted to the rechargeable battery
106
is previously determined by the charging device
103
. And the value of the full rated current Is determines the charging efficiency, i.e., how much time the charging process spends.
FIG. 3B
shows a diagram that the charging voltage of the rechargeable battery
106
increases with time during the charging process when the full rated current inputted to the rechargeable battery
106
is Is
2
. Referring to
FIGS. 3B and 3C
, because the full rated current Is
2
is larger than the full ra
Liao Yu-Shin
Shen Wen-Chun
Patel Rajnikant B.
Perkins Coie LLP
Quanta Computer Inc.
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