Electricity: measuring and testing – Electrolyte properties
Reexamination Certificate
2002-03-05
2004-02-10
Le, N. (Department: 2858)
Electricity: measuring and testing
Electrolyte properties
C324S444000, C324S433000, C340S636200, C340S636150
Reexamination Certificate
active
06690171
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a charge detection device and method and, in particular, to a charge detection device and method for measuring the charge capacity of a battery.
2. Related Art
The measurement of voltage output from a battery in the prior art mostly utilizes a voltage divider. The voltage at a detecting point is sent to a microprocessor for comparison to detect the charge capacity of the battery. As shown in
FIG. 1
, the voltage V
cc
of the battery provides the work power for the microprocessor
11
. The voltage VR
2
is extracted from the voltage divider through resistor R
2
. When the voltage of the battery drops, the voltage VR
2
also decreases. The input detection pin I of the microprocessor
11
is mainly used to receive the voltage VR
2
. When the voltage VR
2
received by the detection pin is lower than a lower threshold voltage in the microprocessor
11
, i.e. when the detection pin changes from a logic H to a logic L, then the charge capacity of the battery is insufficient. Although the above-mentioned method can easily measure the charge capacity of the battery, such a detection circuit using partial resistors may result in a leaking current
12
, wasting the energy of the battery.
With reference to
FIGS. 2A and 2B
, since the detection circuit in
FIG. 1
results in a leaking current, another method was proposed to connect the ground terminal GND of the resistor R
2
to the output pin O of the microprocessor
11
. The detection device uses a program to set the initial value of the output pin O of the microprocessor
11
as a logic high H (with a potential V
cc
), so that no leaking current occurs to the resistor circuit. When the microprocessor
11
measures the charge capacity of a battery, the output pin O of the microprocessor
11
switches from a logic high H to the logic low L (i.e. GND). The input terminal I of the microprocessor uses the above-mentioned partial voltage principle to measure the charge capacity of the battery. After the measurement is done, the output pin O is returned to the logic high H. As shown in
FIG. 2B
, the battery capacity detection device has the function of sectional charge measurements. The microprocessor
11
uses several input terminal pins I
1
, I
2
and I
3
to measure the partial voltages to measure the charge capacity during the drop of the voltage output of the battery.
Although the charge detection device shown in
FIGS. 2A and 2B
can effectively avoid the occurrence of leaking currents, the microprocessor
11
employed has more pins. Therefore, even though the microprocessor
11
can use more resources to measure the capacity of the battery, the function of the microprocessor
11
often cannot be fully utilized.
A primary objective of the invention is to provide a battery capacity detection device and method to measure the work voltage and charge using the RC charging time and a look-up table.
Another objective of the invention is to provide a battery capacity detection device. Using the combination of an RC circuit and a microprocessor, only a single pin of the microprocessor is needed to detect the battery charge capacity in a continuous way.
SUMMARY OF THE INVENTION
In view of the problems of leaking currents and more microprocessor I/O pins in the conventional battery capacity detection device, the invention proposes a battery charge detection method. The battery charges an RC-loop and the charging time reflects the charge of the battery. The method includes the steps of: forming a discharge loop for the capacitor of the RC-loop until the capacitor discharges down to level 0; and measuring the time needed for the battery to charge the RC-loop until the capacitor is charged to a designated level so that the current charge capacity of the battery can be computed.
In accordance with a battery capacity detection device disclosed herein, it includes an RC-loop consisting of a battery, a resistor R and a capacitor C; and a microprocessor; wherein the microprocessor utilizes a work-mode programmable pin to measure the capacitor C in the RC-loop. When the microprocessor measures the charge of the battery, the programmable pin of the microprocessor is in the output mode, outputting a low level to form a discharge loop until the capacitor discharges to level 0. Afterwards, the programmable pin is set to the input mode to measure the time needed for the pin to transit from the low level to a high level. This is the charge time for the capacitor in the RC-loop to be charged from level 0 to the high level. The charge capacity of the battery is then computed from the charge time.
According to a preferred embodiment of the invention, the battery capacity detection method needs an RC-loop consisting of a battery, a resistor R and a capacitor C and a microprocessor with a programmable pin. The method includes the steps of: turning the microprocessor pin from an input mode to an output mode; having the programmable pin output a low level so that the capacitor in the RC-loop discharges to level 0; turning the microprocessor pin from the output mode to the input mode; and computing by the microprocessor the time needed for the pin to make the transition from the low level to a high level. The charging time needed for the pin to make the transition from the low level to a high level is used to compute the charge capacity of the battery.
REFERENCES:
patent: 4409495 (1983-10-01), Enomoto et al.
patent: 5349282 (1994-09-01), McClure
Bacon & Thomas PLLC
Chicony Electronics Co. Ltd.
Le N.
Nguyen Vincent Q.
LandOfFree
Battery capacity detection device and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Battery capacity detection device and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Battery capacity detection device and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3295222