JPH05276679A - Power source for portable computer - Google Patents

Abstract

PURPOSE:To increase available time of a power source for a portable computer. CONSTITUTION:A power source for a portable computer is composed of a dry cell 4 and a large-capacity capacitor 5 connected in parallel with the cell 4. The capacitor has a capacity of 1F or more and an internal resistance of 0.4 times as large as that of the cell. Thus, a variation in a voltage to be applied to a computer body 2 is reduced, and the power source can be used for a longer time than that of prior art with the same cell.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for a portable computer, which has been used for a long time.

[0002]

2. Description of the Related Art In recent years, portable computers have been remarkably widespread, but dry batteries are used as the power source. Figure 2
Fig. 1 shows a conventional power supply for a portable computer. In FIG. 2, 1 is a portable computer, 2 is a computer main body,
Reference numeral 3 is a power supply unit, and 4 is a dry battery. The power supply unit 3 is composed of only dry batteries, for which, for example, nickel-cadmium batteries or the like are used.

[0003]

(Problem) However, the above-mentioned conventional power supply for portable computer has a problem that the portable computer cannot operate normally before the battery capacity is sufficiently consumed. there were.

(Explanation of Problems) The current flowing through the portable computer fluctuates within a range of several mA to several thousand mA.
Therefore, when the internal resistance of the dry battery 4 increases, the value of the voltage obtained by multiplying the internal resistance by the current also changes. The value reduced by the voltage drop due to the internal resistance is applied to the computer main body 2. Therefore, when the current is large, a value that is much lower than the voltage of the dry cell 4 when there is no load is applied to the computer main body 2.

However, in the portable computer, when the applied voltage drops below a predetermined value, an abnormal operation such as resetting of the built-in memory occurs. Therefore, the lower limit voltage for use is set so that such an abnormal operation does not occur. Therefore, until the applied voltage when the maximum voltage fluctuation occurs falls to the lower limit voltage for use, the dry battery 4
It means the usage time.

FIG. 7 is a diagram showing the relationship between the operating time and the voltage in a conventional portable computer power supply. 1.5
It shows a case where two V dry cells are connected in series as a power source (therefore, the maximum voltage value is approximately 3 V). U is a curve showing the maximum value of the applied voltage (that is, the no-load voltage of the dry battery 4), and L is the minimum value of the applied voltage (that is, the maximum voltage fluctuation considered with reference to the current fluctuation of the portable computer). In this case, it is a curve representing the voltage applied to the computer main body 2. Therefore, the voltage applied to the computer main body 2 varies between the curve U and the curve L, and gradually decreases with the lapse of use time.

If a voltage of 2.2 V is used as a lower limit voltage,
Since the curve L has dropped to this voltage in 3 hours, the dry battery 4 in use cannot be used in 3 hours. However, when looking at the curve U, the value is considerably higher than 2.2V at the time point of 3 hours, which shows that the capacity of the battery is not yet sufficiently consumed. An object of the present invention is to extend battery life by consuming more battery capacity than before.

[0008]

In order to solve the above-mentioned problems, a power source for a portable computer according to the present invention comprises a dry battery,
It is connected in parallel to the dry battery and has an internal resistance of 0.4 of the dry battery.
A large-capacity capacitor having a double internal resistance or less and a capacitance of 1 F or more is provided.

[0009]

[Operation] A power supply for a portable computer is composed of a dry battery and a large-capacity capacitor connected in parallel with it. As the large-capacity capacitor, one having a capacity of 1 F or more and an internal resistance of 0.4 times or less the internal resistance of the dry battery is used. In this way, the fluctuation of the voltage applied to the computer main body is reduced, and it becomes possible to use the same dry battery for a longer time than before.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing a power supply for a portable computer according to the present invention. The reference numeral corresponds to that of FIG. 2, and 5 is a large-capacity capacitor. In the present invention, the dry battery 4 of the power supply unit 3
A large-capacity capacitor 5 is connected in parallel with. Since the device incorporating the large-capacity capacitor 5 is a power source for a portable computer, the large-capacity capacitor 5 must also be small and lightweight. As such a large capacity capacitor 5, for example, an electric double layer capacitor is suitable.

The capacity of the large-capacity capacitor 5 is 1F.
(Farad) or more, the internal resistance of the large-capacity capacitor 5 is selected to be 0.4 times or less the internal resistance of the dry battery 4. The reason for selecting such a value will be described below.

FIG. 3 is a diagram showing the relationship between the capacity of the large-capacity capacitor 5 connected in parallel to the power supply and the power supply voltage fluctuation.
The curve is obtained by measuring the voltage fluctuations of various capacitances with the value of the internal resistance C _R of the large-capacity capacitor 5 being constant. Here, C _R = 0.5Ω. In addition,
The voltage fluctuation in the case of the power supply voltage of 3V is taken as an example. According to this, if the capacitance of the capacitor is 1 F or more, the voltage fluctuation can be suppressed to a value of about 0.27 V or less.

The reason why the use time of the dry battery 4 becomes longer when the voltage fluctuation is reduced by connecting the large capacity capacitor 5 in parallel will be described. FIG. 6 is a diagram showing that the usage time changes depending on the magnitude of the power supply voltage fluctuation. The reference numeral is FIG.
_VL corresponds to the lower limit voltage (2.2 V in FIG. 7).
(A) represents the voltage fluctuation when the large capacity capacitor 5 is not connected, and (b) represents the voltage fluctuation when the large capacity capacitor 5 is connected.

In the case of the voltage fluctuation B, the voltage greatly fluctuates, so that it falls to the lower limit voltage _VL for use at the time point T ₁ . On the other hand, in the case of the voltage fluctuation b, the fluctuation is small, so that even if T ₁ is exceeded, the lower limit voltage _VL is not immediately lowered, and at time T ₂ , the lower limit voltage _{VL is} gradually reached. descend. That is, if the voltage fluctuation becomes small, the dry battery 4
The usage time of can be extended.

Next, the internal resistance of the large-capacity capacitor 5 is
The reason why the internal resistance of the dry battery 4 is preferably 0.4 times or less is described. FIG. 5 is a diagram showing the relationship between the internal resistance ratio of the capacitor to the power supply (dry battery 4) and the power supply voltage fluctuation. The internal resistance ratio referred to here can be expressed by the following equation:
It becomes as follows.

In FIG. 5, the capacitance 3.
The result of having measured 0F and 7.0F as a parameter is shown. According to this, since the curves of the two parameters are substantially the same, it can be seen that the fluctuation of the power supply voltage hardly depends on the capacitor capacity. It depends on the internal resistance ratio. The internal resistance ratio is preferably 0.4 or less in order to reduce fluctuations in the power supply voltage.

FIG. 4 is a diagram showing the relationship between the internal resistance ratio of the capacitor to the power source and the usable time ratio. The usable time ratio is a ratio of how many times the battery can be used when the large-capacity capacitor 5 is connected in parallel as compared with the case of only the dry battery 4 as in the conventional example. According to this, when the internal resistance ratio is 0.4 or more, there is not much difference from the case of only the dry battery 4. Comprehensive results obtained in FIGS. 5 and 4 reveal that it is desirable to select the internal resistance ratio to 0.4 or less.

FIG. 8 is a diagram showing the relationship between the operating time and the voltage in the power supply for portable computer of the present invention. The reference numerals correspond to those in FIG. 7. The capacity C = 5 F, the internal resistance C _R of the large capacity capacitor C = 0.3 Ω, the dry battery 4
It is the result of an experiment under the condition that the ratio of the internal resistance of the large-capacity capacitor 5 to the internal resistance of the above is 0.3.

The voltage applied to the computer main body 2 fluctuates within the range between the curve U and the curve L, and gradually decreases. However, since the fluctuation range is smaller than in the past, it took 6 hours for the curve L to drop to the lower limit voltage of 2.2V. In the conventional example of FIG. 7, 3
Since it was time, the usage time was doubled while using the same dry battery 4.

[0020]

As described above, the power supply for a portable computer of the present invention is composed of a dry battery and a large capacity capacitor connected in parallel with it. And the large-capacity capacitor is
It has a capacity of 1F or more and 0.4 of the internal resistance of the dry battery.
Use the one that has an internal resistance not more than double. By doing so, the fluctuation of the voltage applied to the computer main body is reduced, and the same dry battery can be used for a longer time than before.

[Brief description of drawings]

FIG. 1 is a diagram showing a power supply for a portable computer according to the present invention.

FIG. 2 is a diagram showing a conventional power supply for a portable computer.

FIG. 3 is a diagram showing a relationship between a capacity of a capacitor connected in parallel to a power supply and power supply voltage fluctuation.

FIG. 4 is a diagram showing a relationship between an internal resistance ratio of a capacitor to a power source and a usable time ratio.

FIG. 5 is a diagram showing the relationship between the internal resistance ratio of the capacitor to the power supply and the power supply voltage fluctuation.

FIG. 6 is a diagram showing that the operating time changes depending on the magnitude of the fluctuation of the power supply voltage.

FIG. 7 is a diagram showing a relationship between a usage time and a voltage in a conventional power supply for a portable computer.

FIG. 8 is a diagram showing a relationship between operating time and voltage in the power supply for portable computer of the present invention.

[Explanation of symbols]

1 ... portable computer, 2 ... computer main body, 3 ...
The power source unit, 4 ... dry battery, and 5 are large-capacity capacitors.

Claims (1)

[Claims] 1. A dry battery, and a large-capacity capacitor connected in parallel to the dry battery and having an internal resistance of 0.4 times or less the internal resistance of the dry battery and a capacity of 1 F or more. Power supply for portable computers.