JPH05281311A - Device for display remaining power of battery, having ambient temperature compensating function - Google Patents

Abstract

PURPOSE:To easily measure the remaining power of a battery considering the ambient temperature by connecting a resistance element the resistance of which changes in accordance with the ambient temperature to an amplifier and changing the cumulation results of detected currents in accordance with the ambient temperature. CONSTITUTION:An amplifier 3 obtains a signal proportional to the current flowing through a resistor 1 by amplifying a slight voltage drop across both ends of the resistor 1 for detecting current interposed between a battery 2 and negative pole and an adder 5a obtains a value representing the integrated value of the current flowing through the resistor 1 with respect to the time by adding the signal to the cumulated value of the current fed back from a register 5b. However, since the characteristics of the battery 2 generally depend on the temperature, the amplification degree of the amplifier 3 is changed in accordance with the ambient temperature by using a resistance temperature element 8 of a thermistor, etc., as the feedback resistor of the amplifier 3 and when the gain is raised in case the ambient temperature rises and lowered in case the temperature drops, the current flowing to the negative pole can be integrated with respect to time by taking into account the ambient temperature and the remaining power of the battery 2 can be accurately displayed 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery power remaining amount display device having an ambient temperature compensation function, and is capable of easily knowing the battery power remaining amount by integrating the current flowing through a load.

[0002]

2. Description of the Related Art In a conventional portable video, when a battery is discharged, a lamp warning that the voltage is insufficient is turned on and stopped. FIG. 1 is a characteristic diagram of a nickel-cadmium battery generally used as the battery. The portable video has a rating of 12V and stops when the battery voltage drops to 10.5V. Therefore, a lamp that issues a warning at 10.7V is turned on. However, as is apparent from FIG. 1, this type of battery has a characteristic of rapidly dropping when the voltage starts to drop. Because of the warning voltage of 10.7
There is only 30 seconds of time to drop from V to the stop voltage of 10.5V. Since the battery suddenly runs out like this, you must always carry a spare battery with you.

On the other hand, in a portable video having a feature of simplicity, especially in a recently developed 8 mm video, a spare cassette is special, and carrying a spare battery is not preferable because it impairs the above features. However, since the features of the battery are as shown in FIG. 1, the battery cannot be used in a short time after the warning of the insufficient voltage in the detection by the voltage, and it is necessary to carry the spare battery after all.

Therefore, there is proposed a method in which the remaining amount of electric power is detected based on the amount of electric power used, which is obtained by accumulating the current flowing in the load. It is not possible to detect the remaining amount. This is because the characteristics of the battery depend on temperature.

In view of the above-mentioned prior art, the present invention is a compact battery power remaining amount display device with an ambient temperature compensating function, which allows the user to easily determine with high accuracy the ambient temperature at the time of use and how many minutes can be left. The purpose is to provide.

[0006]

The structure of the present invention which achieves the above-mentioned object is a resistor interposed between a battery and a load, an amplifier for detecting and amplifying a current flowing through the resistor, and an amplifier for this amplifier. An A / D converter for A / D converting the output, an accumulator for integrating the output of the A / D converter, and an indicator for displaying the remaining power level of the battery by the accumulation result of the accumulator. And the accumulation result of the accumulator is changed according to the ambient temperature.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIG. 2, the resistor 1 is a resistor for detecting a current and is interposed between the battery 2 and a load (not shown). The amplifier 3 amplifies a weak voltage drop across the resistor 1 and obtains a signal proportional to the current flowing through the resistor 1 as its output. This output signal is A / D
It is converted into a digital signal of about 4 bits to 6 bits by the converter 4 and sent to the adder 5a of the accumulator 5. The adder 5a adds the output of the A / D converter 4 and the output fed back from the register 5b and sends it to the register 5b. The register 5b uses the clock pulse sent from the clock pulse generator 6 to adder 5
Read and store the output of a. Thus, the output of the adder 5a represents the time integrated value of the current flowing through the resistor 1. The display 7 displays the contents of the register 5b, and can be constructed by arranging, for example, about 10 liquid crystals in a rod shape. At this time, the integrated consumption current amount is displayed as each step of 10 steps. Therefore, if the full scale is made to correspond to the capacity of the battery 2, the remaining amount of power can be displayed by the length of the bar formed by the liquid crystal. Furthermore, in order to improve the display accuracy of this type of battery power remaining amount display device, the ambient temperature and self-discharge of the battery 2 must be taken into consideration. This is because the characteristics of the battery 2 generally depend on the temperature, the battery 2 can be used for a long time at a high temperature, and a loss due to self-discharge always occurs over time. In the present embodiment, the gain of the amplifier 3 is changed by the resistance temperature element 8 which is the former measure. That is, the resistance temperature element 8 such as a thermistor is used as the feedback resistance of the amplifier 3, and the gain may be lowered when the temperature rises and the gain may be increased when the ambient temperature changes. In the present embodiment, the clock pulse of the clock pulse generator 6 is used for clocking as the latter measure. That is, when the clock pulse of the clock pulse generator 6 is counted by the counter 9 and reaches a predetermined number, in other words, when a predetermined time has elapsed, 1
This pulse is added to the minimum digit of the adder 5a. Therefore, the number of counts may be set in consideration of the time-dependent self-discharge characteristic of the battery 2 and the amount of decrease in the battery power over time.

Since the present embodiment has a self-discharge compensation function which uses clock pulses for clocking, when the portable video to which this is applied is not used, that is, the battery 2 is used.
It is necessary to back up the accumulator 5, the clock pulse generator 6 and the counter 9 so that they can function even when the main switch connected to is opened. In addition, it is needless to say that the accumulator 5 and the counter 9 must be cleared when the battery 2 is replaced, but this can be easily done by using, for example, the cancellation of the backup when the battery 2 is replaced. obtain.

In the above embodiment, it is premised that the battery 2 is always replaced with a new one. In other words, the display becomes confused when it is replaced with a used product. However, it is quite possible that the user may inadvertently exchange the item for a used item. This can be solved by the following measures. That is, as shown in FIG. 3A, all the circuits shown in FIG. 2 are integrally incorporated in the case 2a of the battery 2 so that the display 7 can be viewed through the window 2b provided in the case 2a. You can do it. By the way, the circuit shown in FIG.
There is no problem because it can be sufficiently housed in the pin IC package. Such a battery 2 is, for example, as shown in FIG. 3B, a grip 10 a of a portable video 10, for example.
The display 7 is housed in the grip 10a and can be viewed through the window 10b provided in the grip 10a. Further, in this case, the accumulator 5 or the like can be cleared easily by using the charge completion signal.

[0010]

As described above in detail with reference to the embodiments, according to the present invention, the current flowing through the load is integrated with respect to the ambient temperature, so that the remaining battery power can be accurately displayed. obtain. Therefore, for example, when applied to a portable video, it is possible to leave the spare battery in a car or the like without having to carry a spare battery and go to a video location at ease.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing characteristics of a nickel-cadmium battery.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is an external view (a) showing a case where the embodiment shown in FIG. 2 is integrally incorporated in a battery case, and an external view (b) showing a portable video using the same.

[Explanation of symbols]

 1 resistance 2 battery 5 accumulator 7 indicator

Claims (3)

[Claims] 1. A resistor interposed between a battery and a load, an amplifier for detecting and amplifying a current flowing through the resistor, and an A / D converter for A / D converting the output of the amplifier. An accumulator that integrates the output of this A / D converter,
A surrounding area characterized by having a display for displaying the remaining amount of power of the battery by the accumulation result of the accumulator, and the accumulation result of the accumulator is changed according to the ambient temperature. Battery power level indicator with temperature compensation function. 2. The ambient temperature according to claim 1, wherein the accumulation result of the accumulator is changed by changing the amplification degree of the amplifier according to the ambient temperature. Battery power level indicator with compensation function. 3. The remaining amount of battery power with an ambient temperature compensation function according to claim 2, wherein the amplifier is connected to a resistance element whose resistance value changes according to ambient temperature. Display device.