FI97921C - Integrated battery capacitor and its use - Google Patents

Description

97921

Integrated battery capacitor and its use -Integrerad batteri-kondensator ooh användning därav. The present invention relates to a battery according to the preamble of claim 1, in particular to a battery used as a power source for a small portable device, such as a radio telephone.

The characteristics of the batteries include, as an inherent factor, the internal impedance, which, when the battery is loaded, manifests itself as a variation in the terminal voltage. For example, in TDMA (Time-Division Multiple-Access) mobile phones, the transmission is time-divisional, which causes a pulsed current draw from the battery. Depending on the system and the type of battery, the voltage variation shown at the battery terminals is different. Such detrimental voltage fluctuations have traditionally been compensated for by electrically connecting the capacitor in parallel with the battery, in mobile phones usually in connection with the "telephone" electronics, since the battery is usually located in its own separate compartment.

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The capacitor compensating for the voltage fluctuations of the battery is selected according to the type of battery used, whereby its capacitance can vary widely, e.g. in the range of 1 to 50 mF, but more usually in the range of 5 to 15 mF. It would be optimal to select the smallest possible capacitance for each case, because a capacitor of this magnitude is usually round and requires a lot of space, and in addition the size increases as the capacitance increases. Placing this capacitor usually presents difficulties in phone design.

30. Since, for example, different batteries with different charge capacities and different internal impedances are available for a mobile phone, the capacitance and other characteristics of the compensating capacitor must be dimensioned according to the highest requirements. As a result, the choice is usually not optimal.

2,97921

The object of the invention is to show such a solution in which the optimal capacitor function according to the battery type and its structure can be provided in each case.

5

The inventive idea is based on combining the compensating capacitance in a battery or battery pack as an integrated battery capacitor. In this case, for example, it is not necessary to reserve space for a capacitor in the "telephone part" of the mobile telephone, and nevertheless, optimal compensation for each type of battery and its advantageous execution are provided.

The invention is characterized in that the capacitance is a capacitor formed in the housing structure of the battery or accumulator.

According to the invention, the battery is used as a power source for a small portable device, preferably a radio telephone. The invention can be used regardless of the type of battery.

20

The invention will now be described in more detail by means of exemplary embodiments with reference to the accompanying drawing, in which: Figure 1 shows the basic connection of an integrated battery-capacitor according to the invention when the battery pack comprises three cells. In the embodiment of Figure 1a, each cell has its own capacitance. In the case of Figure Ib, a common capacitance is connected in parallel with the battery pack; Fig. 2 shows, in a simplified manner, structural embodiments of an integrated battery capacitor according to the invention, in which Fig. 2a shows a capacitor connected to the battery cell housing, and Fig. 2b shows a capacitor connected to the battery pack housing.

35 3 97921

The battery cells used in mobile phones and other small and light devices are of the nickel-cadmium (NiCd), metal hybrid, lithium, etc. type. e.g. 3.6 to 9.6 V. Battery cells are generally prismatic or round rods in cross section. The invention can, of course, be applied to batteries of different sizes and shapes, as well as, for example, to a battery pack in which the battery 10 forms part of a switch-type power supply.

Figure 1a shows three battery cells B1 to B3 connected in series, the poles of the battery pack formed by them being marked V1 and V2. Alongside each cell, 15 integrated capacitances C1, C2, C3 are arranged. In Fig. 1b, a common capacitance C1 is connected between the terminals VI to V2 in parallel with the battery pack B1 to B3. One skilled in the art will appreciate that the principles of Figures 1a and Ib may be applied to other combinations. Thus, the number of battery cells can be 1 to 20 8 and also larger. On the other hand, e.g. the battery pack units according to Fig. Ib can be used to form multi-unit batteries, alternatively each unit could have a different number of cells B. Connecting capacitors structural aspects. The dimensions of the various parallel / series connections of the capacitances are known per se to a person skilled in the art.

Figure 2a outlines the application of the invention in practice. The battery cell B can be a battery cell known per se, e.g. a NiCd battery with a round cross-section, rod-shaped, from which unnecessary layers of paper, plastic or other packaging have been removed. A suitable insulating jacket D is arranged around the cell B. In this schematic representation, a capacitor C is wound on the insulator D. In practice 97921 4 could contain the required number of electrode film layers (not shown) insulated by the insulating film, e.g. helically wound. The capacitor is protected by a sheath S in a manner known per se.

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Fig. 2a does not show the connection of the capacitor C to the terminals V of the battery cell (Fig. 1), but one skilled in the art will appreciate that connections between the membranes and the terminals of the capacitor C can be made by at the ends. It would also be conceivable for the capacitor films to be formed in one-piece extension strips which extend beyond the protective insulator D and which are attached to the terminals of the battery cell.

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Fig. 2b shows a capacitor C formed in the housing of the battery pack. In this case, the battery pack has the cells B1 to B3 connected in series as shown in Fig. 1b. The structure is otherwise similar to that in Figure 2a. In this case, the capacitor C (C1 in Fig. Ib) is connected directly to the terminals VI, V2 of the battery pack in one of the ways outlined above.

A capacitor wrapped in the jacket of a battery cell or package is a preferred embodiment because the capacitance of the capacitor is directly proportional to the surface area of the electrodes. The electrodes can be made of any suitable film and insulated with a suitable insulating film, in which case the superimposed films are wrapped as a strip in a battery jacket. In this case, there is no problem with a conventional wrapped capacitor when the initial turns have to be wrapped with a small radius.

Instead of a twisted capacitor film strip, it is, of course, conceivable to use layered film packages, in which case the film packages could be placed at a specific location in the battery cell or at several locations in several parallel-connected film packages. According to such an alternative, the capacitor could be a package extending to the bottom or top of the battery rod, around which is wrapped an extended sheath of the battery having substantially the same diameter as the sheath of the battery cell.

The structures 5 of the integrated battery-capacitor described above can in principle be simply implemented, e.g. by taking commercially available battery cells, which are desired to be connected as a battery pack. A suitably made strip of capacitor electrodes and insulators can be wrapped around these battery cells or the finished battery pack, after which the electrodes are connected to the battery terminals and surrounded by a protective sheath.

Of course, it is also possible to make the integrated battery-capacitor according to the invention as a uniform series of operations in connection with the manufacture of a battery. In this case, it would be possible to connect the capacitor strip, e.g. on the film strip forming the lithium battery cell, and wrap these strips together into a spiral wrapper provided with a suitable sheath and suitable terminals to which the capacitor terminals 20 are connected. In integrated manufacturing, jacket structures can be made more simply.

Naturally, when designing a capacitor integrated in a battery, it must be taken into account that a small internal resistance of 25 capacitors is required. In addition, the materials of the capacitor must be chosen so that they can adequately withstand the temperature generated by charging / discharging the battery. However, these practical design factors will not be discussed in more detail here, as their solutions are known per se to a person skilled in the art.

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Claims (7)

1. Battery in which a capacitance (C) is electrically integrated, dangerously connected in parallel with the battery (B), whereby the capacitance is dimensioned so that it substantially compensates the variations in the battery's voltage (V1-V2) as in the case of pulse load. is caused by the internal impedance of the battery, characterized in that the capacitance is a capacitor (C) formed in the battery (B1-B3) or the housing of the battery cell (B). Battery according to claim 1, characterized in that the capacitor (C) is formed by rewinding a splice strip of electrode diaphragm and insulating diaphragm for a housing parallel to the battery (B) perimeter. Battery according to claim 1, characterized in that the capacitor is formed by placing piles of strips of electrode membrane and insulating membrane for these at one or more places on the outer casing of the battery. Battery according to claim 1, characterized in that both the capacitor and the battery cell consist of band-like elements, which are placed on each other in coil and surrounded by a common housing to form an integrated cell unit consisting of battery and capacitor. 25 Battery according to any of the preceding claims, characterized in that it consists of one or more NiCd, metal hybrid, lithium or similar cells. Battery according to any of the preceding claims, characterized in that the capacitance (C) connected to the battery cell is of the order of 1 - 50 mF, preferably 5-15 in mF. 1 Use of a battery according to any of the preceding claims as a power source for a small portable device, preferably a radio telephone.