Electricity: electrical systems and devices – Electrolytic systems or devices
Patent
1996-08-02
1998-08-11
Kincaid, Kristine L.
Electricity: electrical systems and devices
Electrolytic systems or devices
361303, 361503, 361523, H01G 900
Patent
active
057936021
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to capacitors.
BACKGROUND OF THE INVENTION
Capacitors are used to store an electric charge and comprise a dielectric insulator which separates a pair of conducting plates.
Conventionally, a wire or a conductor suitable for use with the capacitor is connected between each plate and a respective one of a pair of external terminals. A current necessary to apply the charge to each plate may then be fed to the terminals.
Disadvantageously, the resistance of the conductors and capacitor plates causes a limitation in performance, particularly where the material is chosen, not for its low resistivity but, as in the case of an electrolytic capacitor, for compatibility with the chemical environment of the capacitor.
One common use of a capacitor within a power supply circuit is as a filter to smooth the voltage wave form from a rectifier output. In such an application the capacitor is repeatedly charged and discharged, perhaps many times a second. The charging current is delivered to the plates from the rectifier using the same conductor which delivers the output current to the part of the circuit to be supplied.
Disadvantageously, conductor and capacitor plate imperfections are highlighted in this and other applications, for instance signal and/or power supply decoupling in audio amplifiers, where, perhaps large, incoming currents flow in the same conductor that is supplying current to the circuit being driven. As a result of these imperfections, fluctuations occur in the current and voltage due to the resistance of the conductors and capacitor plates, and these are superimposed on the output to the circuit being driven. This results in a significant degradation of performance.
It is known to provide a capacitor, known as a feedthrough capacitor, for use with high frequency signals in which a pair of connections are made to each plate from respective ones of a pair of external terminals.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved capacitor which overcomes the disadvantages of the above prior art.
According to the present invention there is provided a capacitor, comprising at least two conducting elements for connection to an external circuit, said elements being separated by dielectric means and at least one element having a plurality of electrical connectors through which current will flow, so that incoming and outgoing current flows to/from each said at least one element remain substantially separated and current and voltage fluctuations are minimised.
The connectors may be attached to the at least one element at a common position thereon. Alternatively, the connectors may be connected to the element at separate positions thereon. Advantageously, in order to provide an outgoing current flow virtually completely free of resistive losses, a connector carrying said outgoing current flow may be connected to a respective element intermediate a pair of connectors carrying incoming current flow which conveniently are attached to said element at its opposite ends.
It is envisaged that the above construction may be applied to any form of capacitor although it is particularly suitable for use with electrolytic type capacitors, and inparticular to slit-foil capacitors, where the slits in the foil are arranged to channel the flow of incoming and outgoing current. Such a capacitor is described in U.K. Patent No. 0 169 226.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to aid in understanding the invention specific embodiments thereof will now be described by way of example and with reference to the accompanying drawings in which:
FIG. 1 is a perspective view of a prior art cylindrical electrolytic capacitor, shown unrolled with the dielectric removed for clarity;
FIG. 2 is a similar view of a capacitor according to the invention;
FIG. 3 is a similar view of a variant of the capacitor of FIG. 2;
FIG. 4 is a circuit diagram illustrating a circuit utilizing the capacitor of FIG. 2;
FIGS. 5a and 5b are graphs showing the results of
REFERENCES:
patent: 4274124 (1981-06-01), Feinberg et al.
Dinkins Anthony
Kincaid Kristine L.
Morecroft Denis N.
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