GB2069240A - An electrical capacitor - Google Patents

Abstract

An electrical capacitor comprises a ceramic disc shaped dielectric body (1) having a corrugated centre region (2) on which two metal coating layers (4,5) are formed, one on each side of the dielectric body (1), the coating layers being separated from each other by a metal-free bead-like edge (3) of the dielectric body (1). <IMAGE>

Description

SPECIFICATION An electrical capacitor The invention relates to an electrical capacitor comprising a ceramic, disc-shaped dielectric body with a metal coating layer on each of its two main faces, the two metal coating layers being separated from each other by a bead-like edge which is free of metal.

This type of capacitor is known for example from German Gebrauchsmuster No. 78 12819 and from German Gebrauchsmuster No. 78 31 224. In these known capacitors the ceramic dielectric body is flat however so that the value of the capacitance, which is directly proportional to the area of the metal layers of the coating which are opposite to each other, is limited in terms of relatively high values.

The invention seeks to provide a capacitor of the type stated at the outset which has a substantially higher capacitance value while the external dimensions are otherwise the same and the resistance to voltage is also the same.

According to the invention, there is provided an electrical capacitor comprising a ceramic, discshaped dielectric body with a metal coating layer on each of its two main faces, the two metal coating layers being separated from each other by a beadlike edge which is free of metal, wherein the dielectric body has a corrugated centre region.

The advantages achieved by the invention lie in manufacturing the capacitor simply and in the ability to achieve substantially higher capacitance values than is the case in known capacitors with the same resistance to voltage and the same dimensions.

The invention will now be described in greater detail by wayof example, with reference to the drawing, the single figure of which shows one embodiment of the invention in section.

The capacitor has a disc-shaped ceramic dielectric body 1 with a corrugated centre region 2, which increases the area of two metal coating layers 4 and 5which coverthetwo main surfaces ofthe dielectric body and which in turn are opposite each other. The two metal coating layers 4 and 5 are insulated electricially from each other by means of an encirculing, bead-like metal-free edge 3. In order to dissipate heat from the dielectric body 1 in improved manner, cooling coils in accordance with the type known from German Gebrauchsmutter No. 7812 819 may be fixed in the depressions of the corrugated centre region 2. It is also possible to weld a disc of sheet metal to the elevations of the corrugations and to pass a cooling liquid through the resultant cavities formed from the depressions in the corrugations.

1. An electrical capacitor comprising a ceramic, disc-shaped dielectric body with a metal coating layer on each of its two main faces, the two metal coating layers being separated from each other by a bead-like edge which is free of metal wherein the dielectric body has a currugated centre region.

2. An electrical capacitor according to Claim 1, wherein the corrugated centre region is rotationally symmetrical.

3. An electrical capacitor according to Claims 1 or 2 wherein the amplitude of the corrugated centre region is smaller than or at most equal to the width of the bead-like edge of the dielectric body.

4. An electrical capacitor according to any one of Claims 1 to 3 wherein the corrugations of the corrugated centre region are rounded or angular.

5. An electrical capacitor according to any one of Claims 1 to 4, wherein the wall thickness of the dielectric body is constant in the corrugated centre region.

6. An electrical capacitor substantially as described herein with reference to the drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION An electrical capacitor The invention relates to an electrical capacitor comprising a ceramic, disc-shaped dielectric body with a metal coating layer on each of its two main faces, the two metal coating layers being separated from each other by a bead-like edge which is free of metal. This type of capacitor is known for example from German Gebrauchsmuster No. 78 12819 and from German Gebrauchsmuster No. 78 31 224. In these known capacitors the ceramic dielectric body is flat however so that the value of the capacitance, which is directly proportional to the area of the metal layers of the coating which are opposite to each other, is limited in terms of relatively high values. The invention seeks to provide a capacitor of the type stated at the outset which has a substantially higher capacitance value while the external dimensions are otherwise the same and the resistance to voltage is also the same. According to the invention, there is provided an electrical capacitor comprising a ceramic, discshaped dielectric body with a metal coating layer on each of its two main faces, the two metal coating layers being separated from each other by a beadlike edge which is free of metal, wherein the dielectric body has a corrugated centre region. The advantages achieved by the invention lie in manufacturing the capacitor simply and in the ability to achieve substantially higher capacitance values than is the case in known capacitors with the same resistance to voltage and the same dimensions. The invention will now be described in greater detail by wayof example, with reference to the drawing, the single figure of which shows one embodiment of the invention in section. The capacitor has a disc-shaped ceramic dielectric body 1 with a corrugated centre region 2, which increases the area of two metal coating layers 4 and 5which coverthetwo main surfaces ofthe dielectric body and which in turn are opposite each other. The two metal coating layers 4 and 5 are insulated electricially from each other by means of an encirculing, bead-like metal-free edge 3. In order to dissipate heat from the dielectric body 1 in improved manner, cooling coils in accordance with the type known from German Gebrauchsmutter No. 7812 819 may be fixed in the depressions of the corrugated centre region 2. It is also possible to weld a disc of sheet metal to the elevations of the corrugations and to pass a cooling liquid through the resultant cavities formed from the depressions in the corrugations. CLAIMS

1. An electrical capacitor comprising a ceramic, disc-shaped dielectric body with a metal coating layer on each of its two main faces, the two metal coating layers being separated from each other by a bead-like edge which is free of metal wherein the dielectric body has a currugated centre region.

2. An electrical capacitor according to Claim 1, wherein the corrugated centre region is rotationally symmetrical.

3. An electrical capacitor according to Claims 1 or 2 wherein the amplitude of the corrugated centre region is smaller than or at most equal to the width of the bead-like edge of the dielectric body.

4. An electrical capacitor according to any one of Claims 1 to 3 wherein the corrugations of the corrugated centre region are rounded or angular.

5. An electrical capacitor according to any one of Claims 1 to 4, wherein the wall thickness of the dielectric body is constant in the corrugated centre region.

6. An electrical capacitor substantially as described herein with reference to the drawing.