US 2065921 A
Description (OCR text may contain errors)
Dec. 29, 1936. F. GERTH ET AL CONDENSER Filed July 8, 1935 4 mm 0 y mam r Patented Dec. 29, 1936 PATENT OFFICE CONDENSER Fell! Ge hl Klelhorn, Berlin-Pankow,
and Richard Germany, alsignorl to C. Lorenz Aktiengesellschaft. Berlin-Tempelhof, Germany, a company Application July s, 1935, Serial No. some In Germany July I, 1934 Claims.
(Granted under the provisions of sec. 14, act of March 2, 1927; 357 0. G.
It has been proposed to use as a dielectric for high frequency condensers the ceramic materials nowadays put on the market, which have a high dielectric constant with small losses.
6 This proposal has been made on the one hand in order to diminish the spatial dimensions of the condensers as far as possible and to utilize to such end the high dielectric constant, and on the other hand to avoid the use of mica, as this material is very costly. with the customary condenser constructions however it is not possible to simply replace the intermediate layers of mica or of another dielectric, such as hard paper or the like, by ceramic discs. The ceramic material on the contrary requires special forms of condensers to be used in order to comply with the mechanical properties of such material. The reason why the dielectric intermediate layers of the prior constructions cannot be substituted by ceramic layers mainly is, that ceramic plates slightly differ in thickness and above all are a little uneven, and that in addition such plates are in general somewhat warped. This is due to the burning process which these materials must undergo.
The invention mainly consists in assembling condensers of elements formed of ceramic discs provided on both sides with a metal coating. These elements are kept together by means of a common pressure bolt. The ceramic discs are preferably thickest in their middle. In this way a condenser construction is obtained which is similar to a voltaic pile or resembles the customary dry rectii'lers.
The invention is described hereafter by way .of example, reierencebeing had to the accompanying drawing in which-'- Fig. 1 is a sectional view of one embodiment of the invention, Fig. 2 a sectional view illustrating another embodiment, Fig. 3 shows a section on the line 3-4 of Fig. 2.
The condenser represented in Fig. 1 consists of ceramic discs I disposed aside each other on a bolt 2 and pressed against one another by a screw nut I. These discs are of a substantially lozenge-shaped cross-sectional area, that is to say, are thickest at their centre portion. Their sides are provided with metal coatings 4. These metal coatings do not join each other at the circumferential edges 8 of the discs I and by preference do not reach the bore of the discs, as indicated at 6.
The coatings 4 are applied to the discs I by means of the methods known in this respect. They may for instance be applied thereto by a spraying process or by melting. For effecting the melting, a metal coating is provided on the discs and then slightly burned in, as is well known per se. It is however possible also to apply a metal coating by means 01 the well known I cathode disintegration or cathode sputtering or a similar method. Each of these discs will thus constitute a condenser element. At I the metal coatings 4 make contact with each other, so that the condenser elements are connected in 10 series. Further it is possible to tap the condenser by means ,pf strips 8 interposed between the coatings 4. The strips 8 are insulated from the bolt 2 by a ring 9.
By this construction the said diillculties, which 16 have been due to the use of ceramic materials, are overcome. The condenser elements are only in the middle pressed against each other and are thus subjected only to pressure but not to bending forces. The novel condenser is also 20 well cooled, the cooling surface being very great owing to the peculiar shape of the condenser elements.
In the arrangement shown in Figs. 2 and 3 the discs I are flat and are provided on both 26 sides with central annular projections III of a roll-shaped character, as shown in Fig. 2. The circumferential edges 5 of the discs I may likewise be roll-shaped, in order to avoid sparking at the coatings 4 in a manner well known per se. The metal coatings 4 do not cover the rollshaped edges 5 and do not reach the bolt 2 on which the discs I are arranged in the same manner as described with reference to Fig. 1. The projections I0 however are completely cov- 35 ered by the coatings 4. 7
If the ceramic material is of the same thickness at I0 and 5 then there are between the portions 5 air gaps that equal'the thickness of the metal coatings 4. The metal at In being soft to some extent slightly yields under the pressure exerted upon the condenser elements, so as to afford a good contact. In order to facilitate the access of air the portions 5 might be somewhat thinner than shown. However, for reasons of the ceramic processes the ceramic portions 5 are preferably made as thick as are the ceramic portions III. For in this case the discs I to be burnt can be placed horizontally 50 in the saggar so as to be supported at 5 as well as at III. The discs are hereby prevented from warping, whereas they would not be so if the edges 5 were not supported during the burning process. 56
It will be seen that this construction too has the advantages stated with respect to Fig. 1.
What is claimed is:
1. In a condenser, elements consisting of ceramic discs thickened adjacent their center portion and having a metal coating on either side, a bolt carrying these discs. and means for pressing them together so that the metal coatings make contact with each other 2. In a condenser according to claim 1. tapping means disposed between said metal coatings to make contact therewith.
3. A condenser according to claim 1, wherein the said ceramic discs have roll-shaped central enlargements covered by said metal coatings and making the said contact.
4. A condenser according to claim 1, wherein the said ceramic discs have roll-shaped central enlargements covered by said metal coatings and making the said contact, and have also circumierential enlargements not covered by the said metal coatings.
FELIX GERTH. RICHARD KIELHORN.