Patent ID: 9564300
Date: 2017-02-07
CPC Classifications: C23C,H01J

Claim:
1. A disc-shaped plate with a holder, which together constitute a system “plate-holder,” comprising: the disc-shaped plate having a circular surface extending across regions of its circumference and having an outer plate edge, and the plate consists essentially of a material having a first thermal expansion coefficient α1; and the holder having a circular opening extending across regions of its circumference, which is delimited by an inner holder edge, and the holder consists essentially of a material having a second thermal expansion coefficient α2; wherein, at room temperature, a circumference of the opening of the holder is greater than the circumference of the surface of the plate, as a result of which with a centered position of the plate in the opening of the holder, there is a gap with a defined gap width S between the outer plate edge and the inner holder edge; and α2<α1; and the outer plate edge has one or more protrusions, which, viewed from a center point of the circular surface, extend for protrusion lengths from the outer plate edge in a radial direction and engage in corresponding recesses with recess lengths of the inner holder edge and/or the outer plate edge has one or more recesses, which, viewed from the outer plate edge, extend for recess lengths toward the center point of the circular surface and are engaged by corresponding protrusions with protrusion lengths on the inner holder edge; the system “plate-holder” has at least three such recess/protrusion pairs; and for the recess/protrusion pairs, the lengths are selected so that at room temperature, except for a radial spacing of at most d, the recesses are each engaged in the radial direction by a protrusion, whose size corresponds to the size of the gap width S; and for the recess/protrusion pairs in a tangential direction, width profiles are matched to each other so that a recess can function as a guide rail for a corresponding protrusion, whose play sp in the tangential direction is less than S, and as a result, both at room temperature and at higher temperatures, at which the plate expands more than the holder, the expanding plate is anchored so that the plate is always centered in the holder except for at most the play sp; and wherein the width profile in guide regions of at least one of the protrusions in an axial direction i) has no edges, which makes it impossible for a jamming to occur in the guide rail that is formed by the corresponding recess or ii) has parallel, straight walls at least in a radial subsection in which the recess is guided.