The present invention refers to a film holder for dental technique, comprising a bite portion and an approximately U-shaped film clip. A film holder of this kind is described in European Patent No. 0,397,599. The film holder described in this reference, which has been on the market for a long time, is an X-ray film holder that includes a pointer device, inter alia. The X-ray film holder of the prior art comprises a U-shaped film clip including a back plate as well as a clamping shank, the dimensions of the back plate exactly corresponding to film format no. 0.
The U-shaped configuration of the film clip is disadvantageous in that a clamping action on the entire film surface is only achieved in one ideal case, namely when the thickness of the film conforms to the angle of curvature of the U-shaped junction of the two shanks and to the mutual distance of the shanks. Lately, the conventional, relatively thick X-ray films have increasingly been replaced by digital picture plates. The latter consist of a very thin carrier material provided with a radiation-sensitive storage layer. These digital picture plates are not only very then, but they also have a very smooth surface. Moreover, the surface may not be exposed to mechanical irritations or injuries that might cause erroneous signals in the scanner and the computer and thereby result in a faulty image on the monitor and in incorrect information.
On the background of this prior art, the object of the present invention is to provide a film holder whose film clip takes in account not only the inequal thickness of films and of digital picture plates, but also of possibly existing variations in thickness and border beads as well as of the particular properties of digital picture plates, so as to ensure a sufficiently firm retention for keeping the plates in place when introducing and positioning them inside the patient""s mouth without damaging them.
This object is attained with a film holder wherein the film clip comprises an oral and a facial plate, the oral plate being more rigid than the facial plate, and the facial plate being designed such as to obtain a pressure distribution adapted to different thicknesses and/or topographies of films or digital picture plates. Further embodiments are described in the dependent claims.
USPTO Backgrounds
USPTO Backgrounds