1984-05-15
1985-06-18
Gonzales, John
G03B 1744
Patent
active
045238243
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device designed for a photographic camera having a frame-type back which defines a bearing face for a photographic negative material or for a cassette containing said negative material, and having a pressure means located behind the camera back and movably connected thereto by means of springs that strive to urge said pressure means toward the bearing face of the camera back.
A device of the type mentioned above can for example be found in a cassette-loading camera for professional purposes. The pressure means which is connected to the camera back by means of springs can be lifted off the camera back against the force of the springs in order to insert a cassette containing the photographic negative material between the camera back and the pressure member. The purpose of the springs is to continually urge the pressure means toward the camera back so that the inserted cassette is in abutting relation with the bearing face of the camera back. To ensure that this occurs in any position of the camera even if, in a manner in itself known, auxiliary equipment such as, for example, a focusing screen and possibly other viewing accessories, are attached, the spring force acting on the pressure means must be relatively great. If, in a manner known from the prior art, the pressure means is at the same time designed as a focusing-screen holder for viewing and for sharp focusing, said springs also have the additional function of holding the pressure means in abutting relation with the bearing face of the camera back when the cassette is removed, such that the ground side of the focusing screen will lie in the same plane as the photosensitive layer of the photographic material in the cassette after the latter has been removed.
The relatively great spring force of the springs connecting the pressure means in the camera back has the disadvantage of rendering difficult the lifting of the pressure means off the camera back in order to insert the cassette containing the photographic negative material. Also, relatively high accelerations and correspondingly high speeds of movement result when the pressure means through the force of the springs return to the position for holding the inserted cassette in place or even to the position where it is in abutting relation with the camera back. When the pressure means strikes the inserted cassette or the camera back, this produces unwanted vibrations of the camera, harmful mechanical stresses within components, and disturbing noises.
Therefore, the major object of this invention is to provide a device of the type mentioned in the introduction to overcome the above drawbacks such that, without reducing the spring force that urges the pressure member against the camera back, the latter's impact upon the inserted cassette or upon the camera back is no longer a contributing factor.
According to the teachings of the invention, this object is achieved by the features defined in the claims.
The foregoing and other objects and advantages of the invention will appear more fully from the following description, made in connection with the accompanying drawings, of a preferred embodiment of the invention given solely by way of illustrative example
FIG. 1 shows in side elevation a device as taught by the invention for a focusing-screen and cassette-loading camera, specifically in the position for viewing and focusing;
FIG. 2 is a view of the same device viewed from the left in FIG. 1;
FIG. 3 is a side elevation of the device similar to FIG. 1 showing the position of the parts prepared for cassette insertion;
FIG. 4 shows the same device together with a cassette inserted in the shooting position, likewise in side elevation similar to FIG. 1;
FIG. 5 shows, on a larger scale, a longitudinal section through a hydraulic damping means, which is a constituent part of the device depicted in FIGS. 1 to 4.
The focusing screen assembly for a large-size cassette-loading camera illustrated in FIGS. 1 to 4 has a frame-type camera back 11 defining a cassette bearing face 12 and a likew
REFERENCES:
patent: 304406 (1884-09-01), Blair
patent: 2549670 (1951-04-01), Dalton
patent: 3896464 (1975-07-01), Galvin
patent: 4149791 (1979-04-01), Van der Meer
Datwyler Peter
Gfeller Karl
Gonzales John
Sinar AG Schaffhausen
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