Photography – With power supply detail
Reexamination Certificate
1999-12-03
2001-07-31
Perkey, W. B. (Department: 2851)
Photography
With power supply detail
C396S532000
Reexamination Certificate
active
06269222
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a camera, in particular to a system camera, with a camera housing and an interchangeable lens, which can be interchangeably fitted by means of a connection device, in particular a bayonet attachment, in a connecting device of the camera housing, in particular a bayonet receptacle.
Of interest are system cameras with interchangeable lenses, such as e.g. reflex system cameras and viewfinder system cameras, in which the lenses can be removed from the camera housing for transporting the reflex camera. Such lenses also make it possible to optionally use different lenses depending on the required framing. The lenses generally have electrical loads, such as, for example, an electrically actuable focus adjusting device and an electrically actuable aperture adjusting device. The lens and the camera housing have a plurality of electrical contacts, of which some serve to supply power to the lens and others to transmit signals between the lens and the camera housing for the selection of the various lens settings. In this case, the electrical contacts are arranged in the annular region of the bayonet fitting around the optical path of the cylindrical lens.
Since the electrical contacts are arranged essentially annularly next to one another on the lens and the camera housing, when a lens is fitted to the camera housing, undesirable momentary electrical connections may be made between contacts which are not supposed to be connected to one another. These momentary electrical connections can trigger short circuits and faulty connections which, under certain circumstances, can lead to damage to electronic parts of the lens or camera housing or cause functional disturbances in the adjusting devices of the lens. Moreover, the contacts can be abraded and blocked by dirt or moisture entering the connection region.
SUMMARY OF THE INVENTION
In view of the foregoing, it would be desirable to provide an interchangeable lens for a camera that minimizes spurious, momentary electrical connections which may lead to damage to electronic parts of the lens or camera housing. Accordingly, an object of the present invention is to provide a relatively simple connection device between the interchangeable lens and camera housing that ensures high functional reliability and interference immunity.
This object is achieved according to one embodiment of the invention by a camera, in particular a system camera, comprising a camera housing and an interchangeable lens, which can be interchangeably fitted by a connection device, in particular a bayonet attachment, in a connecting device of the camera housing, in particular a bayonet receptacle, in which, for supplying power to electrical actuating devices in the interchangeable lens, the connecting device of the camera housing has only two power supply contacts, to which two connection contacts are assigned in the connection device of the interchangeable lens, while exclusively an opto-coupling is provided in the interface for the purpose of transmitting control signals from the interchangeable lens to the camera housing and/or vice versa, wherein the opto-coupling in each case includes an optical signal generator and a signal receiver (or pickup) assigned thereto.
According to one embodiment of the invention, the signal transmission is thus separated from the power supply by the use of an opto-coupling for the purpose of signal transmission. As a result, any undesirable contact between the signal connections and power supply connections of the lens and of the camera housing during fitting of the lens is minimized. In principle, neither current nor information can be transmitted between the electrical contacts of the power supply and the opto-coupling components.
It is possible, in principle, for a momentary faulty connection to occur between the two connection contacts of the lens and the two power supply contacts of the camera housing, in which a contact of the lens touches the wrong contact of the camera housing and the other contacts are exposed. However, since no electric circuit is closed in such a case, no current can flow in this case either. Consequently, in the case of a design according to an embodiment of the invention of the lens or a camera having a lens of this type, a short circuit can no longer be triggered and erroneous information can no longer be transmitted.
In the case of the optical signal transmission, the optical signal emission and the optical signal reception can advantageously be separated by using a respective terminal just for the signal emission and another one just for the signal reception. This can be achieved in particular by the use of light emitting diodes for the signal emission and photodiodes for the signal reception.
Further features of the invention form the subject matter of the claims and will be explained in more detail, in conjunction with further advantages of the invention, with reference to exemplary embodiments.
REFERENCES:
patent: 4439029 (1984-03-01), Okura et al.
patent: 4440484 (1984-04-01), Komoto et al.
patent: 4541700 (1985-09-01), Bletz et al.
patent: 4637704 (1987-01-01), Ishimura et al.
patent: 5079578 (1992-01-01), Kohno et al.
patent: 34 38 322 (1986-04-01), None
patent: 34 43 443 (1986-05-01), None
Foley & Lardner
Perkey W. B.
Rollei Fototechnic GmbH
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