Photography – Camera release control circuit – Safety lock
Reexamination Certificate
2001-02-09
2001-10-30
Adams, Russell (Department: 2851)
Photography
Camera release control circuit
Safety lock
C396S296000, C396S355000, C396S373000, C396S511000
Reexamination Certificate
active
06311022
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a camera in which an exchangeable film back is removably attached to a camera body, and particularly relates to a film back exchangeable camera having a light shielding function in a film back.
In a film back exchangeable camera in which a film back is removably attached to a camera body, light shielding means is used so as to prevent a film in the film back from being exposed when the film back is not attached to the camera body. The light shielding means is generally configured so that a photographer manually removes a light shielding member such as a light shielding plate or the like after attaching the film back to the camera body. Therefore, the photographer, who fails to remove the light shielding member, may carry out a photographic operation. Some film back exchangeable cameras in the background art are arranged so that a shutter is made inoperable by a release lock when a light shielding member is not removed. However, only by the release lock, the photographer cannot be informed of the fact that the photographer has failed the removal of the light shielding member unless the photographer carries out a shutter release operation actually. Thus, the photographer would often lose a shutter release opportunity.
SUMMARY OF THE INVENTION
Taking the foregoing problem into consideration, the present invention was developed. It is an object of the present invention to provide a film back exchangeable camera which reduces the possibility of a photographic mistake caused due to the failure of removing a light shielding member.
According to the present invention, there is provided a film back exchangeable camera comprising: a camera body; an exchangeable film back removably attached to the camera body;
a light shielding member removably attached to the film back so that a film in the film back is prevented from being exposed when the light shielding member is attached to the film back, and so that the film is permitted to be exposed when the light shielding member is removed from the film back; film back attachment detecting means for detecting attachment of the film back to the camera body; light shielding member attachment detecting means for detecting attachment of the light shielding member to the film back; release lock means for switching a shutter between an operable state and an inoperable state; and viewfinder lock means for switching a viewfinder between an observable state and an unobservable state; wherein the shutter is brought into the inoperable state by the release lock means and the viewfinder is brought into the unobservable state by the viewfinder lock means when attachment of the film back to the camera body is detected by the film back attachment detecting means and attachment of the light shielding member to the film back is detected by the light shielding member attachment detecting means. According to this configuration, when a photographer has failed to remove the light shielding member, the photographer can sense and recognize a photographing impossible state when the photographer looks through the viewfinder prior to a shutter release operation. Thus, the possibility of a photographic mistake such as losing a shutter release opportunity is reduced.
According to the present invention, in the film back exchangeable camera, there is further provided photo-metering means for carrying out photo-metering in response to turning-on of a photo-metering switch in addition to the release lock means, the shutter is brought into the inoperable state by the release lock means and the photo-metering means is prevented from carrying out photo-metering even if the photo-metering switch is turned on, when attachment of the film back to the camera body is detected by the film back attachment detecting means and attachment of the light shielding member to the film back is detected by the light shielding member attachment detecting means. Thus, if an operation to be executed practically in response to the turning-on of the photo-metering switch is not executed, there increases a possibility for the photographer to notice that the photographer has failed to remove the light shielding member prior to the shutter release operation. It is therefore possible to reduce a photographic mistake.
According to the present invention, in the film back exchangeable camera, there is still further provided external display means provided in an outer surface of the camera body in addition to the release lock means, the shutter is brought into the inoperable state by the release lock means and an indication of the photographing impossible state is displayed by the external display means, when attachment of the film back to the camera body is detected by the film back attachment detecting means and attachment of the light shielding member to the film back is detected by the light shielding member attachment detecting means. Also by such a warning based on external display, the photographer can recognize the fact that the photographer has failed to remove the light shielding member at a time earlier than the case where only a release lock is used.
That is, when the light shielding member is not removed though the film back is attached to the camera body, the photographer can recognize the photographing impossible state prior to a shutter release operation by three new measures: making the viewfinder unobservable; rejecting an input from the photo-metering switch; and displaying a photographing impossible mark on an external portion; in addition to the release lock. These three measures can be combined desirably. That is, only one of them may be carried out, or two or three of them may be carried out in combination.
In the case where the viewfinder is made unobservable by the viewfinder lock means, preferably, the viewfinder lock means has a mirror in the camera body, the mirror being able to move between an observation position where the mirror is located on a photographic optical path so as to guide luminous flux passing through a camera lens to an optical system of the viewfinder, and a photographing position where the mirror escapes from the photographic optical path so as to allow the luminous flux to reach the film back, and the mirror is moved to the photographing position when the film back is attached to the camera body and the light shielding member is attached to the film back. Further, in the above film back exchangeable camera, the viewfinder lock means may have a movable eyepiece shutter which is able to be opened/closed in an optical system of the viewfinder, the eyepiece shutter being closed when the film back is attached to the camera body and the light shielding member is attached to the film back. Further, in the above film back exchangeable camera, the viewfinder lock means may have a light-transmission adjusting medium in an optical system of the viewfinder, the light-transmission adjusting medium being able to change between a transparent state and a light scattering state to scatter incident light, and at least a part of a view-field area of the viewfinder is brought into the light scattering state by the light-transmission adjusting medium when the film back is attached to the camera body and the light shielding member is attached to the film back. The light-transmission adjusting medium may be, for example, a light-transmissible liquid crystal.
In the case where the camera has a photo-metering switch, the camera further comprises automatic focusing means for carrying out a focusing operation in response to turning-on of the photo-metering switch, and the automatic focusing means can be prevented from carrying out the focusing operation even if the photo-metering switch is turned on when the film back is attached to the camera body and the light shielding member is attached to the film back. Preferably, the camera further has an in-viewfinder display which is lit in response to turning-on of the photo-metering switch, so that the in-viewfinder display is prevented from being lit even if the photo-metering swit
Adams Russell
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Whittington Kenneth J
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