Photography – With object illumination for exposure – Having exposure synchronizer
Reexamination Certificate
1999-04-05
2001-06-26
Perkey, W. B. (Department: 2851)
Photography
With object illumination for exposure
Having exposure synchronizer
C396S403000, C396S463000
Reexamination Certificate
active
06253030
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a camera shutter construction and, more particularly, to a camera shutter for carrying out an exposure operation by controlling the opening and closing of shutter sectors.
2. Background Information
In a conventional camera shutter, opening and closing operations of an opening lever and a closing lever for opening and closing sectors of the shutter, respectively, are controlled, inter alia, by electromagnets for carrying out an exposure operation. The opening and closing operations of the opening and closing levers are controlled by changing the timing for turning OFF a current supplied to the electromagnets to thereby carry out the exposure operation. Furthermore, contact pieces for outputting a trigger signal of a stroboscope for emitting light are installed at a position in the vicinity of the opening lever, so that when the opening operation of the opening lever is completed, the contact pieces output the trigger signal and the stroboscope emits light. Likewise, contact pieces for outputting a signal for winding-up film are installed at a position in the vicinity of the closing lever, so that when the closing operation of the closing lever is completed, the contact pieces output the signal to wind-up the film.
In a conventional method of determining whether the operation for opening the shutter sectors has been carried out in the foregoing conventional camera shutter construction, a non-opening state of the shutter sectors is detected when the signal for winding-up the film has been outputted before the current supplied to the electromagnet associated with the opening lever is turned OFF after the shutter is released.
However, in the foregoing conventional shutter structure and operation, even when current supplied to the electromagnet associated with the opening lever is turned OFF, a determination of whether the operation for opening the shutter sectors has been carried out cannot be effectively made and, therefore, a non-opening state of the shutter sectors cannot be effectively detected.
The present invention overcomes many of the disadvantages inherent in conventional camera shutters by providing a camera shutter which is capable of effectively detecting a non-opening state of shutter sectors.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a camera shutter which can effectively detect a non-opening state of shutter sectors.
Another object of the present invention is to provide a camera shutter which can detect a non-opening state of shutter sectors by detecting a state in which closing sectors have completed a shutter closing operation before opening sectors have completed a shutter opening operation. The shutter opening and closing operations are detected by means of a trigger signal of a stroboscope for emitting light and a signal for winding up a film, respectively.
Another object of the present invention is to provide a camera shutter which is simple in construction and can be manufactured at low cost.
The foregoing and other objects of the present invention are carried out by a camera shutter comprising a base plate having a shutter opening, a plurality of opening sectors for undergoing opening movement in an operational state to open the shutter opening during a shutter release operation, and a plurality of closing sectors for undergoing closing movement in an operational state to close the shutter opening during the shutter release operation. A first detecting device detects the operational state of the opening sectors. A second detecting device detects the operational state of the closing sectors. A non-opened state of the shutter opening is detected after the shutter release operation when it is determined that the second detecting device detects the operational state of the closing sectors before the first detecting device detects the operational state of the opening sectors.
In another embodiment, a camera shutter according to the present invention comprises a base plate having a shutter opening, a plurality of opening sectors for undergoing opening movement in an operational state to open the shutter opening during a shutter release operation, and a plurality of closing sectors for undergoing closing movement in an operational state to close the shutter opening during the shutter release operation. A first detecting device detects the operational state of the opening sectors. A second detecting device detects the operational state of the closing sectors. A timer measures a preselected time interval from a point at which the first detecting device detects the operational state of the opening sectors. A non-opened state of the shutter opening is detected after the shutter release operation when it is determined that a time period from the point at which the first detecting device detects the operational state of the opening sectors to a point at which the second detecting device detects the operational state of the closing sectors is shorter than the preselected time interval.
In another embodiment, a camera shutter according to the present invention comprises a base plate having a shutter opening, a plurality of opening sectors for undergoing opening movement in an operational state to open the shutter opening during a shutter release operation, and a plurality of closing sectors for undergoing closing movement in an operational state to close the shutter opening during the shutter release operation. A first detecting device detects the operational state of the opening sector. A second detecting device detects the operational state of the closing sectors. An abnormal state of the camera shutter is detected when it is determined that the first detecting device detects the operational state of the opening sectors before the shutter release operation.
REFERENCES:
patent: 4334747 (1982-06-01), Shimada et al.
patent: 5181063 (1993-01-01), Tagami et al.
Miyauchi Osamu
Takahashi Kunioki
Adams & Wilks
Perkey W. B.
Seiko Precision Inc.
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