Photography – Camera release control circuit – Safety lock
Reexamination Certificate
1999-11-19
2001-08-14
Perkey, W. B. (Department: 2851)
Photography
Camera release control circuit
Safety lock
C396S403000, C396S408000, C396S536000
Reexamination Certificate
active
06275660
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a manual-wind camera provided with a wind lever which is manually operated to wind the film frame by frame.
2. Description of the Related Art
Manual-wind cameras using roll-film bearing no sprocket holes such as Brownie film (e.g., 120 or 220 format film) and having a film winding mechanism provided with a wind lever (i.e., thumb-operated lever) which is manually operated to wind the film frame by frame are known.
In this type of manual-wind camera, the following operations are performed by the user when a roll-film is loaded in the camera: firstly a roll-film is placed in the film chamber with the rear cover open; secondly the film end is placed on the take-up spool; thirdly the wind lever is turned several times to wind the film on the take-up spool until mark (start mark) printed on the backing paper of the film reaches the reference marking formed on the camera body; fourthly the rear cover is closed; and lastly the wind lever is turned a predetermined number of times to position the first frame over the photographic aperture.
Such conventional manual-wind cameras require a dummy roll-film to be loaded when performing a shutter test in which the shutter is released without exposing an image onto film. In this case, firstly the dummy film is placed in the film chamber with the rear cover open, secondly the rear cover is closed, and thirdly the wind lever is turned before the shutter is released by depressing the release button. Other cameras of this type are provided with a mechanism which makes it possible to perform the shutter test without using the dummy film. In this case, the shutter test is performed after a predetermined operation is performed.
However, in the former case, it is necessary to use a dummy film each time the shutter test is performed, which is troublesome. In the latter case, a predetermined operation needs to be performed each time the shutter test is performed, which is also troublesome.
Hence, it is preferable that the shutter test can be performed without the dummy film loaded in the camera. In such a case, it is preferable that the camera automatically determines whether the film has been loaded.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a manual-wind camera using a roll-film having no sprocket holes, wherein the camera can determine with software whether film has been loaded, without providing the camera with any mechanical film detector used solely for determining whether film has been loaded.
To achieve the object mentioned above, according to an aspect of the present invention, there is provided a manual-wind camera having a wind lever in which a film having no sprocket holes is loaded, the film being wound on a take-up spool, frame by frame, by manually operating the wind lever, the camera including a pulse generator which generates pulses in accordance with movement of the film wound by the wind lever; a rear-cover state detector which detects whether a rear cover of the camera is open or closed; and a control device. The control device determines whether the film is loaded into the camera in accordance with pulses generated by the pulse generator when the wind lever is fully turned from an initial operational position to a maximum operational position thereof.
Preferably, a shutter of the camera is permitted to be released without the take-up spool being locked.
Preferably, the control device prohibits the pulse generator from generating the pulses if the control device determines that the film is not in the camera.
Preferably, the control device prohibits a shutter of the camera from being released until a first frame of the film is positioned over the photographic aperture while allowing the wind lever to continue being turned to wind the film until the first frame of the film is positioned over the photographic aperture.
Preferably, the control device does not detect whether the film is in the camera when the wind lever is operated for the first time after the rear cover is closed.
Preferably, the control device prohibits the shutter of the camera from being released when the rear cover is open, while allowing the wind lever to be rotated.
Preferably, the control device allows the shutter of the camera to be released if the control device detects that no film is loaded into the camera.
According to another aspect of the present invention, a manual-wind camera having a wind lever is provided, a film being wound by manually turning the wind lever from an initial operational position to a maximum operational position thereof, the camera including a pulse generator which generates pulses in accordance with movement of the film wound by the wind lever; a rear-cover state detector which detects whether a rear cover of the camera is open or closed; and a control device. The control device detects the pulses generated by the pulse generator; and the control device determines whether the film is loaded into the camera in accordance with pulses detected by the control device when the wind lever is fully turned from the initial operational position to the maximum operational position after the rear-cover state detector detects that the rear cover is closed.
Preferably, a take-up spool is further included on which the film is wound when the wind lever is turned in a direction from the initial operational position to the maximum operational position; and an electromagnetic clutch, which connects the take-up spool with the wind lever when power via the frictional connection of the electromagnetic clutch, is not supplied to the electromagnetic clutch; wherein the electromagnetic clutch disconnects the take-up spool from the wind lever when power is supplied to the electromagnetic clutch.
Preferably, a film holding device is further included which prohibits the take-up spool from rotating to thereby prohibit the film from being wound on the take-up spool only when power is supplied to the film holding device.
Preferably, the control device supplies power to the electromagnetic to disconnect the take-up spool from the wind lever and at the same time supplies power to the film holding device to prohibit the film from being wound on the take-up spool when a counter value of the counter reaches a predetermined value.
According to another aspect of the present invention, a manual-wind camera is provided having a wind lever in which a film having no sprocket holes is loaded, the film being wound on a take-up spool, frame by frame, by manually operating the wind lever. The camera includes: a pulse generator which generates pulses in accordance with movement of the film wound by the wind lever; a rear-cover state detector which detects whether a rear cover of the camera is open or closed; and a control device. Upon the rear cover being closed, the control device judges whether the film is loaded into the camera in accordance with pulses generated by the control device when the wind lever is fully rotated from an initial operational position to a maximum operational position.
Preferably, upon the rear cover being closed, the control device judges whether the film is loaded into the camera according to pulses generated after pulses generated after the wind lever is initially rotated to the maximum operational position.
According to another aspect of the present invention, a manual-wind camera is provided having a wind lever in which a film having no sprocket holes is loaded, the film being wound on a take-up spool, frame by frame, by manually operating the wind lever. The camera includes a pulse generator which generates pulses in accordance with movement of the film wound by the wind lever; a rear-cover state detector which detects whether a rear cover of the camera is open or closed; and a control device. Upon the rear cover being closed, the control device judges whether the film is loaded into the camera when the wind lever has been fully rotated to a maximum operational position a second time.
Preferably, the film is Brownie film.
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Perkey W. B.
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