Photography – Disposable or recyclable camera
Reexamination Certificate
2001-12-12
2004-03-02
Gray, David M. (Department: 2851)
Photography
Disposable or recyclable camera
C396S179000, C396S459000, C396S505000
Reexamination Certificate
active
06701070
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an aperture stop changing device for a camera. More particularly, the present invention relates to an aperture stop changing device for a camera having a simple structure, and also in which performance of a taking lens can be free from being influenced by the relevant elements for the aperture stop changing.
2. Description Related to the Prior Art
A lens-fitted photo film unit is a single use camera pre-loaded with photo film. Various mechanisms and elements in the lens-fitted photo film unit are simplified for the purpose of lowering the manufacturing cost. The lens-fitted photo film unit includes a shutter unit which a single shutter blade is biased in a closed position, and is knocked instantaneously toward an open position so as to take an exposure by opening and closing a shutter opening. In addition to the shutter unit, the lens-fitted photo film unit is provided with an aperture stop changing mechanism for the purpose of adjusting an exposure. An aperture changing plate of the aperture stop changing mechanism includes a stop-down opening, is movable but is different from the shutter blade. A photometric value or brightness is measured, according to which the aperture changing plate is changed over to change the aperture stop.
The aperture changing plate is movable between first and second positions, and when in the first position, sets the stop-down opening in the light path, and when in the second position, sets away the stop-down opening from the light path. Control of a solenoid causes the aperture changing plate to move, to change over an aperture stop. A photoreceptor is provided, and started upon depression of a shutter release button to detect an amount of object light. The solenoid is actuated by evaluating the object light amount. Therefore, it is possible to adjust an exposure even by use of a simple construction.
To reduce the manufacturing cost, the lens-fitted photo film unit is a structurally simplified product even in relation to a taking lens. Generally, the taking lens is constituted by one or two lens elements
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. Specifically, the type of the taking lens having two lens elements is advantageous, as effective in compensation for aberrations. Behind the taking lens is disposed a preset open aperture defining an open aperture in the lens-fitted photo film unit. A lens holder having a holder barrel portion is disposed on a front side of the preset open aperture. A first one of the lens elements is disposed on the rear side, and has a large diameter. A second one of the lens elements is disposed on the front side, and has a small diameter.
If the lens-fitted photo film unit having the taking lens of the two-lens-element type is provided with the aperture stop changing mechanism as described above, it is preferable to dispose the aperture changing plate between the lens elements, because of structures of elements near the end holder, and because high quality can be obtained and the camera should be compactly designed. The stop-down opening moves in a path and settable even to the front of the taking lens. If the aperture changing plate is inserted between the lens elements, it is likely that an end or tip of the aperture changing plate contacts and interferes with a lens surface to scratch or damage the same. It is also conceivable to dispose members for keeping the aperture changing plate positioned in the optical axis direction to avoid interference with the lens surface. However, this raises the number of the required parts, and is inconsistent to reducing the product size. This is not preferable due to those problems.
SUMMARY OF THE INVENTION
In view of the foregoing problems, an object of the present invention is to provide an aperture stop changing device for a camera having a simple structure, and also in which performance of a taking lens can be free from being influenced by the relevant elements for the aperture stop changing.
Another object of the present invention is to provide an aperture stop changing device for a camera in which an aperture changing plate can be positioned to move on a suitable plane, and can be prevented from interference with a lens surface.
In order to achieve the above and other objects and advantages of this invention, an aperture stop changing device for a camera is provided. The camera includes a preset open aperture for introducing object light to photo film, and a taking lens disposed in a light path of the object light, and having at least one lens element. In the aperture stop changing device, an aperture changing plate includes a stop-down opening having a small diameter, is disposed close to the taking lens, is movable between a small diameter position and a large diameter position, wherein the stop-down opening, when the aperture changing plate is in the small diameter position, is set in the light path for stopping down the preset open aperture, and when the aperture changing plate is in the large diameter position, is set away from the light path. A spacer is secured to a partial section of a peripheral portion of the taking lens, for defining a passage gap or cutout at a remaining partial section of the peripheral portion of the taking lens, the passage cutout allowing passage of the aperture changing plate moving between the small and large diameter positions.
The camera is a lens-fitted photo film unit.
Furthermore, a guide projection portion is formed to project from the peripheral portion of the taking lens toward the aperture changing plate, for contacting the aperture changing plate being moved, to regulate the aperture changing plate in an optical axis direction of the taking lens.
Furthermore, a lens holder is disposed behind the taking lens, for supporting the taking lens.
The guide projection portion is a ring-shaped ridge.
Furthermore, a retention plate is disposed in front of the taking lens, for securing the taking lens to the lens holder. A first retention portion is formed with the lens holder or the retention plate. A second retention portion is formed to project from a peripheral edge of the taking lens, fitted on the first retention portion, for retaining the taking lens on the lens holder or the retention plate.
Furthermore, a holder barrel portion is formed to project from a front surface of the lens holder, and fitted on the peripheral edge of the taking lens. A passage cutout is formed in the holder barrel portion, for allowing the aperture changing plate to move in and out.
Furthermore, a ring-shaped outer ridge is formed to project backwards from the retention plate, fitted on a peripheral edge of the holder barrel portion, for positioning to the lens holder.
The first retention portion is a retention cutout formed in the outer ridge, and the second retention portion is a retention projection.
Furthermore, a biasing mechanism biases the aperture changing plate to the small diameter position. A stopper portion is disposed in a moving path of the aperture changing plate, for contacting the aperture changing plate moved by the biasing mechanism, to keep the aperture changing plate from moving beyond the small diameter position.
Furthermore, a ring-shaped first positioning ridge is formed to project backwards from the retention plate, disposed inside the outer ridge, for pushing the peripheral portion of the taking lens.
Furthermore, a ring-shaped second positioning ridge is formed to project from a front surface of the taking lens, fitted on the first positioning ridge, for positioning the taking lens behind the retention plate.
According to a preferred embodiment, the spacer is a spacer projection formed to project from the lens holder toward the taking lens.
The aperture changing plate is disposed between the taking lens and the lens holder, the guide projection portion projects from a rear surface of the taking lens, and the spacer projection has a height equal to or more than a height of the guide projection portion.
Furthermore, a ring-shaped positioning projection is formed to project from a rea
Fuji Photo Film Co. , Ltd.
Gray David M.
Young & Thompson
LandOfFree
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