Shutter mechanism with integral blade, spring, and trigger

Details Shutter mechanism with integral blade, spring, and trigger Shutter mechanism with integral blade, spring, and trigger

1997-10-06

1999-07-06

Blankenship, Howard B.

Photography

Camera detail

Shutter

G03B 936

Patent

active

059207396

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to improvements in or relating to shutter mechanisms, and is more particularly, although not exclusively, concerned with shutter mechanisms for single-use cameras (SUCs).


BACKGROUND OF THE INVENTION

It is well known that photographic exposure of a photographic material is achieved by the combined effect of image intensity and the time this energy is allowed to act on the photographic material. Accurate control of the duration for which energy is allowed to act on the photographic material is therefore important. Shutter mechanisms are used to effect this control.
Shutter mechanisms can be categorised in accordance with their positioning within the camera, for example, front shutters, `between-lens` shutters and focal plane shutters. Most modern cameras employ a type of `between-lens` shutter.
In its simplest form, the `between-lens` shutter is a sector shutter comprising a circular metal plate with an elongated aperture. The metal plate is positioned perpendicular to the light path and makes one rotation when operated. Speed is controlled by a simple spring which is usually tensioned by a part of a release lever. Sector shutters are inexpensive and are often fitted to cheap cameras where inconsistencies which develop over a period of time and the limited speed range are not important.
The most commonly used type of photographic shutter is the bladed or diaphragm shutter. This type of shutter comprises three to five thin metal blades which open and shut across the light path. The blades are designed to minimise the time taken for opening and closing during the exposure cycle. Each shutter blade is pivoted at its outer edge and linked to a ring which is rotated to open the blades. Power for this rotation comes from a main driving spring which is tensioned prior to the shutter being activated. Diaphragm shutters are compact and offer a wide range of speeds.


Problem to be Solved by the Invention

The shutters described above are complicated and comprise many components which need to be accurately moved so that light is uniformly incident on the photographic material within the camera.
Moreover, such shutter mechanisms are expensive to manufacture and assemble, and they take up a substantial amount of space within a camera. This is particular a problem in single-use cameras where a single film or frame is to be exposed, and the size of the camera is to be minimised. The components of such cameras are recycled/re-used where appropriate.


SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a shutter mechanism which is simple both to manufacture and to assemble.
It is a further object of the present invention to provide a shutter mechanism for use in a single-use camera which only exposes a single image.
It is yet another object of the present invention to provide a shutter mechanism which is very thin and occupies little space. Such a shutter mechanism may be useful in any type of camera.
In accordance with one aspect of the present invention, there is provided a shutter mechanism for a camera, the mechanism comprising: relative to the support means, the shutter means being movable between a first position and a second position to allow light into the camera; which, when activated, moves linearly between a first stable state and a second stable state to drive the shutter means from its first position to its second position.
In a preferred embodiment, the bi-stable trigger and the shutter means are integral such that the shutter means moves linearly following activation of the trigger. Alternatively, the shutter means may move in an arc following activation of the trigger.
The shutter means may be pivotally attached to the trigger. If this is the case, a link may join the shutter means to the trigger, which link pivots during use about a region between the shutter means and the trigger. The activation means preferably comprise spring means mounted on the support means which urge the trigger into the first and second sta

REFERENCES:
patent: 3650194 (1972-03-01), Ib
patent: 5016033 (1991-05-01), Chan
patent: 5043751 (1991-08-01), Rice

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