Camera shutter unit

Details Camera shutter unit Camera shutter unit

2001-09-21

2003-04-15

Gray, David M. (Department: 2851)

Photography

Camera detail

Shutter

C396S461000, C396S463000, C348S362000

Reexamination Certificate

active

06547457

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a camera shutter unit adapted to a digital still camera or the like and, more particularly to a camera shutter unit which is separately provided with a shutter blade for opening and closing an exposure aperture and a diaphragm blade for stopping down the aperture.
2. Description of the Related Art
Unexamined Japanese Patent Publication kokai) No.10-221740, for example, discloses a conventional camera shutter unit which is separately provided with a shutter blade for opening and closing an exposure aperture where through light passes and a diaphragm blade for stopping down the aperture.
This camera shutter unit includes a shutter blade arranged at a periphery of the aperture so as to move back and forth to open and close the aperture, one electromagnetic drive source for driving the shutter blade, a diaphragm blade arranged so as to move back and forth to stop down the aperture and release the stopping-down, and another electromagnetic drive source for driving the diaphragm blade.
Thereupon, when respective electromagnetic drive sources start, the shutter blade moves back and forth between an opening position wherein the aperture is opened and a closing position wherein the aperture is closed to open and close the aperture and the diaphragm blade moves back and forth between a stopping-down position wherein the aperture is stopped down and an evacuating position wherein the aperture is not stopped down. Also, when respective electromagnetic drive sources are not energized, the shutter blade is held in either the opening position or the closing position and the diaphragm blade is held in either the stopping-down position or the evacuating position.
By the way, with respect to the above conventional camera shutter unit, separate drive sources are provided for driving the shutter blade and the diaphragm blade. Therefore, the shutter blade and the diaphragm blade can be driven separately without using a complicated linkage. However, since separate electromagnetic drive sources are provided, the unit is large-sized, heavyweight, high-cost or the like and consumes a large amount of power in accordance with the number of electromagnetic drive sources.
Also, upon drive of the diaphragm blade and so on, in case only the electromagnetic drive source starts to move the diaphragm blade, when being positioned in a predetermined stopping-down position, the diaphragm blade may bounce and therefore, when stopping down rapidly, the response characteristic of diaphragm blade is not preferable.
In view of the foregoing, an object of the present invention is to provide a a camera shutter unit which adopts a mechanism for interlocking a diaphragm blade with a shutter blade without complexity of the unit so that the shutter blade and the diaphragm blade can function reliably and the diaphragm blade can be positioned to perform a desired stopping-down operation reliably, with a small size, lightweight, low-cost, or the like.
SUMMARY OF THE INVENTION
To achieve the above-mentioned object, a camera shutter unit according to the first aspect of the present invention comprises a base plate having an exposure aperture, a diaphragm blade arranged to be capable of moving between a stopping-down position wherein the aperture is stopped down and an evacuating position wherein the aperture is opened (is not stopped down), a shutter blade arranged to be capable of moving between an opening position wherein the aperture is opened and a closing position wherein the aperture is dosed, and a drive-control mechanism for drive-controlling the shutter and diaphragm blades. The drive-control mechanism is composed of a single electromagnetic drive source which can drive the shutter and diaphragm blades to interlock the diaphragm blade with the shutter blade such that the opening position corresponds to the evacuating position and a travel of from a way position between the opening position and the dosing position to the closing position corresponds to the stopping-down position, a restricting means for restricting movement of the shutter blade toward the dosing position when the diaphragm blade is positioned in the stopping-down position and for releasing its restriction by a predetermined or more level drive force which is generated by the electromagnetic drive source, and a control means for controlling the electromagnetic drive source. The control means controls, when moving to position the diaphragm blade in the stopping-down position, to move the shutter blade to the closing position in advance and next move in reverse the shutter blade by a predetermined amount.
Accordingly, when the single electromagnetic drive source starts, the shutter blade moves from the opening position to the closing position or from the closing position to the opening position, and the diaphragm blade moves from the evacuating position to the stopping-down position or from the stopping-down position to the evacuating position while following the shutter blade. Thus, the single electromagnetic drive source can drive the shutter and diaphragm blades and there is provided the restricting means, which can restrict movement of the shutter blade and can release its restriction, in accordance with the amount of drive force generated by the electromagnetic drive source. Therefore, the shutter and diaphragm blades can function reliably and the unit can be downsized, lightened, or the like. Also, in case the stopping-down operation by the diaphragm blade is carried out, the diaphragm blade is first moved to the dosing position and then is moved in reverse by a predetermined amount, thereby being positioned in the stopping-down position. Therefore, the bouncing of diaphragm blade upon stopping-down operation can be restrained or prevented, whereby the stopping-down operation can be carried out rapidly and reliably.
A camera shutter unit according to the second aspect of the present invention comprises a base plate having an exposure aperture, a diaphragm blade arranged to be capable of moving between a stopping-down position wherein the aperture is stopped down and an evacuating position wherein the aperture is opened (is not stopped down), a shutter blade arranged to be capable of moving between an opening position wherein the aperture is opened and a closing position wherein the aperture is closed, and a drive-control mechanism for drive-controlling the shutter and diaphragm blades. The drive-control mechanism is composed of a single electromagnetic drive source which can drive the shutter and diaphragm blades to interlock the diaphragm blade with the shutter blade such that the opening position corresponds to the evacuating position and a travel of from a way position between the opening position and the closing position to the closing position corresponds to the stopping-down position, a restricting means for restricting movement of the shutter blade toward the dosing position when the diaphragm blade is positioned in the stopping-down position and for releasing its restriction by a predetermined or more level drive force which is generated by the electromagnetic drive source, and a control means for controlling the electromagnetic drive source. The control means controls, when moving to position the diaphragm blade in the stopping-down position, to move the shutter blade up to a nearby position beyond a way position corresponding to the stopping-down position in advance and next move in reverse the shutter blade by a predetermined amount.
Accordingly, when the single electromagnetic drive source starts, the shutter blade moves from the opening position to the closing position or from the closing position to the opening position, and the diaphragm blade moves from the evacuating position to the stopping-down position or from the stopping-down position to the evacuating position while following the shutter blade. Thus, the single electromagnetic drive source can drive the shutter and diaphragm blades and there is provided the restricting means, which can restri

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