Light intensity adjustment device and imaging device

Abstract

To provide a light quantity adjustment device that can maintain a diaphragm in an open state even when supply of power to a camera is stopped.SOLUTION: A light quantity adjustment device comprises: a base member that forms an opening through which light passes; a driving unit that is provided outside the opening and on the base member; a power transmission member that is driven by the driving unit, the power transmission member in which an engagement part on its one side rotates on one side in a width direction of the base member, and an engagement part on the other side rotates on the other side being on the opposite side of one side in the width direction; a blade group composed of a plurality of blades that are engaged with the engagement parts on one side and the other side of the power transmission member, move on the base member, and advance and retreat with respect to the opening; and a holding unit that, when power supply to the driving unit is stopped, holds the position of the power transmission member so that the blade group has entered the opening and an aperture formed by the blade group is open in a predetermined amount.SELECTED DRAWING: Figure 3

Claims

1. A base member that forms an opening through which light passes, A driving means provided on the base member outside the aforementioned opening, A power transmission member driven by the aforementioned driving means, wherein one of its engaging portions rotates on one side in the width direction of the base member, and the other engaging portion rotates on the other side opposite to the aforementioned side in the width direction, A group of blades consisting of multiple blades that engage with the engagement portions on one and the other side of the power transmission member, move along the base member, and advance and reciprocate relative to the opening, When power supply to the drive means is stopped, a holding means holds the position of the power transmission member such that the group of blades enters the opening and the opening formed by the group of blades becomes an intermediate or minimum aperture, A light intensity control device characterized by comprising the following features.

2. The light intensity adjustment device according to claim 1, characterized in that the holding means has a stopper against which the power transmission member abuts.

3. The light intensity adjustment device according to claim 1 or 2, wherein the driving means comprises a rotor magnet magnetized to two poles, a coil for rotationally driving the rotor magnet, and a yoke made of a magnetic material surrounding the rotor magnet, and the holding means holds the power transmission member in a predetermined position by the action of the rotor magnet magnetized to two poles on the shape of the yoke.

4. The light intensity adjustment device according to claim 1, wherein the driving means comprises a rotor magnet magnetized to two poles, a coil for rotationally driving the rotor magnet, and a yoke made of a magnetic material surrounding the rotor magnet, and the holding means holds the power transmission member in a predetermined position by the action of a projection made of a magnetic material arranged in a part of the circumferential direction of the yoke and the rotor magnet magnetized to two poles.

5. The light intensity adjustment device according to claim 4, characterized in that the mounting position of the projection can be selected from a plurality of positions inside the yoke.

6. The light intensity adjustment device according to claim 2, characterized in that the holding means holds the power transmission member in contact with the stopper by the force of a torsion spring stretched between the base member and the power transmission member.

7. The light intensity adjustment device according to any one of claims 1 to 6, characterized in that the holding means holds the position of the power transmission member such that the opening formed by the group of blades becomes the minimum aperture.

8. The light intensity adjustment device according to any one of claims 2 to 6, characterized in that the group of blades can be completely closed, and the holding means holds the position of the power transmission member such that the opening formed by the group of blades opens from the completely closed position to the intermediate aperture or minimum aperture.

9. An imaging device comprising a light intensity adjustment device according to any one of claims 1 to 8, and an image sensor for imaging light that has passed through the light intensity adjustment device.

Images