Zoom lens device

Abstract

When a cam barrel 24 is rotated on an outer periphery of a fixed barrel 23 during varying of power, a lens holding frame 22 that has cam followers 27, which engage with cam portions 29 provided in the cam barrel 24 and forward movement guide openings 28 provided in the fixed barrel 23, is moved straight forward in an optical axis direction by a cooperation between the cam portions 29 and the forward movement guide openings 28. A projection portion 30 is provided in an outer periphery of the diaphragm mechanism 15. A diaphragm aperture diameter is changed by rotating the projection portion 30 around an optical axis. The projection portion 30 engages with a diaphragm control cam member 31 fixed to an inner surface of the fixed barrel 23, and changes the diaphragm aperture diameter in response to movement of the lens holding frame 22.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view showing the configuration of a projector using a zoom lens barrel, the upper portion of FIG. 1 shows a state at the WIDE end, and the lower portion of FIG. 1 shows a state at the TELE end.

FIG. 2 is a section view showing a main portion of the zoom lens barrel taken along an optical axis.

FIG. 3 is a section view, which is perpendicular to the optical axis, which shows the main portion of the zoom lens barrel and which shows a state where a diaphragm mechanism has the smallest diameter of a diaphragm aperture at the WIDE end.

FIG. 4 is a section view, which is perpendicular to the optical axis, which shows the main portion of the zoom lens barrel, and which shows a state where the diaphragm mechanism has a full diameter of the diaphragm aperture at the TELE end.

FIG. 5 is an exploded perspective view showing the configuration of the diaphragm mechanism.

FIG. 6 is an explanatory view showing a state of diaphragm blades at the WIDE end.

FIG. 7 is an explanatory view showing a state of the diaphragm blades at the TELE end.

Claims

1. A zoom lens device comprising: a lens group that constitutes a part of a zoom lens optical system and moves in an optical axis direction during varying of power of the zoom lens with being inside a fixed barrel;a diaphragm mechanism disposed in front of or in rear of the one lens group in the optical axis direction, wherein a diaphragm aperture diameter of the diaphragm mechanism is changed by moving a projection portion, which protrudes to an outside, around an optical axis;a diaphragm frame body, which holds the diaphragm mechanism so that the projection portion protrudes to the outside and which moves straight forward in the optical axis direction during the varying of the power with being inside the fixed barrel; anda diaphragm control cam member, which is fixed to an inner surface of the fixed barrel, which always engages with the projection portion during the varying of the power and which moves the projection portion around the optical axis in response to the movement of the diaphragm frame body.

2. The device according to claim 1, wherein the diaphragm frame body holds the lens group together with the diaphragm mechanism.

3. A zoom lens device comprising: a lens holding frame that holds a lens group constituting a part of a zoom lens optical system;a fixed barrel formed with forward movement guide openings, which engage with cam followers provided in the lens holding frame to guide the lens holding frame in an optical axis direction;a cam barrel that is held on an outer periphery of the fixed barrel so as to be rotatable, the cam barrel that comprises cam portions, which engage with the respective cam followers and which are used to move the lens holding frame in the optical axis direction, wherein when the cam barrel is rotated with respect to the fixed barrel during varying of a power of the zoom lens, the lens holding frame is moved straight forward in the optical axis direction by cooperation between the cam portions and the forward movement guide openings with the lens holding frame being inside the fixed barrel;a diaphragm mechanism, which is disposed in front of or in rear of the lens holding frame in the optical axis direction, which is moved along with the lens holding frame during the varying of the power, and which comprises a projection portion protruding to an inner surface of the fixed barrel, wherein a diaphragm aperture diameter of the diaphragm mechanism is changed by moving the projection portion around an optical axis; anda diaphragm control cam member, which is fixed to the inner surface of the fixed barrel, which has at least such a length that the projection portion engages with the diaphragm control cam member at least during a period in which the lens holding frame moves in the optical axis direction, and which moves the projection portion around the optical axis in response to the movement of the lens holding frame.

4. A zoom lens device comprising: a plurality of lens groups that constitute all or a part of a zoom lens optical system;a fixed barrel that supports the lens groups movably inside the fixed barrel, the fixed barrel comprising forward movement guide portions that engage with respective cam followers provided in the respective lens groups;a cam barrel that is held on an outer periphery of the fixed barrel so as to be rotatable, the cam barrel comprising a plurality of cam portions that engage with the respective cam followers to move the respective lens groups in the optical axis direction;a diaphragm mechanism, which is disposed in front of or in rear of one lens holding frame that holds one of the plurality of lens groups in the optical axis direction and which is moved together with the lens holding frame, wherein a diaphragm aperture diameter of the diaphragm mechanism is changed by moving a projection portion, which protrudes to an inner surface of the fixed barrel, around an optical axis; anda diaphragm control cam member, which is fixed to the inner surface of the fixed barrel, which has at least such a length that the projection portion engages with the diaphragm control cam member at least during a period in which the lens holding frame moves in the optical axis direction, and which moves the projection portion around the optical axis in response to the movement of the lens holding frame.