JPH0717046Y2 - Lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a lens barrel capable of automatic focusing, which has a transmission member for transmitting a driving force to a focusing lens group for automatic focusing. is there.

(Background of the Invention) A lens barrel of this type is mounted on a camera body having an automatic focus detection device, and a focusing lens group is driven by a driving force transmitted from the camera body for automatic focusing. . As shown in FIG. 4, this lens barrel has a focusing ring 1 to which a focusing lens group G1 is fixed.
An internal fixed lens barrel 7 in which a variable power lens group G2 and a correction lens group G3 are slidably fitted and a fixed lens group G4 is fixedly installed.
A zoom cam ring 13 fitted to the outer periphery of the internal fixed lens barrel 7 and driven by the variable power lens group G2 and the correction lens group G3.
An external fixed lens barrel 4 on which a mount 11 and the like are fixedly mounted; and a drive ring 3 for transmitting a driving force to the focusing lens ring 1 between the zoom cam ring 13 and the external fixed lens barrel 4. There is. The drive ring 3 is formed in a cylindrical shape, an internal gear 3a is formed at the end on the mount 11 side, and an elongated hole 3b extending in the optical axis direction is formed at the other end.
The internal gear 3 a of the drive ring 3 is a first gear member 6
The driving force from the camera body (not shown) that is meshed with the gear portion 6a of the above and is transmitted to the second gear member 10 through the first gear member 6 is transmitted. As shown in FIG. 2 (B), the first gear member 6 has gear portions 6a and 6b, and the second gear member 10 includes a gear portion 10b meshing with the gear portion 6b and a camera body (not shown). It has a coupler 10a that engages with a coupling shaft that transmits a driving force. This first gear member 6
The second gear member 10 is rotatably supported by bearings 9 and 12 and a mount 11 which are fixed to the external fixed lens barrel 4. Further, a pin 5 planted in the focusing ring 1 is slidably fitted in the elongated hole 3b of the drive ring 3 in the optical axis direction, and the rotation of the drive ring 3 causes the pin 5 to focus through the pin 5. The lens ring 1 is extended in the optical axis direction by a helicoid screw member 2 fixed to the internal fixed lens barrel 7.

First, the focusing operation by the focusing lens group G1 will be described. When the focusing lens group G1 is driven by the driving force from the camera body and the automatic focusing operation is performed, the coupling axis of the camera body is mounted on the lens barrel mount 11.
The driving force from the camera body is engaged with the coupler 10a exposed from a part of the second gear portion 10 and the first gear portion 6
Drive force is transmitted to the internal gear 3a of the drive ring 3 through the drive ring 3, and the drive ring 3 is rotated by the drive force, and the rotation is transmitted to the focusing ring 1 via the pin 5 to extend the focusing lens group G1. Focus. Further, when the focusing lens group G1 is driven manually to perform focusing, the focusing ring 1 may be rotated.

Next, in the zooming operation by the variable power lens group G2 and the correction lens group G3, the zoom cam ring 13 is rotated by a known zooming mechanism, and the variable power lens group G2 and the correction lens group G3.
Is moved in the optical axis direction.

The conventional lens barrel must be driven through the drive ring 3 in order to drive the focusing lens group G1 located at the tip of the lens barrel by the driving force on the camera body side during the automatic focusing operation. The drive ring 3 has a cylindrical shape with a larger diameter than the internal fixed lens barrel 7 and the zoom cam ring 13, and the focusing ring 1 located at the tip of the lens barrel.
In order to transmit the driving force transmitted from the mount 11 side, the length is also increased. Therefore, the weight of the lens barrel itself becomes large, the load for driving becomes large, the driving speed for automatic focusing becomes slower, and the driving ring 3 enters the lens barrel, so that the lens There is a drawback that the lens barrel becomes larger.

(Object of the Invention) An object of the present invention is to solve these drawbacks, to reduce the load at the time of automatic focusing, and to provide a downsized lens barrel.

(Embodiment) FIGS. 1 to 3 show an embodiment of the present invention. FIG. 1 is a sectional view of a lens barrel capable of automatic focusing, and FIG. 2 (A) is an inside of the lens barrel. FIG. 2B is a perspective view of the fixed lens barrel, FIG. 2B is a perspective view of the gear portion of the lens barrel, and FIG. 3 is a front view of the diaphragm mechanism of the lens barrel.

The lens barrel shown in FIG. 1 has substantially the same configuration as the lens barrel capable of automatic focusing shown in FIG. 4, and the different configuration will be mainly described here. The lens barrel shown in FIG. 1 and the lens barrel shown in FIG. 4 are substantially different from each other in that the drive ring 3 in the lens barrel shown in FIG. 4 is replaced by another member in the lens barrel shown in FIG. I am here. In FIG. 1, the drive ring 3 is formed in a U-shape, and has a long hole 3b which fits the pin 5 planted in the focusing ring 1 at one end thereof and a first hole at the other end thereof. An internal gear 3c that meshes with the gear 6a of the one gear portion 6 is formed, and the meshing portion of the focusing ring 1 and the helicoid member 2 is inserted inside the drive ring 3 thereof. In FIGS. 2 (A) and 2 (B), the first gear portion 6 is designed to enter the notches 7a and 7b formed in the internal fixed barrel 7.
The gear 6a is in the cutout portion 7b, and the shaft of the first gear portion 6 is in the cutout portion 7a. Therefore, the first gear portion 6 does not interfere with other driven members (eg, zoom cam ring, diaphragm member, etc.). The straight-moving grooves 7d and 7e of the internal fixed lens barrel 7 are used for the zoom lens group G2 during zooming operation.
And for extending the correction lens group G3. Further, in order to prevent the strength of the internal fixed lens barrel 7 from being weakened due to the cutouts 7a and 7b, the inner fixed lens barrel 7 serves as a bridge that connects the cutouts 7a to the entire circumference of the lens barrel 7 as a ring zone portion. 7c is provided. The ring zone 7c is provided in order to prevent the strength of the fixed lens barrel from being weakened, and does not necessarily have to be the ring zone, and it is sufficient if it connects a part of the cutout 7a. Since the axis of the first gear portion 6 extends from the tip of the lens barrel toward the mount 11 direction, that is, from the front stage on the lens tip side to the rear stage on the body side of the diaphragm unit 8, A concave portion 8a through which the shaft of the first gear portion 6 passes is formed in a part of the diaphragm portion 8 located in the middle of the lens barrel (Fig. 3). The diaphragm unit 8 has a plurality of diaphragm blades 14, and the operation of the diaphragm blades 14 is the first gear 6
It is not affected by the axis of. The zoom cam ring 13 is fitted to the outer peripheral side of the internal fixed lens barrel 7 having the first gear portion 6 therein,
The lens barrel 7 is positioned by the ring zone 7c.

First, the focusing operation by the focusing lens group G1 will be described. When the focusing lens group G1 is driven by the camera body to perform the automatic focusing operation, the coupling axis of the camera body engages with the coupler 10a exposed from a part of the mount 11 of the lens barrel, and the camera body Driving force from the driving ring 3 is transmitted to the internal gear 3c of the driving ring 3 via the second gear portion 10 and the first gear portion 6,
Is rotated by its driving force, and the rotation is transmitted to the focusing ring 1 via the pin 5 to extend the focusing lens group G1 to perform focusing. Further, when the focusing lens group G1 is driven manually to perform focusing, the focusing ring 1 may be rotated.

Next, in the zooming operation by the variable power lens group G2 and the correction lens group G3, the zoom cam ring 13 is rotated by a known zooming mechanism, and the variable power lens group G2 and the correction lens group G3.
Is moved in the optical axis direction.

(Effect of the Invention) As described above, according to the present invention, a rod-shaped shaft portion having at one end a gear that meshes with the internal gear of the drive ring that drives the focusing lens group that is arranged in front of the diaphragm portion. To
By arranging along the notch of the fixed lens barrel, which is formed long in the optical axis direction from the front stage to the rear stage of the diaphragm, the lens barrel can be downsized and the driving force transmitting member can be There is no interference with driven members (for example, zoom cam ring, diaphragm member, etc.). Further, by providing the bridge in the vicinity of the end portion of the cutout portion for disposing the shaft portion, the accuracy or strength of the lens barrel does not deteriorate even if the size of the cutout portion is large.

In this embodiment, the first gear portion 6 for transmitting the driving force from the camera body for automatic focusing to the focusing ring 1 is passed through the notches 7a and 7b formed in the internal fixed lens barrel 7. Focusing ring 1 located at the tip of the lens barrel
The driving force is transmitted to. Therefore, the lens barrel does not become large as in the conventional case, and the drive ring 3 that operates during focusing does not become large, so that the load for automatic focusing can be lightened. Further, since the inner fixed lens barrel 7 is provided with the ring zone portion 7c, the notch portions 7a, 7 into which the first gear portion 6 is inserted.
Even if b is provided, the strength of the lens barrel itself does not decrease.

[Brief description of drawings]

FIG. 1 is a sectional view of a lens barrel which is an embodiment of the present invention, and FIG. 2A is a perspective view of an internal fixed lens barrel of the lens barrel.
FIG. 2B is a perspective view of the driving force transmission member of the lens barrel, and FIG. 3 is a front view of the diaphragm portion. FIG. 4 is a sectional view of a conventional lens barrel. (Description of symbols of main parts) G1 ... Focusing lens group 1 ... Focusing ring, 3 ... Drive ring 4 ... External fixed lens barrel, 7 ... Internal fixed lens barrel 6 ... First gear section, 10 ... ... Second gear

Claims (1)

[Scope of utility model registration request] 1. A lens barrel having a focusing lens group which is mounted on a camera body having an automatic focus detection device and is driven based on the output of the automatic focus detection device, wherein the driving force transmitted from the camera body is A rod-shaped first shaft portion which has a driving force transmission gear for transmitting at one end and is arranged in parallel with the optical axis direction, and the focusing unit which is longer than the first shaft portion and which is arranged in front of the diaphragm portion. A rod-shaped second shaft portion that has a gear that meshes with the internal gear of the drive ring that drives the lens group and that is disposed in the optical axis direction, and the first shaft that is disposed at a stage subsequent to the diaphragm portion. Driving force transmission member including a transmission member that transmits the rotation of the shaft portion to the second shaft portion, and a notch portion that is long in the optical axis direction are provided parallel to the optical axis from the front stage to the rear stage of the diaphragm unit. Fixed lens barrel and near the end of the notch. And a reinforcing member provided on the fixed lens barrel so as to surround the fixed lens barrel and having a thickness in the radial direction, and the second shaft portion is arranged along the cutout portion. The lens barrel is provided, and the reinforcing member has a thin radial thickness in the vicinity of the cutout portion so that the second shaft portion is disposed.