JPS6112243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interchangeable lens, mainly a zoom type interchangeable lens, which can be operated in conjunction with an automatic focusing device.

Recently, it has become popular to install an autofocus device on the camera body so that the focusing operation can be performed automatically, but it is difficult to simply apply this to interchangeable lenses, especially zoom-type interchangeable lenses. The interlocking mechanism that connects the autofocus device and the focusing ring becomes long and the entire mechanism becomes large.In other words, zoom-type interchangeable lenses usually have a first lens group dedicated to focusing on the subject side, and a variator for zooming. It consists of a second lens group called the compensator, a third lens group called the compensator, and a fourth lens group called the relay lens or master lens, which is placed in a fixed position at the rear.The lens barrel itself is quite long, and it focuses Since the focus ring for the camera is located far away from the camera body, not only does the interlocking mechanism with the autofocus device become long, but the appearance also becomes unsightly.

Therefore, this invention was made to improve the above-mentioned problems, and it is possible to attach an automatic focusing device to the lens body, and the mechanism for linking with the distance adjustment ring for focusing does not become long, and the structure is This provides an interchangeable lens that is easy to use and has a good appearance.A transmission mechanism that meshes with the terminal gear of an automatic focusing device is attached to the outer periphery of the rear of the fixed lens barrel of the lens body, which is arranged to move multiple zoom lens groups inside. A gear is provided to rotate, an arm is attached to the transmission gear that extends through the notch of the zoom ring and extends toward the distance adjustment ring that holds the first lens group, and the distance adjustment ring is rotated via the arm. It is characterized by the following.

The present invention will be described below with reference to the drawings.
In Figures 1 to 3, reference numeral 2 indicates an interchangeable lens body, whose fixed lens barrel 7 has its rear end attached to the camera body A, and has a helicoid 8 engraved on the outer periphery of its front end. The first lens group L ₁
A distance adjusting ring 6 incorporating the lens is screwed together and rotated to move back and forth in the optical axis direction via the helicoid 8 to perform focusing.

Lens frames a and b incorporating a second lens group L ₂ and a third lens group L ₃ for zooming are movably fitted inside the fixed lens barrel 7, and a fourth lens group is attached to the rear end. _L4 is fixed to the camera body A via a mounting frame c.

A cam barrel 13 having a rear end integrally provided with a zoom ring 12 having an operating knob 15 is rotatably fitted to the outer periphery of the central portion of the fixed lens barrel 7.
Two cam holes 13a, 13b bored in the peripheral wall of No. 3
The pins a' and b' implanted in the lens frames a and b pass through and engage with the long holes 7a in the optical axis direction provided in the fixed lens barrel 7, so that the rotation of the zoom ring 12, i.e. The lens frames a and b are rotated by the rotation of the cam cylinder 13.
are moved relative to each other in the optical axis direction, and zooming is performed as appropriate.

On the other hand, a transmission gear 5 is provided on the outer periphery of the rear end of the fixed lens barrel 7.
is rotatably disposed, and a covering outer cylinder 14 is fixed to the rear side with a rear inward flange in contact with the cover outer cylinder 14. An arm 10 having a long hole 11 in the optical axis direction is fixed to a part of the transmission gear 5 so as to face forward parallel to the optical axis, and is formed between a zoom ring 12 and a cam barrel 13 as shown in FIG. arc-shaped notch 1
3' (this is formed in an angular range that is approximately 1,000 times larger than the sum of the rotation angle α for zooming, the rotation angle θ required for distance adjustment, and the arm width t), and the distance adjustment ring 6 is A pin 9 provided on the inner surface of the extension part 6' engages with a long hole 11 facing into the rear extension part 6', so that the distance adjustment ring 6 and the transmission gear 5 rotate together.

The rear peripheral wall of the covered outer cylinder 14 has a slightly wide window hole 4 that enables engagement between the terminal gear 3 of the automatic focusing device 1 described later and the transmission gear 5, and a knob 15 of the zoom ring 12 that enables the operation of the knob 15. A slit 16 of a certain range is provided to cover the outer cylinder 14. Furthermore, an outer ring 17 having a window hole 18 of a required length is rotatably provided on the rear outer periphery of the covering outer cylinder 14. The window hole 18 and the window hole of the outer cylinder 14 4, the terminal gear 3 of the automatic focusing device can be meshed with the transmission gear 5. In FIGS. 1 and 2, reference numeral 1 denotes an automatic focusing device that is detachably attached to the rear outer periphery of the covered outer cylinder 14 in close proximity to the camera body A via the front side projecting flange of the case C. As is well known, the automatic focusing device 1 in the embodiment includes a fixed mirror 1a, a scanning mirror 1b supported by a rotating arm, and light receiving elements 1c, 1c for receiving and comparing optical signals from both mirrors, inside a case C. ', a cam member 1d for swinging the scanning mirror 1b, an interlocking gear member 1e, a servo motor 1m for controlling the cam member 1e, and the like are housed. The obtained image is guided to light receiving elements 1c and 1c', and both light receiving elements 1
The control circuit drives the servo motor 1m to a position corresponding to the angle of the scanning mirror 1b where the images of c and 1c' coincide, and rotates the distance adjustment ring 6 via the interlocking gear member 1e. A part of the gear 3 protrudes from the case C and meshes with the transmission gear 5 on the fixed lens barrel 7 through the outer ring 17 and the window holes 18 and 4 of the covering outer cylinder 14.

Therefore, in conjunction with the shutter release for photographing, the servo motor 1m of the autofocus device 1 is first activated, and the scanning mirror 1b is rotated from infinity to the near distance side or from the near distance to infinity, and at the same time Interlocking gear member 1e by servo motor 1m
is driven, and therefore, the transmission gear 5 on the fixed lens barrel 7 is rotated via the terminal gear 3, and the arm 10 attached to this gear 5 is also rotated along the arc-shaped notch 13'. The rotation is transmitted to the distance adjustment ring 6 due to the engagement relationship between the elongated hole 11 and the pin 9, and the helicoid 8
Due to the action, the ring 6 moves back and forth in the optical axis direction together with the first lens group _L1 to adjust the distance.
As described above, when the image of the subject obtained by the fixed mirror 1a and the image obtained by the scanning mirror 1b match, the servo motor 1m is stopped and the first lens group _L1 is set at a desired distance position.

On the other hand, by rotating the operating knob 15 in either the left or right direction, the zoom ring 12 and the cam cylinder 13 integrated therewith are rotated appropriately, and the pins engaged in the cam holes 13a and 13b are rotated. Zooming is performed by moving the second and third lens groups relatively in the optical axis direction via a' and b'.

Furthermore, when the automatic focusing device 1 is not required, it is sufficient to remove the mounting screw of the case C and release the meshing relationship between the terminal gear 3 and the transmission gear 5.
At this time, the outer ring 17 is rotated a few thousand turns to shift the position of the window hole 18 and the window hole 4 of the covering outer tube 14, thereby preventing dust, water droplets, etc. from entering into the lens body 2.

As described above, according to the present invention, the autofocus device can be attached to the lens body at any time, and the interlocking mechanism connecting the autofocus device and the front distance adjustment ring is shortened compared to a device that is attached to the camera body. The structure is simple, and since the interlocking mechanism is housed within the lens body and is not exposed to the outside, it can be compactly packed without increasing the outer diameter of the lens body, and does not spoil the appearance of the lens body.
When an automatic focusing device is not required, the positions of the window hole in the outer ring and the window hole in the covering outer tube can be shifted to prevent dust, water droplets, etc. from entering the lens body.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the invention. FIG. 2 is a front view cut along the line X--X in FIG. 1. FIG. 3 is an exploded perspective view of the main components. Figure 4 is Figure 1 Y-
A cross-sectional view along the Y line. In the figure, 1... automatic focus device, 2... lens body, 3... terminal gear, 4, 18... window hole, 5...
Transmission gear, 6... Distance adjustment ring, 7... Fixed lens barrel, 8... Helicoid, 9... Pin, 10... Arm, 11... Long hole, 12... Zoom ring, 1
3...Cam cylinder, 14...Coated outer cylinder, 17...Exterior ring.

Claims (1)

[Claims] 1. A transmission gear that engages with an automatic focus device is rotatably provided on the outer periphery of the rear end of a fixed lens barrel of a lens body in which a plurality of zoom lens groups are arranged to move inside, while a wide window hole and A covered outer cylinder with slits in a certain range is attached, and an outer ring with a window hole of a required length is rotatably arranged on the rear outer periphery of the covered outer cylinder, and a zoom ring notch is provided in the upper transmission gear. The automatic focusing device is linked with an automatic focusing device characterized in that an arm is attached that extends through the part and extends to the distance adjustment ring side that holds the first lens group for focusing, and the distance adjustment ring is rotated via the arm. Interchangeable lenses.