Floating lens barrel, lens barrel, and a common lens barrel...

Details Floating lens barrel, lens barrel, and a common lens barrel... Floating lens barrel, lens barrel, and a common lens barrel...

2000-03-30

2001-05-22

Epps, Georgia (Department: 2873)

Optical: systems and elements

Lens

With support

C359S694000, C359S703000, C359S827000

Reexamination Certificate

active

06236523

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a floating lens barrel, a lens barrel, and a lens barrel system for common use.
2. Description of the Related Art
In a known floating lens system, especially for spherical aberration correction, a focusing lens group is split into a front lens group and a rear lens group, so that a slight relative movement of the front lens group and the rear lens group occurs upon focusing in accordance with the object distance. Hitherto, it has been necessary for a lens barrel for the floating lens system to be provided with a plurality of concentric helicoids whose center is located on the optical axis, so that the relative movement takes place between the front and rear lens groups in accordance with the rotation of a distance adjusting ring which is driven by the power for the focusing operation. However, a lens barrel using a plurality of helicoids has many drawbacks: the drive torque is increased, a deviation tends to occur between the axes of the front and rear lens groups, the distance between the front and rear lens groups tends to change during the assembly, it is difficult to adjust the distance between the front and rear lens groups, and it is difficult to adjust the flange back (FB).
SUMMARY OF THE INVENTION
It is an object of the present invention to eliminate the above-mentioned drawbacks of the floating lens barrel.
Another object of the present invention is to provide a lens barrel having no floating function, which can be easily assembled.
Yet another object of the present invention is to provide a common lens barrel system, a part of which can be used commonly as a pair of floating lens barrels or a is floating lens barrel and a non-floating lens barrel.
According to an aspect of the present invention, there is provided a floating lens barrel having a focusing front lens group and a focusing rear lens group which includes: a stationary barrel to be connected to a camera body; a rotation ring which is rotatable relative to the stationary barrel and which is rotated in accordance with focusing operation of the camera; a female helicoid ring provided on the stationary barrel; a front lens support ring which supports the focusing front lens group and which is guided to move linearly in the optical axis direction; a male helicoid ring which is supported by the front lens support ring so as to rotate relative thereto but not to move in the optical axis direction relative to the front lens support ring, the male helicoid ring being provided with a cam groove; a rotation transmission mechanism for transmitting the rotation of the rotation ring to the male helicoid ring; and a rear lens support ring which holds the focusing rear lens group and which is guided to move linearly in the optical axis direction by the front lens support ring, the rear lens support ring being moved relative to the front lens support ring in the optical axis direction in accordance with the cam groove of the male helicoid ring when the male helicoid ring is rotated.
Preferably, the rotation transmission mechanism includes a rotation transmission groove which extends in parallel with the optical axis and which is formed on one of either the rotation ring or the male helicoid ring, and a rotation transmission pin which is provided on the other of the either the male helicoid ring or the rotation ring, the rotation transmission pin being inserted into the rotation transmission groove.
Preferably, the female helicoid ring is made separate from the stationary barrel and wherein the relative angular position therebetween is adjustable.
Preferably, the female helicoid ring is detachably attached to the stationary barrel, so that when the female helicoid ring is detached from the stationary barrel, the front lens support ring, the male helicoid ring, and the rear lens support ring are detached together from the stationary barrel and the rotation ring.
Preferably, the rotation ring is rotated in accordance with the rotation of a distance adjusting ring which is manually rotated or driven by an AF drive shaft.
Preferably, the front lens support ring is guided in a linear movement guide groove which is formed in the stationary barrel and which extends in parallel with the optical axis.
Preferably, a spacer washer is provided between a flange of the front lens support ring and a flange of the front lens support frame which is supported by the front lens support ring to adjust the relative position between the front lens support ring and the front lens support frame in the optical axis direction.
According to another aspect of the present invention there is provided a lens barrel which includes: a stationary barrel to be connected to a camera body; a rotation ring which is rotatably supported by the stationary barrel and which is rotated in accordance with a focusing operation; a female helicoid ring provided on the stationary barrel; a lens support ring which supports a focusing lens and which is guided to move linearly in the optical axis direction; a ale helicoid ring which is supported by the lens support ring so as to rotate relative thereto but not to move in the optical axis direction relative to the front lens support ring; and a rotation transmission mechanism for transmitting the rotation of the rotation ring to the male helicoid ring.
According to another aspect of the present invention there is provided a common lens barrel system which includes: a common lens barrel which constitutes a stationary barrel which can is connected to a camera body, and a rotation ring which is rotatably supported by the stationary barrel and which is rotated in accordance with a focusing operation of the camera; a first separate lens barrel which constitutes a female helicoid ring which can be detachably attached to the stationary barrel from the front thereof, a front lens support ring which supports a focusing front lens group and which can be inserted in the stationary barrel, the front lens support ring being guided to move linearly in the optical axis direction, a male helicoid ring which is supported by the front lens support ring so as to rotate relative thereto but not to move in the optical axis direction relative to the front lens support ring, the male helicoid ring being engaged by the female helicoid ring, a rotation transmission groove provided on one of the rotation ring and the male helicoid ring and a rotation transmission pin provided on the other of the male helicoid ring and the rotation ring, the rotation transmission pin being fitted in the rotation transmission groove, and a rear lens support ring which holds a focusing rear lens group and which is guided to move linearly in the optical axis direction by the front lens support ring, the rear lens support ring being moved relative to the front lens support ring in the optical axis direction in accordance with a cam groove formed in the male helicoid ring; and a second separate lens barrel which comprises a female helicoid ring which can be detachably attached to the stationary barrel from the front thereof, a lens support ring which supports a focusing lens group and which can be inserted in the stationary barrel, the front lens support ring being guided to move linearly in the optical axis direction, a male helicoid ring which is supported by the lens support ring so as to rotate relative thereto but not to move in the optical axis direction relative to the lens support ring, the male helicoid ring being engaged by the female helicoid ring, and a rotation transmission groove provided on one rotation ring and the male helicoid ring and a rotation transmission pin provided on the other male helicoid ring or the rotation ring, the rotation transmission pin being fitted in the rotation transmission groove; wherein the first separate lens barrel and the second separate lens barrel is selectively attached to the common lens barrel.
Preferably, the relative angular position of the female helicoid rings of the first and second separate lens barrels and the stationary barrel is

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