Photography – With exposure objective focusing means – focusing aid – or... – Auto/manual mode selection
Reexamination Certificate
2003-10-15
2004-09-07
Perkey, W. B. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Auto/manual mode selection
C359S825000
Reexamination Certificate
active
06788890
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lens barrel which can be used as a photographing lens of an AF camera, and more specifically, to a switching mechanism of such a lens barrel for switching between automatic focusing and manual focusing.
2. Description of the Related Art
FIGS. 8 through 11
show a conventional interchangeable lens barrel having a switching mechanism between an automatic focusing mode and a manual focusing mode. The lens barrel
01
includes a stationary barrel
03
having a small-diameter ring portion
07
and a large-diameter ring portion
05
positioned radially outside the small-diameter ring portion
07
. A distance adjustment ring
09
is positioned between the small-diameter ring portion
07
and the large-diameter ring portion
05
to be freely rotatable about an optical axis O. An AF/MF switching ring
011
for switching between an automatic focusing mode and a manual focusing mode is fitted on the large-diameter ring portion
05
. The AF/MF switching ring
011
is freely rotatable about the optical axis O and movable along the optical axis O relative to the large-diameter ring portion
05
between an AF position and an MF position to switch between an automatic focusing mode and a manual focusing mode, respectively. A lens holding ring
013
for holding a focusing lens group L is screw-engaged with the small-diameter ring portion
07
. A rotation of the distance adjustment ring
09
causes the lens holding ring
013
to move along the optical axis O while rotating about the optical axis O. The lens barrel
01
is provided between the large-diameter ring portion
05
and the small-diameter ring portion
07
with an AF drive mechanism
015
which transfers a rotation of an AF motor (provided in a camera body (not shown) to which the lens barrel
01
is mounted) to the distance adjustment ring
09
to perform an autofocusing operation when the AF/MF switching ring
011
is in the AF position (automatic focusing mode). When the AF/MF switching ring
011
is in the MF position (manual focusing mode), the AF drive mechanism
015
is disengaged from the distance adjustment ring
09
.
The large-diameter ring portion
05
is provided, on an outer peripheral surface thereof at the front end of the large-diameter ring portion
05
, with a plurality of stop grooves
017
which extend in a direction of the optical axis O (i.e., optical axis direction). The plurality of stop grooves
017
are arranged in a circumferential direction of the large-diameter ring portion
05
. An AF engaging member
019
is fixed to an inner peripheral surface of the AF/MF switching ring
011
. The AF engaging member
019
is engaged with one of the plurality of stop grooves
017
to prevent the AF/MF switching ring
011
from rotating when the AF/MF switching ring
011
is in the AF position (see FIGS.
8
and
10
). The distance adjustment ring
09
is provided at the front end thereof with a plurality of engaging grooves
021
which extend in the optical axis direction (see FIG.
11
). The plurality of engaging grooves
021
are arranged in a circumferential direction of the distance adjustment ring
09
. The AF/MF switching ring
011
is provided at the front end thereof with an inner flange
023
. An MF engaging pin
025
projects rearwards from a rear surface of the inner flange
023
to be engaged with any one of the plurality of engaging grooves
021
. The MF engaging pin
025
is engaged in one of the plurality of engaging grooves
021
when the AF/MF switching ring
011
is in the MF position to transmit rotation of the AF/MF switching ring
011
to the distance adjustment ring
09
.
In the lens barrel
01
having the above described structure, the MF engaging pin
025
is disengaged from the plurality of engaging grooves
021
when the AF/MF switching ring
011
is in the AF position to allow the AF drive mechanism
015
to perform an auto-focusing operation. When the AF/MF switching ring
011
is in the MF position, the MF engaging pin
025
is engaged in one of the plurality of engaging grooves
021
so that a rotation of the AF/MF switching ring
011
is transferred to the distance adjustment ring
09
to perform a focusing operation (manual focusing operation) when the AF/MF switching ring
011
is manually rotated.
Installation of both the AF engaging member
019
and the MF engaging pin
025
at different positions on the AF/MF switching ring
011
increases the cost of production, the cost of assembly and the size of the lens barrel
01
.
SUMMARY OF THE INVENTION
The present invention provides a lens barrel having a switching mechanism between an automatic focusing mode and a manual focusing mode, wherein the cost of production and the cost of assembly of the lens barrel can be reduced while further miniaturizing the lens barrel.
According to an aspect of the present invention, a switching mechanism of a lens barrel for switching between an automatic focusing mode and a manual focusing mode, the switching mechanism including a stationary barrel having at least one stop groove; a lens holding ring, positioned concentrically with the stationary barrel, the lens holding ring holding at least one lens group; a distance adjustment ring which is positioned concentrically with the stationary barrel, immovable along an optical axis relative to the stationary barrel, and rotatable about the optical axis relative to the stationary barrel, wherein a rotation of the distance adjustment ring causes the lens holding ring to move along the optical axis, and wherein the distance adjustment ring includes at least one engaging groove; and an AF/MF switching ring which is positioned concentrically with the stationary barrel, movable along the optical axis relative to the stationary barrel, and rotatable about the optical axis relative to the stationary barrel, wherein movement of the AF/MF switching ring relative to the stationary barrel between an AF position and an MF position switches between the automatic focusing mode and the manual focusing mode, respectively, and wherein the AF/MF switching ring includes an engaging member which is selectively engaged with the stop groove and the engaging groove. The AF/MF switching ring is prevented from rotating relative to the stationary barrel by engagement of the engaging member with the stop groove while a driving force is transferred from a power source to the distance adjustment ring to move the lens holding ring along the optical axis when the AF/MF switching ring is in the AF position. A rotation of the AF/MF switching ring is transferred to the distance adjustment ring to move the lens holding ring along the optical axis via engagement of the engaging member with the engaging groove while the driving force is prevented from being transferred from the power source to the distance adjustment ring when the AF/MF switching ring is in the MF position.
It is desirable for the engaging member to include a first engaging portion and a second engaging portion which are fixed at opposite ends of a leaf spring in the optical axis direction to be engageable with the stop groove and the engaging groove, respectively, the leaf spring being elongated in the optical axis direction and a central portion thereof being fixed to said AF/MF switching ring. The leaf spring is resiliently deformed to move the first engaging portion to a non-engaging position thereof, wherein the first engaging portion is disengaged from the stop groove, when the AF/MF switching ring moves from the MF position to the AF position in the case where the first engaging portion is not aligned with the stop groove in the circumferential direction thereof. The leaf spring is resiliently deformed to move the second engaging portion to a non-engaging position thereof wherein the second engaging portion is disengaged from the engaging groove when the AF/MF switching ring moves from the AF position to the MF position in the case where the second engaging portion is not aligned with the engaging groove in the circumferential direction
Greenblum & Bernstein P.L.C.
PENTAX Corporation
Perkey W. B.
LandOfFree
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