Camera

Details Camera Camera

2000-11-09

2002-05-21

Perkey, W. B. (Department: 2851)

Photography

Having variable focal length of camera objective

Having focus operation

C396S349000

Reexamination Certificate

active

06393218

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a camera provided with a zoom lens having a plurality of lens groups.
2. Description of Relevant Art
Conventionally, a compact camera provided with a lens shutter type zoom lens has been used extensively. Many of the commercialized cameras are made thinner and more compact by retracting the zoom lens barrel in a collapsed position beyond a focal length variable region of the zoom lens when a photograph is not taken, so that the top end portion of the lens will not protrude from the camera main body. Most of these types of cameras adopt a focus adjusting method, in which focus adjustment is effected by adjusting a relative positional relation of the lens groups that constitute the zoom lens at their respective zooming positions (focal distance positions). For example, in case of a so-called dual-group zoom lens, the focus adjustment is effected by adjusting the position of the rear lens group with respect to the front lens group.
However, with the above focus adjusting method, the relative position of the rear lens group with respect to the front lens group may be displaced from the position where it is supposed to be, and even a slight displacement can give an enormous adverse effect to the resolution of the lens. For this reason, in order to obtain a satisfactory image, it is necessary to maintain the relative positions of the lens groups accurately. Thus, highly accurate-components and assembly are required, which makes it difficult to manufacture inexpensive cameras.
SUMMARY OF THE INVENTION
The present invention is devised to solve the above problems, and therefore, has an object to provide a camera capable of obtaining stable resolution and saving the cost.
In order to fulfill the above object, a first camera of cameras of the present invention is a camera provided with a zoom lens having a plurality of lens groups for forming an image of a subject on a predetermined image forming plane by the zoom lens, characterized by comprising: a first driving source; a second driving source; and a lens driving mechanism for effecting (1) a focusing operation by driving the first driving source while maintaining distances among the plurality of lens groups, and (2) a zooming operation by driving the second driving source while changing the distances among the plurality of lens groups.
With the first camera of the present invention, a picture is taken by effecting the zooming operation by driving the second driving source while changing the distances among the plurality of lens groups, and after a desired magnification is obtained by changing the relative distances among the plurality of lens groups, effecting the focus operation by driving the first driving source while maintaining the distances among the plurality of lens groups. Thus, compared with the prior art, by which the focus adjustment is effected by adjusting the position of the rear lens group with respect to the front lens group, for example, the focusing operation can be effected while maintaining the lens resolution accurately by maintaining the relative positions of these lens groups, thereby making it possible to obtain a picture with stable resolution.
The first camera includes the following embodiment. That is, a camera provided with a zoom lens having a plurality of lens groups for forming an image of a subject on a predetermined image forming plane by the zoom lens, characterized by comprising: a first driving source; a rotatable ring, which is allowed to rotate around an optical axis when driven by the first driving source; a focus cylinder connected to the rotatable ring so as to move linearly in an optical axis direction in association with a rotation of the rotatable ring;
a second driving source;
a rotationally movable cylinder engaged with the focus cylinder in the optical axis direction so as to move in association with a movement of the focus cylinder in the optical axis direction, and provided rotatably around the optical axis with respect to the focus cylinder in a rotating direction so as to rotate when driven by the second driving source; and
a plurality of lens holding frames, each holding their respective lens groups and linked to the rotationally movable cylinder so as to move in the optical axis direction relatively with respect to the rotationally movable cylinder in association with a rotation thereof.
With the camera of the above embodiment, a picture is taken by effecting (1) the zooming operation, wherein each of the plurality of lens groups moves relatively in the optical axis direction in association with a rotation of the rotational movable cylinder by driving the second driving source, and thereby changing the distances among the plurality of lens groups, and (2) the focusing operation while maintaining the distances among the plurality of lens groups in association with a rotation of the rotatable ring that is allowed to rotate around the optical axis when driven by the first driving source. Thus, compared with the prior art, by which the focus adjustment is effected by adjusting the position of the rear lens group with respect to the front lens group, stable resolution can be obtained.
The first camera of the present invention may be arranged in such a manner that the first driving source effects the focusing operation by means of rotational driving, and the focusing operation is effected by driving the first driving source to rotate in a forward direction.
Also, the first camera of the present invention may be arranged in such a manner that the first driving source effects the focusing operation by means of rotational driving, and the focusing operation is effected by driving the first driving source to rotate in an inverse direction.
In this manner, the first camera of the present invention may be arranged so as to effect the focusing operation by means of rotational driving toward the zooming up side or toward the zooming down side.
Further, it is preferable that the focus cylinder retracts the rotationally movable cylinder in a camera main body to a collapsed position where no photograph can be taken.
By arranging the focus cylinder in such a manner so as to retract the rotationally movable cylinder in the camera main body to the collapsed position where no photograph can be taken, the camera can be made thinner and more compact.
Also, in order to fulfill the above object, a second camera of the cameras of the present invention is a camera, characterized by comprising: a zoom lens enclosed therein; and a linking portion for linking a first barrel assembly for varying a focal length by changing a relative positional relation in an optical axis direction among a plurality of lens groups forming the zoom lens to a second barrel assembly for changing a position of the first barrel assembly in the optical axis direction with respect to a shooting focus plane, wherein the second barrel assembly is driven first by using a driving force of a driving source, and thence the driving force from the second barrel assembly is delivered to the first barrel assembly through the linking portion.
The second camera includes the following embodiment. That is, a camera, characterized by comprising: a zoom lens enclosed therein; and a linking portion for linking a first barrel assembly for varying a focal length by changing a relative positional relation in an optical axis direction among a plurality of lens groups forming the zoom lens to a second barrel assembly for changing a position of the first barrel assembly in the optical axis direction with respect to a shooting focus plane, wherein: the second barrel assembly is driven first by using a driving force of a single driving source, and thence the driving force is delivered to the first barrel assembly by driving the second barrel assembly; a driving force non-delivering region where the driving force is not delivered is formed within the linking portion of the first barrel assembly and second barrel assembly; and a focus adjustment is effected while the second ba

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