Zoom and focus control method and system

Details Zoom and focus control method and system Zoom and focus control method and system

2001-02-23

2004-03-30

Adams, Russell (Department: 2851)

Photography

Having variable focal length of camera objective

Having focus operation

C396S082000, C396S087000, C359S691000, C359S693000, C359S698000

Reexamination Certificate

active

06714731

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to photography, and more particularly to a method for controlling photographic lenses.
BACKGROUND
An internal-focus lens group is often used in a camera to reduce the size and weight of the overall lens. Referring to
FIG. 1
, a standard internal-focus lens
100
is shown. The mechanism or mechanisms for moving the lenses, as well as any control electronics, are not shown for clarity. The internal-focus lens
100
includes a number of other lenses, including a focus lens
102
, which itself can include one or more elements. The focus lens
102
can move between a rear focusing position
120
to focus on an object at infinity and a front focusing position
122
to perform macro focusing. Macro focusing is typically utilized when a photographer wishes to focus on an object located particularly close to the camera itself. In one embodiment, the focus lens
102
focuses an image on an image detector
130
such as a charge-coupled device (CCD), or photographic film. In another embodiment, the image detector
130
is not used, and the focus lens
102
creates an image that can be viewed with the human eye. In such an embodiment, the lens
100
may be used in a binocular or telescope device, or other type of viewing device. The internal-focus lens
100
can include a single zoom lens adapted to move relative to the focus lens
102
, or a zoom lens group
104
having a first zoom lens
106
and a second zoom lens
108
adapted to move relative to one another and the focus lens
102
. Each zoom lens
106
,
108
can include one or more elements. By moving the zoom lenses
106
,
108
relative to one another along the optical axis
110
, the degree of magnification can be controlled. When the zoom lenses
106
,
108
are close together, they are in a telephoto position where a greater degree of magnification is provided. When the zoom lenses
106
,
108
are further apart, they are in a wide-angle position where a lesser degree of magnification is provided. The second zoom lens
108
moves forward to a front zoom position
124
when the zoom lenses
106
,
108
are closest together for the greatest magnification, and moves backward to a rear zoom position
126
when the zoom lenses
106
,
108
are furthest apart for the greatest wide angle view.
In order to save space within a camera, the front focusing position
122
of the focus lens
102
may be located in front of the rear zoom position
126
of the second zoom lens
108
. Thus, the focus lens
102
can collide with the second zoom lens
108
within a potential collision zone
128
between the front focusing position
122
and the rear zoom position
126
. Such a collision can damage the focus lens
102
and/or the second zoom lens
108
. During normal operation of the camera, the focus lens
102
and the second zoom lens
108
typically will not collide, as the macro feature is rarely used in normal operation, and it is usually used when the zoom lens group
104
is in telephoto position. However, even a single collision between the focus lens
102
and the second zoom lens
108
can ruin those lenses, requiring the user to repair them at some expense, or discard the camera altogether.
SUMMARY
A focus lens and a zoom lens group are controlled in an internal focus camera to maintain a minimum safe distance between the focus lens and an adjacent zoom lens.
In one aspect of the invention, the focus lens and a zoom lens group having a first zoom lens and a second zoom lens are controlled separately from one another.
In another aspect of the invention, the positions of the focus lens and the second zoom lens in the zoom lens group are tracked.
In another aspect of the invention, the focus lens and the second zoom lens are controlled to approach no closer to one another than a minimum safe distance. In this way, collision between the focus lens and the second zoom lens is prevented, thereby preventing damage to the lenses.
The invention will be more fully understood upon consideration of the detailed description below, taken together with the accompanying drawings.


REFERENCES:
patent: 5028773 (1991-07-01), Hata
patent: 5146071 (1992-09-01), Ookubo et al.
patent: 5264963 (1993-11-01), Ueyama
patent: 5371631 (1994-12-01), Takada
patent: 11-281869 (1999-10-01), None

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