Optical: systems and elements – Lens – With support
Reexamination Certificate
2001-07-17
2003-07-08
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With support
C359S820000, C359S822000
Reexamination Certificate
active
06590720
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-216406, filed Jul. 17, 2000; and No. 2001-210984, filed Jul. 11, 2001, the entire contents of both of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an optical lens unit, more particularly to a mechanism for adjusting the focal point of the optical lens incorporated in an optical lens unit.
Recent years have seen a remarkable advance in portable photographing devices and portable communication devices. The amount of data that a portable communication device can transmit is ever increasing. Along with this increase in transmittable data amount, there undergoes development of portable communication device, such as mobile telephones, each equipped with an image sensor. A mobile telephone with an image sensor functions not only as an audio communication device, but also as an image communication device. One of the components indispensable to photographing devices is an optical lens unit, which is assembled directly to the image sensor. In a camera system in which an image is focused through a lens, it is essential that lens position is adjusted such that lens focus point comes to the focal plane of the image sensor.
A conventional optical lens unit will be described with reference to
FIG. 1
, which is a sectional view of the optical lens unit.
As
FIG. 1
shows, the optical lens unit
10
comprises a lens holder
11
, an optical lens
12
, a lens barrel
13
, and a fastening ring
14
. The small range focal point adjusting mechanism can be applied to adjust the small variation of focal distance in an optical lens or to adjust the flange back variation in the manufacturing process of a lens unit to the image sensor.
The lens holder
11
is a hollow cylinder. The lens holder
11
has a female screw
15
in the inner circumferential surface.
The lens barrel
13
is a hollow cylindrical component. The lens barrel
13
has a male screw
16
on the outer circumferential surface. The lens barrel
13
is held in part in the lens holder
11
, with the male screw
16
in mesh with the female screw
15
of the lens holder
11
. When rotated, the lens barrel
13
moves along the optical axis
1
of the optical lens unit
10
.
The optical lens
12
has a collar. The collar
12
is clamped between the lens barrel
13
and the fastening ring
14
. The optical lens
12
is thereby held by and secured to the lens holder
11
.
A light source
2
applies-a light beam to the optical lens
12
. The optical lens
12
focuses the light beam, forming an image in an image-forming plane. The lens barrel
13
may be rotated, thereby moving the optical lens
12
in the lens holder
11
, along the optical axis of the optical lens unit
10
. As the lens
12
is so moved, its focal point is moved or adjusted.
In the optical lens unit
10
of
FIG. 1
, the female screw
16
of the lens holder
13
and the female screw
16
of the lens barrel
13
constitute a mechanism for adjusting the focal point of the optical lens
12
. The focal point adjusting mechanism enables each optical lens units to be adjusted after assembly. This is indispensable to achieve high precision focusing, using low cost production process of a camera module incorporating a lens unit. This eliminates the need to make accurate lens assembly. Also, optical lens may have a variation on the focal distance that differs from the design value, for the following reason.
Generally, low cost plastic optical lenses are mass-produced by means of molding. In the molding, molten resin is poured into molds and cooled therein, forming lenses, and the lenses thus formed are removed from the molds. The resin is gradually cooled down in the molds, thereby improving the characteristics of the resultant lenses. There is the trend that the resin cool down process is done in a short time in order to enhance the productivity of optical lenses. Consequently, the lenses have characteristics, including the focal distance, which may vary from the design values. To adjust the focal distance of each individual lens to a desired value, it is necessary to use the focal point adjusting mechanism described above. There are also variations of dimension in the lens collar
12
, the lens holder
13
, not to mention assembly positioning variation of image sensor and base substrate as well.
As described above, the female screw
15
of the lens holder
13
and the female screw
16
of the lens barrel
13
constitute the focal point adjusting mechanism in the optical lens unit
10
. When the barrel
13
is rotated, the lens
12
, barrel
13
and ring
14
move together. Both the holder
11
and the barrel
13
have a relatively large diameter. It is inevitably difficult to render the optical lens unit
10
smaller. Further, it is difficult to assemble the lens unit
10
to the image sensor with high precision, which constitutes the focal point adjusting mechanism. Additionally, dust may be generated as the screws
15
and
16
slide one upon the other in frictional contact. Dust, if generated, floats in the lens holder
11
through which the light beam travels from the lens
12
toward the focal point. The dust may therefore adversely influences the image formed in the image-forming plane.
BRIEF SUMMARY OF THE INVENTION
An optical lens unit according to an aspect of the present invention comprises: an optical lens for focusing a light beam; a hollow cylindrical lens holder having, on an inner circumferential surface, a support section located on one side of the optical lens and supporting a circumferential part thereof; an elastic member interposed between the support section and the optical lens; and a lens fastener movable along an optical axis of the optical lens, clamping the optical lens jointly with the lens holder, contacting, at one end, the other side of the optical lens, and pushing the circumferential part thereof, thereby to deform the elastic member to adjust the position of a focal point of the optical lens.
REFERENCES:
patent: 3696725 (1972-10-01), Lange
patent: 3970370 (1976-07-01), Kawai
patent: 4072396 (1978-02-01), Ross
patent: 4194811 (1980-03-01), Barry
patent: 4431267 (1984-02-01), Finck et al.
patent: 4457619 (1984-07-01), Takahashi et al.
patent: 4496217 (1985-01-01), Aoyagi
patent: 4679905 (1987-07-01), Westover
patent: 4720167 (1988-01-01), Okura
patent: 5052782 (1991-10-01), Myer
patent: 5177641 (1993-01-01), Kobayashi et al.
patent: 5262900 (1993-11-01), Gerber
patent: 5548450 (1996-08-01), Kang
patent: 5557474 (1996-09-01), McCrary
patent: 6144505 (2000-11-01), Nakanishi et al.
patent: 0 366 984 (1990-05-01), None
Paatent Abstracts of Japan, JP 59 040608, Mar. 6, 1984.
Kabushiki Kaisha Toshiba
Thompson Timothy J
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