Optical: systems and elements – Protection from moisture or foreign particle – Sealing
Reexamination Certificate
2001-11-28
2004-05-11
Robinson, Mark A. (Department: 2872)
Optical: systems and elements
Protection from moisture or foreign particle
Sealing
C359S601000
Reexamination Certificate
active
06733143
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a light shielding structure for shielding light, for example, to a light shielding structure for use in light shielding among a plurality of lens barrels of a camera provided with a zooming function.
BACKGROUND ART
Conventionally, with a light shielding seal forming a light shielding structure such as a zoom lens section or the like of a camera of this type, a strong force is not applied to the seal itself and sliding is performed at a relatively low speed and less frequently compared with an oil seal or the like.
As a structure conventionally known, there are, for example, (1) a light shielding seal of oleo-silicone rubber, (2) a light shielding seal of silicone rubber coated with PTFE, (3) a light shielding seal of oleo-silicone rubber baked on a metal fitting and (4) a light shielding seal of silicone rubber coated with PTFE which is baked on a metal fitting.
FIG. 11
shows the light shielding seal of (4). In
FIG. 11
, a light shielding seal
100
is configured by adhering a seal lip section
101
consisting of a ring of silicone rubber coated with PTFE and a reinforcing section
102
consisting of a metal ring as a metal fitting.
An end of a seal bore of the seal lip section
101
is provided on a diameter that is slightly smaller than an outer diameter of a lens barrel
200
.
Then, in use, the lens barrel
200
is inserted into the seal bore and the seal lip section
101
is deformed in an L shape and closely adhere to the lens barrel
200
by its tensile force, whereby light and dusts are prevented from entering the seal bore when the lens barrel moves back and forth in zooming in and out and light shielding property and sealing property are given.
In this way, the conventional light shielding seal realizes decrease of a sliding resistance by impregnating the seal lip section with oil or coating it with PTFE.
However, in the case of the above-mentioned conventional art, the following problems occur.
In recent years, a compact camera has been miniaturized and realizes multi-functionality. On the other hand, an amount of an electric power from a power source of the compact camera is limited, thus reduction of an electric power is intended for each unit.
Under such circumstances, with the conventional light shielding seal, however much effort is consumed to reduce a sliding resistance by impregnating the light shielding seal with oil or coating it with PTFE, its reducing effect is limited due to sliding by the lens barrel and the light shielding seal that are solids contacting with each other. For example, even with the above-mentioned light shielding seal of (4) having a relatively low sliding resistance, a sliding resistance per piece is large at 20 to 100 gf.
Since the sliding resistance of the light shielding seals is large as described above, a relatively large amount of an electric power is consumed during zooming.
On the other hand, when a lens barrel expands and contracts, since a space for installing a light shielding seal varies according to an eccentric quantity of the lens barrel, if an eccentric quantity is large, a light shielding seal is crushed where the space for installing a light shielding seal is small and a gap arises where the space is large and thus leakage of light occurs even if the entire light shielding seal is made of rubber.
Thus, with a conventional light shielding device, it is required to provide a space S that is equal to or larger than an eccentric quantity on an outer diameter side of a light shielding seal as shown in
FIG. 11
even if the light shielding device is intended to be miniaturized. The light shielding device is configured such that, if a lens barrel is eccentric, this space S absorbs an eccentric quantity to prevent a function of the light shielding seal from being deteriorated as shown in FIG.
12
.
In addition, in some cases, a lens barrel has a flash (parting line) on a parting surface, from which light leaks.
The present invention has been devised in order to solve the above-mentioned problems of the conventional art, and a technical subject of a first aspect of the present invention to provide a light shielding structure that is capable of reducing a sliding resistance and at the same time improving light shielding property and further realizing saving of a space.
It is another technical subject of a second to fourth and fourteenth aspects of the present inventions to provide a light shielding structure that is capable of securing a larger power for holding magnetic fluid and shielding light more surely.
It is another technical subject of a fifth aspect of the present invention to provide a light shielding structure that is capable of securing a larger power for holding magnetic fluid and effectively absorbing an error even if an error of assembling or the like occurs among a plurality of members.
It is another technical subject of a sixth aspect of the present invention to provide a light shielding structure that is capable of further improving a light shielding effect.
It is another technical subject of seventh and eighth aspects of the present invention to provide a light shielding structure that is capable of securing a larger power for holding magnetic fluid and shielding light more surely.
It is another technical subject of a ninth aspect of the present invention to provide a light shielding structure that is capable of performing light shielding surely among lens barrels in a camera having a plurality of lens barrels.
It is another technical subject of a tenth aspect of the present invention to provide a light shielding structure of a lens barrel of a camera in which a lens barrel is easily.
It is another technical subject of an eleventh aspect of the present invention to provide a light shielding structure that is capable of effectively absorbing the error even if an error occurs in an axial centers of lens barrels of a camera.
It is another technical subject of a twelfth aspect of the present invention to provide a light shielding structure that is capable of effectively preventing dusts from entering the inside of a lens barrel from the outside.
It is another technical subject of a thirteenth aspect of the present invention to provide a light shielding structure that is capable of holding magnetic fluid surely in a position of magnetic force generating means without allowing the magnetic fluid contacting a lens barrel to flow away even if the lens barrel of a camera moves forward or backward.
It is another technical subject of a fourteenth aspect of the present invention of the present invention to provide a light shielding structure that is capable of preventing wetting of magnetic fluid when it contacts a member and further improving light shielding property.
DISCLOSURE OF THE INVENTION
In order to attain the above-mentioned technical subject, the first aspect of the present invention is a light shielding structure, which is provided among a plurality of members arranged spaced a predetermined distance apart to be movable relatively to each other and is capable of preventing light from entering from gaps which are formed among these plurality of members, comprising magnetic force generating means arranged in any one of the above-mentioned plurality of members and magnetic fluid which is magnetically held by this magnetic force generating means and contacts the other member and shielding the gaps which are formed among the above-mentioned plurality of members with the above-mentioned magnetic fluid.
Here, the magnetic force generating means refers to a so-called magnet, and the magnetic fluid refers to fluid in which ferromagnetic particulates are steadily dispersed by causing a surface-active agent to be adsorbed on the surface of the magnetic particulates. Base oil of hydrocarbon, fluorine, silicone or the like mixed with magnetic particulates having a surface-active agent adsorbed there on is used as the magnetic fluid. With these magnetic particulates of a predetermined density, a required light shielding property can be appropriately realized in relation t
Anzai Hiroshi
Imamoto Yoshimi
Kanno Takao
Namba Takemi
Yamamoto Hirokazu
Jacobson & Holman PLLC
NOK Corporation
Robinson Mark A.
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