Patent Application
20080084532
Inasmuch as the two lens units are mirror images of each other, only one will be discussed.
The actuator may be coupled to the rear ring 20 of lens unit 10 through link 13. The link 13 (and its mirror mate on the left lens unit 10′ (not shown)) correspond to the links 35 and 36 in the above referenced patent. The link 13 may be attached to the rear ring directly, or may be attached via a tab 11. As described in detail in U.S. Pat. No. 7,008,054, adjustment of slider 30 (24 in the referenced patent) will cause the links 13 to move, which, in turn causes the rear ring 20 to move in an arcuate manner, as will be discussed below.
Each lens unit includes three physically distinct lenses: a fixed power front lens 14, a fixed power rear lens 15, and a variable power liquid lens 16. The combination of the three lenses results in a lens unit that is optically equivalent to a single lens such as is commonly used in an ordinary pair of single vision spectacles, except that the lenses in the invented spectacles have adjustable optical powers. In the preferred embodiment of the invention, the front lens is a “prescription” lens in the sense that it is preferably made to include all or almost all of the intended user's distance prescription. This is not a required condition, however; the user's prescription can be realized in the front lens, in the rear lens, or distributed among all three lenses of a lens unit, as may be convenient. For example, the front lens could have no optical power, and the intended user's distance prescription could be entirely in the rear and liquid lenses, or possibly entirely in the rear lens. In some other case, the rear lens might have zero optical power, and in such case the intended user's distance prescription would be entirely in the front and liquid lenses.
The preferred magnet material is of the rare earth type, such as samarium cobalt or neodymium iron boron because their magnetic properties permit relatively high holding forces. Other magnetic materials are, of course, also possible. The magnets are attracted to the front ring 19 of the focus module (which ring is preferably fabricated from ferromagnetic material, as for example, 17-4PH steel). The magnetic attraction thereby holds the front lens to the focus module. This arrangement permits the front lenses to be removed for cleaning, for replacement by sun lenses, or for other reasons.
Rear lens 15 is held by rear ring 20, and the combination is coupled to the front ring 19 through an elastomeric bellows 21, which allows the rear ring to move with respect to the front ring. A thin membrane of transparent distensible plastic film 22, such as saran, is attached to the rear of the front ring, between it and the bellows. For purposes of convenience, the front ring may be referred to as a membrane support member or structure. The space between the film and the rear lens is filled with a clear liquid 16, such as Dow-Corning DC-705 silicone fluid [which liquid (and the film) forms the liquid lens referred to above]. The clear liquid 16 is retained between the rear lens 15 and the film 22 by the elastomeric bellows 21.
A leaf hinge 23 couples the front and rear rings together at a point approximately opposite link 13. For explanatory clarity, the leaf hinge 23 is shown scabbed onto the circumference of the rings, but in practice, appearance and style may possibly dictate that the hinge be inset or otherwise partially or wholly hidden.
For purposes of explanation, the rear lens, the filling liquid, and the film are assumed to have approximately the same index of refraction, although this is not an essential requirement. The preferred liquid, Dow-Corning DC-705, one of the preferred lens materials, polycarbonate, and the preferred film, saran, all have indices of refraction about 1.58, and thus satisfy this preference. It is preferred that the front surface of the film 22 have a small positive optical power when the focus module is set for distance viewing, for example, +1 diopter. The reason for this last preference is that the actuating mechanism described in U.S. Pat. No. 7,008,054 is capable of exerting force in only one direction, and if an actuator of that type is used, an external restoring force is required to return the system to its distance position. Positive film curvature (which implies tension in the film) can be used to supply at least a part of the needed restoring force. The bellows 21 and/or leaf hinge 23 can each also provide part of the needed force
If the rearmost (i.e., exterior) surface of the rear lens has a negative curvature amounting to an optical power of −1 diopter, the focus module as a whole, when in the position illustrated in
When the link 13 is retracted toward the position shown in
If, as set out in the example described above, the focus module has a net zero optical power when adjusted to the distance position, the front lens would preferably be made to contain the intended user's actual distance refractive demand, including both its spherical and cylindrical components (and possibly prism). If the focus module were constructed to have a distance optical power other than zero, say, for example, +2 diopters of spherical power, then the front lens would preferably be fabricated with the intended user's prescription, less 2 diopters of sphere.
The term “detachable”, referring to the front lens, is intended to mean that the front lens is removable from the focus module by the wearer without the use of tools. Front lens removal may be desired for a number of reasons, including cleaning, or for replacement with tinted lenses to achieve sun protection. The front lenses of a pair of spectacles may be separate items, as shown, or they may be fastened together by a bridge of their own. They may be attached to the focus module by magnets, as illustrated, or by spring clips or other means. Even bayonet type connections may be used, if desired.
Referring now to
To fill a lens unit, the needle of a hypodermic syringe filled with filling liquid is inserted through the hole 25 in leaf hinge 23, and also through the rubber at that section. Liquid can then be pumped into the lens unit interior, and air correspondingly removed, until the lens unit is completely full. It is preferred that a pencil point, or otherwise non-coring needle, be used so that when the needle is removed, the hole will seal.
When in use, as described above, membrane 22 moves with respect to the front lens 14 as the focus of the spectacles is adjusted. This motion would cause the air pressure between the liquid lens and the front lens to vary if the space between them were sealed. It will be recognized that an increase in air pressure (as would occur when ring 20 is moved closer to the membrane) might dislodge the front lens from the focus unit, or possibly cause other undesirable effects. Accordingly, it is desirable that a purposeful air leak exist between the front lens and the focus module. In the presently preferred embodiment of the invention, this leak is achieved by having the magnets 18 protrude slightly above the top of the groove 24 and epoxy filling 26. Hence, when the front lens is in place, there will be a small gap between the front lens and the front ring 19 that allows air to pass.
One important class of users of the present invention is expected to be airline pilots. While extremely unlikely, portions of the outer skin of airliners have been known to detach in flight at high altitude. If such were to happen, pressurization in the cabin could fail suddenly, and the pressure around a pilot could suddenly drop. If a front lens were to detach under such conditions, obvious problems could result. For airline pilots, therefore, the gap between the front lens and the front ring mentioned in the previous paragraph should be adequately sized to permit sufficient airflow to assure that the air pressure on the rear of the front lens will drop rapidly enough under sudden cabin decompression conditions to assure that the front lenses are not dislodged.
| Number | Date | Country | |
|---|---|---|---|
| 60850742 | Oct 2006 | US |
