Light transmission adjustable spectacles

A light transmission adjustable spectacle structure comprises for each lens set thereof a fixed polaroid lens and a rotatable polaroid lens which has a number of non-polarized aperture-like areas formed thereon so that when the rotatable lens is rotated relative to the fixed lens to have the polarization directions thereof normal to each other, light is only allowed to pass through the apertures of the rotatable lens. This significantly cuts down the transmission of light through the lens set. In addition, by suitably selecting the size of the aperture-like areas, the depth of focus of retinal image occurring to a wearer of the spectacles is properly increased to provide a more clear view to the wearer.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates generally to spectacles and in particular to 
spectacles with double polaroid lenses of which one having multiple 
non-polarized aperture-like areas thereon by perforating or de-polarizing 
of portions of the lens. 
(2) Description of the Prior Art 
Eyeglasses with polarized elements are well known in the art. The concept 
of providing variable light transmission characteristics to an ophthalmic 
device by employing light polarizing elements which may be rotated with 
respect to each other is not new. For background information on systems of 
this type reference should be made to U.S. Pat. No. 2,005,246 issued to 
Edwin H. Land on Jun. 18, 1935, U.S. Pat. No. 2,251,330 issued to Murray 
N. Fairbank on Aug. 5, 1941, U.S. Pat. No. 2,565,362 issued to V. K. 
Eloranta on Aug. 21, 1951, U.S. Pat. No. 3,944,346 issued to A. Shindler 
on Mar. 16, 1976, U.S. Pat. No. 4,119,369 issued to V. K. Eloranta on Oct. 
10, 1978, U.S. Pat. No. 4,113,364 issued to M. V. Dussich on Sep. 12, 
1978, U.S. Pat. No. 4,386,832 issued to G. Nannini on Jun. 7, 1983. Each 
of the forgoing generally related to devices for providing variable light 
transmission by employing light polarizers. In those patents the light 
transmission will be cut down almost completely if the direction of the 
polarizers are held perpendicular to each other. This will be dangerous 
when the application is used as a sunglass of an automobile driver. 
Referring to U.S. Pat. No. 3,867,020 issued to H. N. Braunhut on Feb. 18, 
1975 which teaches a polarizer set with exactly centrally located aperture 
and concentrically arranged opaque elements, which prevent light 
transmission having an angle of incidence greater than a predominant angle 
of acceptance. It is particularly used to control viewing angle. While 
fishing, it can eliminate the glare of water surface. But the light 
transmission is not homogeneously through the lens set, and because the 
aperture is single and exactly centrally located, the offset of visual 
axis due to pupil distance variation will significantly influence the 
actual application. 
The present invention possesses many advantages over above mentioned 
designs in that it provides uniformly distributed multiple light 
transmission apertures and is relatively easily approached by visual axis. 
Centering of the application to visual axis is not so necessary. It 
eliminates the risk of totally shut down the light by providing residual 
light transmission through the multiple apertures. 
In the art of photography, picture will be clearer when it is taken by a 
small aperture than a larger aperture. This is because the smaller 
aperture will increase the depth of focus. This is also true in our 
invention, by properly selected aperture size. When the light transmission 
is cut down maximally, the light transmission is only through the 
apertures, and it acts like reduced camera aperture to provide an 
increased depth of focus to the retinal image of the viewer. Hence it will 
increase the visual acuity of the viewer. 
SUMMARY OF THE INVENTION 
The principal objective of the present invention is to provide a light 
transmission adjustable spectacle structure which comprises, for each lens 
set, two polaroid lenses of which one is rotatable relative to the other 
and has a number of non-polarized aperture-like areas thereon so that when 
the two polaroid lenses are oriented to block light transmission 
therethrough, a minor portion of the light is still allowed to pass the 
multiple aperture-like areas thereof. 
It is also an objective of the present invention to provide a spectacle 
structure which comprises, for each lens set, two polaroid lenses, of 
which one has a number of non-polarized aperture-like areas formed thereof 
so that when the two polaroid lenses are oriented to only allow light to 
pass through the aperture-like areas, these apertures serve to increase 
the depth of focus of retinal image for the wearer. 
To achieve the above objectives, there is provided a light transmission 
adjustable spectacle structure which comprises for each lens set thereof a 
fixed polaroid lens and a rotatable polaroid lens which has a number of 
non-polarized aperture-like areas formed thereon so that when the 
rotatable lens is rotated relative to the fixed lens to have the 
polarization directions thereof normal to each other, light is only 
allowed to pass through the aperture-like areas of the rotatable lens. 
This significantly cuts down the transmission of light through the lens 
set. In addition, by suitably selecting the size of the aperture-like 
areas, the depth of focus of retinal image occurring to a wearer of the 
spectacles is properly increased to provide a more clear view to the 
wearer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the drawings and in particular to FIG. 1, wherein a pair 
of spectacles constructed in accordance with a first embodiment of the 
present invention, generally designated with the reference numeral 20, is 
shown, the spectacles 20 comprise a frame 21 on which two lens sets 80 are 
mounted, each comprising a first polaroid lenses 22 securely fixed on the 
frame 21 and a second polaroid lens 23 rotatably mounted to the fixed lens 
22 to be rotatable relative to the fixed lens 22. On each of the rotatable 
lenses 23, a number of non-polarized aperture-like areas 24 are formed. 
The non-polarized aperture-like areas 24 may be formed by simply drilling 
the lens 23 to form through holes or by de-polarizing the lens 23 to form 
plain, light-transmitting aperture-like areas which are not through holes 
and not polarized. 
As is generally known, each polaroid lens has a specific polarization 
direction which only allows light waves vibrating in that direction to 
pass therethrough. It is also known that by placing two polaroid lenses 
having polarization directions normal to each other together, light can be 
blocked from passing through the lenses. Therefore, by rotating the 
rotatable lenses 23 with respect to the fixed lenses 22, the light 
transmission through the lenses is gradually reduced if the polarization 
directions thereof are changed from being parallel to being normal to each 
other. This is shown in FIGS. 5-7. 
Preferably, as shown in FIGS. 5-7, marks A and A' are respectively provided 
on the rotatable lens 23 and the fixed lens 22 to indicate the relative 
orientation therebetween. 
As can be observed in FIG. 5, wherein the polarization directions of the 
lenses 22 and 23 are generally parallel with each other, under such a 
situation, the light transmitting through the fixed lens 22 will not be 
further attenuated by the rotatable lens 23 and vice versa. Consequently, 
the light transmitting through the two lenses 22 and 23 will behavior as 
passing only one polaroid lens. The situation is almost exactly the same 
for the light transmitting through either the polarized portion or the 
non-polarized aperture-like areas 24 of the rotatable lens 23. The 
intensity of the light transmits through the aperture-like areas 24 is 
almost the same as that transmitting the non-apertured portion of the 
second lens 23 so that the aperture-like areas 24 are most invisible. 
When the second lens 23 is rotated relative to the first lens 22 to have 
the polarization directions thereof no longer parallel with each other, 
nor normal to each other, as shown in FIG. 6, the light transmission 
through the non-apertured portion is reduced but that through the 
aperture-like areas 24 is not changed. This makes the apertures 24 more 
clear. 
As the second lens 23 is rotated to have the polarization direction thereof 
normal to that of the fixed lens 22, as shown in FIG. 7, the light is 
completely blocked by the non-apertured portion of the rotatable lens 23 
but is still allowed to pass through the aperture-like areas 24. This 
brings the apertures 24 to a significant condition for light transmission. 
By suitably selecting the size of the apertures 24, for example diameter 
in the case of small circular holes, the depth of focus to a wearer of the 
spectacles 20 can be increased. This, as mentioned previously, makes 
distant views more clear. 
The change of the relative orientation between the fixed lens 22 and the 
rotatable lens 23 can be observed by noticing the orientation of mark A 
relative to mark A' shown in FIGS. 5-7. 
Back to FIG. 1, to affix the second lenses 23 to the first fixed lenses 22, 
each of second lenses 23 is provided at least an arc slot 25, preferably 
two as shown in FIG. 1, to movably receive therein a guide mounted on the 
first lens 22, such as a screw 26 extending through a hole 27 formed on 
the first lens 23 rotatable with respect to the first lens 22. Nut means 
28 may be provided to secure the second lens 23 on the screw 26 in a 
relatively rotatable manner with respect to the first lens 22. 
In FIG. 2, a pair of spectacles constructed in accordance with a second 
embodiment of the present invention, generally designated with the 
reference numeral 40, is shown. In this drawing, parts similar to those of 
the embodiment of FIG. 1 are designated with similar reference numerals. 
In the second embodiment, each of the second lenses 23 is movably received 
within guiding channels 50 mounted to the respective first lens 22. 
The structure of the guiding channels 50 is shown in detail in FIG. 3. As 
can be observed from FIG. 3, the second lens 23 is loosely received within 
the channels 50 at the peripheral edge thereof to enable the relative 
rotation therebetween. 
In FIG. 4, a pair of spectacles constructed in accordance with a third 
embodiment of the present invention, generally designated with the 
reference numeral 60, is shown. In this drawing, parts similar to those of 
the embodiments of FIGS. 1 and 2 are designated with similar reference 
numerals. In the third embodiment, each of the second lenses 23 is secured 
on a sheet member 70, preferably transparent, which is, for example, 
hinged to the frame 21 along a top edge 71 thereof to be rotatable 
relative to the first lens 22 to bring the second lens 23 to the proximity 
of the first lens 22. The second lens 23 may be also rotatably mounted to 
the transparent sheet 70. 
As shown in FIGS. 2 and 4, preferably a handhold tab 51 is formed on each 
of the second lens 23 for manually rotating the second lens 23 relative to 
the respective first lens 22. 
As shown in FIGS. 8 and 9, the apertures of the second lens 23 can be of 
the same shape of similar area uniformly distributed. 
As shown in FIG. 10, the apertures of the second lens 23 can be of the 
different shapes arranged in a mixed fashion. 
It is apparent that although the invention has been described in connection 
with the preferred embodiments, it is contemplated that those skilled in 
the art may make changes to certain features of the preferred embodiments 
without altering the basic concept of the invention as defined in the 
appended claims.