Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2000-10-23
2001-11-13
Sugarman, Scott J. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S044000, C351S165000
Reexamination Certificate
active
06315411
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a composite glass for protecting the eyesight. It has applications in the optical field adapted to the human or animal eyesight.
BACKGROUND OF THE INVENTION
The eyesight protective glasses against the harmful effects of sunbeams are known. In its simplest form, a glass is made of a glass lamella usually bent in two perpendicular directions and of a substantially constant thickness in the case of a non corrective glass. The material used for producing the lamella may be mass tinted or an absorbing and/or reflecting layer can be arranged superficially in order to obtain a filtering effect for the light rays. Various improvements are also known. It is thus possible to arrange a layer of an anti-reflecting material at the surface of the lamella. Similarly, it is also possible to combine a polarizing film to the glass so as to attenuate polarized light rays in a determined direction and more particularly as a result of a reflection from a surface, usually the ground, covered with snow or water. However, as the polarizing film is made in a plastic material and is relatively breakable, it is glued in sandwich between two glass lamellae.
The resulting structures are therefore made of materials having different filtering and appearance spectral features and the global effect on all the light rays is not always optimal. In particular, it seems difficult to obtain a structure that would be both appropriate to filter the day-time sun light beams which have a broad spectrum and the night-time artificial light sources which vary considerably. The light sources that can be encountered at night are, in the eye sensitivity area, generally monochromatic or comprise few emission lines. This is specially the case for electrical gas discharge light sources that are used for public lighting. Moreover, the automotive lighting, beside broader spectrum incandescence sources, also begins to use discharge lamps that seem to be more aggressive visually. In all cases, the artificial light sources that are most frequently encountered at night have a spectrum that is relatively remote from the sun spectrum.
SUMMARY OF THE INVENTION
The aim of the present invention is therefore to provide a protective glass structure that would be optimised for both day-time and night-time use conditions. To this end, the invention provides a composite glass for protecting the eyesight comprising, in use, an upper part at the top and a lower part at the bottom and towards the ground, said composite glass comprising starting from the inside, from the eye side, towards the outside
a first optically polished mineral glass,
a polarizing film having two sides,
a second optically polished mineral glass, the polarizing film being glued with its first side onto the first glass and with its second side onto the second glass.
According to the invention:
the first glass being approximately 1 mm thick is a high-pass filter, the cut-off wavelength of which is approximately 480 nm and having a yellow base,
the polarizing film is oriented so as to attenuate the light rays reflected by the ground and sent back upwards,
the second glass is colorless, and the first glass comprises at the surface, on the eye side, a light absorbing surface deposit making a film.
In various embodiments of the invention, the following means used alone or with all the technically possible combinations thereof are carried out:
the absorbing surface deposit is a high-pass filter,
the absorbing surface deposit is an attenuating all-pass filter,
the absorbing surface deposit is obtained through high vacuum evaporation of at least a dielectric-metal pair,
the dielectric is selected amongst oxides such as silicon or titanium oxides,
the first glass comprises moreover on the eye side at the surface of the absorbing surface deposit, an anti-reflecting material layer,
the anti-reflection material layer is obtained through high vacuum evaporation of a low refractive index product and which does not absorb the light rays for the visible spectrum,
the thickness of the anti-reflection material layer is in accordance with the light wavelengths reaching the eye,
the layer thickness is preferably equal to approximately ¼ of the average wavelength of the light waves of the visible spectrum,
the anti-reflection material is selected amongst silicon, fluorine or magnesium fluoride monoxides or dioxides,
the second glass comprises moreover on its outer surface a specular strip stepping down towards the upper part and towards the lower part, the reflection coefficient of said strip being minimum upwards and downwards and being maximum between both,
the specular strip is obtained through high vacuum deposition of at least one film of a metal,
the film thickness is comprised in the range from 1 to 10 nm,
the metal is selected amongst metals with a strong glass adherence and a high chemical and mechanical resistance and a high hardness,
the metal is selected amongst chromium, silver, gold, silvered chromium, bluish chromium, golden chromium; the bluish chromium corresponds to chromium and to a stepped down anti-reflection silicon monoxyde,
the high vacuum approximately corresponds to a pressure of about 5.10
−9
Bar.
The present invention also relates to a pair of glasses comprising at least a composite glass according to any one of the independent or combined preceding features.
The use of a composite glass according to the preceding features allows to eliminate the harmful sunbeams of the ultraviolet and infrared types in the case of day-time sight and improves the evaluation of contrasts in all lighting conditions, either at day or night-time. Such a glass also improves the visual comfort upon night-time driving. In foggy weather conditions, it enhances relieves and field depth.
The embodiment in which the glass comprises a median stepped down specular strip is particularly advantageous for driving engine vehicles of the automotive vehicle or aircraft type. In fact, the most luminous area of the vision field substantially corresponds to the horizontal and the less luminous areas to the upper and lower areas comprising the dash-board or the navigation instruments. Thus, the glass according to the invention allows to attenuate and/or reflect preferably the light rays originating from the most luminous area.
REFERENCES:
patent: 3617114 (1971-11-01), Rogers
patent: 5757459 (1998-05-01), Bhalakia et al.
patent: 6145984 (2000-11-01), Farwig
patent: 88/08430 (1988-11-01), None
patent: 91/07674 (1991-05-01), None
patent: 98/27452 (1998-06-01), None
Arent Fox Kintner & Plotkin & Kahn, PLLC
Sporoptic Pouilloux
Sugarman Scott J.
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