EP2457121A1

EP2457121A1 - Vision mask

Info

Publication number: EP2457121A1
Application number: EP10734490A
Authority: EP
Inventors: Didier Clerc; Didier Jacquemin
Original assignee: BNL Eurolens SAS; Logo SAS
Current assignee: BNL Eurolens SAS; Logo SAS
Priority date: 2009-07-21
Filing date: 2010-07-19
Publication date: 2012-05-30
Also published as: US20120120366A1; CN102483524A; WO2011009842A1; FR2948467A1; BR112012001336A2; FR2948467B1

Abstract

The invention relates to a vision screen with a continuous, cylindrical, toroidal or spherical convex surface (2), having a trace in a binocular plane of vision forming an outer arc of circle with a predetermined radius (R), the vision screen having a concave surface with a trace in said same plane of vision forming at least one region around a point where each line of vision (AD, AG) crosses the concave surface of an inner arc of circle (3, 4) with a specific curvature radius (R1), and a centre (C1, C2) other than that of the arc of circle crossed by the other line of vision, characterised in that the specific radius (R1) of each inner arc of circle is other than the radius (R) of the outer arc of circle.

Description

Mask of vision

The present invention relates to a vision mask for the practice of certain activities such as driving at night or certain sports practices in which a visual acuity is essential.

BACKGROUND OF THE INVENTION

The practice of certain activities requires putting a screen on the line of vision for many reasons that are linked to the accomplishment of the activity in the best possible visual conditions.

To illustrate the point, we will take the example of night driving while noting that this activity is not the only one for which the invention finds an application.

We know that at the end of the day, and even more so at night, the change in light transmission induces, in the vast majority of a- or emmetropic subjects, a scotopic myopia called nocturnal myopia.

On the other hand, many studies have shown that yellow filters, selectively cutting short wavelengths (ie blue light), improve the contrast sensitivity and are sometimes recommended for night driving (see document FR 2 684,771).

It has therefore been proposed, for example according to the document FR 2,635,199, corrective glasses of 0.25 diopter negative power stained yellow (wavelength 550 nm), the glasses being subjected or not to certain additional treatments (anti-glare, anti -rights, ...) that can improve the quality / quantity of the transmitted light. In order to satisfy the greatest number of individuals, several models can be provided, differing in the centering of the lenses (interpupillary distance with the possibility of final adjustment by an optician) or in the shape of each lens.

For some activities, a screen is provided that consists of a single optical part that covers both eyes without a solution of continuity, in which no correction takes place. These screens generally have a greater central thickness than that at the lateral ends, so as to offer a correction to the prismatic deflection caused by any curved blade for an axis of vision that is not normal to the faces of the blade. This extra thickness is obtained by manufacturing by shifting, on the geometric axis of the blade, the center of the concave surface with respect to the center of the convex surface of the blade and giving to this concave surface a greater curvature than that of the convex surface.

US-5,614,964 discloses a vision screen according to the preamble of claim 1.

There is a need for a screen that can be a device for improving the vision in certain light conditions or for certain activities, that is to say, to make a correction to the vision (positive or negative) .

OBJECT OF THE INVENTION

Thus, the invention relates to a vision screen having a continuous convex surface, cylindrical, toric or spherical, and having a trace in a binocular vision plane which extends along an outer circular arc of radius R determined, the viewing screen having a concave surface having a trace in the same viewing plane extending, at least in a region around a point of intersection of each axis of vision with the concave surface, according to an arc of inner circle of own radius Rl, and center different from that of the circular arc crossed by the other axis of vision. According to the invention, the inner radius of each inner circular arc is different from that of the outer circular arc. The inner radius of each inner circular arc may be less than or greater than that of the outer arc of a circle, depending on whether a correction is sought at negative or positive power.

The area useful for each eye of the screen is thus treated in a clean way both from the point of view of the ophthalmic correction that that of the correction of the prismatic deflection. By determining the radius of this concave surface portion of the screen traversed by the optical axis of each eye and its center, it is possible on the one hand, to give an optical power to this area, a power that can be common ( for example 0.25 negative dioptres as mentioned above) or customized, taking into account the singularity of each eye (myopic, hyperopic, astigmatic, ...) and secondly, to correct the prismatic deviation ( which necessarily exists because of the outer curvature of the screen, defined in terms of base) to bring it back to acceptable values according to the standards in force, along the axis of vision of each eye.

The screen can be made of any material suitable for corrective optics or not. Advantageously, the screen consists of an injectable thermoplastic material such as, for example and without limitation, polymethyl (meth) acrylate, polycarbonate, polycarbonate / polyester blends, polyamide, polyester, cyclic olefin copolymer, polyurethane, polysulfone and their mixture. It also lends itself to any coloration and functionalized coating. In the case of a screen for night vision, the preferred coloring will be yellow as mentioned above. This coloration can be brought according to the traditional techniques, either by direct incorporation of the dyes or pigments within the thermoplastic material during the injection step, or by post-injection methods of the soaking type (dip-coating in English). , or centrifugation. The functionalized coatings may be deposited in the form of a monolayer or multilayer film or varnish, by any deposition means such as, for example, dipping, centrifugation, spray, evaporation under vacuum or jet of material through the nozzles of an inkjet printing head. They are advantageously chosen from coatings having a function of anti-shock, anti-abrasion, antireflection, antifouling, anti-fogging, antistatic, polarizing, coloring and photochromic type.

In a preferred embodiment, the inner circular arcs have the same inherent radius. Alternatively, inner circle arcs have different rays.

Preferably, the screen has two zones of minimum thickness spaced from each other, in the viewing plane, a value equal to the pupillary spacing.

Each of the concave surfaces is cylindrical, spherical or toric depending on the aesthetics and optical effect sought. Cylindrical surfaces will not have the same correction characteristics as spherical or toric surfaces, as is well known around a point of intersection of each axis of vision with the concave surface.

For reasons of appearance, of adaptation to a frame, of aesthetics of the screen, the concave surface may comprise regions peripheral to the region around a point of intersection, these peripheral regions having surfaces defined by center and curvature different from the surface of the region they surround. One can thus decide to thin the edges of the screen or its central part by the play of these surfaces for which the optical requirements are no longer preponderant.

Other features and advantages of the invention will emerge from the description given below of an exemplary embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Reference will be made to the accompanying drawings in which: FIG. 1 is a sectional view of a screen according to the invention in a horizontal section plane containing the two axes of vision,

FIG. 2 is a sectional view of this screen along a vertical plane containing an axis of vision,

FIG. 3 illustrates, by a view like that of FIG. 1, a screen according to the invention in which the ophthalmic correction is stronger than that of FIG. 1 (0.50 instead of 0.25 negative diopters);

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figures 1 and 2, the screen shown is a blade 1 made of any suitable material to constitute a "glass" correction (polycarbonate in particular).

This blade has a convex surface 2 and a concave surface 3. In the case of the figures, the convex surface is a continuous spherical surface 2 of center C and radius R. The concave surface is more complex. Still in the case of Figures 1 and 2, there are two spherical surfaces 3 and 4 defined as follows:

- the center C1, C2 of each of them is located, in the case of this figure on the line which joins the center C of the convex surface at the point of intersection of the axis of vision AG and AD of each eye of the wearer with the concave surface. It is known that, on average, the axis of vision is separated from the vertical plane of symmetry of this wearer by about 32 millimeters (distance D or pupillary distance equal to 2D). Thus, the smallest thickness e of each part of the screen concerned by an eye, is on the axis of vision AD, AG of this eye.

the radius of curvature R1 of each of them is such that the optical (negative) power of the lens is of the order of -0.25 diopters.

the thickness at the center E of the screen corresponds to the distance which separates the intersection of the spheres 3 and 4 of the the sphere 2 in the plane of vision defined by AG and AD.

In a specific case of FIGS. 1 and 2, for a polycarbonate screen, the value R will be 87.17 mm (which corresponds to a base 6 in the eyewear field, that is to say that the radius in the plane of vision of the glass is in meters the result of the ratio base / (index of refraction minus one), the value R1 is 82.96 mm. The distance d separating each center C1 and C2 from the vertical center plane of the mask is 1.24 mm, the axes AD and AG being distant from D = 32 mm from this plane and the value E of the thickness of the screen is 2.50 mm. The minimum thickness e is here both on the center line C C1 or C2 and on the optical axis AG, AG and is equal to 2.15 mm.

The surfaces in question are all spherical and the ophthalmological correction is 0.25 negative diopter while the correction of the total divergent prismatic deflection (that of the two optics) is 0.7 mm at one meter.

In the case of these figures, the two concave surfaces of radius R1 and center C1 and C2 cover the entire rear (concave) face of the screen. As will be seen with reference to FIG. 3, these surfaces of radius R1 and of center C1, C2 may be limited to areas close to the axis of vision of each eye, the remainder of the rear face of the screen having different surface portions to meet other requirements of the screen, for example of aesthetic order.

The screen may have a cylindrical convex surface and concave surfaces such as 3 and 4, either spherical or cylindrical. In the latter case, the correction of the prismatic deflection will only be in a horizontal direction while the spherical surfaces also provide a correction of the prismatic deflection in the vertical plane.

One can also marry a convex ring surface with concave surfaces also toric or spherical lenses to obtain the most appropriate ophthalmic and deflection corrections for the wearer.

It is within the scope of the invention to provide a concave surface 3, for example spherical, of radius and center, such that the power of the screen facing the left eye is different from that facing the right eye. .

While the above description relates to a negative power correction, the invention also relates to positive corrections (R1 would then be greater than R), or even more specific corrections such as

Astigmatism.

FIG. 3 illustrates a screen according to the invention in which the power of the ophthalmological correction is 0.50 diopters in negative. It can be seen that the various parameters identified in this figure with the same references as in FIG. 1 are substantially different from one case to another for constant R corresponding to a base screen 6 in the same material. These values are as follows (in millimeters):

R = 87, 17

Rl = 79.78

E = 3

el = 2.37 which is not the minimum value of the thickness of the screen which is on the line of the centers L

d = 2.43.

In this FIG. 3 is indicated by mixed lines 5 and 6 concave surface traces which are not identical to the surface 4 to illustrate the fact that the surface 4 can be limited to a region surrounding the axis of vision AD or AG and be surrounded by portions of peripheral surfaces that allow for example to refine the edge and the center of the screen.

Claims

1. Vision screen having a convex surface (2) continuous, cylindrical, toric or spherical, and having a trace in a binocular vision plane forming an outer circular arc radius (R) determined, the viewing screen having a concave surface, having a trace in this same plane of vision forming, at least in a region around a point of intersection of each axis of vision (AD, AG) with the concave surface an inner arc (3, 4) with a proper radius of curvature (Rl), and center

(Cl, C2) different from that of the arc of a circle crossed by the other axis of vision, characterized in that the own radius (Rl) of each inner arc is different from the radius (R) of the arc outside circle.

2. Screen according to claim 1, characterized in that the inner circular arcs have the same radius (Rl) of clean curvature.

3. Screen according to claim 1, characterized in that the inner circular arcs have different radii of curvature.

4. Screen according to one of the preceding claims, characterized in that the radius (Rl) proper to each inner arc is less than that (R) of the outer arc.

5. Screen according to one of the preceding claims, characterized in that the radius (Rl) of each inner arc is greater than that (R) of the outer arc.

6. Screen according to one of the preceding claims, characterized in that the concave surface is, at least in the region around each cross point, cylindrical, spherical or toric.

7. Screen according to one of the preceding claims, characterized in that the concave surface (4) comprises peripheral regions (5, 6) to the region around a point of intersection of an axis of vision with the concave surface, the peripheral regions having surfaces defined by centers and curvature different from the surface of the central region that they surround.