Contrast enhancing filter for eye glasses and contrast enhancing eye glass

Abstract

An optical filter for eye glasses, in particular suitable for spectacle lenses or ski goggles, has a spectral power transmission curve of optical radiations. The spectral power transmission curve exhibits a local maximum spectral transmission (T.sub.max) of radiations in a first wavelength range (Δλ.sub.max). The first wavelength range (Δλ.sub.max) is between 380 nm and 420 nm. The spectral power transmission curve exhibits spectral transmissions (T) of radiation in a second wavelength range (Δλ.sub.th) which are lower than an upper threshold spectral transmission (T.sub.th,u). The second wavelength range (Δλ.sub.th) is between 420 nm and 500 nm and the upper threshold spectral transmission (T.sub.th,u) is smaller than the maximum spectral transmission (T.sub.max). The maximum spectral transmission (T.sub.max) is larger than 21%.

Claims

1. An optical filter for eye glasses comprising: a filter medium defining a spectral power transmission curve of optical radiations; said spectral power transmission curve exhibiting a local maximum spectral transmission (T.sub.max) of radiation in a first wavelength range (Δλ.sub.max); said first wavelength range (Δλ.sub.max) being between 380 nm and 420 nm; said spectral power transmission curve exhibiting spectral transmissions of radiation lower than an upper threshold spectral transmission (T.sub.th,u) in a second wavelength range (Δλ.sub.th); said second wavelength range (Δλ.sub.th) being between 420 nm and 500 nm; said upper threshold spectral transmission (T.sub.th,u) being less than said maximum spectral transmission (T.sub.max); and, said maximum spectral transmission (T.sub.max) being greater than 21%.

2. The optical filter of claim 1, wherein said maximum spectral transmission (T.sub.max) is larger than 22%.

3. The optical filter of claim 1, wherein said first wavelength range (Δλ.sub.max) is between 390 nm and 420 nm.

4. The optical filter of claim 1, wherein said first wavelength range (Δλ.sub.max) is between 395 nm and 420 nm.

5. The optical filter of claim 1, wherein said first wavelength range (Δλ.sub.max) is between 400 nm and 420 nm.

6. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 45% of said maximum spectral transmission (T.sub.max).

7. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 40% of said maximum spectral transmission (T.sub.max).

8. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 35% of said maximum spectral transmission (T.sub.max).

9. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 30% of said maximum spectral transmission (T.sub.max).

10. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 25% of said maximum spectral transmission (T.sub.max).

11. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 15%.

12. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 12%.

13. The optical filter of claim 1, wherein said upper threshold spectral transmission (T.sub.th,u) is smaller than 10%.

14. The optical filter of claim 1, wherein said: spectral power transmission curve in said second wavelength range (Δλ.sub.th) exhibits spectral transmissions of radiations larger than a lower threshold spectral transmission (T.sub.th,l); said lower threshold spectral transmission (T.sub.th,l) is larger than 0.5% of the total power transmission of radiations in a third wavelength range; and, said third wavelength range is between 475 nm and 650 nm.

15. The optical filter of claim 1, wherein: said filter medium further has a polarizing effect of less than 5% in a fourth wavelength range; and, said fourth wavelength range is between 600 nm and 800 nm.

16. The optical filter of claim 1, wherein: said filter medium further has a polarizing effect of less than 2% in a fourth wavelength range; and, said fourth wavelength range is between 600 nm and 800 nm.

17. The optical filter of claim 1, wherein: said filter medium further has a polarizing effect of less than 1% in a fourth wavelength range; and, said fourth wavelength range is between 600 nm and 800 nm.

18. The optical filter of claim 1, wherein: said filter medium further has a polarizing effect of 0% in a fourth wavelength range; and, said fourth wavelength range is between 600 nm and 800 nm.

19. The optical filter of claim 1, wherein the optical filter is configured for spectacle lenses or ski goggles.

20. An optical filter for eye glasses comprising: a filter medium defining a spectral power transmission curve of optical radiations; said spectral power transmission curve exhibiting a local maximum spectral transmission (T.sub.max) of radiation in a first wavelength range (Δλ.sub.max); said first wavelength range (Δλ.sub.max) being between 380 nm and 420 nm; said spectral power transmission curve exhibiting spectral transmissions of radiation lower than an upper threshold spectral transmission (T.sub.th,u) in a second wavelength range (Δλ.sub.th); said second wavelength range (Δλ.sub.th) being between 420 nm and 530 nm; said upper threshold spectral transmission (T.sub.th,u) being less than said maximum spectral transmission (T.sub.max); and, said maximum spectral transmission (T.sub.max) being greater than 21%.

21. The optical filter of claim 20, wherein said second wavelength range (Δλ.sub.th) is between 420 nm and 520 nm.

22. The optical filter of claim 20, wherein said second wavelength range (Δλ.sub.th) is between 420 nm and 510 nm.

23. An eye glass comprising: an optical filter defining a spectral power transmission curve of optical radiations; said spectral power transmission curve exhibiting a local maximum spectral transmission (T.sub.max) of radiation in a first wavelength range (Δλ.sub.max); said first wavelength range (Δλ.sub.max) being between 380 nm and 420 nm; said spectral power transmission curve exhibiting spectral transmissions of radiation lower than an upper threshold spectral transmission (T.sub.th,u) in a second wavelength range (Δλ.sub.th); said second wavelength range (Δλ.sub.th) being between 420 nm and 500 nm; said upper threshold spectral transmission being less than said maximum spectral transmission (T.sub.max); and, said maximum spectral transmission (T.sub.max) being greater than 21%.

24. Optical filter for eye glasses, in particular suitable for spectacle lenses or ski goggles, having a spectral power transmission curve of optical radiations, comprising: said spectral power transmission curve exhibiting a local maximum spectral transmission (T.sub.max) of radiations in a first wavelength range (Δλ.sub.max), whereby said first wavelength range (Δλ.sub.max) being between 380 nm and 420 nm; said spectral power transmission curve exhibiting spectral transmissions of radiations in a second wavelength range (Δλ.sub.th) being lower than an upper threshold spectral transmission (T.sub.th,u), whereby said second wavelength range (Δλ.sub.th) being between 420 nm and 500 nm and whereby said upper threshold spectral transmission (T.sub.th,u) being less than said maximum spectral transmission (Tmax); said maximum spectral transmission (T.sub.max) being greater than 21%; and, said upper threshold spectral transmission (T.sub.th,u) being less than 45% of said maximum spectral transmission (T.sub.max).

25. Optical filter for eye glasses, in particular suitable for spectacle lenses or ski goggles, having a spectral power transmission curve of optical radiations, comprising: said spectral power transmission curve exhibiting a local maximum spectral transmission (T.sub.max) of radiations in a first wavelength range (Δλ.sub.max), whereby said first wavelength range (Δλ.sub.max) being between 380 nm and 420 nm; said spectral power transmission curve exhibiting spectral transmissions of radiations in a second wavelength range (Δλ.sub.th) being lower than an upper threshold spectral transmission (T.sub.th,u), whereby said second wavelength range (Δλ.sub.th) being between 420 nm and 500 nm and whereby said upper threshold spectral transmission (T.sub.th,u) being less than said maximum spectral transmission (T.sub.max); said maximum spectral transmission (T.sub.max) being greater than 21%; and, said upper threshold spectral transmission (T.sub.th, u) being less than 15%.

26. An eye glass comprising: an optical filter defining a spectral power transmission curve of optical radiations; said spectral power transmission curve exhibiting a local maximum spectral transmission (T.sub.max) of radiations in a first wavelength range (Δλ.sub.max), whereby said first wavelength range (Δλ.sub.max) being between 380 nm and 420 nm; said spectral power transmission curve exhibiting spectral transmissions of radiations in a second wavelength range (Δλ.sub.th) being lower than an upper threshold spectral transmission (T.sub.th,u), whereby said second wavelength range (Δλ.sub.th) being between 420 nm and 500 nm and whereby said upper threshold spectral transmission (T.sub.th,u) being less than said maximum spectral transmission (Tmax); said maximum spectral transmission (T.sub.max) being greater than 21%; and, said upper threshold spectral transmission (T.sub.th,u) being less than 45% of said maximum spectral transmission (T.sub.max).

27. An eye glass comprising: an optical filter defining a spectral power transmission curve of optical radiations; said spectral power transmission curve exhibiting a local maximum spectral transmission (T.sub.max) of radiations in a first wavelength range (Δλ.sub.max ), whereby said first wavelength range (Δλ.sub.max) being between 380 nm and 420 nm; said spectral power transmission curve exhibiting spectral transmissions of radiations in a second wavelength range (Δλ.sub.th) being lower than an upper threshold spectral transmission (T.sub.th,u), whereby said second wavelength range (Δλ.sub.th) being between 420 nm and 500 nm and whereby said upper threshold spectral transmission (T.sub.th,u) being less than said maximum spectral transmission (T.sub.max); said maximum spectral transmission (T.sub.max) being greater than 21%; and, said upper threshold spectral transmission (T.sub.th,u) being less than 15%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described with reference to the drawings wherein:

(2) FIG. 1 shows spectral power transmission-curves of three different kinds of filters according to the invention. Curve 1a is a first filter (solid); curve 1b is a second filter (dashed); and, curve 1c is a third filter (dash-dotted);

(3) FIG. 2 shows relative sensitivity curves of the photoreceptors in the eye for S-cones (solid) (curve 2a), M-cones (dashed) (curve 2b) and L-cones (dash-dotted) (curve 2c);

(4) FIG. 3 is a spectral distribution of a blue sky;

(5) FIG. 4 is a spectral distribution of snow exposed to the blue sky;

(6) FIG. 5 is a spectral power transmission curve of a typical blue blocker according to the prior art;

(7) FIG. 6 is a spectral power transmission curve of a typical blue attenuator according to the prior art; and,

(8) FIG. 7 is a spectral distribution of snow exposed to direct sunlight.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(9) FIG. 1 shows spectral power transmission-curves of three different kinds of optical filters according to the invention. The spectral power transmission-curve of the first optical filter is drawn as a solid line. The spectral power transmission-curve of the second optical filter is drawn as a dashed line. The spectral power transmission-curve of the third optical filter is drawn as a dash-dotted line.

(10) The power transmission curve or power transmission characteristic is the mathematical function or graph that describes the power transmission fraction T of an optical filter as a function of wavelength λ.

(11) All three optical filters are suitable for eye glasses, in particular for spectacle lenses or ski goggles. The spectral power transmission curves (1a, 1b, 1c) may be divided or separated into several characteristic wavelength ranges.

(12) There is a first wavelength range Δλ.sub.max between 380 nm and 420 nm in which each of the spectral power transmission curves (1a, 1b, 1c) exhibit a local maximum. The value of this local maximum in the following is called maximum spectral transmission T.sub.max. In order to be able to distinguish between the different maximum spectral transmissions T.sub.max of the different spectral power transmission curves (1a, 1b, 1c) of the three different optical filters, the different T.sub.max as well as the corresponding wavelengths λ.sub.max includes in addition one of the indices a), b) and c), respectively.

(13) The first optical filter has a maximum spectral transmission T.sub.max,a) of 25.5% at a wavelength λ.sub.max,a) of 400 nm. The second optical filter has a maximum spectral transmission T.sub.max,b) of 23% at a wavelength λ.sub.max,b) of 415 nm. The third optical filter has a maximum spectral transmission T.sub.max,c) of 33% at a wavelength λ.sub.max,c) of 400 nm.

(14) There is a second wavelength range Δλ.sub.th between 420 nm and 530 nm for the first and second optical filters (curves 1a and 1b) and in the case of the third optical filter (curve 1c) even between 420 nm and 550 nm in which the spectral transmission T is always below a certain threshold value T.sub.th,u of 10%. The threshold value T.sub.th,u in the following is called upper threshold spectral transmission. Since the maximum spectral transmission T.sub.max is a global maximum within the first wavelength range λΔ.sub.max the upper threshold spectral transmission T.sub.th,u is always lower than the value for the respective maximum spectral transmission T.sub.max.

(15) Characteristic of the invention is that the maximum spectral transmission T.sub.max is always larger than 21%. The upper threshold spectral transmission T.sub.th,u preferably is lower than 25% of the maximum spectral transmission T.sub.max. Furthermore, it is preferred that the spectral range Δλ.sub.th within which the transmission T remains below the threshold value T.sub.th,u covers the complete region where both the S-cones and the M-cones are sensitive, that is, up to a wavelength λ of approximately 550 nm. The third filter having the spectral power transmission-curve 1c already fulfills this rigorous criterion.

(16) There are a lot of possibilities to configure such optical filters according to the invention. For example, U.S. Pat. No. 5,574,517 discloses the possibility to form filters allowing to discriminate between colors. The following paragraph discloses the principal steps in order to produce an optical filter suitable for ski goggles having the spectral power transmission curve 1a.

(17) The production steps for an example of a ski goggle including an optical filter according to the invention are as follows:

(18) Polycarbonate granules of optical grade (for example, sold by SABIC Innovative Plastics under the brand “LEXAN LS2”) are mixed at room temperature with four different dyes, namely

(19) 1. Yellow (sold by Ciba under the brand “Oracet GHS”)

(20) 2. Red (sold by Bayer under the brand “Macrolex E2G”)

(21) 3. Violet (sold by Bayer under the brand “Macrolex B”)

(22) 4. Blue (sold by BASF under the brand “Paliogen L6480”)

(23) After mixing, an extrusion process with a mono screw has been implemented in order to improve the color uniformity.

(24) Subsequently, a dry process for 4 hours at 120° C. and an injection molding process in a ski goggle mold at 280-300° C. follows.

(25) The ski goggle is then dipped in a hard coating resin followed by a polymerization process with thermal curing at 180° C.

(26) It is possible to apply a mirror coating, for example, with a vacuum process according to U.S. Pat. No. 6,794,066 B2.

(27) It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.