JP2002524771A - Protective filter lens - Google Patents

Abstract

The present invention relates to an eye protection filter lens and a method for manufacturing such a lens. The lens has a ratio of Z and Y tristimulus values between 0.25-0.40, a dominant wavelength between 570-580 nm in the color mixing graph, a sharp drop in transmission between 450-500 nm and 30 between 400-450 nm. % Transmittance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] This application relates to US Provisional Patent Application Ser. No. 60 / 099,534, filed Sep. 9, 1998, entitled Protective Filter Lens by TGHavens, DJKerko and BMWedding, and Protective Filter by TGHavens, DJKerko and BMWedding. Claims of a supplemental US Provisional Patent Application No. 60 / 107,380, filed November 6, 1998, entitled Lens.

[0002] Photochromic Filter lens and a manufacturing method thereof having a surface layer which is reduced in order to control the field spectral transmission of the invention.

[0003] BACKGROUND U.S. Patent No. 4,284,686 of the invention (Wedding), a series of filter lens and its manufacturing ophthalmic is described. These lenses are specifically designed to reduce the discomfort experienced by individuals suffering from certain visual defects in bright light.

[0004] All of the commercially important photochromic glasses are glasses containing a precipitated microcrystalline silver halide phase. It is this phase that is believed to be responsible for the reversible darkening of the glass when exposed to light. U.S. Pat. No. 3,208,860 (Armis
tead et al.) explain the basics of this clan glass. Subsequent work has led to the development of many new families of photochromic glasses that exhibit faster darkening and / or bleaching responses. For example, US Patent No. 4,190,451 (Hares et al.) Describes some of the recently developed photochromic glasses of this type.

This patent discloses a glass that is particularly suitable for use in the method of the present invention. Such glasses have about 0-2.5% Li ₂ O, about 0-9% Na ₂ O, about 0-17% K ₂ O, about 0-6 % Cs ₂ O, about 8-20% Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O, about 14-23% B ₂ O ₃ , about 5-25% Al ₂ O ₃
About 0-25% P ₂ O ₅ , about 20-65% SiO ₂ , about 0.004-0.02% CuO, about 0.15-0
Consists essentially of 0.3% Ag, about 0.1-0.25% Cl, and about 0.1-0.2% Br, wherein the molar ratio of alkali metal oxide to B ₂ O ₃ is between about 0.55-0.85. Fluctuates in
The weight ratio of Ag to (Cl + Br) ranges between about 0.65-0.95. These glasses may optionally contain 0-6% ZrO ₂ , 0-3% TiO ₂ , 0-0.5% PbO, 0-7%
% Of BaO, 0-4% of CaO, 0-3% MgO, 0-6% of Nb ₂ O _5, 0-4% of La ₂ O ₃ and 0-2% of the displayed ratios group of F May be included up to about 10% in total. Finally, the compositions are compatible with conventional glass colorants selected from transition metal oxides and rare earth metal oxides. Thus, up to about 1% total transition metal oxide colorant and / or up to 5% total rare earth metal oxide colorant may be included to alter the color of the bulk glass.

[0006] A tinted ophthalmic lens developed according to the teachings of the Wedding patent has provided relief for patients who have problems with sensitivity to light, or glare. Dye-impregnated plastic lenses have been developed as alternatives. The latter is sometimes referred to as a "blocker" because it is stated to absorb all of the light below a certain wavelength.

A major problem with this “blocker” lens is that the total absorption of a portion of the spectrum significantly distorts the perception of color. This may occur in surface-tinted glass lenses due to excessively long processing times. However, the duration of the reduction process may be adjusted to produce a carefully controlled small amount of blue transmission, referred to as "blue leak." This reduces the perceptual distortion of color perception.

[0008] Nevertheless, it would be desirable to further improve the perception of natural colors in protective filter lenses.

[0009] Subsequent developments have made it possible to produce the filter lens disclosed in the Wedding 4,284,686 patent with much shorter bake times. For example, in the visible
A filter lens with a cut-off in the wavelength range of 450-500 nm makes the lens about 476
It can be produced by calcining in flowing hydrogen at 2 ° C. for 2 hours.

However, it is still necessary to “front treat” the lens after firing. This involves removing the reduced glass from the front of the lens. This means
Required to reach actinic radiation to darken the photochromic glass. In addition, if a fused multifocal lens is to be manufactured, it is necessary to remove the reducing layer in order to melt the segments in place.

It is an object of the present invention to obviate the need for a frontside processing step.

It is another object of the present invention to provide a protective filter lens that closely approximates the transmittance of a natural color scene, ie, allows an observer to see the actual undistorted color of a scene. It is in.

It is a further object of the present invention to provide these features to either uncolored lenses or lenses having a fixed color imparted to the glass.

It is also an object to reduce the time factor in processing without compromising the effectiveness of the lens.

[0015] Another object is to be able to process photochromic progressive lenses.

SUMMARY OF THE INVENTION The present invention provides, in part, a ratio of Z / Y tristimulus values between 0.25-0.40, a dominant wavelength between 570-580 nm on a color mixing graph, and a dominant wavelength between 450-500 nm. Sharp drop in transmittance, and 400-
In an eye protection filter lens having a transmittance of less than 30% between 450 nm.

The present invention is further directed to a method of manufacturing an ophthalmic protective filter lens, wherein the Z / Y tristimulus of the lens is less than 20 minutes, but the Z / Y ratio is between 0.25-0.40. The method comprises firing a photochromic glass lens containing silver halide in a hydrogen containing atmosphere at a temperature in the range of 465 ° C. to 495 ° C. for a time long enough to provide a value.

[0018] Based on the simple description the Wedding of U.S. Patent No. 4,284,686 the teachings of the invention, several different protection filter lenses have been developed. One of these lenses, known as CPF 450, is designed to provide a spectral transmission cutoff between 500-450 nm. This lens has proven to be technically effective for that purpose. However, the invention is based on research aimed at improving the natural color perception of this lens, as well as simplifying its manufacture.

As mentioned above, studies have shown that the blue end of the spectrum, ie, about 500 nm
Wavelengths below are shown to be very important in determining the perception of natural colors.
Thus, total blocking of transmission in this region gives significant color sight distortion, as in "blocker" lenses. The transmission at low wavelengths, ie at the blue end of the visible spectrum, is much smaller than at longer wavelengths. Nevertheless, its importance is much greater in determining proximity to the perception of natural colors.

Early work has defined filter lenses for color purity and dominant wavelength for regions in the 1931 CIE color mixture graph. In such a graph, color data is plotted for x and y values on each axis. The values are then calculated by the equidistant wavelength method using a 1931C light source and a CIE standard observer.

The values may be compared to either the C light source, which is a value defined for light from the northern sky, or the A light source, which is a value defined by the spectral distribution from a tungsten lamp. The A light source is generally considered to be white.

According to Applicants' study, the ratio of Z tristimulus values to Y stimulus values, Z / Y, is a very significant factor in defining the spectral transmission at the blue end of the spectrum, ie, in the range of 400-500 nm. It has been shown to be a useful parameter. Therefore, this ratio, rather than spectral purity, was used here to describe the lenses of the present invention.

Currently, CPF 450 filter lenses are manufactured by firing the selected photochromic glass lenses at about 476 ° C. for 2 hours in a hydrogen atmosphere. This selected glass is designated code 8122. The glass has the following composition, calculated as weight percent on an oxide basis:

[Table 1] The inclusions of Er ₂ O ₃ and Pd are included to give a fixed brown lens. These colorants may be omitted if a clear, uncolored glass is desired. The present invention was developed using this glass, but is not limited thereto. For example, other available photochromic glasses may be so treated.

One such glass, Code 8135, has the following composition expressed in weight percent on an oxide basis:

[Table 2] Combinations of CoO and NiO colorants are included to give the lens an achromatic gray. Again, this combination can be used if uncolored glass is desired.
It may be omitted. Other known colorants may be included to provide other fixed colors to the lens.

Protective filter lenses are generally manufactured by firing a suitable photochromic glass lens in a flowing hydrogen atmosphere to provide a reduced film on the entire lens. Other reducing atmospheres may be used, but pure hydrogen has been found to be most effective. After the reduction treatment, the reduction layer on the front surface of the lens is removed and the activating radiation can reach to give photochromic behavior. This is done, for example, by grinding and polishing the front surface of the lens.

It is a feature of the present invention that the need for this operation has been eliminated. Unexpectedly,
Sufficient photochromic activating radiation penetrates through the reduced front surface of the lens of the present invention, eliminating the need for front processing. Thus, the lenses and methods of the present invention eliminate time consuming and expensive grinding and polishing operations. This not only saves significant costs, but also expands the production line to include progressive lenses.

FIG. 1 is a graph in which wavelengths across the visible spectrum are plotted on the horizontal axis in nm, while transmittance in percent is plotted on the vertical axis.

The transmission curves for the two lenses are shown in the figure. Curve A is the current CPF
It is a transmittance curve regarding a 450 lens. Curve B is the transmittance curve for the lens of the present invention identified as Lens 3 in Table I below.

At wavelengths greater than about 460 nm, it is observed that the two curves are substantially identical. However, lens 3, a lens prepared according to the present invention, has significantly higher transmission values in the 400-460 nm wavelength range than current lenses. This large transmission at the blue spectral edge is a key advantage of the present invention.

The transmittance of the lenses of the present invention is generally greater than 10%, but is less than about 30% at any given wavelength in the 400-460 nm range. In contrast, the current CPF 4
Transmission values for 50 lenses are generally less than 10% in this range.

Specific Embodiment Polished planar lenses having a nominal thickness of 2 mm were prepared from both Code 8122 and Code 8135 photochromic glass. The lenses were fired in a flowing atmosphere of hydrogen gas in a tube furnace for various times and temperatures.

Table I below lists the glass and firing cycle time and temperature for each lens tested. Firing time is expressed in minutes and temperature is expressed in ° C.

[0033]

[Table 3] The spectral transmittance at the visible wavelength was measured. Using those data, 1931
Tristimulus values were calculated by the equidistant wavelength method using a CIE standard observer and a C light source. The data is shown in Table II below:

[Table 4] FIG. 2 shows Z / Y for several filter lenses calculated using a C light source.
5 is a plot of ratio versus spectral purity. Also shown is the Z / Y ratio for Illuminant A (IllA) versus the spectral purity seen using the white point of Illuminant C. Z for C light source
The / Y ratio (IllC) is about 1.2, which is far outside the range of FIG. 2 and is not shown.

The filter lens of the present invention has a Z / Y ratio similar to that of the A light source, which is known to provide excellent color rendition. The excellent color rendering performance of these lenses is believed to be the result of this close relationship.

When the chromaticity coordinates of the lens of the present invention are plotted on a color mixture graph, the dominant wavelength is 570.
nm and 580 nm. The preferred range of the Z / Y ratio is 0.25-0.
40.

In the retina of the human eye, there are three types of cone-shaped photoreceptors that provide signals to produce color vision. These are referred to as S, M and L cones, indicating that they are more sensitive in the short, medium, or long wavelength portion of the visible spectrum.

FIG. 3 is a graph in which the relative luminous efficiency is plotted on the vertical axis, while the wavelength of the visible spectrum is plotted in nanometers on the horizontal axis. The relative luminous efficiency for each type of cone photoreceptor is plotted against wavelength. The efficiency curves obtained for each cone are denoted by S, M, or L. L & M
The curve shown as gives the total weighted efficiency for the L and M cones (
The coordinate scale was chosen to have the peaks of the S and L & M curves in harmony.) Since the L and M cones are not present in equal numbers, a weighted sum was used.

In calculating the Y and Z tristimulus values, the standard observer y bar and x bar functions (f
unction) is used. Comparing these y-bar and x-bar functions with the data from FIG. 3, the weighted sum represents the luminous efficiency function for photopic vision, z bar and S bar
It can be seen that the luminous efficiency functions are the same. Thus, the ratio Z / Y relates short wavelength sensitive cone stimulation to light stimulation.

The present invention provides, inter alia, the following: A filter lens having filtering characteristics similar to those of a CPF 450 lens, but having a surface color on both polished surfaces. This eliminates the need for front processing of the lens.

[0040] 2. A lens that looks similar to the CPF 450 product, but has higher transmission at the blue spectral edge. This gives a more natural sight.

[0041] 3. Lenses similar to those made of glass with a fixed color.

[0042] 4. A short-term process for manufacturing a lens with these characteristics.

[Brief description of the drawings]

FIG. 1 is a graph of transmittance data comparing a conventional commercial lens with a lens according to the present invention.

FIG. 2 is a graph in which Z / Y ratios for several different lenses and illuminants are plotted against spectral purity.

FIG. 3 is a graph in which relative luminous efficiencies for three types of cone-shaped photoreceptors are plotted against wavelength of visible light.

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Wedding, Brent M. USA New York 14830 Corning East Third Street 3F Term (Reference) 2H006 BE00 4G062 AA04 BB01 BB05 BB06 DA04 DA05 DA06 DB03 DB04 DC04 DD01 DD02 DD03 DD04 DE01 DF01 EA01 EA02 EA03 EA10 EB01 EB02 EB03 EC01 EC02 EC03 EC04 ED01 EE01 EF01 EG01 FA01 FA10 FB01 FC01 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 H05 H05 H03 H03 H05 H03 H03 H03 H05 JJ07 JJ08 JJ10 KK01 KK03 KK05 KK07 KK10 MM03 NN13

Claims (7)

[Claims] 1. The ratio of Z / Y tristimulus values between 0.25-0.40, 570-5 on the color mixing graph
Dominant wavelength between 80 nm, steep drop in transmittance between 450-500 nm, and 400-450 nm
An ophthalmic filter lens having a transmissivity of 30% or less between. 2. The filter lens according to claim 1, wherein said lens is made of glass containing one or more types of glass coloring agents to give the glass a fixed color. 3. The filter lens according to claim 1, wherein said lens is made of uncolored glass. 4. The method according to claim 1, wherein the lens generates photochromic behavior in the glass.
Containing small amounts of Ag, Cl, Br and CuO sufficient to_TwoO-Al_TwoO _Three -B_TwoO_Three-SiO_Two2. The filter according to claim 1, wherein the filter is made of glass.
Lutha lens. 5. The lens according to claim 1, wherein said lens has a weight percentage of 0-
2.5% Li ₂ O, 0-9% Na ₂ O, 0-17% K ₂ O, 0-6% Cs ₂ O, 8-20% Li ₂ O + Na ₂ O + K ₂ O + Cs ₂ O, 14 -23% B ₂ O ₃ , 5-25% Al ₂ O ₃ , 0-2
5% P ₂ O ₅ , 20-65% SiO ₂ , 0.004-0.02% CuO, 0.15-0.3% Ag, 0
Consisting essentially of 0.1-0.25% Cl, and 0.1-0.2% Br, the molar ratio of alkali metal oxide to B ₂ O ₃ varies between about 0.55-0.85, and Ag to (Cl + Br). 5. The filter lens of claim 4 having a composition with a weight ratio ranging between about 0.65-0.95. 6. A method of manufacturing an ophthalmic protective filter lens, wherein the lens has a length of less than 20 minutes, but the ratio of Z and Y tristimulus values (Z / Y) is between 0.25-0.40. 465 ° C. to 495 ° C. for a long enough time to provide Z and Y tristimulus values
A method comprising baking a photochromic glass lens containing silver halide in a hydrogen-containing atmosphere within a temperature range of up to ° C. 7. The method of claim 6, including firing the glass lens at 476 ° C. for a time-temperature cycle corresponding to about 8 minutes.