MXPA05013218A - Eyewear lens having selective spectral response - Google Patents

Abstract

An eyewear lens provides for selective spectral performance in response to varying light conditions, including both changes in intensity and spectral distribution. The lens responds selectively to both ultraviolet and visible light, and exhibits different spectral transmittance characteristics under different lighting conditions, to provide for better vision for a wearer. In addition to this active response, the lens also may include a polarizer to further control light and to minimize the glare that interferes with clear vision.

Description

before the expiration of the time limit for amending the For two-letter codes and olher abbreviations. refer to the "Gutd-claims and the republished in the event of receipt of anee Notes on Codes and Abbrevialions" appearing to the beggin-amendments no ofeach regular issue of the PCT Gazette.

EYEGLASSES THAT HAVE SELECTIVE SPECTRAL RESPONSE BACKGROUND OF THE INVENTION Any telescope is defined as an optical part to be used with the human eye. This may include nonprescription eyeglasses, such as store-bought sunglasses, prescriptive glasses, and semi-finished lenses designed to match the desired prescriptions. This can also include more extreme forms, such as goggles, visors, masks, eye shields, helmets and the like. Lenses can be produced from a wide range of optical materials including glass, polymeric materials and like glass.

Eyeglasses are typically designed to improve vision. This improvement is most commonly accomplished by the use of a correction lens that increases the ability of the eye to focus light. In addition, glasses can also improve vision by reducing the brightness or modifying the exposure of light (for example in sunglasses) to allow the eye to operate more efficiently on its own. In addition to increasing focus and reducing brightness, a telescope should ideally be adjusted to deviate light conditions to provide visual acuity to improve, regardless of any change in light level or the spectral distribution of that light (ie, the distribution of light at the wavelengths of the visible spectrum). While certain techniques have been tried to provide this adjustment, they should not be completed successfully.

For example, electrochromic lenses have been produced in a manner that allows the user to adjust the transmission of the lenses independently of any external light. However, these lenses require battery power and / or sensors that can be uncomfortable or aesthetically difficult to fit into the lenses of synthetic appeal designs. Also, the factors of cost, weight, environmental stability, life of use and optical density have been sources of difficulty for these lenses.

Lenses made of photochromic crystals have also been used. These lenses are designed to lighten or darken in response to changes in the intensity of light. Most stable photochromic systems are designed to respond more preferentially to ultraviolet light to avoid unwanted darkness of indoor lenses. However, this design criterion offers results in photochromic ones that exhibit low sensitivity in applications in which sun lenses are commonly used, such as behind the windshield of a car, because said windshields filter ultraviolet light. In addition, most photochromic lenses are designed for constant use. This ensures that the lenses do not provide much residual color when used indoors, the photochromic concentration of these lenses has been limited, so that they can not achieve the dark tint of conventional sun lenses even under the outer conditions of more light.

Additionally, in typical light situations, brightness due to polarized light can interfere with good vision. Brightness is particularly a problem when reflections occur from flat expansive surfaces, such as water or roads, but can also be a significant problem under hazy conditions, such as foggy skies or smog. While the dyes, photochromic and electrochromic, all reduce the total light, only polarized lenses will preferably minimize the brightness. Thus, polarized lenses offer a unique advantage to provide improved vision. Polarized lenses are typically a passive device, however they do not conform to optical density to vary light conditions. In addition, a dark polarized sun lens can reduce brightness and provide sufficient transmission in full exposure to sunlight, but does not allow sufficient transmission under low light conditions.

Examples of lenses and related methods combined with these light modification techniques or including additional dyes in the lenses are known in the prior art. The visible spectral signature of the polarizers has been modified by the use of passive additional dyes as described, for example in US Pat. Nos. 6,382,788 and 4,878,748. However, these modifications may not be sufficient to meet the expected light or sharpness conditions, such as those that allow a person to use the lenses to clearly discern the differently colored traffic lights. In addition, said passive filter has the aforementioned insensitivity limitation to vary the light intensities or the spectral distributions. References such as U.S. Patent No. 4,818,086 and U.S. Published Patent Application No. 2003/0075816 describe photochromic materials combined with passive agents that modify the activated color of the resulting photochromic objects. Similarly, the patents that include U.S. Patent Nos. 5,625,427 and 6,145,984 describe photochromatics with polarizers. As these references indicate, the main purpose of the previous activities has been to achieve constant particular colors, rather than adjust the operation of the lenses for optimum visual acuity under varying light conditions. Similarly, US Patent No. 5,608,567 mentions that the photochromic and electrochromic can be completed with each other because the photochromic can have limited response behind the windshield of a car, they can increase the electrochromic outdoor. The invention in the US Patent No. 5,608,567 resides in the use of the photochromic to control the amount of light reaching the electrochromic cell, but this mention of combined techniques, although with very different electrochromic technology, confirms that the additional advantages in the Light control are still of great interest.

Therefore, it is apparent that there is a need for optical lenses that have improved response to common light variant conditions compared to currently available lenses. These lenses should not adjust to variations in light intensity, but they should also adjust that light completely for optimal visual acuity. The present invention covers these needs and provides additional advantages.

SUMMARY OF THE INVENTION The present invention resides in lenses that provide an active response to light in the visible ultraviolet spectral region. The lenses incorporate the following: 1) a portion of the base line in the lenses characterized by a first spectrum of specific visible light transmission; 2) at least one first photochromic activated by ultraviolet light in the range of 300-400 nm to produce a first colored absorption state in the region of visible light and 3) at least one photochromic second activated by visible light in the range of 400 -750 nm to produce a second state of colored absorption in the region of visible light. The lenses can also incorporate a polarizer, which can be characterized by the selective transmission differences of the wavelength through the region of visible light or by the transmission of light that is substantially constant through the region of visible light.

In the preferred embodiments of the lenses of the present invention, the first specific visible light transmission spectrum is characterized by the transmission of light that is substantially constant through the region of visible light or by the selective transmission differences in length of wave through the region of visible light, In the case of the latter, the preferred embodiments of the lenses also incorporate absorbents or reflectors of visible light. The first photochromic can be a different material from that of the second photochromic or the first and second photochromic that can be incorporated into a simple photochromic. In the preferred modalities, the first or second colored absorption state can be characterized by the selective transmission wavelength differences across the region of visible light. Also, the first colored absorption state may be different from the second colored absorption state. The lenses can also incorporate ultraviolet light absorbers or reflectors and can preferably transmit less than 1% of the total light having a wavelength less than 380 nm.

The present invention is also incorporated into lenses that provide an active response to sunlight, characterized by: 1) a first state of highly visible light transmission during exposure to low light illumination; 2) a second state of very low visible light transmission during exposure to bright sunlight illumination and 3) a third intermediate visible light transmission state during exposure to sunlight filtered through a window medium of UV attenuation, such as a window of a car. Preferably, the third state of intermediate visible light is characterized by the absorption that rises from at least one photochromic material activated by visible light and the second, the state of transmission of very limited visible light is characterized by the absorption that rises from at least one photochromic material activated by ultraviolet light and visible light. The photochromic material can also incorporate at least a first photochromic activated by visible light and at least one second photochromic activated by ultraviolet light. In preferred embodiments, the lenses further incorporate a polarizer as described above or visible light absorbers or reflectors.

In preferred embodiments of the invention, the first very high light transmission state is characterized by a light transmission of about 30% and about 85%. The first preferred transmission state is characterized by the differences in selective transmission of wavelength through the region of visible light, which are preferably configured to provide improved visual acuity when the lenses are used in low light conditions. In preferred embodiments, the selective wavelength transmission differences incorporate the absorption of visible light that imparts a yellow or yellow green color to the lenses or the light reflection that imparts a blue or bluish color to the lenses. In another preferred embodiment, another lower light transmitting state is preferably characterized by a light transmission of between about 6% and about 25%. Preferably, the second state of low light transmission is characterized by selective wavelength transmission differences across the region of visible light and can be configured to provide improved visual acuity under bright sunlight conditions. In preferred embodiments, the selective wavelength differences result in a gray or blue-red or reddish color for the lenses. Preferably the third intermediate light transmission state is preferably characterized by a light transmission of between about 10% and about 45% and can be characterized by the selective wavelength transmission differences across the region of visible light. In preferred embodiments, the selective wavelength transmission differences impart a brownish or red-brown color to the lenses.

The present invention also resides in lenses that provide an active response to sunlight. The lenses are characterized by: 1) a first state of very high light transmission during the exposure of the lenses to low light illumination; 2) a second state of very low light transmission during exposure of the lens to bright sunlight illumination and 3) and a third intermediate light transmission state during exposure of the lens to sunlight filtered through a window means that attenuates the UV. The third intermediate light transmitting state is preferably characterized by the rising absorption of at least one photochromic material activated by visible light. The second state of very low light transmission is characterized by the absorption that rises from at least one photochromic material activated by ultraviolet light or by visible and ultraviolet light in which case the photochromic materials can incorporate a photochromic activated by both visible and ultraviolet light . The lenses can also incorporate absorbers or visible light reflectors.

Other features and advantages of the present invention will become apparent from the following description of the preferred methods taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the visible and near UV regions of a standard solar spectrum, (AM1.5) irradiation plot, normalized to 1,000 over the wavelength region 305 nm to 750 nm, where: A = AM 1.5 solar visible spectral radiation B = wavelength (nm) Figure 2 shows the transmission of a typical automotive windshield over the region of visible light.

Figure 3 shows an exemplary visible spectral response for a few lenses within the scope of the present invention, optimized for three light conditions: low intensity sunlight, bright sunlight and typical driving conditions, where: C =% Relative to Through the lens D = Low light conditions E = Driving conditions F = Bright sunlight conditions.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention is incorporated in a telescope that is designed for active response to varying conditions of natural light, including both changes in intensity and in the spectral distribution, without requiring an energy source. The lenses have active and selective response for varying light intensities and spectral distributions. Specifically, the lenses are designed to selectively respond to both visible and UV (ultraviolet) components of sunlight and changes in their intensities and to provide the spectral filter adjusted for better vision.

In the more detailed features of the invention, the lenses are designed to selectively respond to both conditions of emitted or diffused sunlight and bright sunlight. The lenses are also designed to respond to these differences in both direct outdoor exposure and when exposed through a vehicle window, which significantly limits full UV light. It is also carried out by incorporating in the lenses: 1) coloration to the baseline, the largest transmission value appropriate for low light levels; 2) photochromic agents that are selectively activated by visible light for lower transmission and for coloration when exposed to higher levels of light, even behind the window of a vehicle and 3) photochromic agents that are selectively activated by UV light for coloring and even in the lower transmission when exposed to direct higher light levels.

In a preferred embodiment of the invention, the coloration is designed to change the different light conditions, so that the spectral response of the lenses is tuned for improved visual acuity with particular intensity and spectral distribution of the light. In another preferred embodiment, the polarizers are additionally used for the additional control of light and to minimize the brightness that interferes with clear vision. The lenses of the present invention are suitable for both prescription and non-prescription optical parts and can be used in a wide range of spectacles including goggles, visors, shaped masks and masks.

As stated above, the lenses of the present invention are optimized to provide improved visual sensitivity for varying conditions of natural light, by incorporating specific optical characteristics, such as color and transmission and also by incorporating photochromic to actively change these properties in response to the varying light conditions. The design of these lenses considers and accommodates several factors. First, take into account the solar spectrum of the Earth's atmosphere. Figure 1 shows the visible spectral pattern of near standard UV in an air mass of 1.5 including the scattering radiation of the sky, as seen from the sea level through the atmosphere with a southern confrontation tilt of 37 degrees. The 300-400 nm is the UV region and the 400-700 nm region is the visible spectrum. Most of the sunlight at wavelengths of less than 300 nm is absorbed by the earth's atmosphere and the visible spectral intensity of the sun rises to about 480 nm. While Figure 1 shows representative intensities of sunlight irradiation, the actual values and their relative spectral distribution will vary with cloudy or hazy skies, the additional diffusion contributions and the changing position of the sun. In fact, as the sun approaches the horizon or the diffusion effects increase, the irradiation of the total light decreases markedly, but the relative component of the near UV and the blue light increase. Therefore, for the best visual response, some glasses should provide good transmission of the visible component of the light, together with the effective blocking of the UV component of the light, even in low light conditions.

The sensitivity to light of the eye and the spectral discernment are known because they change as a function of the intensity of light. The eye has two types of photodetectors: cones and rods. In low light conditions, the bars detect light very sensitively, but do not discriminate the color. Therefore, under low light conditions, the visual sensitivity is at approximately 507 nm, close to the center of the visible spectrum. As light levels increase, sensitive bar detectors become saturated or photobleach and cones that discern color become more dominant photodetectors. The beta, gamma and rho cones exhibit different wavelength detection regions outstanding through the visible spectrum and their wavelength sensitivity distributions reach approximately 445 nm, 535 nm and 575 nm, respectively. While the eye contains only about 2% beta cones and 64% rho cones, the eye's sensitivity to light in the low wavelength region (close to 445 nm) is comparable to the other visible regions, although there are few detectors (beta cones) they are more sensitive. In addition, under bright light conditions, the regions of peak detection of the cones define a color sensitivity peak close to 555 nm. This known change in the sensitivity of the eye to light and color suggests that lenses that have different visible transmission and possibly different spectral response in low light against bright light conditions are desirable for optimal adjustment of the eye's response mechanisms . The present lenses include said spectral response, as described below.

The lenses of the present invention are also designated for superior operation during travel in a car and another vehicle with windows. This is another important characteristic of lenses, because such travel is a typical attribute of most external activities. Figure 2 shows the visible spectral transmission of a typical laminated glass windshield structure. As mentioned above, while photochromic can actively respond to changes in light intensity, most are activated near UV. This is clear from Figure 2 that with the cut of the laminated glass of the transmitted light close to 400 nm, said photochromic will not be strongly activated inside the vehicle with windows. The reduction of ultraviolet light cut is also typical for other plastic window materials. Precisely it is common in a vehicle with windows, particularly for a driver, who has a significant need to decrease and controlled light exposure, without compromising visual acuity. The lenses of the present invention are designed to address this need.

In view of these considerations, at least four common lighting conditions can be defined so that they would benefit from the active selective response by the lenses within the scope of the present invention. These conditions are: 1) Low light, external exposure, 2) low light exposure through a window; 3) exposure to bright light through a window; 4) bright light, external exposure. These conditions can also be defined in terms of the spectrum of light presented and detected by the eye in each of these four conditions, as described in Table 1 below.

Table 1: Conditions of Light and Response of the Eye Condition of Light Spectral intensity of the Light Response of the Eye to the condition of light Low light, UV external exposure: low Can cause damage Visible: low intensity detection bars with max close to 507 nm, limited color discrimination Low light through the ven- UV: very low-effectively-tana blocked below 390 nm Visible: low Current detection bar Bright light through the UV: very low -effectively window blocked below 390 nm visible: moderate Cone color detection with local maximum near 445, 535 and 575 nm, giving an average max of sensitivity close to 555 nm Bright light, UV exposure: moderate May cause external damage Visible: high Color detection cone with local maximum near 445, 535 and 575 nm, giving a maximum average sensitivity close to 555 nm The lenses of the present invention preferably provide a higher level of transmission for low light conditions than for bright light conditions and will actively respond to, increased dark light intensity. In addition to these changes in average transmission, the lenses preferably provide selective wavelength transmission that spectrally adjusts to the enhanced visual acuity within the different light conditions described above, that is, the apparent color of the lenses, as well as its total transmission, it changes. Here, in low light, when the eye bars are more active, the lenses exhibit a different average transmission and a different selective wavelength transmission that is done under bright light conditions, when the color discernment cones are more assets. In a further aspect of the present invention, the lenses provide an intermediate level of average transmission and selective transmission of wavelength in response to bright light perceived through a window with UV filters.

Preferred lenses within the scope of the present invention incorporate photochromic absorption (activated light) in the visible region. While electrochromic techniques can also be used, they require additional energy sources, as well as possibly detectors and power controls, making assembly of the lenses much more annoying. In contrast to previously known lenses, preferred embodiments of the lenses of the present invention incorporate both activated photochromic visible light and activated UV. By the combination of the activation of visible and UV light in the present invention, active response lenses provide: 1) a lower transmission under external exposure to bright light containing stronger components for both visible and UV light; 2) an intermediate transmission due to the lower response of activated UV photochromic, when bright light is observed through the window with UV filter; 3) Higher transmission under low light external conditions that can provide only limited energy to initiate visibly activated or UV absorption of photochromic agents and 4) Higher transmission under low light conditions when light is filtered through a window that effectively removes all or a large portion of the UV component of the low light spectrum. Under external light exposure, the average light transmission of the lenses is preferably in the range of about 6% to about 25% transmission. A preferred range for the intermediate transmission of the lenses is an average light transmission of about 10% to about 45%. Under low light conditions, a preferred range for average light transmission of the lenses is from about 30% to about 85%.

This active control in transmission stages in response to different levels of light is an important aspect of the lenses of the present invention. Another important aspect of the lenses of the present invention is the selective adjustment of the wavelength of the successive transmission curves of the lenses to improve visual acuity. As indicated in Table 1, under low light conditions, the bars in one eye provide poor color discrimination. Therefore, a highly variable transmission spectrum for lenses having maximum and minimum marked at different visible wavelength locations may not be needed or even especially effective, giving color insensitivity. Instead, keeping transmission relatively high through the visible region can be more effective in optimizing any light presented to the eye. While high transmission is necessarily important under low light conditions, visual acuity, as determined by the ability to differentiate fine details in normal distance observation, is surprisingly improved by some absorption in the shortest wavelength region of the visible spectrum. Specifically, the highest relative transmission close to the maximum of scotopic sensitivity near 505 nm than at shorter wavelengths provides improved definition when fine details are observed. This selective improvement in wavelength is also observed under low light or haze conditions, while it may be due to lenses that limit the eye's exposure to the increased amount of blue light sensitivity under these lighting conditions. Therefore, the transmission and the base color of the lenses can be selected to provide acceptable transmission under general low light conditions and if desired, they can also be adjusted to provide higher transmission near 505 nm than in the longer wavelength regions low.

A preferred base color and transmission can be achieved by adding color agents to the lenses themselves or to coatings or films incorporated with the lenses. The color agents are standard materials known to the optical industry and include dyes, pigments, UV absorbers, thin film coatings, interference filters and the like. These coloring agents interact with light through mechanisms such as absorption or reflection. Their response can be broad, meaning that the agents interact approximately equal with the wavelengths of light over a broad spectrum region or they can be selective reflectors or wavelength absorbers. For example, if a coloring agent selectively absorbs in the blue region of the visible spectrum, the object usually shows a yellowish color (ie absence of blue). An example of said color absorbing agent is as a dye or pigment. On the other hand, if the color agent selectively reflects this light, then the object may appear blue to an external viewer, because the region of blue wavelength is preferably reflected back to the observer. An example of such a reflective coloring agent is an interference thin film coating or filter designed to provide reflection. Here, selective wavelength agents can also impart different perceived colors to the lenses, depending on their operating mechanism.

Under low light conditions, activated and visible UV photochromics may also contribute in some way to the baseline color and absorbance of the lenses. However, a simple baseline spectral design can be effective for both low light conditions (ie, directly observed or filtered through a vehicle window), due to the low levels of light available for activation of the type of photochromic. However, the baseline color and transmission of the lenses may include some limited effect of the photochromic and other activated light-absorbing agents.

In a preferred embodiment of the present invention, the lenses include a polarizer that reduces brightness which may also interfere with visual acuity. The presence of a polarizer will contribute to the color of the baseline and the transmission of the lenses and may alter the quantities or varieties of other color agents necessary to achieve a desired spectral result. A wide range of polarizers can be used and includes neutral gray polarizers, colored polarizers, polarizers incorporating reflectors or reflective interference stakes and the like. In addition, the polarizer can also exhibit selective wavelength or broadband transmission control, as well as brightness reduction and both characteristics that can be appropriately designated within the operation of the lenses. In addition, the polarizer can be combined with other coloring agents, such as those mentioned above. If the reflecting colorants, the broadband reflectors and the interference filters are used with a polarizer, these agents are preferably placed so that the incoming light hits the polarizer before the reflecting agents. This ensures that the polarizer can operate more efficiently to reduce the incoming brightness, without any rotation or random movement of the right light caused by the interference effects or reflectors of these particular coloring agents. Alternatively, some polarizers created with thin film interference stakes can incorporate both specific wavelength controls (reflection, absorption or transmission), while achieving a high degree of polarization.

As described above, many different combinations of techniques can be used within the lenses of the present invention to create the baseline conditions of both complete transmission and if desired, selective transmission of wavelength. Then, to achieve the desired lower transmission under bright light conditions, an activated UV photochromic with resultant absorption in the visible region can be used in the lenses of the present invention. Such photochromes include, for example those described in US Patent No. 4,818,096 incorporated herein by reference, as well as various photochromic developed by Transitions Optical, Inc. as used in their Transitions® photochromic lens technologies. Activated UV photochromics can be incorporated into the lenses using various known processes, including integral blending into the basic lens material, absorption on the surface of the lenses, incorporation into the lens coatings and use of films or photochromic laminates that are embedded or include in or on the lenses.

The lenses of the present invention also include photochromic capable of the activation of visible light for additional response for the brightest external light conditions and for active response behind the UV attenuation window. They are also incorporated with the lenses using the various known processes described above. Particular photochromic are used in the lenses depending on the transmission and the desired spectral distribution, the activation characteristics of the photochromic and possibly also on the particular lens material and other additives for lens coloration or stability. Many photochromic agents currently respond to light over a broad region of wavelength that can cover the visible and UV spectrum. This has been addressed in prior optical applications, as described in US Patent Nos. 4,818,096 and 6,102,543 in this document incorporated by reference. However, in the present invention, this coating can be used advantageously to achieve particular transmission and color values for the different lighting conditions as described above.

Therefore, although the photochromics for use in the present invention are designated as being activated with visible or UV light, they may also exhibit some additional response for another wavelength region. In fact, in the present invention, a lens incorporating one or more photochromes exhibiting marked activation in both UV and visible regions can be advantageously controlled for the response in one or both regions by the use of coloring agents. This selective response can be achieved by using various techniques, including filters, dyes or pigments that absorb light and reflecting or absorbing agents interposed between the photochromic and the light source. This combination of coloring agents and photochromic agents can be used as another variable control mechanism or process in the lenses of the present invention. As needed, the coloring agent can be placed to modulate the amount of light that the photochromic ones reach or to allow the photochromic ones to light up completely. In a further preferred embodiment of the lenses of the present invention, the reflecting agents are placed behind the photochromic and are designated to reflect the activation spectrum. These agents can increase the photochromic activity of the lenses by providing an extra passage of light reflected through the photochromic layer. Here, many different combinations of elements can be used in the lenses of the present invention to control, alter and optimize the active response of the lenses to light.

Depending on sensitivity and competition reactions, certain photochromic agents can be used more efficiently alone or in combination to achieve a desired optical effect. This may result, for example, in optimized color, color density or color consistency throughout the range of a given lighting condition. In addition, a given photochromic can act as a coloring agent with respect to another photochromic, by blocking the incoming light due to preferential absorption or by selectively filtering the light. In addition, some photochromic materials may be more compatible with certain lens materials, coloring agents or lens production techniques than other photochromic materials. For example, common photochromic properties are degraded by the heat of light from injection molding processes that can be used to produce thermoplastic lenses. Similarly, if heat-sensitive polarizers are also incorporated into lenses, they can tolerate even less exposure to high temperature than photochromic ones and could lose efficiency or change color with overheating. If such factors have not been accommodated when the lenses, lens materials and lens additives are combined with the photochromic, the desired resultant color or transmission may not be achieved or may not be stable over time or with exposure. environmental.

Another preferred aspect of the lenses of the present invention incorporates coloring agents and photochromic materials that adjust a selective wavelength transmission curve for these bright light conditions as well as the total transmission of the control. In bright light conditions, the cones provide good response from the dominant eye of color discernment. Preferably, then, the transmission through the lenses should allow good definition through the visible spectrum. It has been surprisingly found that under bright light conditions, good definition can be maintained even when the lenses are designated such that said coloring and / or photochromic agents create maximum and minimum local transmission in different regions of the visible spectrum. This maximum and minimum corresponds to the differences of selective transmission of the wavelength and imparts particular colors to the lenses by reflecting or absorbing preferably the specific wavelengths of light. Here, many fashionable colors can be created without compromising the operation of the lenses of this invention. However, extreme cuts in the visible region can be avoided. First, a marked cut will limit the visibility of that spectral region and therefore affects the sharpness for objects in that color range. Second, the recognition and transmission of the color must be sufficient to pass the red, yellow and green of traffic signal tests, as defined in ANSI Z80.3-1986. The lenses with extreme cuts commonly fail in these tests.

A preferred color for direct external bright light conditions has a relative minimum near about 500 nm and equal or greater transmission in the blue region. This preserves the rich blue in appearance, while maintaining good green and red sensitivity. A rationale for this color preference is that relatively high blue transmission ensures a good visual response from the limited number of beta cones, while maintaining sensitivity in other spectral regions that have more receptors. If this spectral response is achieved by selective absorption of wavelength, the lenses will appear reddish or red-blue. Another exemplary color is a neutral gray, which provides approximately equal transmission across the entire visible spectrum.

Other colors can be manufactured or selected for use in lenses in particular external activities or on the basis of fashionable considerations. For example, a water polo shirt may prefer a bright external color other than that preferred for motorcycle racing. Therefore, it could be thought that the lenses of the present invention are designated with preferred or distinctive colors for use in particular sports, hobbies or professional activities. The variety of coloring agents, photochromic and optional polarizers that can be combined in the lenses of the present invention allow such designs.

Behind a window of a vehicle such as a car, train or tram, the UV component of sunlight will be attenuated or blocked appreciably by the designed or intrinsic cut of the window material. Therefore, the activated UV photochromic will respond very weakly, if it is not to all the light presented through the window. However, the photochromic ones activated by visible light will respond and can be designed to affect the transmission and / or color of the lenses under these conditions of filtered bright light.

A preferred color under these lighting conditions, when the color is the result of absorption is a brown hue. This provides a bright contrast to drive conditions with typical sunlight intensities, allowing good recognition of traffic signals and good visual acuity for other objects. A brown lens has transmission that increases towards the red region of the visible spectrum where most of the cones are more sensitive. In fact, the color sensitivity of the gamma and rho cones extensively covers the entire 550-650 nm region, allowing a high response of approximately 98% of the cone receptors. In addition, as the sun approaches the horizon or under bright cloudy light conditions, the relative irradiance of the lower wavelength region (red end) of the sunlight spectrum decreases even more markedly than the longitude region shortwave. Therefore, increased transmission in this region of red wavelength may be desirable for good sharpness under said lighting conditions.

The lenses of the present invention can provide additional freedom in color selection and transmission of other known lenses due to possible competition pathways for UV and visible excitation of the photochromic ones. For example, if a UV change activated by a photochromic material takes much less energy than that required to activate the same or another selected photochromic in the visible region, the activated UV material can continue to be a color contributor even behind a window. Alternatively, a particular photochromic that can be activated by both visible and UV light can show different maximum and minimum spectral depending on the relative influence of each wavelength region. When these variables are combined with the coloration of the lenses, there is ample control of the color selections for both fashion and vision needs. For example, as mentioned previously, lenses that provide reduced transmission in the short wavelength region may appear yellow if the absorption occurs or blue, if the light of short wavelength is selectively reflected.

Additionally, various techniques can be used to control UV light reaching the eye or activate photochromic lenses. Within the optical industry, several standard methods are used to control or eliminate UV exposure. These include such methods as incorporation of UV absorbers, pigments and cutting dyes in or on the lens material, the use of reflective or UV absorbing coatings and interference filters. In addition, activated UV photochromic or visible activated photochromic light that still respond to ultraviolet light can also activate UV exposure control and the other methods can therefore be modified. Similarly, in the present invention, the attenuation due to the window means and the lower UV irradiation under low light conditions can also be taken into account by designating the additional UV limits in the lenses. In a preferred embodiment, the lenses will exhibit very low light transmission below 380 nm to protect the eye from UV and UVB exposure. Bright UV cutting methods can be used when the limited effect on visible transmission of the lenses is desired. Alternatively, the cut can be structured or gradual to significantly reduce the UV while adjusting the visible transmission. For bright light conditions, a preferred embodiment exhibits less than about 1% of the transmission below 380 nm.

While conditions of natural sunlight have been described, the lenses of the present invention can also be adapted to the intensities of interior illumination and spectral variations. With an optimized mode for response to sunlight, interior lighting would not be expected to activate photochromic as strongly as sunlight conditions, but they can cause some change in absorption and color depending on the light spectrum.

For example, if exposed to intense incandescent lights that approximate a black body source, visible activated photochromic may contribute some optical density and color to the lenses. In the above-mentioned preferred embodiments, this would change the lenses to a slightly brown dye. Similarly, in halogen or bright fluorescent lighting, UV-sensitive photochromic may be activated slightly as well as visible photochromic. Again, for example for the preferred embodiment, this would give the lenses a slightly reddish or gray tint.

The invention will now be described in further detail with reference to the following example.

EXAMPLE A hard resin is prepared to incorporate coloring agents, so that the lenses exhibit a spectrum characterized by a lower transmission in the region of 400-450 and increasing transmission in the 450-500 nm region. In this example, the infiero transmission in the region 400-450 is achieved by absorption, giving a yellowish color to the lenses. The lenses contain an embedded polarizer, characterized by a polarization coefficient of at least 90% and approximately 40-50% of the light transmission, as a passive device to reduce the polarized brightness under all lighting conditions. At least one photochromic material capable of activation by visible light is incorporated in the lenses so that when they are activated, the transmission of visible light of the lenses decreases and imparts a brown color to the lenses, due to the decreased transmission in the region 450-550 nm. Additionally, at least one photochromic material capable of activation by UV light is incorporated in the lenses so that when they are activated, the visible light transmission of the lenses is increased and imparts a reddish-blue color, due to a minimum of local transmission close to 250 nm, but somehow higher relative transmission in the blue region of the spectrum. If required, additional materials can be incorporated into the lenses to limit the UV exposure of the eye, resulting in less than 1% transmission below 380 nm.

The expected response and the appearance of these lenses, given the various light conditions indicated in Table 1 are summarized in Table 2.

Table 2: Response to the different lighting conditions Spectral Intensity Conditions Response of the elements of the Example Appearance of the Example Light of the given light condition of the given light Low light, UV: low UV excess blocked with agents Yellowing for active and passive exposure visible high external transmission Visible: low Base line color: +++ yellow-green Polarizer: +++ Visible activated photochromic: + UV-activated photochromic : + Low light to UV: Very low - UV excess blocked with agents Yellowing, transmission through effectively active or passive high visible window blocked below Base line color: +++ 390 nm Polarizer: +++ Visible activated photochromic: + Photochromic UV activated: - UV bright light: very low - UV excess blocked with agents Coffee, visible transmission through the effectively active or passive intermediate window blocked below Base line color: +++ 390 nm Polarizer: +++ Visible activated photochromic: ++ UV-activated photochromic: +/- Bright light, UV: moderate UV excess blocked with external agents Visible: high active or passive Base line color: +++ Polarizer: +++ Visible activated photochromic: +++ Activated UV photochromic: +++ +++ = very active response ++ = moderately active response + = less active response +/- = limited, if any answer - = minimum response The exemplary transmission spectrum for the lenses of the Example under different lighting conditions are shown in Figure 3. Only an exemplary transmission curve is shown for low light conditions, because this may be similar to both external direct exposure or through a window that attenuates UV. Accordingly, lenses with selective and active response to natural light are obtained which therefore change the color to optimize the visual acuity for the different light conditions.

Although the invention has been described in detail with reference to preferred materials and spectral properties, those skilled in the art will appreciate that additional materials or combinations of materials and techniques can be used to achieve the same spectral properties and also additional spectral properties without departing from scope of the invention. Accordingly, the invention is identified by the following claims.

Claims (43)

1. Lenses that provide an active response to light in the visible ultraviolet spectral region, the lenses comprising: a portion of the lenses in the baseline characterized by a first specified visible light transmission spectrum; at least a first photochromic activated by ultraviolet light in the range of 300-400 nm to produce a first colored absorption state in the region of visible light and at least one second photochromic activated by visible light in the range of 400-750 nm to produce a second colored absorption state in the region of visible light.

2. Lenses in accordance with claim 1, wherein the lenses further comprise a polarizer.

3. Lenses in accordance with claim 2, wherein the polarizer is characterized by the differences in wavelength selective transmission through the region of visible light.

4. Lenses in accordance with claim 2, wherein the polarizer is characterized by the transmission of light that is substantially constant through the region of visible light.

5. Lenses according to claim 2, wherein the first specific visible light transmission spectrum is characterized by the transmission of light that is substantially constant through the region of visible light.

6. Lenses in accordance with claim 1, wherein the first specific visible light transmission spectrum is characterized by the differences in wavelength selective transmission through the region of visible light.

7. Lenses in accordance with claim 6, wherein the lenses further comprise absorbers or visible light reflectors.

8. Lenses according to claim 1, wherein at least one first photochromic comprises a material different from that of at least one second photochromic.

9. Lenses in accordance with claim 1, wherein the first and second photochromic comprise a simple photochromic.

10. Lenses according to claim 1, wherein the first state of colored absorbency is characterized by the differences of wavelength selective transmission through the region of visible light.

11. Lenses according to claim 1, wherein the second colored absorption state is characterized by the differences of wavelength selective transmission through the region of visible light.

12. Lenses according to claim 11, wherein the first colored absorption state is different from the second colored absorption state.

13. Lenses in accordance with claim 1, wherein the lenses further comprises absorbent or reflectors of ultraviolet light.

14. Lenses in accordance with claim 13, wherein the lenses transmit less than 1% of the total light having a wavelength below 380 nm.

15. Lenses that provide an active response to sunlight, characterized by: a first state of highest visible light transmission during exposure to low light illumination; a second state of transmission of lower visible light during exposure to bright sunlight illumination and a third state of intermediate visible light transmission during exposure to sunlight filtered through the UV attenuation window means.

16. Lenses according to claim 15, wherein the UV attenuation window means is a car window.

17. Lenses according to claim 15, wherein the third intermediate visible light transmission state is characterized by the absorption reaching at least one photochromic material activated by visible light.

18. Lenses according to claim 15, wherein the second state of transmission of lower visible light is characterized by absorption that reaches at least one photochromic material activated by ultraviolet light.

19. Lenses according to claim 15, wherein the second state of transmission of lower visible light is characterized by the absorption reaching at least one photochromic material activated by ultraviolet light and visible light.

20. Lenses according to claim 19, wherein at least one photochromic material comprises at least a first photochromic material activated by visible light and at least one second photochromic material activated by ultraviolet light.

21. Lenses in accordance with claim 15, wherein the lenses further comprise a polarizer.

22. Lenses in accordance with claim 21, wherein the polarizer is characterized by selective wavelength transmission differences across the region of visible light.

23. Lenses in accordance with claim 21, wherein the polarizer is characterized by the transmission of light which is a substantially constant transmission through the region of visible light.

24. Lenses according to claim 15, wherein the lenses further comprise absorbers or visible light reflectors.

25. Lenses according to claim 15, wherein the first highest light transmission state is characterized by a light transmission of between about 30% and approximately 85%.

26. Lenses according to claim 15, wherein the first transmission state is characterized by differences in the selective transmission of wavelength through the region of visible light.

27. Lenses in accordance with claim 26, wherein the selective wavelength transmission differences are configured to provide improved visual acuity when the lenses are used in low light conditions.

28. Lenses in accordance with claim 26, wherein the differences in wavelength selective transmission comprise the absorption of visible light that imparts a yellow-green or yellow color to the lenses.

29. Lenses as defined in claim 28, wherein the difference of wavelength selective transmission comprises the light reflection imparting a blue or blue color to the lenses.

30. Lenses according to claim 15, wherein the second lower light transmission state is characterized by a light transmission of between about 6% and about 25%.

31. Lenses according to claim 15, wherein the second lower light transmission state is characterized by the selective wavelength transmission differences across the region of visible light.

32. Lenses according to claim 31, wherein the selective wavelength transmission differences are configured for improved visual acuity under bright sunlight conditions.

33. Lenses according to claim 31, wherein the selective wavelength transmission differences result in a red-blue or reddish color for the lenses.

34. Lenses according to claim 31, wherein the selective wavelength transmission differences result in a gray color for the lenses.

35. Lenses in accordance with claim 15, wherein the third intermediate light transmission state is characterized by a light transmission of between about 10% and about 45%.

36. Lenses according to claim 15, wherein the third intermediate light transmission state is characterized by the selective wavelength transmission differences through the region of visible light.

37. Lenses according to claim 36, wherein the differences of wavelength selective transmission impart a red-brown or brown color to the lenses.

38. Polarized lenses that provide an active response to sunlight, lenses characterized by: a first state of highest light transmission during exposure of the lenses to low light illumination; a second lower transmission state during exposure of the lenses to bright sunlight illumination and a third intermediate light transmission state during exposure of the lenses to sunlight filtered through the UV attenuation window means .

39. Lenses according to claim 38, wherein the third intermediate light transmission state is characterized by the absorption that rises from at least one photochromic material activated by visible light.

40. Lenses according to claim 38, wherein the second lower light transmission state is characterized by the absorption that rises from at least one photochromic material activated by ultraviolet light.

41. Lenses according to claim 38, wherein the second lower light transmission state is characterized by the absorption that rises from the photochromic material activated by ultraviolet and visible light.

42. Lenses according to claim 41, wherein the photochromic materials comprise a photochromic activated by both ultraviolet and visible light.

43. Lenses according to claim 38, wherein the lenses further comprise absorbers or visible light reflectors.