Flexible liquid crystal lens

Abstract

An electrically switchable flexible contact lens adapted to fit the eye of a user is provided, the contact lens having a liquid crystal cell for varying the focal power of the contact lens, the liquid crystal cell having a cell gap thickness between a first surface and a second inner surface, the liquid crystal cell having a diffractive optical element for correcting the user's vision, the diffractive optical element arranged to maintain the cell gap thickness by providing supports at one or more locations within the cell.

Description

[Technical Field]

[0001] This invention relates to flexible contact lenses.

[0002] This invention relates to flexible contact lenses. In particular, it relates to electrically switchable contact lenses, but is not limited thereto. [Background technology]

[0003] Flexible contact lenses having a diffractive optical element are known. Such lenses may include a liquid crystal, which is electrically switchable between two states. In the first state, the refractive index of the liquid crystal does not match that of the diffractive optical element, and the diffractive optical element interacts with and diffracts light. In the second state, the refractive index of the liquid crystal matches that of the diffractive optical element, and there is little to no diffraction of incident light. [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention aims to provide an improved flexible contact lens having a diffractive optical element. [Means for solving the problem]

[0005] According to a first aspect of the present invention, an electrically switchable flexible contact lens having the features described in claim 1 is provided.

[0006] According to a second aspect of the present invention, an electrically switchable flexible contact lens having the features described in claim 10 is provided.

[0007] According to a third aspect of the present invention, an electrically switchable flexible contact lens having the features described in claim 15 is provided.

[0008] According to a fourth aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features described in claim 19 below.

[0009] According to a fifth aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features described in claim 20 below.

[0010] According to a sixth aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features described in claim 21 below.

[0011] According to a seventh aspect of the present invention, there is provided an electrically switchable flexible contact lens having the features described in claim 25 below.

[0012] Preferred but optional features of the present invention are described below and in the dependent claims in a dependent form.

[0013] Of course, it will be understood that the features described with respect to one aspect of the present invention can be incorporated into other aspects.

[0014] Next, embodiments of the present invention will be described with reference to the accompanying drawings, which are merely exemplary.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic side cutaway view of an example of a contact lens as a first aspect of the present invention, showing a state where the contact lens has a liquid crystal cell. [Figure 2] It is a schematic side view of the liquid crystal cell used in FIG. 1. [Figure 3] It is a schematic view of the local alignment of liquid crystal molecules in the liquid crystal cell in the non-switching state. [Figure 4] It is a schematic view of the local alignment of liquid crystal molecules in the liquid crystal cell in the switching state. [Figure 5] This figure shows the intensity of the diffraction profile produced by a lens having a liquid crystal cell with a low refractive index, and illustrates the switching state of the liquid crystal cell. [Figure 6] This figure shows the intensity of the diffraction profile produced by a lens with a liquid crystal cell having a low refractive index, and depicts the liquid crystal cell in a non-switched state. [Figure 7] This figure shows the intensity of the diffraction profile produced by a lens having a liquid crystal cell with a high refractive index, and illustrates the switching state of the liquid crystal cell. [Figure 8] This figure shows the intensity of the diffraction profile produced by a lens with a liquid crystal cell having a high refractive index, and depicts the liquid crystal cell in a non-switched state. [Figure 9] This is a schematic cross-sectional view of an example of a contact lens representing various aspects of the present invention, showing a state in which the contact lens has two liquid crystal cells. [Figure 10] This is a schematic plan view of the alignment of the liquid crystal director located adjacent to the alignment polymer. [Modes for carrying out the invention]

[0016] According to a first aspect of the present invention, the present invention relates to an electrically switchable flexible contact lens that is suitable for the user's eye. Contact lenses are The contact lens has a first liquid crystal cell that changes the focal power, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell includes a diffractive optical element that corrects the user's vision. The diffractive optical element is arranged to maintain the cell gap thickness by providing supports at one or more locations within the cell, thereby providing a contact lens.

[0017] The applicant has discovered that diffractive optical elements can be used as spacers to maintain cell gap thickness within a flexible ophthalmic lens.

[0018] Maintaining the cell gap thickness is important for maintaining the optical properties of the ofsalmic lens. In particular, maintaining the cell gap thickness ensures that it is small enough to allow the liquid crystals to align without haze. In this regard, maintaining the cell gap thickness should include an average decrease in the cell gap thickness of the entire first liquid crystal cell of 15% or less, optionally 12% or less, optionally 10% or less, optionally 8% or less, and optionally 5% or less. Maintaining the cell gap thickness may only allow for relatively small decreases and / or increases in the cell gap thickness. In this regard, the average rate of change in the cell gap thickness from edge to edge of the first liquid crystal cell may be optionally 15% or less, optionally 12% or less, optionally 10% or less, optionally 8% or less, and optionally 5% or less, when the ofsalmic lens is deformed by being placed on the user's eye.

[0019] The average cell gap thickness of the undeformed lens is optionally at least 2.0 microns, optionally at least 3.0 microns, optionally at least 3.5 microns, optionally at least 4.0 microns, optionally at least 4.5 microns, and optionally at least 5.0 microns.

[0020] The average cell gap thickness of the lens in an undeformed state is optionally 7.0 microns or less, optionally 6.5 microns or less, optionally 6.0 microns or less, optionally 5.5 microns or less, optionally 5.0 microns or less, optionally 4.5 microns or less, and optionally 4.0 microns or less.

[0021] As used herein, the micron is identical to the micrometer, as understood by those skilled in the art.

[0022] The average cell gap thickness of the lens in an undeformed state is optionally 2.0 to 7.0 microns, optionally 2.5 to 5.5 microns, optionally 3.5 to 5.0 microns, and optionally 3.5 to 4.5 microns.

[0023] The average height of the diffractive optical element should ideally match the average cell gap thickness. Similarly, the height of the diffractive optical element at a specific point in the first liquid crystal cell should ideally match the cell gap thickness at that specific point in the first liquid crystal cell.

[0024] The first liquid crystal cell is preferably substantially free of other elements (e.g., spacers) to maintain the cell gap thickness by providing supports at several locations within the cell. However, optionally, peripheral spacers may be provided around the first liquid crystal cell in addition to the diffractive optical elements.

[0025] To avoid misunderstanding, a diffractive optical element is a diffractive optical element characterized by a size and scale that is sufficiently small relative to the wavelength of light striking it, so as to produce a controlled and desired optical effect resulting solely from the diffraction of light. To avoid misunderstanding, a diffractive optical element does not include a Fresnel lens.

[0026] The first liquid crystal cell can operate between a first non-switched state and a second switched state. In the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be greater than or less than in the second state. In either the first or second state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be small or zero, i.e., the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be approximately the same. In this context, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may optionally be 0.03 or less, optionally 0.02 or less, or optionally 0.01 or less. Such a difference in refractive index should be calculated for wavelengths in the visible portion of the electromagnetic spectrum (radiation with wavelengths of 450-700 nm). Such a difference in refractive index should preferably be calculated at a wavelength of 450 nm, and optionally at a wavelength of 700 nm. Optionally, such difference may be calculated over multiple wavelengths from 450 nm to 700 nm. In the other of the first and second states, the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element do not match, and therefore the diffractive optical element diffracts the incident light. The first state is often a non-switched state, i.e., the voltage applied to the first liquid crystal cell is zero or low. The second state is often a switched state, i.e., a voltage is applied that switches the liquid crystal in the cell to the second state.

[0027] To avoid misunderstanding, the effective refractive index is the refractive index of the liquid crystal with respect to light incident perpendicularly on the contact lens and the first liquid crystal cell. In the first non-switching state, the effective refractive index is n ave =0.5(n o +n e ) is often the case, and in this case, n o n is the normal refractive index of the liquid crystal, and e This is the abnormal refractive index of the liquid crystal. In the second switching state, the effective refractive index is n o That is the case.

[0028] To avoid misunderstanding, the phrase "corrects user vision" means that it is suitable for correcting the user's near vision, distance vision, and / or intermediate vision.

[0029] The maximum height of a diffractive optical element does not need to be the same throughout the entire element. For example, a diffractive optical element may have an inner and an outer portion. The maximum height of the diffractive optical element in the outer portion should preferably be higher than the maximum height of the diffractive optical element in the inner portion. The maximum height of the diffractive optical element in the outer portion should preferably be up to 20% higher than the maximum height of the diffractive optical element in the inner portion, with optional increases of up to 15%, up to 10%, up to 7.5%, up to 5%, up to 2.5%, and up to 1%. Typically, the height of a diffractive optical element is the height along the optical axis.

[0030] The maximum height of the diffractive optical elements in the outer portion is preferably at least 1%, optionally at least 2%, optionally at least 3%, optionally at least 4%, optionally at least 5%, optionally at least 6%, optionally at least 7%, optionally at least 8%, optionally at least 10%, optionally at least 12.5%, optionally at least 15%, and optionally at least 20%.

[0031] The inner portion should ideally be located at or near the center of the diffractive optical element.

[0032] The height of the diffractive optical element preferably increases with distance from the center of the diffractive optical element. The height of the diffractive optical element preferably increases linearly with distance from the center of the diffractive optical element. The height of the diffractive optical element may increase sublinearly with distance from the center of the diffractive optical element. The height of the diffractive optical element may increase superlinearly with distance from the center of the diffractive optical element.

[0033] At least a portion of the diffractive optical element is preferably mounted on the first surface, and at least a portion of the diffractive optical element is preferably mounted on the second surface.

[0034] As described above, the diffractive optical element preferably has multiple peaks and troughs, optionally annular peaks and annular troughs. The outer portion preferably has outer peaks, for example, optionally one of 10 outermost peaks, optionally one of 8 outermost peaks, optionally one of 5 outermost peaks, and optionally one of 3 outermost peaks. The outer portion preferably includes the outermost peaks. The peak height preferably increases with distance from the center of the diffractive optical element. The peak height preferably increases linearly with distance from the center of the diffractive optical element. The peak height preferably increases sublinearly with distance from the center of the diffractive optical element. The peak height preferably increases mostly linearly with distance from the center of the diffractive optical element.

[0035] At least a portion of one peak should be attached to the second surface.

[0036] The liquid crystals should preferably include cholesteric liquid crystals. In the non-switching state, liquid crystal directors located adjacent to the first and / or second inner surfaces should preferably form angles with respect to the first and second inner surfaces of 20° or less, 15° or less, 10° or less, 8° or less, 5° or less, and 3° or less, as optional. In the non-switching state, liquid crystal directors located far from the first and second inner surfaces (optionally, midway between the first and second inner surfaces) should preferably form angles with respect to the first and second inner surfaces of 20° or less, 15° or less, 10° or less, 8° or less, 5° or less, and 3° or less, as optional. In the switching state, the liquid crystal directors located far from the first and second inner surfaces (optionally, midway between the first and second inner surfaces) should preferably form an angle of at least 60°, optionally at least 70°, optionally at least 80°, and optionally at least 85° with respect to the first and second inner surfaces.

[0037] The refractive index of the diffractive optical element is preferably at least 1.40, at least 1.42, at least 1.44, at least 1.46, or at least 1.48.

[0038] The refractive index of the diffractive optical element should preferably be 1.72 or less, 1.70 or less, 1.68 or less, 1.66 or less, or 1.64 or less.

[0039] For example, the refractive index of the diffractive optical element is preferably 1.40 to 1.72, more preferably 1.42 to 1.70, and more preferably 1.44 to 1.68.

[0040] The contact lens may have another optical element for correcting the user's vision. In this regard, the contact lens may have a lens body for correcting the user's vision. The lens body can provide a positive refractive power (power), for example, +0.5D, +1.0D or +1.5D. The refractive power of the lens body may be fixed. The addition of such a lens body can be particularly useful when the effective refractive index of the liquid crystal matches the refractive index of the diffractive optical element when the first liquid crystal cell is in the second switching state.

[0041] The refractive index of the liquid crystal is optionally 0.80 to 1.20 times the refractive index of the diffractive optical element at both 450 nm and 700 nm. The refractive index of the liquid crystal may be 0.90 to 1.10 times the refractive index of the diffractive optical element at both 450 nm and 700 nm. The refractive index of the liquid crystal may be 0.95 to 1.05 times the refractive index of the diffractive optical element at both 450 nm and 700 nm. The refractive index of the liquid crystal may be 0.97 to 1.03 times the refractive index of the diffractive optical element at both 450 nm and 700 nm. The refractive index of the liquid crystal may be 0.98 to 1.02 times the refractive index of the diffractive optical element at both 450 nm and 700 nm.

[0042] The above refractive index of the liquid crystal may be 0.80 to 1.20 times the refractive index of the diffractive optical element at 500 nm, optionally 0.90 to 1.10 times, optionally 0.95 to 1.05 times, optionally 0.97 to 1.03 times, optionally 0.98 to 1.02 times.

[0043] The above refractive index of the liquid crystal is the average refractive index n ave and thus is calculated as n ave =0.5(n e +n o ) where n e is the extraordinary refractive index and n o is the ordinary refractive index.

[0044] The first liquid crystal cell may contain a cholesteric liquid crystal, and the refractive index of the diffractive optical element is optionally 1.57 or less.

[0045] The first liquid crystal cell preferably contains cholesteric liquid crystal, and the refractive index of the diffractive optical element is optionally 1.58 or less.

[0046] The diffractive optical element may have multiple peaks and troughs, optionally annular peaks and annular troughs. The peaks and troughs may be concentric. At least one peak, optionally two or more peaks, and optionally each of the peaks maintain the cell gap thickness by providing supports at one or more locations within the cell.

[0047] A diffractive optical element may have at least five peaks, optionally at least seven, and optionally at least ten. A diffractive optical element may have 20 or fewer peaks, optionally 15 or fewer peaks, and optionally 10 or fewer peaks.

[0048] The contact lens may have two or more liquid crystal cells. For example, the contact lens may include a second liquid crystal cell. The first and second liquid crystal cells may be arranged so that light passes through both of these liquid crystal cells before entering the wearer's eye. The second liquid crystal cell may have the features described above with respect to a first aspect of the present invention. For example, the second liquid crystal cell may have a diffractive optical element that acts as a spacer within the second liquid crystal cell.

[0049] According to a second aspect of the present invention, an electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. A contact lens is also provided, characterized in that the first liquid crystal cell includes a diffractive optical element for correcting the user's vision, the diffractive optical element having an inner portion and an outer portion, the height of the diffractive optical element in the outer portion being 1% to 20% greater than the height of the diffractive optical element in the inner portion.

[0050] The applicant has found that it is advantageous for the maximum height of the diffractive optical element to be higher in the outer portion of the first liquid crystal cell than in the inner portion of the first liquid crystal cell, but that the difference in maximum height should be limited. In particular, the applicant has found that such an arrangement of diffractive optical elements can compensate for corneal curvature when a contact lens is placed on the cornea. Furthermore, such an arrangement of diffractive optical elements can help improve "straight-ahead viewing," especially at the edges of the lens having the diffractive optical elements. This arrangement of diffractive optical elements helps to make the optical path of light at the edges of the diffractive optical elements substantially the same as the optical path of light at the center of the diffractive optical elements.

[0051] The height of a diffractive optical element is typically aligned with the optical axis.

[0052] The maximum height is typically measured locally, that is, relative to the base or bottom of the diffractive optical element.

[0053] The maximum height of the diffractive optical elements in the outer portion should preferably be up to 15% higher than the maximum height of the diffractive optical elements in the inner portion, with optional increases of up to 10%, up to 7.5%, up to 5%, and up to 2.5%.

[0054] The maximum height of the diffractive optical elements in the outer portion should preferably be at least 2% greater than the maximum height of the diffractive optical elements in the inner portion, optionally at least 3%, optionally at least 4%, optionally at least 5%, optionally at least 6%, optionally at least 7%, optionally at least 8%, optionally at least 10%, optionally at least 12.5%, and optionally at least 15%.

[0055] The height of the diffractive optical element should preferably increase with distance from the center of the diffractive optical element. The height of the diffractive optical element should preferably increase linearly with distance from the center of the diffractive optical element. The height of the diffractive optical element should preferably increase sublinearly with distance from the center of the diffractive optical element. The height of the diffractive optical element should preferably increase mostly linearly with distance from the center of the diffractive optical element.

[0056] The inner portion should ideally be located at or near the center of the diffractive optical element.

[0057] The diffractive optical element should extend over a chord length r. The inner portion should include the part of the diffractive optical element that lies within a chord length of r / 8 from the center of the diffractive optical element. The outer portion should include the part of the diffractive optical element having a chord length of r / 4 (optionally, 3r / 8) to r / 2.

[0058] The diffractive optical element may have multiple peaks and troughs, optionally annular peaks and annular troughs. The outer portion may have outer peaks, for example, optionally one of 10 outermost peaks, optionally one of 8 outermost peaks, optionally one of 5 outermost peaks, and optionally one of 3 outermost peaks. The outer portion may have the outermost peaks. The peak height may increase with distance from the center of the diffractive optical element. The peak height may increase linearly with distance from the center of the diffractive optical element. The peak height may increase sublinearly with distance from the center of the diffractive optical element. The peak height may increase mostly linearly with distance from the center of the diffractive optical element.

[0059] The liquid crystal should preferably include cholesteric liquid crystal. In the non-switched state, the liquid crystal directors located far from the first and second inner surfaces (optionally, midway between the first and second inner surfaces) should preferably form angles with respect to the first and second inner surfaces of 20° or less, 15° or less, 10° or less, 8° or less, 5° or less, and 3° or less, as optional. In the switched state, the liquid crystal directors located far from the first and second inner surfaces (optionally, midway between the first and second inner surfaces) should preferably form angles with respect to the first and second inner surfaces of 60°, optionally at least 70°, optionally at least 80°, and optionally at least 85°.

[0060] The average cell gap thickness of the lens in its undeformed state is optionally at least 2.0 microns, optionally at least 3.0 microns, optionally at least 3.5 microns, optionally at least 4.0 microns, optionally at least 4.5 microns, and optionally at least 5.0 microns.

[0061] The average cell gap thickness of the lens in an undeformed state is, as an option, 7.0 microns or less, as an option, 6.5 microns or less, as an option, 6.0 microns or less, as an option, 5.5 microns or less, as an option, 5.0 microns or less, as an option, 4.5 microns or less, and as an option, 4.0 microns or less.

[0062] The average cell gap thickness of the lens in an undeformed state is optionally 2.0 to 7.0 microns, optionally 2.5 to 5.5 microns, optionally 3.5 to 5.0 microns, and optionally 3.5 to 4.5 microns.

[0063] A contact lens according to a second aspect of the present invention may include any of the features of a contact lens according to a first aspect of the present invention.

[0064] According to a third aspect of the present invention, an electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell includes a diffractive optical element for correcting the user's vision, and a cholesteric liquid crystal. The first liquid crystal cell can operate between a first non-switched state and a second switched state, where in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state. At both 450nm and 700nm, the average refractive index of the liquid crystal is 0.80 to 1.20 times that of the refractive index of the diffractive optical element, and the average refractive index of the liquid crystal is n ave Thus, the average refractive index is n ave =0.5(n e +n o ) is calculated as, and in this formula, n e This is the extraordinary refractive index, and n o The present invention provides a contact lens characterized by having an ordinary refractive index.

[0065] The applicant has discovered that it is advantageous for the average refractive index of a liquid crystal to be approximately the same as that of a diffractive optical element in the visible portion of the electromagnetic spectrum.

[0066] The average refractive index of the liquid crystal and the refractive index of the diffractive optical element should be calculated at ambient temperature, for example, 20°C or 25°C, or at a temperature matching body temperature (approximately 37°C), or at a temperature matching the temperature of the cornea of ​​the eye (approximately 34°C).

[0067] The average refractive index of liquid crystals is 0.90 to 1.10 times that of diffractive optical elements at both 450 nm and 700 nm. It is preferable that the average refractive index of liquid crystals is 0.95 to 1.05 times that of diffractive optical elements at both 450 nm and 700 nm. It is preferable that the average refractive index of liquid crystals is 0.97 to 1.03 times that of diffractive optical elements at both 450 nm and 700 nm. It is preferable that the average refractive index of liquid crystals is 0.97 to 1.03 times that of diffractive optical elements at both 450 nm and 700 nm. It is preferable that the average refractive index of liquid crystals is 0.98 to 1.02 times that of diffractive optical elements at both 450 nm and 700 nm.

[0068] The average refractive index of liquid crystals, as mentioned above, is preferably 0.80 to 1.20 times that of the refractive index of the diffractive optical element at 500 nm, with optional values ​​of 0.90 to 1.10 times, 0.95 to 1.05 times, 0.97 to 1.03 times, and 0.98 to 1.02 times.

[0069] The average refractive index of a liquid crystal is the average refractive index n. ave And thus, n ave =0.5(n e +n o ) is calculated as, in this case, n e This is an anomalous refractive index, and n o This is the normal refractive index.

[0070] The refractive index of the liquid crystal is optionally 0.80 to 1.20 times, 0.90 to 1.10 times, 0.95 to 1.05 times, 0.97 to 1.03 times, and 0.98 to 1.02 times the refractive index of the diffractive optical element at 460nm, 480nm, 500nm, 520nm, 540nm, 540nm, 560nm, 600nm, 620nm, 640nm, 660nm, and 680nm.

[0071] The effective refractive index of liquid crystals is 0.80 to 1.20 times the refractive index of diffractive optics at virtually all wavelengths from 450 nm to 700 nm, as an option. The refractive index of liquid crystals is often 0.90 to 1.10 times the refractive index of diffractive optics at virtually all wavelengths from 450 nm to 700 nm, with options of 0.95 to 1.05 times, 0.97 to 1.03 times, and 0.98 to 1.02 times. Those skilled in the art will understand that it is not necessary to measure the refractive index at all wavelengths, and that the refractive index changes with wavelength in roughly the same way for most materials. Typically, the refractive index decreases continuously from 450 nm to 700 nm, with no minimum, maximum, or inflection point.

[0072] The first liquid crystal cell can operate between a first state and a second state. In the first state (typically the non-switched state), the liquid crystal directors located far from the first and second inner surfaces (and optionally midway between the first and second inner surfaces) are preferably at angles of 20° or less, optionally 15° or less, optionally 10° or less, optionally 8° or less, optionally 5° or less, and optionally 3° or less with respect to the first and second inner surfaces. In the switching state (e.g., the second state), the liquid crystal directors located far from the first and second inner surfaces (optionally midway between the first and second inner surfaces) are preferably at angles of at least 60°, optionally at least 70°, optionally at least 80°, and optionally at least 85° with respect to the first and second inner surfaces.

[0073] A lens according to a third aspect of the present invention may include any of the features of a lens according to a first and / or second aspect of the present invention.

[0074] According to a fourth aspect of the present invention, an electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell includes a diffractive optical element for correcting the user's vision, and a cholesteric liquid crystal. The first liquid crystal cell can operate between a first non-switched state and a second switched state, where in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state. A contact lens is provided characterized in that the refractive index of the diffractive optical element is 1.57 or less.

[0075] The applicant has discovered that when the refractive index of the diffractive optical element is relatively low, the optical performance of the contact lens in the second state exhibits a good refractive index that matches good near-field performance over a wide wavelength range.

[0076] In the first or second state, however preferably in the second state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be small or zero, that is, the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element are approximately the same. In the second state, due to the matching refractive indices, the diffractive optical element does not significantly diffract the incident light. In the first or second state, however preferably in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is preferably larger than in the other state, and as a result, the diffractive optical element diffracts the incident light.

[0077] In the first non-switching state, the effective refractive index of the liquid crystal is preferably the average refractive index of the liquid crystal, that is, n ave =0.5(ne +n o ) and in this case, n e This is an anomalous refractive index, and n o This is the normal refractive index. In the second switching state, the effective refractive index of the liquid crystal is n o In other words, it is preferable that it has a normal refractive index.

[0078] The contact lens preferably has a lens body that corrects the user's vision. The lens body can provide a positive refractive power, for example, +0.5D, +1.0D, or +1.5D. The refractive power of the lens body preferably is fixed. The lens body is preferably located at or near the uppermost part of the lens, and this uppermost part is oriented away from the part of the lens that contacts the wearer's eye. The addition of such a lens body is particularly useful when the first liquid crystal cell is in the second switching state and the effective refractive index of the liquid crystal matches the refractive index of the diffractive optical element.

[0079] The refractive index of the diffractive optical element is optionally 1.55 or less, and optionally 1.53 or less.

[0080] The refractive index of the diffractive optical element is optionally at least 1.43, optionally at least 1.45, optionally at least 1.47, or optionally at least 1.49.

[0081] The refractive index of the diffractive optical element is optionally 1.43-1.57, optionally 1.45-1.55, and optionally 1.47-1.55.

[0082] Liquid crystal directors located far from the first and second inner surfaces (optionally, midway between the first and second inner surfaces) should, in the non-switched state, form an angle of 20° or less, optionally 15° or less, optionally 10° or less, optionally 8° or less, optionally 5° or less, and optionally 3° or less with respect to the first and second inner surfaces. In the switched state, liquid crystal directors located far from the first and second inner surfaces (optionally, midway between the first and second inner surfaces) should form an angle of at least 60°, optionally at least 70°, optionally at least 80°, and optionally at least 85° with respect to the first and second inner surfaces.

[0083] A lens according to the fourth aspect of the present invention may include any of the features of a lens according to the first, second, and / or third aspect of the present invention.

[0084] According to a fifth aspect of the present invention, an electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell includes a diffractive optical element for correcting the user's vision, and a cholesteric liquid crystal. The first liquid crystal cell can operate between a first non-switched state and a second switched state, where in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state. A contact lens is provided, characterized in that the refractive index of the diffractive optical element is at least 1.58.

[0085] The applicant has discovered that when the refractive index of a diffractive optical element is relatively high, the optical performance of the lens exhibits low sensitivity to wavelengths that are different from each other in a first state.

[0086] In the first or second state (however, preferably the first state), the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element may be small or zero, that is, the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element are approximately the same. In the first state, due to the matching refractive indices, the diffractive optical element does not significantly diffract the incident light. In the first or second state (however, preferably the second state), the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is often larger than in the other state, and as a result, the diffractive optical element diffracts the incident light, which contributes to the refractive power of the contact lens.

[0087] In the first non-switching state, the effective refractive index of the liquid crystal is preferably the average refractive index of the liquid crystal, that is, n ave =0.5(n e +n o ) and in this case, n e This is an anomalous refractive index, and n o This is the normal refractive index. In the second switching state, the effective refractive index of the liquid crystal is n o In other words, it is preferable that it has a normal refractive index.

[0088] The refractive index of the diffractive optical element is optionally at least 1.58, optionally at least 1.60, optionally at least 1.62, optionally at least 1.64, and optionally at least 1.66.

[0089] The refractive index of the diffractive optical element is optionally 1.70 or less, optionally 1.68 or less, and optionally 1.66 or less.

[0090] The refractive index of the diffractive optical element is optionally 1.58-1.70, optionally 1.60-1.68, and optionally 1.62-1.66.

[0091] In the non-switched state, the liquid crystal directors located far from the first and second inner surfaces, and optionally from the midpoint between the first and second inner surfaces, should form an angle of 20° or less, optionally 15° or less, optionally 10° or less, optionally 8° or less, optionally 5° or less, and optionally 3° or less with respect to the first and second inner surfaces. In the switched state, the liquid crystal directors located far from the first and second inner surfaces, and optionally from the midpoint between the first and second inner surfaces, should form an angle of at least 60°, optionally at least 70°, optionally at least 80°, and optionally at least 85° with respect to the first and second inner surfaces.

[0092] According to the sixth perspective, an electrically switchable flexible contact lens that is adapted to the user's eye, wherein the contact lens is The contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell includes a diffractive optical element that corrects the user's vision. A diffractive optical element has multiple peaks and troughs, and the peaks extend in a direction from the first inner surface to the second inner surface. A contact lens is provided, characterized in that at least a portion of at least one of the peaks is attached to a second inner surface.

[0093] By attaching at least one peak of a diffractive optical element to the second inner surface, the motion of the liquid crystal within the cell can be restricted, which may be undesirable.

[0094] The diffractive optical element is preferably positioned to maintain the cell gap thickness by providing supports at one or more locations within the cell.

[0095] The diffractive optical element preferably has a central peak and a plurality of outer peaks, and at least a portion of at least one of the outer peaks is attached to a second inner surface.

[0096] At least one outer peak, optionally two or more outer peaks, each preferably being ring-shaped. Optionally, one or more outer peaks, all of which preferably are concentric.

[0097] At least a large portion, and virtually all, of at least one peak is preferably mounted on the second surface. Such an arrangement prevents the passage of liquid crystal beyond the peak, even if the first liquid crystal cell is deformed.

[0098] It is preferable that virtually all of the two or more peaks be attached to the second inner surface.

[0099] Each peak should be mounted on the second inner surface. Essentially, every single peak should be mounted on the second inner surface.

[0100] The attachment of the peak to the second inner surface may be achieved, for example, using an adhesive. In a modified example, at least one of the peak and the second inner surface may be provided with a molten polymer that is heated and attached to the peak and the second inner surface during cooling.

[0101] According to a seventh aspect of the present invention, an electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The contact lens has a first liquid crystal cell that alters at least one optical property, the first liquid crystal cell having a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell includes a diffractive optical element that corrects the user's vision, and the diffractive optical element has a natural operating wavelength, which is 450 nm to 510 nm. The first liquid crystal cell includes a cholesteric liquid crystal, A contact lens is provided characterized in that the first liquid crystal cell can operate between a first non-switching state and a second switching state, and in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state.

[0102] The applicant has found that it is advantageous to use a diffractive optical element that has a natural operating wavelength lower than the natural operating wavelength typically used for other lenses, such as eyeglass lenses.

[0103] The intrinsic operating wavelength is preferably, for example, 560 nm or less, optionally 550 nm or less, optionally 540 nm or less, optionally 530 nm or less, optionally 520 nm or less, optionally 510 nm or less, optionally 500 nm or less, optionally 490 nm or less, and optionally 480 nm or less. The applicant has discovered that blue diffraction artifacts, which may cause problems in eyeglass lenses at up to 550 nm, do not cause problems in contact lenses, making it possible to obtain a feasible contact lens with an intrinsic operating wavelength of up to approximately 550 nm.

[0104] The intrinsic operating wavelength is preferably, for example, at least 460 nm, optionally at least 470 nm, and optionally at least 480 nm.

[0105] The natural operating wavelength should preferably be, for example, 460-560 nm, with an optional 460-550 nm, an optional 470-490 nm, an optional 470-490 nm, and an optional 480 nm.

[0106] Next, an exemplary embodiment will be described with reference to Figures 1 to 9, but these are merely illustrative examples.

[0107] Figures 1 and 2 show examples of electrically switchable flexible contact lenses as embodiments of the first and second aspects of the present invention. Figure 1 is a schematic cross-sectional view of a contact lens, all denoted by reference numeral 1, which has a flexible lens body 2 made of any suitable material, such as a silicone hydrogel material, a silicon compound-free hydrogel material, and a silicone elastomer material, which incorporates a liquid crystal cell, all denoted by reference numeral 3. Figure 2 is a cross-sectional view of a portion of the contact lens 1. To avoid clutter in the drawings and to facilitate explanation, the liquid crystal cell 3 is shown in Figure 2 as flat / plate-shaped. Those skilled in the art will recognize that this is not the case, and the shape of the liquid crystal cell is correctly shown in Figure 1. The liquid crystal cell 3 has a diffractive optical element 4 and liquid crystal 5 that correct the user's vision. In summary, the liquid crystal is switchable between a first non-switchable state and a second switchable state. With respect to one of the switching state and the non-switching state, the refractive index of the liquid crystal matches the refractive index of the diffractive optical element, and the diffractive optical element has a first focal capability. With respect to the other of the switching state and the non-switching state, the refractive index of the liquid crystal does not match the refractive index of the diffractive optical element, and the diffractive optical element has a second focal capability different from the first focal capability.

[0108] The diffractive optical element 4 has multiple peaks and troughs, with a central peak 10A and eight annular peaks 10B, 10C, 10D, 10E, 10F, 10G, 10H, and 10I arranged concentrically around the central peak, thereby providing nine diffraction zones (one zone is provided between each pair of adjacent peaks). To avoid cluttering the drawings, the relevant troughs are not denoted by reference numerals. Such diffractive elements are known to those skilled in the art of optical instruments. In known lenses, spacer beads or similar are sometimes used to maintain the cell spacing between a first inner surface 6 and a second inner surface 7. In this embodiment, the diffractive optical element 4 acts as a spacer to maintain the cell spacing between the first inner surface 6 and the second inner surface 7. Figure 2 shows the central peak 10A not in contact with the second inner surface, which is done so simply to show that the height of peak 10A is lower than the height of peak 10I, which will be explained in detail below. Spacer 11 is provided around the periphery of the liquid crystal cell 3 outside the diffractive optical element 4. This spacer 11 is formed of beads with a diameter of approximately 4 microns dispersed within the glue. The distance between the first inner surface 6 and the second inner surface 7 is approximately 4 microns, but this distance is greater in the outer region 22 of the liquid crystal cell 3 than in the inner region 21. This difference is approximately 5%, and this difference is due to the difference in the maximum height of the diffractive optical element 4 in the inner portion 21 and the outer portion 22. The maximum height h2 of the diffractive optical element 4 in the outer portion 22 is 4.0 microns, and the maximum height h1 of the diffractive optical element 4 in the inner portion 21 is 3.85 microns. Although this difference in maximum height is small, it improves optical performance. In particular, the applicant has discovered that this arrangement of diffractive optical elements can compensate for the curvature of the cornea when the contact lens is placed on the cornea. Furthermore, this arrangement of diffractive optical elements can help improve the "straight-view appearance," particularly at the edges of lenses containing diffractive optical elements. By increasing the height of the diffractive optical elements at the edges, the optical path at these edges becomes approximately the same as that at the center of the diffractive optical element.With this arrangement of diffractive optical elements, the wavelength at which optimal optical performance is achieved is nearly identical across the entire width of the diffractive optical element. Unless the height is increased, the optical path at the edge of the diffractive optical element becomes slightly shorter than that at the center of the diffractive optical element, which is undesirable.

[0109] The height of peaks 10A to 10I increases with increasing distance from the center of the diffractive optical element 4. The height of peaks 10A to 10I may increase sublinearly, linearly, or predominantly linearly with increasing distance from the center of the diffractive optical element.

[0110] The diffractive optical element 4 is a "chopped" sphere such that the wavefront passing through the diffractive optical element exhibits a 2π phase shift across each zone boundary (acknowledging that, strictly speaking, the 2π shift occurs at only one wavelength). As expected, instead of a simple sphere (which gives a simple and uniform spherical power across the region of the diffractive optical element), the shape of the diffractive optical element may be simply modified to have different refractive powers across the entire region of the diffractive optical element. For example, an oval-shaped diffractive optical element may be used to treat astigmatism.

[0111] The diffractive optical element 4 maintains a gap between the first inner surface 6 and the second inner surface 7, and this diffractive optical element prevents a significant reduction in the gap that may occur when the lens 1 (and thus the liquid crystal cell 3) is deformed, for example, when the lens is placed on the wearer's cornea. The cornea is generally aspherical, and the lens deforms when a contact lens is placed on the wearer's cornea. In the absence of the diffractive optical element 4 acting as a spacer, a significant reduction in the gap between the first inner surface 6 and the second inner surface 7 may be observed in some parts of the liquid crystal cell 3 if the contact lens 1 were placed on the wearer's eye. Furthermore, by maintaining the cell gap thickness, a cell gap thickness small enough to allow the liquid crystals to align without haze is maintained.

[0112] The applicant argues that if the contact lens deforms as it would be if the peaks were not attached to the inner surface 7 and were placed on the user's cornea, the liquid crystal may be moved outward toward the outer portion of the contact lens from the space between peaks 10A and 10B, thereby creating a considerable amount of excess liquid crystal between the diffractive optical element and the inner surface 7, increasing the gap between the first inner surface 6 and the second inner surface 7 by up to 1 micron in the region of peaks 10G, 10H, and 10I. To help reduce the displacement of the liquid crystal, at least one, optionally two or more, and optionally each of the peaks 10A to 10I may be attached to the inner surface 7 using an adhesive. As an alternative to adhesive, the peaks 10A to 10I may be attached to the inner surface by melting, pressurizing, and cooling a polymer 9. Furthermore, the peaks may be attached by physical adhesion, for example, by using a plasma treatment process. However, attaching one or more peaks to the inner surface 7 is not essential, because the optical properties of the optical component are not significantly negatively affected by the liquid crystal displacement caused by the diffractive element.

[0113] In liquid crystal device 3, the liquid crystal is a cholesteric liquid crystal consisting of a nematic liquid crystal doped with a chiral dopant. Such nematic liquid crystals are well known to those skilled in the art of liquid crystal science, and may include, for example, E7, BL037, and / or BL038. Such chiral dopants, for example, Merck ZLI-3786, CB15, and S811, are also well known to those skilled in the art of liquid crystal science. The state of local alignment of molecules in liquid crystal device 3 is schematically shown in Figure 3. Referring to Figure 2, the inner surfaces 6 and 7 are formed of alignment polymers that align liquid crystal molecules located adjacent to the rubber polymer. Such alignment of liquid crystal molecules located adjacent to the alignment polymer gives a specific orientation to liquid crystals located far from the alignment polymer, depending on the viscoelastic properties of the liquid crystal. Referring to Figure 2, the layer of polymer 9 is located adjacent to the liquid crystal 5. In this case, the alignment polymer 9 is a UV-curable polymer (Rolic ROP-103 / 2CP). The polymer is cured using appropriately polarized UV radiation, and as a result, this polymer provides a desirable alignment to the liquid crystal adjacent to it. A similar UV-cured polymer layer is provided on the top of the diffractive optical element 4, but this is not shown. The alignment polymer layer is preferably such that the director (average direction of liquid crystal molecules) adjacent to the rubber polymer layer is approximately parallel to the first inner surface 6 and the second inner surface 7, but is typically tilted by several degrees (indicated by small circles adjacent to the first inner surface 6 and the second inner surface 7) (a phenomenon known to those skilled in the art as "pre-tilt"). The tilt of the directors adjacent to the first inner surface 6 and the second inner surface 7 is preferably greater than several degrees. For example, the inclination of the directors located adjacent to the first inner surface 6 and the second inner surface 7 is preferably 10 to 30 degrees. Between the first inner surface 6 and the second inner surface 7, the directors of the liquid crystal 5 form a helical structure. This is shown in Figure 3. As suggested by the shape of the rod, the liquid crystal directors are approximately parallel to the first inner surface 6 and the second inner surface 7, and are located within the plane of the figure. In this non-switching state, the effective refractive index of the liquid crystal is polarization-independent, and nave =0.5(n e +n o Given (Equation 1), in this equation, n e , is an anomalous refractive index, n o This is a normal refractive index. Those skilled in the art will recognize that for a liquid crystal to behave with reasonable approximation as a single refractive index object, it is desirable that the pitch of the liquid crystal be 500 nm or less (i.e., approximately the same as or smaller than the wavelength of incident light). The applicant has found that contact lenses can operate satisfactorily when the liquid crystal has a relatively high pitch (e.g., 600-700 nm) while minimizing significant optical artifacts. This is beneficial because using a relatively high pitch can reduce the switching voltage.

[0114] The alignment of the liquid crystal director adjacent to the alignment polymer 9 is shown in Figure 10, with the arrow indicating the direction of the liquid crystal director adjacent to the alignment polymer. Such alignment is used to provide polarization-independent operation of the contact lens. The alignment of the liquid crystal director adjacent to the polymer layer formed on the diffractive optical element 4 is essentially identical to the alignment shown in Figure 10.

[0115] The constituent materials of the liquid crystal 5 and the diffractive optical element 4 are preferably selected to achieve the desired optical results. For example, the materials used to manufacture the liquid crystal and the diffractive optical element are preferably selected such that the effective refractive index of the liquid crystal matches the effective refractive index of the material used to manufacture the diffractive optical element. In this case, the diffractive optical element does not contribute to the focal capability of the lens. As a variation, if the effective refractive index of the liquid crystal does not match the effective refractive index of the material used to manufacture the diffractive optical element, the diffractive optical element contributes to the focal capability of the lens.

[0116] When an appropriate voltage is applied to the electrodes (8A, 8B) of the liquid crystal cell, the liquid crystal molecules are switched to a homeotropic state schematically shown in Figure 4, in which case the liquid crystal director in the central portion 30 of the liquid crystal cell 3 is perpendicular to the first inner surface 6 and the second inner surface 7. This realignment of the liquid crystal results in different effective refractive indices. In some cases, when the liquid crystal is in the switched state, the effective refractive index of the liquid crystal often matches the refractive index of the material used to manufacture the diffractive optical element 4, in which case the diffractive optical element does not contribute to the focal capability of the lens. Conversely, when the liquid crystal is in the switched state, the effective refractive index of the liquid crystal may not match the refractive index of the material used to manufacture the diffractive optical element 4, in which case the diffractive optical element contributes to the focal capability of the lens.

[0117] Next, an embodiment of a contact lens according to a third aspect of the present invention will be described with reference to Figures 1 and 2. An electrically switchable flexible contact lens is indicated by reference numeral 1. The lens 1 has a liquid crystal cell 3 that changes the focal power of the contact lens. The liquid crystal cell 3 has a diffractive optical element 4 that corrects the user's vision and a cholesteric liquid crystal 5. The liquid crystal cell 3 is operable between a switched state and a non-switched state. The diffractive optical element is made of MR10 and has a refractive index of 1.63. In the non-switched state, the effective refractive index of the liquid crystal cell and the effective refractive index of the diffractive optical element are the same, and therefore the diffractive optical element does not contribute to the focal power of the lens. The average refractive index of the liquid crystal is calculated according to equation 1 described above. The average refractive index of the liquid crystal is effectively matched to the refractive index of the diffractive optical element at all visible wavelengths, i.e., 450 to 700 nm. Thus, matching the refractive index across all visible wavelengths improves optical performance because the amount of diffraction observed from the diffractive optical element is minimized due to the matching of the refractive index across the entire visible spectrum. Those skilled in the art will recognize that a precise matching of the refractive index across the entire visible spectrum is not required.

[0118] Next, an example of an embodiment of a contact lens according to a fourth aspect of the present invention will be described with reference to Figures 1 and 2. The contact lens is collectively denoted by reference numeral 1 and has a liquid crystal cell 3 that changes the focal capacity of the contact lens. The liquid crystal cell 3 has a diffractive optical element 4 that corrects the user's vision and a cholesteric liquid crystal 5. A +1D bulge (not shown) is further provided on the upper surface of the contact lens. The liquid crystal cell 3 can operate between a first non-switching state and a second switching state. In the first state, the liquid crystal molecules are oriented as described above with reference to Figure 3. The average refractive index of the liquid crystal is 1.63. The diffractive optical element 4 is made of Trivex, and this diffractive optical element has a refractive index of 1.51. In the first non-switching state, there is a mismatch between the refractive index of the liquid crystal and the refractive index of the diffractive optical element. As a result, the diffractive optical element contributes to the focal capacity of the lens. The diffractive optical element contributes -1D to the contact lens, and therefore, taking into account this contribution of the diffractive optical element 4 and the +1D bulge, the total power of the lens is 0D. This can be considered the distance vision state. In the second switching state, the effective refractive index of the liquid crystal 5 is 1.51, and there is a match between the refractive index of the liquid crystal and the refractive index of the diffractive optical element. As a result, the diffractive optical element does not contribute to the focal power of the lens. Therefore, the total power of the lens is +1D. This is the near vision state. In the case of insufficient power, the contact lens defaults to distance vision, i.e., the refractive power is 0D.

[0119] The applicant has discovered that it is possible to obtain an excellent match between the effective refractive index of the liquid crystal and the effective refractive index of the material used to create the diffractive optical element for all visible wavelengths of light when the liquid crystal cell is switched to a second state. Figure 5 shows the effective refractive index (n) of the liquid crystal. oThe effective refractive index of the liquid crystal and the material used to make the diffractive optical element is shown to be substantially the same for all visible wavelengths of light once the liquid crystal cell is switched to the second state. In this relationship, the solid line shows the effective refractive index of the liquid crystal and the diffractive optical element. The effective refractive index of the liquid crystal and the diffractive optical element is substantially the same from 400 nm to 700 nm. As a result of this excellent match of refractive indices, the diffractive optical element does not contribute to the refractive power of the lens. Furthermore, Figure 5 shows the intensity of diffraction profiles of various orders observed from the diffractive optical element. In this relationship, the dashed line shows the 0th order diffraction profile, the dashed line (long dash separated by dots) shows the 1st order diffraction profile, and the dotted line shows the 2nd order diffraction profile. Note that the 1st and 2nd order diffraction profiles shown in Figure 5 are shown multiplied by 100. It can be seen that virtually all of the light incident on the contact lens is transmitted, and only a very small amount of light is diffracted, resulting in very small 1st and 2nd order diffraction profiles at all wavelengths.

[0120] Figure 6 shows the intensity of various diffraction peaks from the diffractive optical element as a function of wavelength when the liquid crystal cell 3 is in the first non-switching state. In this case, there is a mismatch between the effective refractive index of the liquid crystal and the effective refractive index of the diffractive optical element, and therefore the diffractive optical element contributes to the focal capability of the lens. In this relationship, the dashed line shows the zero-order diffraction profile, the dashed line (long dash separated by dots) shows the first-order diffraction profile, and the dotted line shows the second-order diffraction profile. Figure 6 shows that although there is some wavelength dependence, the optical performance of the lens is still good. Surprisingly, the applicant found that despite some wavelength dependence of the optical response of the contact lens, the lateral iridescence observed in spectacle lenses is not observed in contact lenses. Therefore, the applicant demonstrated that lenses with good optical performance can be obtained using diffractive optical elements with relatively low refractive indices (i.e., 1.57 or less).

[0121] Next, an example of an embodiment of a contact lens according to a fifth aspect of the present invention will be described with reference to Figures 1 and 2. The contact lens is collectively denoted by reference numeral 1 and has a liquid crystal cell 3 that changes the focal power of the contact lens. The liquid crystal cell 3 has a diffractive optical element 4 that corrects the user's visual acuity and a cholesteric liquid crystal 5. The liquid crystal cell 3 can operate between a first non-switching state and a second switching state, and the difference between the refractive index of the liquid crystal and the refractive index of the diffractive optical element in the first state is smaller than in the second state. The refractive index of the diffractive optical element is 1.63. In the first non-switching state, the effective refractive index of the liquid crystal is 1.63, and there is a match between the refractive index of the liquid crystal and the refractive index of the diffractive optical element. As a result, the diffractive optical element does not contribute to the focal power of the lens. Therefore, the total power of the contact lens is 0D. This can be considered to be the distance visual acuity state. In the second switching state, the effective refractive index of liquid crystal 5 is 1.51, and there is a mismatch between the refractive index of the liquid crystal and the refractive index of the diffractive optical element. As a result, the diffractive optical element contributes to the focal power of the lens. Therefore, the total power of the lens is +1D. This is the near or close-vision state. In the case of insufficient power, the contact lens defaults to distance vision, i.e., the refractive power is 0D.

[0122] The applicant discovered that when the liquid crystal cell is in a first non-switching state, a good agreement can be obtained between the effective refractive index of the liquid crystal and the effective refractive index of the material making up the diffractive optical element for all visible wavelengths of light, with only a slight difference in refractive index at lower wavelengths (below 500 nm). In this relationship, the refractive index of the liquid crystal is shown as a solid line, and the refractive index of the diffractive optical element is shown as a thin dashed line located immediately next to the solid line. As a result of this excellent agreement in refractive index, the diffractive optical element does not contribute much to the refractive power of the lens. Figure 7 shows the intensity of diffraction profiles of various orders observed from the diffractive optical element. In this relationship, the thick dashed line shows the 0th-order diffraction profile, the dashed line (long dash separated by dots) shows the 1st-order diffraction profile, and the dotted line shows the 2nd-order diffraction profile. Note that the 1st and 2nd-order diffraction profiles shown in Figure 7 are shown multiplied by 100. It can be seen that virtually all of the light incident on the contact lens is transmitted, with only a very small amount of light being diffracted, resulting in extremely small primary and secondary diffraction profiles at all wavelengths.

[0123] Figure 8 shows the intensity of various diffraction peaks from the diffractive optical element as a function of wavelength when the liquid crystal cell 3 is in the second switching state. In this case, there is a mismatch between the effective refractive index of the liquid crystal and the effective refractive index of the diffractive optical element, and the diffractive optical element contributes to the focal capability of the lens. In this relationship, the thick dashed line shows the zero-order diffraction profile, the dashed line (long dash separated by dots) shows the first-order diffraction profile, and the dotted line shows the second-order diffraction profile. Figure 8 shows that there is a very slight wavelength dependence and the optical performance of the lens is still good. Thus, the applicant has demonstrated that a lens with good optical performance can be obtained using a diffractive optical element with a relatively high refractive index (i.e., at least 1.58). Surprisingly, the applicant found that the lateral iridescence observed in spectacle lenses is not observed in contact lenses, despite the presence of some wavelength dependence of the optical response of contact lenses.

[0124] The contact lens described above exhibits unexpectedly good peripheral imaging performance. In this relationship, light is expected to enter the diffractive optical element from a wide range of angles, and due to the wide variation in the angle of incidence and the curvature of the cornea, a large change in the optical path length passing through the diffractive optical element occurs, resulting in poor optical performance. However, the applicant has discovered that peripheral light entering the contact lens and traveling through the pupil passes through a portion of the diffractive optical element that is almost perpendicular to the incident light; that is, this light is from almost the same direction and there is almost no variation in the angle of incidence. This results in good peripheral imaging performance.

[0125] Furthermore, as the angle of incidence of light increases from the perpendicular, the amount of light passing through the diffractive optical element decreases. At a certain angle, virtually no light passes through the diffractive optical element, and no optical artifacts are observed. For example, with incident light at approximately 53° and a pupil size of 5mm, about half of the detected light beam enters the diffractive optical element, and the other half passes through the non-diffractive region of the contact lens. For light with a larger angle of incidence than this, the effective area of ​​the diffractive optical element exposed to the light decreases further, so if the light beam completely exits the diffractive region, optical artifacts become non-negligible. Therefore, as far as the user is concerned, there should be no abrupt start / stop of the diffractive region, only a smooth change in the amplitude of contribution. In the concrete example of eyeglass lenses, this appears as a sharp leap between viewing through the diffractive optical element and not viewing through it.

[0126] The applicant also found that the astigmatism of peripheral light caused by incident light passing through the diffractive optical element at a non-right angle is acceptable (average approximately 0.3D).

[0127] Next, an example of an embodiment of a flexible contact lens according to the seventh aspect of the present invention will be described with reference to Figure 1. This contact lens is essentially the same as the contact lens described in relation to the fifth aspect of the present invention. The contact lens is collectively denoted by reference numeral 1, and the contact lens 1 has a liquid crystal cell 3 that changes the focal capacity of the contact lens, and the contact lens has a cell gap thickness between a first inner surface and a second inner surface. The liquid crystal cell 3 has a diffractive optical element 4 that corrects the user's vision, and a cholesteric liquid crystal 5. The liquid crystal cell 3 can operate between a first state and a second state, and the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element in the first state is greater than in the second state. The liquid crystal cell and the diffractive optical element have a natural operating wavelength, which is 450 nm to 510 nm. The natural operating wavelength is the wavelength at which one or more characteristics of the lens are optimized. For example, the transmittance of the lens is preferable when the liquid crystal cell is in a state where the effective refractive index of the liquid crystal matches the effective refractive index of the diffractive optical element, or when the effective refractive index of the liquid crystal does not match the effective refractive index of the diffractive optical element. Figure 8 shows how the properties of a contact lens can be optimized at 480 nm. Those skilled in the art will understand that other optical properties can be optimized at or near 480 nm. Those skilled in the art will understand that optimization can be determined, for example, by changing the liquid crystal to change the refractive index of the liquid crystal or the cell spacing between the first inner surface and the second inner surface.

[0128] The effective refractive index of a liquid crystal depends on the orientation of the liquid crystal molecules. For example, in the non-switching state, the effective refractive index of the liquid crystal is the average refractive index calculated by equation 1 as described above. In the switching state, the effective refractive index of the liquid crystal is n o That is the case.

[0129] All contact lenses according to various aspects of the present invention may have two or more liquid crystal cells, which will be described below with reference to Figure 9. An example of a contact lens according to the first aspect of the present invention is shown collectively by reference numeral 101. The lens 101 has a first liquid crystal cell 3 and a second liquid crystal cell 3' provided within the lens body 2. The first liquid crystal cell 3 is substantially the same as described above with respect to the contact lens according to the first aspect of the present invention. The second liquid crystal cell 3' is substantially identical to the first liquid crystal cell 3. Those skilled in the art will understand that this is not necessary.

[0130] Those skilled in the art will understand that the lens of the present invention may have a different diffractive optical element than the lens described above. In this relationship, the number of diffraction zones is directly proportional to the refractive power (expressed as diopters) of the diffractive lens and also directly proportional to the square of the diameter of the diffractive optical element. Therefore, the smaller the diffractive optical element, the fewer diffraction zones are required to produce a given refractive power. Table 1 below shows the number of diffraction zones required to give a given focal capacity for a given diameter of the diffractive optical element. TIFF0007846218000001.tif34153 Table 1 - Number of diffraction zones required to achieve a certain focal capacity for a given diameter of a diffractive optical element

[0131] Naturally, it will be understood that features described in relation to one aspect of the present invention can be incorporated into another aspect of the present invention. For example, a method of the present invention may include any of the features described in relation to the apparatus of the present invention, and vice versa.

[0132] Next, another aspect of the present invention will be described with reference to the following embodiment descriptions. [Embodiment Item A1] An electrically switchable flexible contact lens that fits the user's eye, and the above contact lens is, The above-mentioned contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell described above includes a diffractive optical element that corrects the user's vision. A contact lens in which the diffractive optical element is arranged to maintain the cell gap thickness by providing supports at one or more locations within the cell. [Embodiment A2] The contact lens according to embodiment 1A, further comprising a peripheral spacer provided around the first liquid crystal cell, which maintains the cell gap thickness in addition to the diffractive optical element. [Embodiment A3] The contact lens according to Embodiment A1 or A2, wherein the first liquid crystal cell includes a cholesteric liquid crystal, the first liquid crystal cell is capable of operating between a first non-switching state and a second switching state, and in one of the first and second states, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater than in the other of the first and second states. [Embodiment Section A4] In the other of the first and second states described above, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is approximately zero, as described in Embodiment A3 of the contact lens. [Embodiment A5] The contact lens according to any one of embodiments A1 to A4, wherein the diffractive optical element has an inner portion and an outer portion, and the height of the diffractive optical element in the outer portion is greater than the height of the diffractive optical element in the inner portion. [Embodiment A6] A contact lens according to any one of embodiments A1 to A5, wherein at least a portion of the diffractive optical element is preferably attached to the first inner surface, and at least a portion of the diffractive optical element is preferably attached to the second inner surface. [Embodiment Item A7] At both 450nm and 700nm, the average refractive index of the above liquid crystal is 0.80 to 1.20 times the refractive index of the above diffractive optical element, and the above average refractive index is n ave =0.5(n e +n o ) and in this equation, n e This is the extraordinary refractive index, and n o The contact lens is one of the embodiments A1 to A6, wherein the refractive index is that of an ordinary light source. [Embodiment A8] The contact lens according to Embodiment A7, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.95 to 1.05 times the refractive index of the diffractive optical element. [Embodiment B1] An electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The above-mentioned contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell described above includes a diffractive optical element for correcting the user's vision, wherein the diffractive optical element has an inner portion and an outer portion, and the height of the diffractive optical element in the outer portion is 1% to 20% greater than the height of the diffractive optical element in the inner portion, in a contact lens. [Embodiment B2] The contact lens according to Embodiment B1, wherein the height of the diffractive optical element in the outer portion is at least 3% and up to 15% greater than the height of the diffractive optical element in the inner portion. [Embodiment B3] The contact lens according to embodiment B1 or B2, wherein the diffractive optical element has multiple peaks and troughs, and the outer portion has an outer peak, optionally the outermost peak. [Embodiment Section B4] The contact lens according to any one of embodiments B1 to B13, wherein the diffractive optical element extends over a chord length r, the inner portion consists of a part of the diffractive optical element that lies within a chord length range of r / 8 from the center of the diffractive optical element, and the outer portion consists of a part of the diffractive optical element having a chord length of 3r / 8 to r / 2. [Embodiment B5] The above liquid crystal is made of cholesteric liquid crystal, and optionally, in the non-switched state, the director of the liquid crystal is preferably at an angle of 5° or less with respect to the first and second inner surfaces, and in the switched state, the director of the liquid crystal is preferably at an angle of at least 60° with respect to the first and second inner surfaces, and optionally at least 70°, optionally at least 80°, and optionally at least 85°, the contact lens according to any one of the embodiments B1 to B4. [Implementation item C1] An electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The above-mentioned contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell described above includes a diffractive optical element for correcting the user's vision and a cholesteric liquid crystal. The first liquid crystal cell described above can operate between a first non-switched state and a second switched state, and in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state. At both 450nm and 700nm, the average refractive index of the above liquid crystal is 0.80 to 1.20 times that of the refractive index of the above diffractive optical element, and the average refractive index of the above liquid crystal is n ave And thus, n ave =0.5(n e +n o ) is calculated as, In the above equation, n e This is the extraordinary refractive index, and n o This is a contact lens with a normal refractive index. [Embodiment Section C2] The contact lens according to embodiment C1, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.95 to 1.10 times the refractive index of the diffractive optical element. [Embodiment C3] The contact lens according to embodiment C1 or C2, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.95 to 1.05 times the refractive index of the diffractive optical element. [Action Section C4] The contact lens according to any one of embodiments C1 to C3, wherein the average refractive index of the liquid crystal is 0.95 to 1.05 times that of the refractive index of the diffractive optical element at 500 nm. [Embodiment D1] An electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The above-mentioned contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell described above includes a diffractive optical element for correcting the user's vision and a cholesteric liquid crystal. The first liquid crystal cell described above can operate between a first non-switched state and a second switched state, and in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state. A contact lens in which the refractive index of the above-mentioned diffractive optical element is 1.57 or less. [Initiation Item E1] An electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The above-mentioned contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell described above includes a diffractive optical element for correcting the user's vision and a cholesteric liquid crystal. The first liquid crystal cell described above can operate between a first non-switched state and a second switched state, and in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state. A contact lens in which the refractive index of the diffractive optical element is at least 1.58. [Embodiment F1] An electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The above-mentioned contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell described above includes a diffractive optical element that corrects the user's vision. The above diffractive optical element has a plurality of peaks and troughs, and the peaks extend in a direction from the first inner surface toward the second inner surface. A contact lens in which at least a portion of at least one of the peaks is attached to the second inner surface. [Embodiment F2] The contact lens according to embodiment F1, wherein the diffractive optical element has a central peak and a plurality of outer peaks, and at least a portion of at least one of the outer peaks is attached to the second inner surface. [Embodiment F3] The contact lens according to Embodiment F2, wherein at least one, optionally two or more, of the above-mentioned outer peaks is annular, each optionally being cyclic. [Embodiment F4] A contact lens according to any one of embodiments F1 to F3, wherein at least a large portion of at least one peak, and optionally substantially the entire periphery, is attached to the second inner surface. [Embodiment Section G1] An electrically switchable flexible contact lens that fits the user's eye, wherein the contact lens is The above-mentioned contact lens has a first liquid crystal cell that changes at least one optical property, wherein the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell described above includes a diffractive optical element that corrects the user's vision, and the diffractive optical element has a natural operating wavelength, which is 450 nm to 510 nm. The first liquid crystal cell described above includes a cholesteric liquid crystal, The first liquid crystal cell described above can operate between a first non-switching state and a second switching state, and in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater or smaller than in the second state, in a contact lens. [Embodiment Section G2] The contact lens according to Embodiment G1, wherein the above-mentioned intrinsic operating wavelength is 460nm to 490nm, optionally 470nm to 490nm, and optionally 480nm.

[0133] Although the present invention has been described and illustrated with respect to specific embodiments, those skilled in the art will understand that the present invention can be implemented in a wide variety of modifications not specifically shown herein. Some possible modifications are described below, but these are merely illustrative.

[0134] The use of diffractive optical elements is not limited to liquid crystal cells made of cholesteric liquid crystals. For example, other types of liquid crystal cells, including undoped nematic and smectic liquid crystals, can be used.

[0135] Where the above description refers to integers or elements for which known, obvious, or predictable equivalents exist, such equivalents are incorporated herein as if they were individually described. The claims defining the true scope of the invention should be referred to, and such true scope should be understood to include any such equivalents. Furthermore, it will be understood that integers or features of the invention described as preferred, advantageous, convenient, etc., are optional and do not limit the scope of the invention as described in the independent claims. Moreover, such optional integers or features may be beneficial in some embodiments of the invention, but may be undesirable and therefore should not be described in other embodiments.

Claims

1. An electrically switchable flexible contact lens that is adapted to the user's eye, wherein the flexible contact lens is The flexible contact lens has a first liquid crystal cell that changes the focusing ability, and the first liquid crystal cell has a cell gap thickness between a first inner surface and a second inner surface. The first liquid crystal cell includes a diffractive optical element that corrects the user's vision. The diffractive optical element is arranged to maintain the cell gap thickness by providing supports at one or more locations within the cell. The diffractive optical element has an inner portion and an outer portion, and the maximum height of the diffractive optical element in the outer portion is greater than the maximum height of the diffractive optical element in the inner portion. As a result, the diffractive optical element in the outer portion is supported by the first inner surface and the second inner surface, and the distance between the first inner surface and the second inner surface is longer in the outer region of the first liquid crystal cell than the distance in the inner region of the first liquid crystal cell. A flexible contact lens wherein the diffractive optical element has a plurality of peaks and troughs, and by providing the support at one or more locations within the cell, one or more of the plurality of peaks of the diffractive optical element maintains the cell gap thickness.

2. The flexible contact lens according to claim 1, further comprising a peripheral spacer provided around the first liquid crystal cell, which maintains the cell gap thickness in addition to the diffractive optical element.

3. The flexible contact lens according to claim 1, wherein the first liquid crystal cell includes a cholesteric liquid crystal, the first liquid crystal cell is capable of operating between a first non-switching state and a second switching state, and in one of the first and second states, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is greater than in the other of the first and second states.

4. The flexible contact lens according to claim 3, wherein in the other of the first and second states, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element is approximately zero.

5. The flexible contact lens according to claim 1, wherein the diffractive optical element has an inner portion and an outer portion, and the height of the diffractive optical element in the outer portion is greater than the height of the diffractive optical element in the inner portion.

6. The flexible contact lens according to claim 1, wherein at least a portion of the diffractive optical element is attached to the first inner surface, and at least a portion of the diffractive optical element is attached to the second inner surface.

7. At both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.80 to 1.20 times the refractive index of the diffractive optical element, and the average refractive index is n ave = 0.5(n e +n o ) and in this equation, n e This is the anomalous refractive index, n o The flexible contact lens according to claim 1, wherein the refractive index is that of an ordinary light source.

8. The flexible contact lens according to claim 7, wherein at both 450 nm and 700 nm, the average refractive index of the liquid crystal is 0.95 to 1.05 times the refractive index of the diffractive optical element.

9. The flexible contact lens according to claim 1, further comprising a second liquid crystal cell that changes the focusing ability of the flexible contact lens, wherein the second liquid crystal cell has the characteristics of the first liquid crystal cell.

10. The flexible contact lens according to claim 1, wherein the height of the diffractive optical element in the outer portion is at least 3% and up to 15% greater than the height of the diffractive optical element in the inner portion.

11. The flexible contact lens according to claim 1, wherein the diffractive optical element extends over a chord length r, the inner portion consists of a part of the diffractive optical element that lies within a chord length range of r / 8 from the center of the diffractive optical element, and the outer portion consists of a part of the diffractive optical element having a chord length of 3r / 8 to r / 2.

12. The flexible contact lens according to claim 10, wherein the liquid crystal is made of cholesteric liquid crystal, and in the non-switched state, the director of the liquid crystal is at an angle of 5° or less with respect to the first and second inner surfaces, and in the switched state, the director of the liquid crystal is at an angle of at least 60° with respect to the first and second inner surfaces.

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