Flexible liquid crystal-containing lenses

Abstract

The present invention provides an electrically switchable flexible contact lens conforming to the eye of a user. The lens includes: a liquid crystal cell for changing the power of the contact lens, the liquid crystal cell having a cell gap thickness between a first inner surface and a second inner surface, the liquid crystal cell including a diffraction optical element for correcting the user's vision, wherein the diffraction optical element is configured to maintain the cell gap thickness by providing support 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. More specifically, but not exclusively, this invention relates to an electrically switchable contact lens. [Previous Technology]

[0003] A flexible contact lens including a diffractive optical element is known. The lens may have a liquid crystal that can be electrically switched between two states. In a first state, the refractive index of the liquid crystal does not match the refractive index of the diffractive optical element, and the diffractive optical element interacts with and diffracts the light. In a second state, the refractive index of the liquid crystal matches the refractive index of the diffractive optical element, and the incident light is either not diffracted or exhibits very little diffraction.

[0004] The present invention provides a modified flexible contact lens comprising one of a diffractive optical elements. [Summary of the Invention]

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

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

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

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

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

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

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

[0012] Preferred but preferred features of the invention are set forth below and in the accompanying technical solutions.

[0013] Of course, it should be understood that features described in one aspect of the present invention may be incorporated into other aspects.

Implementation Method

[0025] According to a third aspect of the present invention, an electrically switchable flexible contact lens conforming to the eye of a user is provided, the lens comprising: a first liquid crystal cell for changing a power of the contact lens and having a cell gap thickness between a first inner surface and a second inner surface, the first liquid crystal cell including a diffraction optical element for correcting the vision of a user, wherein the diffraction optical element is configured to maintain the cell gap thickness by providing support at one or more locations within the cell.

[0026] The applicant has found that it is feasible to use a diffractive optical element as a spacer to maintain the thickness of one unit gap in a flexible ophthalmic lens.

[0027] Maintaining the inter-cell thickness is important for maintaining the optical properties of ophthalmic lenses. Specifically, maintaining the inter-cell thickness maintains a sufficiently small inter-cell gap so that the liquid crystal can be aligned without haze. In this regard, maintaining the inter-cell thickness may include an average reduction of one of the inter-cell thicknesses across the first liquid crystal cell by no more than 15%, depending on the situation no more than 12%, depending on the situation no more than 10%, depending on the situation no more than 8%, and depending on the situation no more than 5%. Maintaining the inter-cell thickness may only allow a relatively small reduction and / or increase in one of the inter-cell thicknesses. In this regard, when the ophthalmic lens is deformed due to being placed on a user's eye, the average change in the inter-cell thickness across the first liquid crystal cell may depending on the situation no more than 15%, depending on the situation no more than 12%, depending on the situation no more than 10%, depending on the situation no more than 8%, and depending on the situation no more than 5%.

[0028] The average inter-unit gap thickness in an undeformed lens is, depending on the circumstances, at least 2.0 micrometers, depending on the circumstances, at least 3.0 micrometers, depending on the circumstances, at least 3.5 micrometers, depending on the circumstances, at least 4.0 micrometers, depending on the circumstances, at least 4.5 micrometers, and depending on the circumstances, at least 5.0 micrometers.

[0029] The average inter-unit gap thickness in an undeformed lens is, depending on the circumstances, no greater than 7.0 micrometers, no greater than 6.5 micrometers, no greater than 6.0 micrometers, no greater than 5.5 micrometers, no greater than 5.0 micrometers, no greater than 4.5 micrometers and no greater than 4.0 micrometers.

[0030] As used herein and as understood by one skilled in the art, micron is the same as micrometer.

[0031] The average inter-unit gap thickness in an undeformed lens is, depending on the circumstances, from 2.0 micrometers to 7.0 micrometers, depending on the circumstances, from 2.5 micrometers to 5.5 micrometers, depending on the circumstances, from 3.5 micrometers to 5.0 micrometers, and depending on the circumstances, from 3.5 micrometers to 4.5 micrometers.

[0032] The average height of the diffractive optical element can correspond to the average cell gap thickness. Similarly, the height of the diffractive element at a point in the first liquid crystal cell can correspond to the cell gap thickness at that point in the first liquid crystal cell.

[0033] The first liquid crystal cell may substantially be without other elements (such as spacers) for maintaining the cell gap thickness by providing support at the location within the cell. However, depending on the circumstances, a peripheral spacer may also be provided at the periphery of the first liquid crystal cell in addition to diffraction optical elements.

[0034] To avoid any doubt, a diffractive optical element is one whose size and dimensions are sufficiently small relative to the wavelength of light incident upon it in order to cause one of the characteristics of controlled and desired optical effects arising solely from the diffraction of light. To avoid any doubt, the diffractive optical element does not contain a Fresnel lens.

[0035] The first liquid crystal cell can operate between a first unswitched 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 can be greater or lower 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 can be small or zero, i.e., the effective refractive indices of the liquid crystal and the diffractive optical element can 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, depending on the circumstances, be no greater than 0.03, no greater than 0.02, and no greater than 0.01. Such differences in refractive index are to be calculated for one wavelength in the visible portion of the electromagnetic spectrum (radiation having a wavelength from 450 to 700 nm). Such differences in refractive index can be calculated at a wavelength of 450 nm, and depending on the circumstances, at a wavelength of 700 nm. Depending on the circumstances, such differences can be calculated at a plurality of 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 are mismatched, and therefore, the diffractive optical element diffracts the incident light. The first state can be an unswitched state, i.e., in which no voltage or a low voltage is applied to the first liquid crystal cell. The second state can be a switched state, i.e., in which a voltage is applied to switch the liquid crystal in the cell to one of the second states.

[0036] To avoid any doubt, the effective refractive index is the refractive index of the liquid crystal for light normally incident on the contact lens and the first liquid crystal cell. In the first unswitched state, the effective refractive index can be nave = 0.5(no + ne), where no is the ordinary refractive index of the liquid crystal and ne is the extraordinary refractive index of the liquid crystal. In the second switched state, the effective refractive index can be no.

[0037] To avoid any doubt, "for the purpose of correcting a user's vision" includes the use of correcting a user's myopia, hyperopia and / or intermediate vision.

[0038] The maximum height of a diffracting optical element does not need to be the same across the entire diffracting optical element. For example, a diffracting optical element may include an inner portion and an outer portion. The maximum height of the diffracting optical element at the outer portion may be greater than the maximum height of the diffracting optical element at the inner portion. The maximum height of the diffracting optical element at the outer portion may be up to 20%, possibly up to 15%, possibly up to 10%, possibly up to 7.5%, possibly up to 5%, possibly up to 2.5%, and possibly up to 1% greater than the maximum height of the diffracting optical element at the inner portion. The height of the diffracting optical element is typically along the optical axis.

[0039] The maximum height of the diffractive optical element at the outer portion may be at least 1% greater than the maximum height of the diffractive optical element at the inner portion, and may be at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 10%, at least 12.5%, at least 15%, and at least 20%.

[0040] The internal part may be located at or near the center of the diffractive optical element.

[0041] The height of the diffractive optical element can increase with the distance from the center of the diffractive optical element. The height of the diffractive optical element can increase linearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element can increase sublinearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element can increase superlinearly with the distance from the center of the diffractive optical element.

[0042] At least a portion of the diffractive optical element may be attached to the first surface and at least a portion of the diffractive optical element may be attached to the second surface.

[0043] As mentioned above, the diffractive optical element may include a plurality of peaks and valleys, and, where appropriate, annular peaks and valleys. The outer portion may include an outer peak, for example, one of ten outermost peaks, one of eight outermost peaks, one of five outermost peaks, and one of three outermost peaks. The outer portion may include an outermost portion. The height of the peak may increase with distance from the center of the diffractive optical element. The height of the peak may increase linearly with distance from the center of the diffractive optical element. The height of the peak may increase sublinearly with distance from the center of the diffractive optical element. The height of the peak may increase superlinearly with distance from the center of the diffractive optical element.

[0044] At least a portion of one peak may be attached to the second surface.

[0045] The liquid crystal may include a cholesteric liquid crystal. In an unswitched state, a pointer of the liquid crystal adjacent to the first and / or second inner surfaces may form an angle with the first and second inner surfaces of no more than 20 degrees, no more than 15 degrees, no more than 10 degrees, no more than 8 degrees, no more than 5 degrees, and no more than 3 degrees. In an unswitched state, a pointer of the liquid crystal located away from the first and second inner surfaces (and, depending on the middle between the first and second inner surfaces) may form an angle with the first and second inner surfaces of no more than 20 degrees, no more than 15 degrees, no more than 10 degrees, no more than 8 degrees, no more than 5 degrees, and no more than 3 degrees. In a switched state, a pointer of the liquid crystal located away from the first and second inner surfaces (and, depending on the middle between the first and second inner surfaces) may form an angle with the first and second inner surfaces of at least 60 degrees, at least 70 degrees, at least 80 degrees, and at least 85 degrees.

[0046] The refractive index of the diffractive optical element may be at least 1.40, at least 1.42, at least 1.44, at least 1.46 and at least 1.48, depending on the circumstances.

[0047] The refractive index of the diffractive optical element may be no greater than 1.72, no greater than 1.70, no greater than 1.68, no greater than 1.66 and no greater than 1.64, depending on the circumstances.

[0048] For example, the refractive index of the diffractive optical element may be from 1.40 to 1.72, preferably from 1.42 to 1.70, and even more preferably from 1.44 to 1.68.

[0049] The contact lens may include a further optical element for correcting a user's vision. In this respect, the contact lens may include a lens body for correcting a user's vision. The lens body may provide a positive optical diopter, such as +0.5, +1.0, or +1.5D. The optical diopter of the lens body may be fixed. The addition of this lens body may be particularly useful when the first liquid crystal cell is in a second switching state if the effective refractive index of the liquid crystal matches the refractive index of the diffractive optical element.

[0050] At both 450 nm and 700 nm, the refractive index of the liquid crystal is, depending on the case, 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.

[0051] At 500 nm, the refractive index of the liquid crystal can be 0.80 to 1.20 times that of the refractive index of the diffractive optical element, which may be 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 that of the diffractive optical element, depending on the circumstances.

[0052] The refractive index of the liquid crystal is the average refractive index n ave, so it is calculated as: n ave = 0.5(ne + no), where ne is the unusual refractive index and no is the ordinary refractive index.

[0053] The first liquid crystal unit may include a cholesteric liquid crystal, and the refractive index of the diffractive optical element is not greater than 1.57 as appropriate.

[0054] The first liquid crystal unit may include a cholesteric liquid crystal, and the refractive index of the diffractive optical element is at least 1.58, depending on the case.

[0055] A diffractive optical element may include a plurality of peaks and valleys, which may be annular. The peaks and valleys may be concentric. At least one peak, or more than one peak, and each peak may maintain the inter-element thickness by providing support at one or more locations within the element.

[0056] A diffractive optical element may include at least 5 peaks, at least 7 peaks, and at least 10 peaks. A diffractive optical element may include no more than 20 peaks, at least 15 peaks, and at least 10 peaks.

[0057] A contact lens may include more than one liquid crystal cell. For example, a contact lens may include a second liquid crystal cell. The first and second liquid crystal cells may be configured such that light travels through both liquid crystal cells before reaching the wearer's eye. The second liquid crystal cell may include the features described above in relation to the first aspect of the invention. For example, the second liquid crystal cell may include a diffraction optical element serving as a spacer in the second liquid crystal cell.

[0058] According to a second aspect of the present invention, an electrically switchable flexible contact lens conforming to the eye of a user is also provided, the lens comprising: a first liquid crystal unit for changing the power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface; the first liquid crystal unit comprising a diffraction optical element for correcting the vision of a user, the diffraction optical element comprising an inner portion and an outer portion, the maximum height of the diffraction optical element at the outer portion being greater than the maximum height of the diffraction optical element at the inner portion by 1% to 20%.

[0059] The applicant has found that it is advantageous for a diffractive optical element to have a greater maximum height at the outer portion of one of the first liquid crystal cells than at the inner portion, but the difference in maximum height should be limited. Specifically, the applicant has found that this configuration of the diffractive optical element can compensate for the curvature of the cornea when a contact lens is placed on the cornea. Furthermore, particularly at the edge of a lens including a diffractive optical element, this configuration of the diffractive optical element can help improve "direct vision." This configuration of the diffractive optical element helps ensure that the optical path of light at the edge of the diffractive optical element is approximately the same as the optical path of light at the center of the diffractive optical element.

[0060] The height of a diffractive optical element is usually the height along the optical axis.

[0061] The maximum height is usually measured locally (i.e., relative to the substrate or bottom of one of the diffractive optical elements).

[0062] The maximum height of the diffractive optical element at the outer part may be up to 15%, up to 10%, up to 7.5%, up to 5%, and up to 2.5% greater than the maximum height of the diffractive optical element at the inner part.

[0063] The maximum height of the diffractive optical element at the outer portion may be at least 2%, and possibly at least 3%, possibly at least 4%, possibly at least 5%, possibly at least 6%, possibly at least 7%, possibly at least 8%, possibly at least 10%, possibly at least 12.5%, and possibly at least 15%.

[0064] The height of the diffractive optical element can increase with the distance from the center of the diffractive optical element. The height of the diffractive optical element can increase linearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element can increase sublinearly with the distance from the center of the diffractive optical element. The height of the diffractive optical element can increase superlinearly with the distance from the center of the diffractive optical element.

[0065] The internal part may be located at or near the center of the diffractive optical element.

[0066] The diffractive optical element may extend within a chord length r. The inner portion may include a portion of the diffractive optical element within a chord length r / 8 from a center of the diffractive optical element. The outer portion may include a portion of the diffractive optical element having a chord length from r / 4 (and, in some cases, from 3r / 8) to r / 2.

[0067] The diffractive optical element may include a plurality of peaks and valleys, and, where appropriate, annular peaks and valleys. The outer portion may include an outer peak, for example, one of ten outermost peaks, one of eight outermost peaks, one of five outermost peaks, and one of three outermost peaks. The outer portion may include an outermost portion. The height of the peak may increase with distance from the center of the diffractive optical element. The height of the peak may increase linearly with distance from the center of the diffractive optical element. The height of the peak may increase sublinearly with distance from the center of the diffractive optical element. The height of the peak may increase superlinearly with distance from the center of the diffractive optical element.

[0068] The liquid crystal may include a cholesteric liquid crystal. In an unswitched state, a pointer of the liquid crystal located at a distance from the first inner surface and the second inner surface (and, depending on the situation, the middle between the first and second inner surfaces) may form an angle with the first and second inner surfaces of no more than 20 degrees, no more than 15 degrees, no more than 10 degrees, no more than 8 degrees, no more than 5 degrees, and no more than 3 degrees, depending on the situation. In a switched state, a pointer of the liquid crystal located at a distance from the first and second inner surfaces (and, depending on the situation, the middle between the first and second inner surfaces) may form an angle with the first and second inner surfaces of at least 60 degrees, at least 70 degrees, at least 80 degrees, and at least 85 degrees, depending on the situation.

[0069] The average inter-unit gap thickness in an undeformed lens is, depending on the circumstances, at least 2.0 micrometers, depending on the circumstances, at least 3.0 micrometers, depending on the circumstances, at least 3.5 micrometers, depending on the circumstances, at least 4.0 micrometers, depending on the circumstances, at least 4.5 micrometers, and depending on the circumstances, at least 5.0 micrometers.

[0070] The average inter-unit gap thickness in an undeformed lens is, depending on the circumstances, no greater than 7.0 micrometers, no greater than 6.5 micrometers, no greater than 6.0 micrometers, no greater than 5.5 micrometers, no greater than 5.0 micrometers, no greater than 4.5 micrometers and no greater than 4.0 micrometers.

[0071] The average inter-unit gap thickness in an undeformed lens is, depending on the circumstances, from 2.0 micrometers to 7.0 micrometers, from 2.5 micrometers to 5.5 micrometers, from 3.5 micrometers to 5.0 micrometers, and from 3.5 micrometers to 4.5 micrometers.

[0072] The second state of the contact lens of the present invention may include any feature of the first state of the contact lens of the present invention.

[0073] According to a third aspect of the present invention, an electrically switchable flexible contact lens conforming to the eye of a user is provided, the lens comprising: a first liquid crystal unit for changing the power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface, the first liquid crystal unit comprising a diffractive optical element for correcting the vision of a user and a cholesterol liquid crystal, the first liquid crystal unit being operable between a first unswitched state and a second switched state, wherein 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 than or less than in the second state, wherein 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, the average refractive index of the liquid crystal being nave, and therefore calculated as: nave = 0.5(ne + no), where ne is an unusual refractive index and no is an ordinary refractive index.

[0074] The applicant has found that it is advantageous for the average refractive index of a liquid crystal to be similar to that of a diffractive optical element in the visible portion of the electromagnetic spectrum.

[0075] The average refractive index of the liquid crystal and the refractive index of the diffractive optical element can be determined at an ambient temperature (e.g., 20˚C or 25˚C), or at a temperature corresponding to the temperature of the human body (about 37˚C), or at a temperature corresponding to the temperature of the cornea of ​​an eye (about 34˚C).

[0076] At both 450 nm and 700 nm, the average refractive index of the liquid crystal can be 0.90 to 1.10 times that of the refractive index of the diffractive optical element. At both 450 nm and 700 nm, the average refractive index of the liquid crystal can be 0.95 to 1.05 times that of the diffractive optical element. At both 450 nm and 700 nm, the average refractive index of the liquid crystal can be 0.97 to 1.03 times that of the diffractive optical element. At both 450 nm and 700 nm, the average refractive index of the liquid crystal can be 0.98 to 1.02 times that of the diffractive optical element.

[0077] At 500 nm, the average refractive index of the liquid crystal may be 0.80 to 1.20 times the refractive index of the diffractive optical element, which may be 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, depending on the circumstances.

[0078] The average refractive index of the liquid crystal is the average refractive index n ave, so it is calculated as: n ave = 0.5(ne + no), where ne is the unusual refractive index and no is the ordinary refractive index.

[0079] At 460 nm, 480 nm, 500 nm, 520 nm, 540 nm, 560 nm, 580 nm, 600 nm, 620 nm, 640 nm, 660 nm and 680 nm, one of the refractive indices of the liquid crystal is, in some cases, 0.80 to 1.20 times the refractive index of the diffractive optical element, in some cases, 0.90 to 1.10 times, in some cases, 0.95 to 1.05 times, in some cases, 0.97 to 1.03 times and in some cases, 0.98 to 1.02 times the refractive index of the diffractive optical element.

[0080] Over substantially the entire wavelength range from 450 nm to 700 nm, the refractive index of a liquid crystal is, in cases, 0.80 to 1.20 times that of a diffractive optical element. Over substantially the entire wavelength range from 450 nm to 700 nm, the refractive index of a liquid crystal can be, in cases, 0.90 to 1.10 times that of a diffractive optical element, in cases, 0.95 to 1.05 times, in cases, 0.97 to 1.03 times, and in cases, 0.98 to 1.02 times. Those skilled in the art will recognize that it is not necessary to measure the refractive index over the entire wavelength range; the refractive index varies with wavelength in a similar manner for most materials. Generally speaking, the refractive index decreases continuously from 450 nm to 700 nm without a minimum, maximum, or deflection point.

[0081] The first liquid crystal cell can operate between a first state and a second state. In the first state (typically an unswitched state), a pointer of the liquid crystal located at a distance from the first and second inner surfaces (and, depending on, the middle between the first and second inner surfaces) can form an angle with the first and second inner surfaces of no more than 20 degrees, depending on the situation no more than 15 degrees, depending on the situation no more than 10 degrees, depending on the situation no more than 8 degrees, depending on the situation no more than 5 degrees, and depending on the situation no more than 3 degrees. In a switched state (e.g., the second state), a pointer of the liquid crystal located at a distance from the first and second inner surfaces (and, depending on the situation, the middle between the first and second inner surfaces) can form an angle with the first and second inner surfaces of at least 60 degrees, depending on the situation at least 70 degrees, depending on the situation at least 80 degrees, and depending on the situation at least 85 degrees.

[0082] The lens of the third state of the present invention may include any feature of the lens of the first and / or second state of the present invention.

[0083] According to a fourth aspect of the present invention, an electrically switchable flexible contact lens conforming to the eye of a user is provided, the lens comprising: a first liquid crystal unit for changing the power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface, the first liquid crystal unit comprising a diffractive optical element for correcting the vision of a user and a cholesteric liquid crystal; the first liquid crystal unit is operable between a first unswitched state and a second switched state, wherein 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 than or less than in the second state, wherein the refractive index of the diffractive optical element is not greater than 1.57.

[0084] The applicant has discovered that if the refractive index of the diffractive optical element is relatively low, the optical performance of a contact lens exhibits good refractive index matching with good near-field performance in a second state over a wide wavelength range.

[0085] In the first state or the second state, but preferably the second state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element can be small or zero, that is, the refractive indices of the liquid crystal and the diffractive optical element are approximately the same. In the second state, due to the matching of refractive indices, the diffractive element does not significantly diffract the incident light. In the first state or the second state, but preferably the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element can be greater than in other states, causing the diffractive optical element to diffract the incident light.

[0086] In the first unswitched state, the effective refractive index of the liquid crystal can be the average refractive index of the liquid crystal, nave = 0.5(ne + no), where ne is the unusual refractive index and no is the ordinary refractive index. In the second switched state, the effective refractive index of the liquid crystal can be no, the ordinary refractive index.

[0087] The contact lens may include a lens body for correcting a user's vision. The lens body may provide a positive optical power, such as +0.5, +1.0, or +1.5D. The optical power of the lens body may be fixed. The lens body may be positioned at or near the uppermost part of the lens, which is away from the portion of the lens that contacts the wearer's eye. The addition of this lens body may be particularly useful when the first liquid crystal unit is in a second switching state, provided that the effective refractive index of the liquid crystal matches the refractive index of the diffractive optical element.

[0088] The refractive index of the diffractive optical element is not greater than 1.55 and is not greater than 1.53, depending on the circumstances.

[0089] The refractive index of the diffractive optical element is at least 1.43, at least 1.45, at least 1.47 and at least 1.49, depending on the circumstances.

[0090] The refractive index of the diffractive optical element is, depending on the circumstances, from 1.43 to 1.57, from 1.45 to 1.55, and from 1.47 to 1.55.

[0091] In an unswitched state, a pointer of the liquid crystal located at a distance from the first and second inner surfaces (and, depending on the situation, the middle between the first and second inner surfaces) may form an angle with the first and second inner surfaces of no more than 20 degrees, no more than 15 degrees, no more than 10 degrees, no more than 8 degrees, no more than 5 degrees, and no more than 3 degrees, depending on the situation. In a switched state, a pointer of the liquid crystal located at a distance from the first and second inner surfaces (and, depending on the situation, the middle between the first and second inner surfaces) may form an angle with the first and second inner surfaces of at least 60 degrees, at least 70 degrees, at least 80 degrees, and at least 85 degrees, depending on the situation.

[0092] The fourth type of lens of the present invention may include any feature of the first, second and / or third type of lens of the present invention.

[0093] According to a fifth aspect of the present invention, an electrically switchable flexible contact lens conforming to the eye of a user is provided, the lens comprising: a first liquid crystal unit for changing a power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface, the first liquid crystal unit comprising a diffractive optical element for correcting the vision of a user and a cholesteric liquid crystal; the first liquid crystal unit is operable between a first unswitched state and a second switched state, wherein 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 than or less than in the second state, wherein the refractive index of the diffractive optical element is at least 1.58.

[0094] The applicant has found that if the refractive index of the diffractive optical element is relatively high, the optical performance of the lens in the first state exhibits less sensitivity to different wavelengths.

[0095] In the first or second state (but preferably the first state), the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element can be small or zero, that is, the effective refractive indices of the liquid crystal and the diffractive optical element are approximately the same. In the first state, due to the matching of refractive indices, the diffractive element does not significantly diffract the incident light. In the first or second state, but preferably the second state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffractive optical element can be greater than in other states, causing the diffractive optical element to diffract the incident light and contribute to the optical refractive power of the contact lens.

[0096] In the first unswitched state, the effective refractive index of the liquid crystal can be the average refractive index of the liquid crystal, nave = 0.5(ne + no), where ne is the unusual refractive index and no is the ordinary refractive index. In the second switched state, the effective refractive index of the liquid crystal can be no, the ordinary refractive index.

[0097] The refractive index of the diffractive optical element is at least 1.58, at least 1.60, at least 1.62, at least 1.64 and at least 1.66, depending on the circumstances.

[0098] The refractive index of the diffractive optical element is, depending on the circumstances, not greater than 1.70, not greater than 1.68 and not greater than 1.66.

[0099] The refractive index of the diffractive optical element is, depending on the circumstances, from 1.58 to 1.70, from 1.60 to 1.68, and from 1.62 to 1.66.

[0100] In an unswitched state, a pointer of the liquid crystal located at a distance from the first and second inner surfaces and, depending on the situation, between the first and second inner surfaces, may form an angle with the first and second inner surfaces of no more than 20 degrees, depending on the situation, no more than 15 degrees, depending on the situation, no more than 10 degrees, depending on the situation, no more than 8 degrees, depending on the situation, no more than 5 degrees, and depending on the situation, no more than 3 degrees. In a switched state, a pointer of the liquid crystal located at a distance from the first and second inner surfaces and, depending on the situation, between the first and second inner surfaces, may form an angle with the first and second inner surfaces of at least 60 degrees, depending on the situation, at least 70 degrees, depending on the situation, at least 80 degrees, and depending on the situation, at least 85 degrees.

[0101] According to a sixth embodiment, an electrically switchable flexible contact lens for conforming to the eye of a user is provided, the lens comprising: a first liquid crystal cell for changing the power of the contact lens and having a cell gap thickness between a first inner surface and a second inner surface, the first liquid crystal cell including a diffraction optical element for correcting the vision of a user, the diffraction optical element including a plurality of peaks and valleys, the peaks extending in a direction from the first inner surface to the second inner surface, at least a portion of at least one peak being attached to the second inner surface.

[0102] The attachment of at least one peak of the diffractive optical element to the second inner surface can restrict the movement of the liquid crystal within the cell, which may be undesirable.

[0103] Diffraction optical elements can be configured to maintain the cell gap thickness by providing support at one or more locations within the cell.

[0104] A diffractive optical element may include a central peak and a plurality of external peaks, at least a portion of at least one of the external peaks being attached to a second inner surface.

[0105] At least one of these external peaks, or more than one, and each of them may be annular. More than one of these external peaks may all be concentric.

[0106] At least a majority and substantially all of at least one peak can be attached to the second surface. In the event of deformation of the first liquid crystal cell, this configuration suppresses the liquid crystal from traveling through the peak.

[0107] All of the more than one peak can be attached to the second inner surface.

[0108] Each peak can be attached to the second inner surface. In fact, all of the peaks can be attached to the second inner surface.

[0109] For example, an adhesive can be used to achieve attachment of a peak to the second inner surface. Alternatively, at least one of the peak and the second inner surface can be provided with a molten polymer that attaches the peak to the second inner surface when heated and cooled.

[0110] According to a seventh aspect of the present invention, an electrically switchable flexible contact lens conforming to the eye of a user is provided. The lens includes: a first liquid crystal unit for changing the power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface; the first liquid crystal unit includes a diffraction optical element for correcting the vision of a user, the diffraction optical element having an operating characteristic wavelength from 450 nm to 510 nm; the first liquid crystal unit includes a cholesteric liquid crystal; the first liquid crystal unit is operable between a first unswitched state and a second switched state, wherein in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffraction optical element is greater than or less than in the second state.

[0111] The applicant has found it advantageous to use a diffractive optical element having an operating characteristic wavelength that is lower than that commonly used for other lenses (such as eyeglasses).

[0112] For example, the operating characteristic wavelength may be no greater than 560 nm, depending on the situation, no greater than 550 nm, depending on the situation, no greater than 540 nm, depending on the situation, no greater than 530 nm, depending on the situation, no greater than 520 nm, depending on the situation, no greater than 510 nm, depending on the situation, no greater than 500 nm, depending on the situation, and depending on the situation, no greater than 490 nm and no greater than 480 nm. The applicant has found that it is feasible to obtain a contact lens with an operating characteristic wavelength of up to about 550 nm, because blue diffraction artifacts that can cause problems in glasses at up to 550 nm can cause problems for contact lenses.

[0113] For example, the operating characteristic wavelength may be at least 460 nm, at least 470 nm and at least 480 nm.

[0114] For example, the operating characteristic wavelength may be from 460 to 560 nm, from 460 to 550 nm as appropriate, from 470 to 550 nm as appropriate, from 460 to 490 nm as appropriate, from 470 to 490 nm as appropriate, and 480 nm as appropriate.

[0115] The exemplary embodiments will now be described by way of example only with reference to Figures 1 to 9.

[0116] Figures 1 and 2 illustrate an example of an electrically switchable flexible contact lens according to one embodiment of the first and second versions of the present invention. Figure 1 is a schematic cross-sectional view of a contact lens, generally indicated by element symbol 1, and includes a flexible lens body 2 in which a liquid crystal cell, generally indicated by element symbol 3, is incorporated. The flexible lens body 2 comprises any suitable material, such as polysiloxane hydrogel material, polysiloxane-free hydrogel material, and polysiloxane flexible material. Figure 2 is a partial cross-sectional view of the contact lens 1. For clarity and ease of illustration, the liquid crystal lens 3 is depicted as flat / planar in Figure 2. Those skilled in the art will recognize that this is not the case, and the shape of the liquid crystal cell is more appropriately shown in Figure 1. The liquid crystal cell 3 includes a diffractive optical element 4 for correcting a user's vision and a liquid crystal 5. In short, the liquid crystal can switch between a first unswitched state and a second switched state. In one of the switched and unswitched states, 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 length. In the other of the switched and unswitched states, 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 length different from the first focal length.

[0117] The diffractive optical element 4 includes a plurality of peaks and valleys, wherein a central peak 10A and eight annular peaks 10B, 10C, 10D, 10E, 10F, 10G, 10H, and 10I are concentrically arranged around the central peak, thereby providing nine diffraction zones (one zone is disposed between each pair of adjacent peaks). For simplicity, associated valleys are not labeled. Such diffractive elements are known to those skilled in the art of optics. In known lenses, spacer beads or the like are used to maintain the unit spacing between the first inner surface 6 and the second inner surface 7. In this example, the diffractive optical element 4 serves as a spacer to maintain the unit spacing between the first inner surface 6 and the second inner surface 7. Although Figure 2 shows that the central peak 10A is not in contact with the second inner surface, this is only to illustrate that the height of peak 10A is less than the height of 10I, which will be described in more detail below. A spacer 11 is disposed around the periphery of the liquid crystal cell 3 outward from the diffractive optical element 4. The spacer 11 is formed from beads with a diameter of approximately 4 micrometers dispersed in an adhesive. The distance between the first inner surface 6 and the second inner surface 7 is approximately 4 micrometers, but the distance is greater in the outer region 22 of the liquid crystal cell 3 than in the inner region 21, with a difference of approximately 5%. This difference is attributed 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 micrometers, while the maximum height h1 of the diffractive optical element 4 in the inner portion 21 is 3.85 micrometers. This difference in maximum height is small, but it improves optical performance. Specifically, the applicant has found that this configuration of the diffractive optical element can compensate for the curvature of the cornea when a contact lens is placed on the cornea. Furthermore, especially at the edge of a lens including a diffractive optical element, this configuration of the diffractive optical element can help improve "straight vision". The increased height at the edges of the diffractive optics ensures that the optical path at the edges is approximately the same as that at the center of the diffractive optics. This configuration ensures that the wavelength for optimal optical performance is approximately the same across the width of the diffractive optics. Without this increased height, the optical path at the edges of the diffractive optics would be slightly shorter than that at the center, which would be undesirable.

[0118] The heights of peaks 10A to 10I increase with the distance from the center of the diffractive optical element 4. The heights of peaks 10A to 10I can increase sublinearly, linearly, or superlinearly with the distance from the center of the diffractive optical element.

[0119] The diffractive optical element 4 is a sphere that is "shredded" so that the wavefront traveling through the diffractive optical element has a 2π phase shift across the boundaries of each region (it should be acknowledged that, strictly speaking, the 2π shift occurs only at a single wavelength). It is anticipated that one can modify the shape of the diffractive optical element to have different optical refractive powers across the regions of the diffractive optical element rather than a simple sphere (giving a simple uniform spherical power over the regions of the diffractive optical element). For example, an elliptical diffractive optical element can be used to handle astigmatism.

[0120] The diffractive optical element 4 maintains the spacing between the first inner surface 6 and the second inner surface 7, and it suppresses a significant reduction in the spacing that may occur when the lens 1 (and therefore the liquid crystal cell 3) is deformed. The cornea is typically aspherical, and the placement of a contact lens on a wearer's cornea causes lens deformation. In the absence of a diffractive optical element 4 acting as a spacer, a significant reduction in the spacing between the first inner surface 6 and the second inner surface 7 can be observed for certain portions of the liquid crystal cell 3 if the contact lens 1 is placed on a wearer's eye. Furthermore, the cell gap thickness is maintained at a sufficiently small level to allow the liquid crystal to be aligned without haze.

[0121] The applicant has observed that, in cases where peaks are not attached to the inner surface 7 and the contact lens deforms as it would when placed on a user's cornea, liquid crystal can move outward from the space between peaks 10A and 10B toward the outer portion of the contact lens, thereby generating a large amount of excess liquid crystal between the diffractive optical element and the inner surface 7, increasing the distance between the first inner surface 6 and the second inner surface 7 by up to 1 micrometer in the regions of peaks 10G, 10H, and 10I. To help reduce liquid crystal displacement, an adhesive can be used to adhere at least one, or more than one, of peaks 10A to 10I to the inner surface 7. As an alternative adhesive, peaks 10A to 10I can be attached to the inner surface by melting, pressing, and cooling the polymer 9. Furthermore, peaks can be attached by physical adhesion (such as by using a plasma processing procedure and the like). However, it is not critical to adhere one (or several) peaks to the inner surface 7, because due to the diffraction element, the optical properties of the optical device will not be significantly negatively affected by the liquid crystal displacement.

[0122] In the liquid crystal device 3, the liquid crystal includes a cholesteric liquid crystal, one of which is a nematic liquid crystal doped with a pair of palm-shaped dopants. Such nematic liquid crystals are well known to those skilled in liquid crystal science and may include, for example, E7, BL037, and / or BL038. Such palm-shaped dopants are well known to those skilled in liquid crystal science, such as Merck ZLI-3786, CB15, and S811. Figure 3 schematically illustrates the local alignment of molecules in the liquid crystal device 3. Referring to Figure 2, the inner surfaces 6 and 7 are formed by an alignment polymer that imparts alignment to the liquid crystal molecules of the adjacent rubber polymer. Depending on the viscous properties of the liquid crystal, this alignment of the liquid crystal molecules of the adjacent alignment polymer imparts a specific orientation to the liquid crystal distant from the alignment polymer. Referring to Figure 2, a layer of adjacent liquid crystal 5 is present in the polymer 9. In this case, the alignment polymer 9 is a UV-curable polymer (Rolic ROP-103 / 2CP). A polymer cured by suitable polarized UV radiation is used to impart a desired alignment to the liquid crystal of the adjacent polymer. A UV-curable polymer layer, but not shown, is disposed on top of the diffractive optical element 4. The friction-aligned polymer layer allows the directional vectors (average orientation of the liquid crystal molecules) of the adjacent rubber polymer layer to be approximately parallel to the first inner surface 6 and the second inner surface 7, but typically tilted by a few degrees (a phenomenon known to those skilled in the art as "pre-tilt"). (As shown by the small circles adjacent to the first inner surface 6 and the second inner surface 7). The tilt of the directional vectors adjacent to the first inner surface 6 and the second inner surface 7 can be greater than a few degrees. For example, the tilt of the directional vectors adjacent to the first inner surface 6 and the second inner surface 7 can be 10 to 30 degrees. Between the first inner surface 6 and the second inner surface 7, the directional vectors of the liquid crystal 5 form a helical structure. This is shown in Figure 3. The rod-shaped indicator shows that the directional vectors of the liquid crystal are approximately parallel to the first inner surface 6 and the second inner surface 7, and are in the plane of the figure. In this unswitched state, the effective refractive index of the liquid crystal is independent of polarization and is given by nave = 0.5(ne + no) (Equation 1), where ne is the unusual refractive index and no is the ordinary refractive index. Those skilled in the art will recognize that the pitch of the liquid crystal is expected to be no greater than 500 nm (i.e., approximately equal to or less than the wavelength of the incident light) so that the liquid crystal behaves as a monorefractive material to a reasonable approximation. The applicant has found that if the liquid crystal has a higher pitch (i.e., 600 to 700 nm) without significant optical artifacts, the contact lens can operate satisfactorily. This is advantageous because using a higher pitch reduces the switching voltage.

[0123] Figure 10 shows the alignment of the director of the liquid crystal of the adjacent aligned polymer 9, where the arrows indicate the direction of the director of the liquid crystal of the adjacent aligned polymer. This alignment is used to provide polarization-independent operation of the contact lens. The alignment of the director of the liquid crystal of the polymer layer adjacent to the diffractive optical element 4 is substantially the same as the alignment shown in Figure 10.

[0124] The liquid crystal 5 and the materials from which the diffractive optical element 4 is generated can be selected to achieve a desired optical result. For example, the liquid crystal and the materials used to manufacture the diffractive optical element can be selected such that the effective refractive index of the liquid crystal matches the effective refractive index of the materials used to manufacture the diffractive optical element, and in this case, the diffractive optical element does not contribute to the focal power of the lens. Alternatively, if the effective refractive index of the liquid crystal does not match the effective refractive index of the materials used to manufacture the diffractive optical element, then the diffractive optical element will contribute to the focal power of the lens.

[0125] When a suitable voltage is applied to the electrodes (8A, 8B) of the liquid crystal cell, the liquid crystal molecules switch to a linear state schematically shown in FIG. 4, wherein the director of the liquid crystal in the central portion 30 of the liquid crystal cell 3 is normal to the first inner surface 6 and the second inner surface 7. This realignment of the liquid crystal provides a different effective refractive index. In some cases, when the liquid crystal is in a switching state, the effective refractive index of the liquid crystal can match 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 power of the lens. Conversely, when the liquid crystal is in a switching 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 power of the lens.

[0126] An example of an embodiment of a contact lens according to a third aspect of the present invention will now be described with reference to Figures 1 and 2. The electrically switchable flexible contact lens is indicated by element symbol 1. The lens 1 includes a liquid crystal unit 3 for changing the power of the contact lens. The liquid crystal unit 3 includes a diffractive optical element 4 for correcting a user's vision and a cholesteric liquid crystal 5. The liquid crystal unit 3 is operable between a switched state and an unswitched state. The diffractive optical element is made of MR10 and has a refractive index of 1.63. In the unswitched state, the effective refractive index of the liquid crystal matches that of the diffractive optical element, and therefore, the diffractive optical element does not contribute to the power of the lens. The average refractive index of the liquid crystal is calculated according to Equation 1 above. The average refractive index of the liquid crystal effectively matches the refractive index of the diffractive optical element across the entire visible wavelength range (i.e., from 450 to 700 nm). This matching of refractive indices across the entire visible wavelength range provides improved optical performance because the amount of diffraction observed from diffractive optics is minimized due to the matching of refractive indices across the visible spectrum. Those familiar with this technique will realize that precise matching of refractive indices across the entire visible spectrum is not required.

[0127] An example of an embodiment of a fourth type of contact lens according to the present invention will now be described with reference to Figures 1 and 2. The lens is generally indicated by element symbol 1 and includes a liquid crystal unit 3 for changing the power of the contact lens. The liquid crystal unit 3 includes a diffraction optical element 4 for correcting a user's vision and a cholesteric liquid crystal 5. The lens further has a +1D protrusion (not shown) on its upper surface. The liquid crystal unit 3 is operable between a first unswitched state and a second switched 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 diffraction optical element 4 is made of Trivex and has a refractive index of 1.51. In the first unswitched state, there is a mismatch between the refractive indices of the liquid crystal and the diffraction optical element. This causes the diffraction optical element to contribute to the power of the lens. The diffraction optical element contributes -1D to the lens, and therefore, considering the contribution of the diffraction optical element 4 and the +1D protrusion of the lens, the total power of the lens is 0D. This can be considered as a distance vision state. In the second switching state, the effective refractive index of liquid crystal 5 is 1.51, and there is a matching between the refractive indices of the liquid crystal and the diffractive optical element. This results in the diffractive optical element not contributing to the lens power. Therefore, the total power of the lens is +1D. This is the myopic vision state. In the event of a power failure, the contact lens is preset to distance vision, i.e., 0D optical power.

[0128] The applicant has discovered that when the liquid crystal cell is switched to the second state, it is feasible to obtain an excellent match between the effective refractive index of the liquid crystal and the material constituting the diffractive optical element for all visible wavelengths of light. Figure 5 shows that when the liquid crystal cell is switched to the second state, the effective refractive index (no) of the liquid crystal and the material constituting the diffractive optical element is substantially the same for all visible wavelengths of light. In this regard, solid lines represent the effective refractive indices of the liquid crystal and the diffractive optical element. The effective refractive indices of the liquid crystal and the diffractive optical element are effectively the same from 400 nm to 700 nm. This excellent match of refractive indices results in the diffractive optical element not contributing to the optical refractive power of the lens. Furthermore, Figure 5 shows the intensity of various orders of diffraction profiles observed from the diffractive optical element. In this regard, dashed lines represent the 0th order diffraction profile, chain lines (long dashed lines separated by dots) represent the 1st order diffraction profile, and dotted lines represent the 2nd order diffraction profile. Note that the 1st and 2nd order diffraction profiles shown in Figure 5 are multiplied by 100 before being displayed. It is evident that virtually all light incident on the contact lens is transmitted, with very little light diffracted at all wavelengths with very small first and second order diffraction profiles.

[0129] Figure 6 shows the intensity of various diffraction peaks from the diffraction optical element, varying with wavelength, when the liquid crystal cell 3 is in the first unswitched state. In this case, there is a mismatch between the effective refractive index of the liquid crystal and the diffraction optical element, and therefore, the diffraction optical element contributes to the lens power. In this regard, the dashed line shows the 0th order diffraction profile, the chain line (a long dashed line separated by dots) shows the 1st order diffraction profile, and the dotted line shows the 2nd order diffraction profile. Figure 6 shows that there is some wavelength dependence, but the optical performance of the lens is still good. Surprisingly, the applicant has found that despite some wavelength dependence of the optical response of the contact lens, the lateral rainbow effect that would be observed in eyeglasses is not observed in the contact lens. Therefore, the applicant has demonstrated that it is feasible to obtain a lens with good optical properties using a diffraction optical element with a relatively low refractive index (i.e., not greater than 1.57).

[0130] An example of an embodiment of a contact lens according to a fifth aspect of the present invention will now be described with reference to Figures 1 and 2. The lens is generally indicated by element symbol 1 and includes a liquid crystal unit 3 for changing the power of the contact lens. The liquid crystal unit 3 includes a diffractive optical element 4 for correcting a user's vision and a cholesteric liquid crystal 5. The liquid crystal unit 3 is operable between a first unswitched state and a second switched state, wherein in the first state, the difference in refractive index between the liquid crystal and the diffractive optical element is smaller than in the second state. The refractive index of the diffractive optical element is 1.63. In the first unswitched state, the effective refractive index of the liquid crystal 5 is 1.63, and there is a match between the refractive indices of the liquid crystal and the diffractive optical element. This results in the diffractive optical element not contributing to the power of the lens. Therefore, the total power of the lens is 0D. This can be considered a distance vision state. In the second switched state, the effective refractive index of the liquid crystal 5 is 1.51, and there is a mismatch between the refractive indices of the liquid crystal and the diffractive optical element. This results in the diffractive optical element contributing to the power of the lens. Therefore, the total power of the lens is +1D. This can be considered as a near vision or near distance vision status. In the event of a power failure, the contact lens is preset to distance vision, i.e., 0D optical diopter.

[0131] The applicant has discovered that when the liquid crystal cell is in a first unswitched state, it is feasible to obtain a good match between the effective refractive index of the liquid crystal and the material constituting the diffractive optical element for all visible wavelengths of light, with only a small difference between the refractive indices at lower wavelengths (below 500 nm). In this regard, 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 non-thick dashed line adjacent to the solid line. This excellent match of refractive indices results in the diffractive optical element not significantly contributing to the optical refractive power of the lens. Figure 7 shows the intensity of various orders of diffraction profiles observed from the diffractive optical element. In this regard, the thick dashed line represents the 0th order diffraction profile, the chain line (a long dashed line separated by dots) represents the 1st order diffraction profile, and the dotted line represents the 2nd order diffraction profile. The 1st and 2nd order diffraction profiles shown in Figure 7 are multiplied by 10. It is evident that virtually all light incident on the contact lens is transmitted, with very little light diffracted at all wavelengths with very small first and second order diffraction profiles.

[0132] Figure 8 shows the intensity of various diffraction peaks from the diffraction optical element, varying with 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 diffraction optical element, and therefore, the diffraction optical element contributes to the lens power. In this regard, the bold dashed line shows the 0th order diffraction profile, the chain line (a long dashed line separated by dots) shows the 1st order diffraction profile, and the dotted line shows the 2nd order diffraction profile. Figure 8 shows that there is very little wavelength dependence, and the optical performance of the lens is still good. Therefore, the applicant has demonstrated that it is feasible to obtain a lens with good optical properties using a diffraction optical element with a relatively high refractive index (i.e., at least 1.58). Surprisingly, the applicant has found that despite some wavelength dependence of the optical response of the contact lens, the lateral rainbow effect that would be observed in eyeglasses is not observed in the contact lens.

[0133] The exemplary contact lens described above provides unexpectedly good peripheral imaging performance. In this respect, one can expect light to be incident on the diffractive optics from a wide range of angles, and this wide variation in the angle of incidence and the curvature of the cornea results in a large variation in the optical path length through the diffractive optics, thus leading to poor optical performance. However, the applicant has discovered that a portion of the peripheral light entering the contact lens and traveling through the pupil travels through the diffractive optics approximately normal to the incoming light, i.e., the light comes from approximately the same direction and there is less variation in the angle of incidence. This results in good peripheral imaging performance.

[0134] Furthermore, as the angle of incidence of light increases from the normal, the amount of light traveling through the diffraction optics decreases. At a certain angle, virtually no light travels through the diffraction optics, and no optical artifacts are visible. For example, with light incident at approximately 53° and a pupil size of 5 mm, about half of a detected beam is incident on the diffraction optics, while the other half travels through the non-diffraction area of ​​the contact lens. For light with even higher angles of incidence, the effective area exposed to the diffraction optics decreases even further, making optical artifacts negligible when the beam completely moves out of the diffraction area. Therefore, from the user's perspective, there is no abrupt start / stop of the diffraction area, only a smooth variation in contribution. In an eyeglass lens implementation, there appears to be a sharp jump between viewing through the diffraction optics and viewing without them.

[0135] The applicant has also found that the astigmatism of the peripheral light caused by the incident light traveling through the diffractive optical element at an illegal angle is acceptable (approximately 0.3D on average).

[0136] An example of an embodiment of a flexible contact lens according to a seventh aspect of the present invention will now be described with reference to FIG. 1. The lens is essentially the lens described above in relation to the fifth aspect of the present invention. The lens is generally indicated by element symbol 1 and includes a liquid crystal cell 3 for changing the power of the contact lens and having a cell gap thickness between a first inner surface and a second inner surface. The liquid crystal cell 3 includes a diffraction optical element 4 for correcting a user's vision and a cholesteric liquid crystal 5. The liquid crystal cell 3 is operable between a first state and a second state, wherein in the first state, the difference in effective refractive index between the liquid crystal and the diffraction optical element is greater than in the second state. The liquid crystal cell and the diffraction optical element have an operating characteristic wavelength, which is from 450 nm to 510 nm. The operating characteristic wavelength is a wavelength in which one or more properties of the lens are optimized. For example, one or more properties may include the lens transmission when the liquid crystal cell is in a state in which the effective refractive index of the liquid crystal matches the effective refractive index of the diffractive optical element or in a state in which the effective refractive index of the liquid crystal does not match the effective refractive index of the diffractive optical element. Figure 8 illustrates how one property of a contact lens can be optimized at 480 nm. Those skilled in the art will recognize that other optical properties can be optimized at or near 480 nm. Those skilled in the art will recognize that optimization can be determined by changing the liquid crystal (e.g.) to change the refractive index of the liquid crystal or the cell spacing between the first and second inner surfaces.

[0137] The effective refractive index of a liquid crystal depends on the orientation of its molecules. For example, in the unswitched state, the effective refractive index of the liquid crystal is the average refractive index calculated using Equation 1, as mentioned above. In the switched state, the effective refractive index of the liquid crystal is no.

[0138] All forms of contact lenses of the present invention may include more than one liquid crystal cell, as will now be described with reference to FIG. 9. An example of a first form of contact lens according to the present invention is generally indicated by element symbol 101. Lens 101 includes a first liquid crystal cell 3 and a second liquid crystal cell 3' disposed in a lens body 2. The first liquid crystal cell 3 is substantially as described above with respect to the first form of contact lens of the present invention. The second liquid crystal cell 3' is substantially the same as the first liquid crystal cell 3. Those skilled in the art will appreciate that this is not necessary.

[0139] Those skilled in the art will recognize that the lenses of the present invention may include diffractive optical elements different from those described above. In this respect, the number of diffraction zones is proportional to the optical diopter of the diffractive lens (in diopters) and also 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 optical diopter. Table 1 below shows the number of diffraction zones required to produce a given diopter for a given diameter of a diffractive optical element. Diameter of diffractive optical element Diopter (or refractive power) 1 2 3 6 8 16 twenty four 4 4 9 14 3 2 4 6 Table 1 - Number of diffraction zones required to achieve a specific focal length for a given diameter of one of the diffractive optical elements

[0140] Of course, it should be understood that features described in one aspect of the invention may be incorporated into other aspects of the invention. For example, the method of the invention may be incorporated into any feature of the device description with reference to the invention, and vice versa.

[0141] Further aspects of the invention will now be described with reference to the following clauses: Clause A1 - An electrically switchable flexible contact lens conforming to the eye of a user, the lens comprising: a first liquid crystal cell for changing the power of an ophthalmic lens and having a cell gap thickness between a first inner surface and a second inner surface, the first liquid crystal cell including a diffraction optical element for correcting the vision of a user, wherein the diffraction optical element is configured to maintain the cell gap thickness by providing support at one or more locations within the first liquid crystal cell. Clause A2 - The lens of Clause A1, comprising a peripheral spacer disposed at the periphery of the first liquid crystal cell to also maintain the cell gap thickness in addition to the diffraction optical element. Item A3 - A lens as described in items A1 or A2, wherein the first liquid crystal unit comprises a cholesteric liquid crystal, and the first liquid crystal unit is operable between a first unswitched state and a second switched state, wherein 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. Item A4 - A lens as described in item A3, 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. Item A5 - A lens as described in any one of items A1 to A4, wherein the diffractive optical element comprises an inner portion and an outer portion, and the height of the diffractive optical element at the outer portion is greater than the height of the diffractive optical element at the inner portion. Clause A6 - A lens as described in any one of clauses A1 to A5, 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 attachable to the second inner surface. Clause A7 - A lens as described in any one of clauses A1 to A6, wherein 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 nave = 0.5(ne + no), where ne is an unusual refractive index and no is an ordinary refractive index. Clause A8 - A lens as described in clause 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. Clause B1 - An electrically switchable flexible contact lens conforming to the eye of a user, the lens comprising: a first liquid crystal unit for changing a power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface; the first liquid crystal unit including a diffractive optical element for correcting the vision of a user, the diffractive optical element including an inner portion and an outer portion, the height of the diffractive optical element at the outer portion being greater than the height of the diffractive optical element at the inner portion by 1% to 20%.Clause B2 - A lens as described in Clause B1, wherein the height of the diffractive optical element at the outer portion is at least 3% and at most 15% greater than the height of the diffractive optical element at the inner portion. Clause B3 - A lens as described in Clauses B1 or B2, wherein the diffractive optical element comprises a plurality of peaks and valleys, and the outer portion comprises an outer peak, whichever is more prominent. Clause B4 - A lens as described in any one of Clauses B1 to B3, wherein the diffractive optical element extends within a chord length r, the inner portion comprises a portion of the diffractive optical element within a chord length r / 8 from a center of the diffractive optical element, and the outer portion comprises a portion of the diffractive optical element having a chord length from 3r / 8 to r / 2. Clause B5 - A lens as described in any of Clauses B1 to B4, wherein the liquid crystal comprises a cholesteric liquid crystal, and, depending on the situation, in an unswitched state, one of the pointers of the liquid crystal can form an angle of no more than 5 degrees with the first and second inner surfaces, and in a switched state, one of the pointers of the liquid crystal can form an angle of at least 60 degrees, depending on the situation at least 70 degrees, depending on the situation at least 80 degrees, and depending on the situation at least 85 degrees with the first and second inner surfaces. Clause C1 - An electrically switchable flexible contact lens conforming to the eye of a user, the lens comprising: a first liquid crystal unit for changing the power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface, the first liquid crystal unit including a diffractive optical element for correcting the user's vision and a cholesterol liquid crystal, the first liquid crystal unit being operable between a first unswitched state and a second switched state, wherein 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 than or less than in the second state, wherein 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, the average refractive index of the liquid crystal being nave, and therefore calculated as nave = 0.5(ne + no): where ne is the unusual refractive index and no is the ordinary refractive index. Clause C2 - A lens as described in Clause C1, wherein at both 450 nm and 700 nm, the refractive index of the liquid crystal is from 0.90 to 1.10 times that of the refractive index of the diffractive optical element. Clause C3 - A lens as described in Clauses C1 or C2, wherein at both 450 nm and 700 nm, the refractive index of the liquid crystal is from 0.95 to 1.05 times that of the refractive index of the diffractive optical element. Clause C4 - A lens as described in any one of Clauses C1 to C3, wherein at 500 nm, the refractive index of the liquid crystal is from 0.95 to 1.05 times that of the refractive index of the diffractive optical element.Clause D1 - An electrically switchable flexible contact lens conforming to the eye of a user, the lens comprising: a first liquid crystal unit for changing the power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface, the first liquid crystal unit including a diffractive optical element for correcting the user's vision and a cholesteric liquid crystal, the first liquid crystal unit being operable between a first unswitched state and a second switched state, wherein 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 than or less than in the second state, wherein the refractive index of the diffractive optical element is not greater than 1.57. Clause E1 - An electrically switchable flexible contact lens conforming to the eye of a user, the lens comprising: a first liquid crystal unit for changing a power of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface, the first liquid crystal unit including a diffractive optical element for correcting the user's vision and cholesteric liquid crystal, the first liquid crystal unit being operable between a first unswitched state and a second switched state, wherein 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 than or less than in the second state, wherein the refractive index of the diffractive optical element is at least 1.58. Item F1 - An electrically switchable flexible contact lens conforming to the eye of a user, the lens comprising: a first liquid crystal cell for changing the power of an ophthalmic lens and having a cell gap thickness between a first inner surface and a second inner surface, the first liquid crystal cell including a diffraction optical element for correcting the user's vision, the diffraction optical element including a plurality of peaks and valleys, the peaks extending in a direction from the first inner surface to the second inner surface, at least a portion of at least one peak being attached to the second inner surface. Item F2 - A lens as in Item F1, wherein the diffraction optical element includes a central peak and a plurality of outer peaks, at least a portion of at least one of the outer peaks being attached to the second inner surface. Item F3 - A lens as in Item F2, wherein at least one of the outer peaks may be more than one and may be annular. Clause F4 - For any of Clauses F1 to F3, at least a majority of at least one peak and, where applicable, the entire periphery of the lens is attached to the second inner surface.Clause G1 - An electrically switchable flexible contact lens conforming to the eye of a user, the lens comprising: a first liquid crystal unit for altering at least one optical property of the contact lens and having a unit gap thickness between a first inner surface and a second inner surface; the first liquid crystal unit including a diffraction optical element for correcting the user's vision, the diffraction optical element having an operating characteristic wavelength from 450 nm to 510 nm; the first liquid crystal unit including a cholesteric liquid crystal; the first liquid crystal unit being operable between a first unswitched state and a second switched state, wherein in the first state, the difference between the effective refractive index of the liquid crystal and the refractive index of the diffraction optical element is greater than or less than in the second state. Clause G2 - A lens as in Clause G1, wherein the operating characteristic wavelength is from 460 to 490 nm, and optionally from 470 to 490 nm and optionally 480 nm.

[0142] Although the invention has been described and illustrated with reference to specific embodiments, those skilled in the art will understand that the invention is adaptable to many different variations not specifically illustrated herein. Some possible variations will now be described by way of example only.

[0143] The use of a diffractive optical element is not limited to a liquid crystal cell including a cholesteric liquid crystal. For example, other types of liquid crystals including undoped nematic and smectic liquid crystals can be used.

[0144] Where, in the foregoing description, an integer or element having a known, obvious, or foreseeable equivalent is mentioned, such equivalent is incorporated herein as if individually stated. Reference should be made to the claims of the invention used to determine the true scope of the invention, which should be interpreted as covering any such equivalent. The reader also understands that integers or features of the invention described as preferred, advantageous, convenient, or similar are chosen and do not limit the scope of the appended claims. Furthermore, it should be understood that while such chosen integers or features may be beneficial in some embodiments of the invention, they may be undesirable and therefore absent in other embodiments. [Simplified Explanation of the Diagram]

[0014] Embodiments of the present invention will now be described by way of example with reference to the accompanying illustrative drawings, wherein:

[0015] FIG1 shows a schematic side sectional view of an example of a contact lens according to a first state of the present invention, the contact lens including a liquid crystal unit;

[0016] Figure 2 shows a schematic side view of one of the liquid crystal cells used in Figure 1;

[0017] Figure 3 shows a schematic representation of partial alignment of liquid crystal molecules in a liquid crystal cell in an unswitched state;

[0018] Figure 4 shows a schematic representation of partial alignment of liquid crystal molecules in one of the liquid crystal cells in a switching state;

[0019] Figure 5 shows the intensity of the diffraction profile generated by a lens including a liquid crystal cell, wherein the diffraction optical element has a low refractive index and the liquid crystal cell is in a switching state.

[0020] Figure 6 shows the intensity of the diffraction profile generated by a lens including a liquid crystal cell, wherein the diffraction optical element has a low refractive index and the liquid crystal cell is in an unswitched state;

[0021] Figure 7 shows the intensity of the diffraction profile generated by a lens including a liquid crystal cell, wherein the diffraction optical element has a high refractive index and the liquid crystal cell is in an unswitched state;

[0022] Figure 8 illustrates the intensity of the diffraction profile generated by a lens including a liquid crystal unit, wherein the diffraction optical element has a high refractive index, and the liquid crystal unit is in a switching state; and

[0023] Figure 9 shows a schematic cross-sectional view of one example of a contact lens according to various forms of the present invention, the contact lens including two liquid crystal units; and

[0024] Figure 10 shows a schematic plan view of the alignment of the pointers of liquid crystals adjacent to an aligned polymer.

Claims

1. An electrically-switchable flexible contact lens for conforming to the eye of one of the users, the lens comprising: A first liquid crystal cell for changing the focal power of a contact lens and having a cell gap thickness between a first inner surface and a second inner surface, the first liquid crystal cell including a diffractive optical element for correcting a user's vision, wherein the diffractive optical element is configured to maintain the cell gap thickness by providing support at one or more locations within the cell, and the diffractive optical element includes an inner portion and an outer portion, the maximum height of the diffractive optical element in the outer portion being greater than the maximum height of the diffractive optical element in the inner portion, such that the diffractive optical element in the outer portion provides support for the first inner surface and the second inner surface, and the first inner surface and the second inner surface are spaced apart at a greater distance in an outer region of the first liquid crystal cell than in an inner region of the first liquid crystal cell.

2. The electrically switchable flexible contact lens of claim 1 further includes a peripheral spacer disposed at the periphery of the first liquid crystal cell to maintain the cell gap thickness in addition to the diffraction optical element.

3. The electrically switchable flexible contact lens of claim 1, wherein the first liquid crystal unit includes a cholesterol liquid crystal, and the first liquid crystal unit is operable between a first unswitched state and a second switched state, wherein in one of the first and second states, the difference between the effective refractive index of the cholesterol 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 electrically switchable flexible contact lens of claim 3, wherein in the other of the first and second states, the difference between the effective refractive index of the cholesteric liquid crystal and the refractive index of the diffractive optical element is approximately zero.

5. The electrically switchable flexible contact lens of 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 attachable to the second inner surface.

6. The electrically switchable flexible contact lens of claim 3, wherein at both 450 nm and 700 nm, the average refractive index of the cholesteric liquid crystal is 0.80 to 1.20 times that of the refractive index of the diffractive optical element, and the average refractive index is nave = 0.5(ne + no), where ne is the unusual refractive index and no is the ordinary refractive index.

7. The electrically switchable flexible contact lens of claim 6, wherein at both 450 nm and 700 nm, the average refractive index of the cholesteric liquid crystal is 0.95 to 1.05 times that of the refractive index of the diffractive optical element.

8. The electrically switchable flexible contact lens of claim 1, comprising a second liquid crystal unit for changing a power of the contact lens, the second liquid crystal unit comprising the features of the first liquid crystal unit.

9. The electrically switchable flexible contact lens of claim 1, wherein the maximum height of the diffractive optical element at the outer portion is greater than the maximum height of the diffractive optical element at the inner portion by 1% to 20%.

10. The electrically switchable flexible contact lens of claim 9, wherein the maximum height of the diffractive optical element at the outer portion is at least 3% and at most 15% greater than the maximum height of the diffractive optical element at the inner portion.

11. The electrically switchable flexible contact lens of claim 9, wherein the diffractive optical element includes a plurality of peaks and valleys, and the outer portion includes an outer peak or an outermost peak.

12. The electrically switchable flexible contact lens of claim 9, wherein the diffractive optical element extends within a chord length r, the inner portion includes a portion of the diffractive optical element within a chord length r / 8 from a center of the diffractive optical element, and the outer portion includes a portion of the diffractive optical element having a chord length from 3r / 8 to r / 2.

13. The electrically switchable flexible contact lens of claim 10, wherein the first liquid crystal unit includes a cholesteric liquid crystal, wherein in an unswitched state, a director of the cholesteric liquid crystal can form an angle of no more than 5 degrees with the first and second inner surfaces, and in a switched state, the director of the cholesteric liquid crystal can form an angle of at least 60 degrees with the first and second inner surfaces.

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