Techniques for creating radial refractive index patterns in liquid crystal materials

Abstract

The present invention discloses a liquid crystal device comprising at least one liquid crystal cell comprising a first half-cell and a second half-cell and a liquid crystal material contained between the first half-cell and the second half-cell; the first half-cell and / or the second half-cell comprising a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material and a second electrode pattern for creating a second radial refractive index pattern at least partially in the first region of the liquid crystal material; and the liquid crystal device can be switched between starting the first electrode pattern and starting the second electrode pattern.

Description

TECHNICAL FIELD

[0001] This application relates to creating a radial refractive index pattern in a liquid crystal material. A radial refractive index pattern in a liquid crystal material can be used, for example, to manipulate electromagnetic radiation, such as visible light. For example, a radial refractive index pattern in a liquid crystal material can act as a positive or negative lens in a wide range of optical devices. BACKGROUND

[0002] One technique for creating a radial refractive index pattern in a region of a liquid crystal material uses a liquid crystal cell that includes a radial electrode pattern on one side of a region of a liquid crystal material, and an unpatterned blanket electrode on the opposite side of the region of the liquid crystal material. In known examples of radial electrode patterns, the stack of such liquid crystal cells can provide a stack of cooperatively aligned refractive index patterns in respective volumes of liquid crystal material that together can cooperatively provide increased optical power.

[0003] The inventors of the present application have endeavored to develop a new technique for creating a radial refractive index pattern in a liquid crystal material. SUMMARY

[0004] A liquid crystal device including at least one liquid crystal cell, wherein the liquid crystal cell includes a first half-cell and a second half-cell and a liquid crystal material contained between the first half-cell and the second half-cell; wherein the first half-cell and / or the second half-cell includes a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern at least partially in the first region of the liquid crystal material; and wherein the liquid crystal device is switchable between activating the first electrode pattern and activating the second electrode pattern.

[0005] The first half-cell can include the first electrode pattern and the second half-cell can include the second electrode pattern.

[0006] The first electrode pattern and the second electrode pattern can be centered on a common axis.

[0007] The first electrode pattern can include a first set of concentric rings and the second electrode pattern can include a second set of concentric rings.

[0008] The first electrode pattern can include a first set of links connecting the first set of concentric rings, and the second electrode pattern can include a second set of links connecting the second set of concentric rings.

[0009] A first link in the first set of links can have a greater electrical resistance than a second link in the first set of links radially outward from the first link in the first set of links, and a first link in the second set of links can have a lower electrical resistance than a second link in the second set of links radially outward from the third link in the second set of links.

[0010] The first set of concentric rings can correspond to the second set of concentric rings in at least one of: area of each ring, radius of each ring, depth of each ring, material of each ring, spacing between each pair of adjacent rings, or number of rings.

[0011] The first set of concentric rings can be substantially aligned with the second set of concentric rings in a direction parallel to a common axis.

[0012] The first electrode pattern and the second electrode pattern can have different radial resistance profiles.

[0013] The first electrode pattern can include a plurality of first concentric sections, where each first concentric section can include a first set of concentric rings and a first set of links connecting the first set of concentric rings; and the second electrode pattern can include a plurality of second concentric sections, where each second concentric section can include a second set of concentric rings and a second set of links connecting the second set of concentric rings; where the electrical resistance of each first set of links can increase sequentially radially inward, and the electrical resistance of each second set of links can decrease sequentially radially inward.

[0014] The first concentric sections can include at least one first concentric section having a radially innermost link exhibiting a higher electrical resistance than a radially outermost link of another radially inward adjacent first concentric section; and the second concentric sections can include at least one second concentric section having a radially innermost link exhibiting a lower electrical resistance than a radially outermost link of another radially inward adjacent second concentric section.

[0015] The first half-cell can include at least one support film, and the first electrode pattern can be located between an innermost support film of the first half-cell and the liquid crystal material; and the second half-cell can include at least one support film, and the first electrode pattern can be located between an innermost support film of the second half-cell and the liquid crystal material.

[0016] The liquid crystal device can be switchable between: (i) applying a potential difference across terminals of the first electrode pattern while terminals of the second electrode pattern are held at a common potential; and (ii) applying the potential difference across terminals of the second electrode pattern while the terminals of the first electrode pattern are held at a common potential.

[0017] The liquid crystal device is operable as an adaptive optical lens.

[0018] The liquid crystal device is operable as an optical lens that is switchable between a positive focal power with the first electrode pattern activated and a negative focal power with the second electrode pattern activated.

[0019] An assembly comprising: a liquid crystal cell comprising first and second half-cells and a liquid crystal material contained between the first and second half-cells; the first and / or second half-cells comprising a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern at least partially in the first region of the liquid crystal material; the liquid crystal device being switchable between activating the first electrode pattern and activating the second electrode pattern; and at least one additional optical element.

[0020] The at least one additional optical element can comprise at least one of: a waveguide, an illumination adjustment component, a lens, an image generating device, a reflection reduction layer, or a protective layer.

[0021] An apparatus comprising: a liquid crystal cell comprising first and second half-cells and a liquid crystal material contained between the first and second half-cells, the first and / or second half-cells comprising a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern at least partially in the first region of the liquid crystal material; at least one processor; and at least one memory including instructions configured to, with the at least one processor, cause the apparatus to switch between: activating the first electrode pattern; and activating the second electrode pattern.

[0022] The apparatus can comprise: at least one electrical connection connected to the first and second electrode patterns; and drive circuitry connected to the at least one electrical connection to apply a potential difference between at least portions of the first and second electrode patterns.

[0023] The apparatus can comprise at least one sensor to obtain eye tracking data, the instructions being configured to, with the at least one processor, cause the apparatus to switch between the activating the first electrode pattern and the activating the second electrode pattern based at least in part on the eye tracking data.

[0024] The apparatus can be configured to be mounted on a human head, wherein the liquid crystal cell is positioned in a field of view of an eye of the human head.

[0025] The device may include: a first lens that includes a first portion of the liquid crystal cell; and a second lens that includes a second portion of the liquid crystal cell.

[0026] The instructions can be configured to use the at least one processor to cause the device to switch the first lens to a first focal length and the second lens to a second focal length different from the first focal length.

[0027] The first focal length can be a positive focal length, and the second focal length can be a negative focal length.

[0028] The field of view of the eye can be the first field of view of the first eye, and the first lens can be assembled to be positioned in the first field of view during use, and the second lens can be assembled to be positioned in the second field of view of the second eye of the human head during use.

[0029] The device may be at least one of the following: an augmented reality display device, a virtual reality display device, or a mixed reality display device.

[0030] A method of operating a liquid crystal device, the liquid crystal device comprising at least one liquid crystal cell, the liquid crystal cell comprising a first half-cell and a second half-cell and liquid crystal material contained between the first half-cell and the second half-cell; the first half-cell and / or the second half-cell comprising a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern in the first region of the liquid crystal material at least partially; the method comprising switching between (i) applying a potential difference across an electrical terminal connected to the first electrode pattern and (ii) applying a potential difference across an electrical terminal connected to the second electrode pattern. Attached Figure Description

[0031] By way of example only, with reference to the examples described in detail below with reference to the accompanying drawings, in which:

[0032] Figure 1 Demonstrates a representation of the device based on an example;

[0033] Figure 2 Showing based on examples Figure 1 Representation of the radial electrode pattern of one half-unit of the device;

[0034] Figure 3 Showing based on examples Figure 1 Representation of the radial electrode pattern of the other half of the device unit;

[0035] Figure 4 and Figure 5 Showing examples for Figure 1 A representation of a pair of radial resistance profiles of the radial electrode pattern of the device;

[0036] Figure 6 and Figure 7 shows a representation of circuitry according to an example for switching a terminal of one of the radial electrode patterns of a device for traversing Figure 1 to a terminal of another of the two radial electrode patterns of a device for traversing Figure 1 ;

[0037] Figure 8 illustrates a refractive index (RI) pattern and a corresponding electrode pattern comprising an array of concentric rings according to an example;

[0038] Figure 9 and Figure 10 illustrates a pair of radial electrode patterns for a device for traversing Figure 1 according to a further example;

[0039] Figure 11 and Figure 12 illustrates a pair of radial resistivity profiles for a radial electrode pattern of a device for traversing Figure 1 according to yet a further example;

[0040] Figure 13 and Figure 14 illustrates a configuration of two radial electrode patterns of a device for traversing Figure 1 according to an example;

[0041] Figure 15 illustrates a refractive index profile for a positive Fresnel lens according to an example;

[0042] Figure 16 shows a representation of electrode patterns for two sides of a Fresnel LC lens device according to an example;

[0043] Figure 17 shows a head-mounted kit incorporating a liquid crystal adaptive optical lens according to an example;

[0044] Figure 18 shows a representation of a system for operating a head-mounted kit for traversing Figure 17 ; and

[0045] Figure 19 schematically shows an apparatus according to an example. DETAILED DESCRIPTION

[0046] The examples herein are directed to a liquid crystal device comprising a liquid crystal cell comprising a liquid crystal material. The liquid crystal cell comprises a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern in at least the first region. By way of example, a radial refractive index pattern refers to a radial spatial variation of the refractive index of the liquid crystal material. By way of example, a radial refractive index pattern can be considered to refer to a change in the refractive index of the liquid crystal material from a center point in the plane of the liquid crystal material towards the periphery of the plane. In use, such a plane may, for example, be substantially perpendicular to an optical propagation axis along which light propagates through the liquid crystal device. In these examples, the liquid crystal device can be switchable between activating the first electrode pattern and activating the second electrode pattern. This means that the first radial refractive index pattern and the second radial refractive index pattern can each be obtained in at least the first region, depending on which of the first electrode pattern and the second electrode pattern is activated. In this way, the liquid crystal cell can be switched between two different radial refractive indices in a direct manner. The number of different radial refractive index patterns that can be obtained by a liquid crystal cell according to the examples can thus be greater than in a liquid crystal cell that is only able to achieve a single radial refractive index pattern. Changing the radial refractive index can be used to vary the focusing effect achieved by the liquid crystal device. Thus, the focusing effect of the liquid crystal device can be controlled in a flexible manner.

[0047] In examples, the first electrode pattern and the second electrode pattern have different radial electrical resistance profiles. This is a relatively direct way of configuring the first electrode pattern and the second electrode pattern to create the first radial refractive index pattern and the second radial refractive index pattern in at least the first region, respectively, depending on the electrical potential applied to the first electrode pattern and the second electrode pattern.

[0048] In examples, the liquid crystal device can be switchable between activating the first electrode pattern and activating the second electrode pattern to switch between a first focal power if the first electrode pattern is activated and a second focal power if the second electrode pattern is activated. In some examples, the first focal power is a positive focal power and the second focal power is a negative focal power (but in other examples, the first focal power is a negative focal power and the second focal power is a positive focal power). In such examples, switchability between a positive focal power and a negative focal power can thus be achieved in a liquid crystal cell (e.g. a single liquid crystal cell).

[0049] A liquid crystal device according to examples comprises at least one liquid crystal cell, such as Figure 1A liquid crystal cell is shown in FIG. 1. The liquid crystal cell includes liquid crystal material 16 contained between two half-cells 2a, 2b. Each half-cell 2a, 2b includes a single flexible support film 4a, 4b (e.g., a flexible organic polymer film such as triacetate cellulose (TAC) film) that supports a layer stack formed in place on the support film. The layer stack includes a patterned conductor layer 8a, 8b that defines conductive lines from a radially central portion of the active area of the cell to a peripheral region outside the active area of the cell. The active area of the cell is the area of the cell over which a radial index of refraction pattern is created in the liquid crystal material 16 as part of the normal operation of the liquid crystal device. Over the patterned conductor layer 8a, 8b is a patterned insulating layer 10a, 10b that defines vias to the conductive lines of the patterned conductor layer 8a, 8b. Over the patterned insulating layer 10a, 10b is a patterned electrode material (e.g., indium tin oxide (ITO)) layer that defines an electrode pattern. The patterned electrode material layer contacts the bus lines through the vias defined by the patterned insulating layer 10a, 10b. Terminals 14a, 15a, 14b, 15b outside the active area enable connection of the output of a power supply across the radially central portion of the electrode pattern and the radially outer portion of the electrode pattern. After the electrode pattern is formed, liquid crystal alignment layers 12a, 12b (e.g., rubbed polyimide layers) are formed to interface the liquid crystal material 16.

[0050] Figure 2 and Figure 3 A pair of radial electrode patterns 6a, 6b for half-cells 2a and 2b according to examples are illustrated. In these examples, after the two half-cells 2a and 2b are assembled, the pair of radial electrode patterns 6a, 6b are centered on a common axis 18. Radial electrode pattern 6a creates a RI pattern (when radial electrode pattern 6b is held at ground potential) across the device area, where the other radial electrode pattern 6b creates a RI pattern (when radial electrode pattern 6a is held to ground), and vice versa. However, according to Figure 13 and Figure 14 In another example, after the two half-cells 2a and 2b are assembled, the pair of radial electrode patterns are offset from each other in a direction parallel to the plane of the radial electrode patterns 6a, 6b (by a distance between the centers of the two radial electrode patterns). The area in which radial electrode pattern 6a creates a refractive index (RI) pattern (when radial electrode pattern 6b is held at ground potential) only occupies a portion of the device area in which the other radial electrode pattern 6b creates a RI pattern, and vice versa. According to Figure 13 and Figure 14In the illustrated example variation, a common electrode 6c is provided at the same level as radial electrode pattern 6a in half-cell 2a to provide a counter electrode for the portion of another radial electrode pattern 6b outside the area occupied by radial electrode pattern 6a; and a common electrode 6d is provided at the same level as radial electrode pattern 6b in half-cell 2b to provide a counter electrode for the portion of another radial electrode pattern 6a outside the area occupied by radial electrode pattern 6b. When radial electrode pattern 6a is activated, radial electrode pattern 6b and counter electrode 6d are maintained at the same counter potential to together provide a counter electrode for the entire radial electrode pattern 6a; and when radial electrode pattern 6b is activated, radial electrode pattern 6a and common electrode 6c are held at the same counter potential to together provide a counter electrode for the entire radial electrode pattern 6b. In Figure 13 and Figure 14 the lines indicate the boundaries of the areas occupied by radial electrode patterns 6a and 6b and common electrodes 6c and 6d. In Figure 13 and Figure 14 the radially outer boundary of common electrode 6c is substantially aligned with a portion of the radially outer boundary of radial electrode pattern 6b, and the radially outer boundary of common electrode 6d is substantially aligned with a portion of the radially outer boundary of radial electrode pattern 6b. Common electrode 6c can or can not be patterned within the area occupied by radial electrode pattern 6b; and common electrode 6d can or can not be patterned within the area occupied by radial electrode pattern 6a.

[0051] In Figure 2 and Figure 3 each electrode pattern includes a series of concentric rings 20a, 20b centered on common axis 18 and each respective link 22a, 22b between each pair of adjacent concentric rings 20a. In other examples, links 22a, 22b can be formed of a material different from the electrode material of concentric rings 20a, 20b. For each radial electrode pattern 6a, 6b, the concentric rings 20a, 20b have equal areas whereby the series of outer radii of concentric rings 20a, 20b exhibit a conic section pattern, as shown in Figure 8 According to one example variation, the series of outer radii of concentric rings 20a, 20b exhibit another non-spherical pattern. For radial electrode pattern 6a, links 22a between adjacent concentric rings 20a are configured to exhibit a decreasing resistance in sequence toward common axis; and for radial electrode pattern 6b, links 22b between adjacent concentric rings 20b are configured to exhibit an increasing resistance in sequence toward common axis 18. The resistance sequence change of the links can involve a constant or different amount of change in the magnitude of resistance between adjacent links, and the resistance between the series of links can decrease and then increase in the direction toward the common axis (and vice versa), as shown in Figure 11 and Figure 12The first link in the first set of links 22a can have a greater electrical resistance than the second link in the first set of links 22a radially outward from the first link of the first set of links 22a, and the first link in the second set of links 22b can have a lesser electrical resistance than the second link in the second set of links 22b radially outward from the second link of the second set of links 22b, in some examples.

[0052] In examples such as Figure 2 and Figure 3 In examples, the first set of concentric rings 20a of the first electrode pattern 6a can substantially match the second set of concentric rings 20b of the second electrode pattern 6b. For example, the first and second sets of concentric rings can match each other within manufacturing tolerances and / or measurement uncertainties. The first and second sets of concentric rings can be identical or substantially identical to each other, but configured in different spatial locations within the liquid crystal cell, for example both centered on the common axis 18 but with a vertical offset therebetween such that the first and second sets of concentric rings 20a, 20b overlap, as shown in Figure 1 In examples, the first set of concentric rings can correspond to (e.g., substantially match, match, closely resemble, or otherwise resemble) the second set of concentric rings in at least one of: an area of each ring (e.g., in a plane perpendicular to an axis about which at least one of the radial electrode patterns 6a, 6b is centered, such as the common axis 18 in Figure 1 ), a radius of each ring (e.g., in the plane), a depth of each ring (e.g., in a direction perpendicular to the plane), a material of each ring (e.g., a material of or included by each ring, such as a compound or chemical composition), a spacing between each pair of adjacent rings (e.g., in the plane), or a number of rings.

[0053] Figure 4 and Figure 5 An example of a pair of resistance profiles for the pair of radial electrode patterns 6a and 6b is illustrated.

[0054] Figure 9 to Figure 12 Radial electrode patterns 6a and 6b according to further examples are illustrated, each including a plurality of concentric segments across which a potential difference can be applied in parallel. For clarity, Figure 9 and Figure 10 Only the radially inner portions of the radial electrode patterns 6a and 6b according to these examples are shown; Figure 11 and Figure 12 Resistance profiles for the entire electrode patterns according to these examples are shown, including the radially outer portions not shown in Figure 9 and Figure 10

[0055] ​According to these examples: each radial electrode pattern 6a, 6b includes a plurality of concentric segments, a potential difference can be applied across the concentric segments in parallel. Each concentric segment of a radial electrode pattern includes a set of concentric rings and links connecting the concentric rings of the concentric segment. Figure 11 and Figure 12 A pair of radial resistance profiles for such a pair of radial electrode patterns, each including three concentric segments, is shown according to examples. For one electrode pattern of these examples, the resistance of the links in each concentric segment decreases radially inward, and there is a reset increase in resistance between the radially innermost link of a concentric segment and the radially outermost link of the radially inward adjacent concentric segment. In other words, the resistance of the radially innermost link of a concentric segment of the electrode pattern is greater than the resistance of the radially outermost link of the radially inward adjacent concentric segment by a predetermined or otherwise set amount. In some examples, the resistance of the radially innermost link of each concentric segment of the electrode pattern is substantially the same as one another. For another electrode pattern of these examples, the resistance of the links in each concentric segment increases radially inward, and there is a reset decrease in resistance between the radially innermost link of a concentric segment and the radially outermost link of the radially inward adjacent concentric segment. In other words, the resistance of the radially innermost link of a concentric segment of the other electrode pattern is less than the resistance of the radially outermost link of the radially inward adjacent concentric segment by a predetermined or otherwise set amount. In some examples, the resistance of the radially innermost link of each concentric segment of the other electrode pattern is substantially the same as one another.

[0056] Figure 15 A refractive index (RI) profile (for a positive Fresnel lens) that can be achieved by the multi-segment electrode patterns described above is shown according to examples.

[0057] The links 22a, 22b provide an in-line resistor network. Differences in resistance between links can be achieved by configuring the links to have substantially the same cross-sectional area but different lengths, such as the same cross-sectional area within manufacturing and / or measurement tolerances. According to further examples, differences in resistance between links can be achieved by configuring the links to have both different widths and different lengths. According to yet further examples, the resistance of the concentric rings themselves can contribute significantly to the resistance profile.

[0058] The exact configuration of each series of links 22a, 22b will depend on the liquid crystal material, and more particularly, the relationship between (i) the refractive index of the liquid crystal material and (ii) the magnitude of the potential difference across the liquid crystal material 16. For liquid crystal materials for which this relationship is not linear; the sequential change in link resistance towards the common axis 18 can account for the non-linear relationship to enable the electrode pattern to achieve a substantially parabolic refractive index pattern in the liquid crystal material 16.

[0059] Figure 6and Figure 7 A representation of circuitry for switching between (i) applying the live output of the power supply to Figure 2 the radially inner terminal 15a of the electrode pattern 6a of Figure 2 the radially outer terminal 14a of the electrode pattern 6a of Figure 3 the two terminals 15b, 14b of the electrode pattern 6b of Figure 6 as shown in Figure 3 and (ii) applying the live output of the power supply 30 to Figure 3 the radially outer terminal 14b of the electrode pattern 6b of Figure 2 the radially inner terminal 15b of the electrode pattern 6b of Figure 7 the two terminals 14a, 15a of the electrode pattern 6a of as shown in

[0060] According to this (DC drive) example of actuating the lens, the potential at the concentric electrodes on one side of the LC material 16 is constant in polarity with respect to the potential at the concentric electrodes on the other side of the LC material 16 over time. According to another (AC drive) example for actuating the concentric electrodes, the potential at the concentric electrodes on one side of the LC material is alternated in polarity with respect to the potential at the concentric electrodes on the other side of the LC material 16 over time at a high switching frequency of, for example, about 60 Hz or higher. The AC drive example can help to better protect the molecules of the LC material 16. According to one example, the device switches between (i) applying synchronous AC voltage waveforms having relatively higher and lower amplitudes to terminals 15a and 14a, respectively, and applying a reference COM potential (e.g., 0 V) to both terminals 14b and 15b; and (ii) applying synchronous AC voltage waveforms having relatively higher and lower amplitudes to terminals 14b and 15b, respectively, and applying a reference COM potential (e.g., 0 V) to both terminals 14a and 15a. The magnitude of the amplitudes of the synchronous AC voltage waveforms controls the magnitude of the RI distribution created in the LC material, and thus the optical power (diopters) of the device.

[0061] When the live output of the power supply 30 is applied to Figure 2 the radially inner terminal 15a of the electrode pattern 6a of Figure 2 the radially outer terminal 14a of the electrode pattern 6a of Figure 3 the two terminals 14b, 15b of the electrode pattern 6b of Figure 6When the charged output of power supply 30 is applied to the radially outer terminal 14b of electrode pattern 6b of Fresnel lens device 10, and the radially inner terminal 15b of electrode pattern 6b of Fresnel lens device 10 is grounded (as shown in FIG. 1), or for example when the above-mentioned synchronized AC voltage waveforms having relatively higher and lower amplitudes are applied to terminals 14b and 15b, respectively, and a reference COM potential (e.g., 0 V) is applied to both terminals 14a and 15a: the potential difference across liquid crystal material 16 decreases toward common axis 18, and the refractive index of liquid crystal material 16 increases toward the common axis (because the refractive index of the liquid crystal material decreases as the potential difference across the liquid crystal material 16 increases). Figure 2 The radial resistance profile of electrode pattern 6a of Fresnel lens device 10 is configured to achieve a radial potential profile in electrode pattern 6a that produces a substantially parabolic radial variation in the refractive index required to achieve negative focal power.

[0062] Similarly, when the charged output of power supply 30 is applied to the radially outer terminal 14b of electrode pattern 6b of Fresnel lens device 10, and the radially inner terminal 15b of electrode pattern 6b of Fresnel lens device 10 is grounded (as shown in FIG. 1), or for example when the above-mentioned synchronized AC voltage waveforms having relatively higher and lower amplitudes are applied to terminals 14b and 15b, respectively, and a reference COM potential (e.g., 0 V) is applied to both terminals 14a and 15a: the potential difference across liquid crystal material 16 decreases toward common axis 18, and the refractive index of liquid crystal material 16 increases toward the common axis (because the refractive index of the liquid crystal material decreases as the potential difference across the liquid crystal material 16 increases). Figure 3 The radial resistance profile of electrode pattern 6b of Fresnel lens device 10 is configured to achieve a radial potential profile in electrode pattern 6b that produces a substantially parabolic radial variation in the refractive index required to achieve positive focal power. Figure 3 Figure 2 Similarly, when the charged output of power supply 30 is applied to the radially outer terminal 14b of electrode pattern 6b of Fresnel lens device 10, and the radially inner terminal 15b of electrode pattern 6b of Fresnel lens device 10 is grounded (as shown in FIG. 1), or for example when the above-mentioned synchronized AC voltage waveforms having relatively higher and lower amplitudes are applied to terminals 14b and 15b, respectively, and a reference COM potential (e.g., 0 V) is applied to both terminals 14a and 15a: the potential difference across liquid crystal material 16 decreases toward common axis 18, and the refractive index of liquid crystal material 16 increases toward the common axis (because the refractive index of the liquid crystal material decreases as the potential difference across the liquid crystal material 16 increases). Figure 7 The radial resistance profile of electrode pattern 6a of Fresnel lens device 10 is configured to achieve a radial potential profile in electrode pattern 6a that produces a substantially parabolic radial variation in the refractive index required to achieve negative focal power. Figure 3 Similarly, when the charged output of power supply 30 is applied to the radially outer terminal 14b of electrode pattern 6b of Fresnel lens device 10, and the radially inner terminal 15b of electrode pattern 6b of Fresnel lens device 10 is grounded (as shown in FIG. 1), or for example when the above-mentioned synchronized AC voltage waveforms having relatively higher and lower amplitudes are applied to terminals 14b and 15b, respectively, and a reference COM potential (e.g., 0 V) is applied to both terminals 14a and 15a: the potential difference across liquid crystal material 16 decreases toward common axis 18, and the refractive index of liquid crystal material 16 increases toward the common axis (because the refractive index of the liquid crystal material decreases as the potential difference across the liquid crystal material 16 increases).

[0063] The radial resistance profile of electrode pattern 6b of Fresnel lens device 10 is configured to achieve a radial potential profile in electrode pattern 6b that produces a substantially parabolic radial variation in the refractive index required to achieve positive focal power. Figure 9 to Figure 12

[0064] Figure 16 ​​A representation of an electrode pattern in a Fresnel lens device including concentric segments 31 (A to E) for both sides of LC material 16 is shown according to some example embodiments. For one side of LC material 16, terminal 14a is connected via busbar wire 32 to the outermost radial concentric electrodes of each of the concentric segments A to E, and terminal 15a is connected via busbar wire 34 to the radially innermost concentric electrodes of each of the concentric segments A to E. On the other side of LC material 16, terminal 14b is connected via busbar wire to the outermost radial concentric electrodes of each of the concentric segments A to E, and terminal 15b is connected via busbar wire 34 to the radially innermost concentric electrodes of each of the concentric segments A to E. Driver chip 36 is connected to terminals 14a, 14b, 15a, 15b via pins of the driver chip.

[0065] According to one (DC drive) example of starting the lens, the potentials at the concentric electrodes of concentric segments A to E on one side of LC material 16 are constant in polarity relative to the potentials at the concentric electrodes of concentric segments A to E on the other side of the LC material over time. According to another (AC drive) example for starting the lens, the potentials at the concentric electrodes of each of concentric segments A to E on one side of LC material 16 are alternated in polarity relative to the potentials at the concentric electrodes of each of concentric segments A to E on the other side of LC material 16 over time, at a high switching frequency of, for example, about 60 Hz or higher. The AC drive example can help to better protect the molecules of the LC material. According to one example: synchronized AC voltage waveforms with relatively higher and lower amplitudes are applied to terminals 15a and 14a, respectively, and a reference COM potential (e.g., 0 V) is applied to terminals 14b and 15b; or synchronized AC voltage waveforms with relatively higher and lower amplitudes are applied to terminals 14b and 15b, respectively, and a reference COM potential (e.g., 0 V) is applied to terminals 14a and 15a. The magnitude of the amplitudes of the synchronized AC voltage waveforms controls the magnitude of the RI distribution created in the LC material, and thus the optical power (diopters) of the device. In this simple example, four inputs from driver chip 36 (to each of four terminals 14a, 15a, 14b, 15b and each of four respective busbars) are used, but other examples can include more busbars, and more respective inputs to those busbars via respective terminals. As Figure 4 and Figure 5 (or Figure 11 and Figure 12 ) as illustrated, in these examples the radial resistance profiles of electrode patterns 6a and 6b differ from each other in order to achieve different kinds of potential profiles in the same pattern of concentric rings 20a, 20b.

[0066] Thus, in examples, liquid crystal material 16 can be switched between a positive power configuration and a negative power configuration.

[0067] A liquid crystal device can include a stack of liquid crystal cells according to examples herein. Including at least one liquid crystal cell according to examples described above in a stack can enable a reduction in the number of liquid crystal cells needed to achieve a given function or range of functions, such as a range of focal powers between positive maximum power and maximum negative power. A reduction in the number of liquid crystal cells can reduce light absorption, scattering, haze, and internal reflections; and can also reduce design and manufacturing complexity.

[0068] The optical quality that can be achieved using a liquid crystal cell can be inversely proportional to the focal power of the liquid crystal cell, as increasing the power of a liquid crystal cell can increase light absorption, scattering, and the like, and thus reduce optical quality. However, examples herein having at least one liquid crystal cell that provides the ability to switch between positive and negative power can improve the optical quality that can be achieved for a particular focal power. As an example, a device including a stack of two liquid crystal cells according to examples herein, each having an individual focal power between -0.5 and +0.5 diopters, can be employed to achieve a focal power (sometimes referred to as optical power) between -1 and +1 diopters. Such a device can provide improved optical quality compared to a device providing the same focal power between -1 and +1 diopters but using a stack of one liquid crystal cell that can be controlled to provide a negative focal power between -1 and 0 diopters and another liquid crystal cell that can be controlled to provide a positive focal power between 0 and +1 diopters.

[0069] The liquid crystal devices described above can for example function as or be used within a switchable lens device or a beam steering device. For example, a device can be or include an adaptive optical lens including a liquid crystal device according to any of the examples herein. Such a device can be or include a head-mounted kit, which can be referred to as a head-mounted display (HMD).

[0070] The liquid crystal devices described above are suitable for a wide range of applications, including ophthalmic lenses (such as eyeglasses), virtual reality (VR), mixed reality (MR), and augmented reality (AR) head-mounted kits; optical projectors; photographic devices; and communication devices.

[0071] For example, LC optical lens devices can be used in augmented reality (AR) head-mounted kits (such as Figure 17push lens, a pull lens, or a combined push / pull lens. The headset 40 includes a support frame 42 that supports an optical assembly configured in an optical series in front of the user's eyes. The optical assembly includes: (i) a push lens 48a, a waveguide 50, and a pull lens 48b for presenting virtual objects to the user; (ii) a front window / lens 44; and (iii) a variable dimmer device 46 between (ii) the front window / lens 44 and (i) the optical assembly for presenting virtual objects to the user.

[0072] at least one optical assembly, such as Figure 17 One or more of the optical assemblies shown in FIGS. 1-3 can be considered to correspond to or be part of an assembly that can be considered to be a display stack including at least one liquid crystal cell according to examples herein. In examples such as Figure 17 In examples such as FIG. 3, such an assembly includes a stack of liquid crystal cells according to examples herein. In Figure 17 In examples such as FIG. 3, the push lens 48a includes at least one liquid crystal cell (e.g., a stack of liquid crystal cells), the pull lens 48b includes at least one liquid crystal cell (e.g., a stack of liquid crystal cells), and the assembly includes the push lens 48a, the waveguide 50, the pull lens 48b, the variable dimmer device 46 (which is an example of a luminance adjustment assembly), and the front window / lens 44. Examples of an assembly including two liquid crystal cells that are spatially separated from each other (e.g., such as the assembly with the push lens 48a with a liquid crystal cell and the pull lens 48b with a liquid crystal cell) can still be considered to include a stack of liquid crystal cells, e.g., where the liquid crystal cells are located within the field of view of the same eye from each other such that the liquid crystal cells are in the optical path of light traveling through the assembly and into the eye. The stacked liquid crystal cells can be aligned along a common optical axis (such as the common axis 18 of FIG. 3). Figure 1 However, in some cases, the optical axes of at least two of the stacked liquid crystal cells can be offset from each other in a direction parallel to the plane of the radial electrode pattern of at least one of the liquid crystal cells (such as in the examples of FIGS. 1-2), with the proviso that light traversing the assembly traverses the stacked liquid crystal cells. Figure 13 and Figure 14 Figure 17 Only the optical assembly for one half of the headset is shown, but a matching set of optical assemblies is also provided for the other half of the headset.

[0073] The waveguide 50 of the headset shows left and right perspectives, respectively, of one or more virtual reality objects that the user perceives as a 3D object by way of the perspectives. Alternatively, other mechanisms can be used to show left / right perspectives of one or more virtual reality objects, such as laser projection.

[0074] ​The left and right eyes of the user need to rotate relative to each other to the extent that the left and right perspectives of the virtual reality object are simultaneously directed onto the fovea of the respective left and right eyes of the user (which is the part of the retina responsible for critical, high-acuity vision necessary for activities such as reading) of the user to determine the distance at which the user perceives the virtual reality object to be located. This mechanism is known as "vergence".

[0075] The LC optical lens devices described above can be used as adaptive lens devices to control the position of the left / right perspectives of a displayed virtual reality object that the eyes of the user perceive to be in focus (i.e., not blurred), which can be referred to as the focal plane. In other words, the LC optical lens devices described above can be used as adaptive lens devices to control the extent to which the lenses in the eyes of the user need to accommodate to perceive the left and right perspectives of a virtual reality object to be in focus (i.e., not blurred). This accommodation mechanism of the lenses in the eyes of the user is known as "accommodation".

[0076] The LC optical lens devices described above can be used to create an optical image (real or virtual) of the left / right perspectives of a virtual reality object at a distance from the eyes of the user that the user perceives the virtual reality object to be located at through the above-mentioned vergence mechanism. This can allow the user to perceive a focused 3D image of the virtual reality object without breaking the vergence-accommodation reflex, by which the focusing action (accommodation) of the lenses in the eyes of the user is unconsciously associated with the above-mentioned rotation (vergence) of the left and right eyes relative to each other. In other words, the LC optical lens devices can be used to avoid or reduce the strain on the eyes of the user that can result from a conflict between the vergence mechanism and the accommodation mechanism, known as the vergence-accommodation conflict. For example, the LC optical lens devices can switch between a positive focal power with the first electrode pattern activated and a negative focal power with the second electrode pattern activated.

[0077] Accordingly, liquid crystal devices according to examples herein can provide lower complexity and / or higher quality systems to actively adjust the focal point to compensate for a focal disparity between a virtual object and a real-world environment visible to a user of a head-mounted set through optical assemblies mounted in front of each eye. This, for example, allows perceived and actual image depth to be brought together in a consistent manner, thereby improving user comfort.

[0078] In Figure 17In particular embodiments, head-mounted kit 40 permits light from the real-world environment surrounding head-mounted kit 40 to at least partially transmit through the optical assembly and to the user's eye. In this example, the optical assembly is at least partially transparent. On a sunny day, the illumination of the environment can be significantly higher outdoors than indoors, such as approximately 100 times higher. This can result in virtual objects appearing washed out and difficult to see when the user is operating the head-mounted kit outdoors unless the illumination of the light transmitted from the environment to the user is properly controlled. In Figure 17 In particular embodiments, variable dimmer device 46 controls the amount of light that is transmitted through the optical assembly and toward the eye, for example, in order to reduce the illumination of the light transmitted from the environment toward the user in bright conditions, and can be used to provide ambient dimming to dim the ambient light transmitted through head-mounted kit 40.

[0079] Variable dimmer device 46 can provide so-called global dimming, in which the illumination of the light from the environment is adjusted by substantially the same amount across the plane of variable dimmer device 46 facing the user (e.g., to reduce the illumination of the light by substantially the same amount across the entire surface area of variable dimmer device 46). In other words, global dimming can allow the illumination of the light transmitted through variable dimmer device 46 to be controlled in a substantially spatially uniform manner (e.g., in order to provide a substantially spatially uniform reduction in illumination across the user's field of view). Variable dimmer device 46 can also or instead provide local dimming, in which variable dimmer device 46 is adjustable to control the illumination of the light transmitted from the environment on a region-by-region basis (where a region can correspond to a single pixel or multiple pixels). Variable dimming can involve adjusting the illumination across less than the entire surface area of variable dimmer device 46, such as within a sub-area of the surface area of variable dimmer device 46. However, in other cases, variable dimming can involve adjusting the illumination across the entire surface area of variable dimmer device 46, but by different amounts in at least two portions of the surface area.

[0080] Although Figure 17 Although not shown in particular embodiments, it should be appreciated that head-mounted kit 40 can be configured to obtain illumination data indicative of the illumination of light within the environment of head-mounted kit 40, for example, from a light sensor of head-mounted kit 40. For example, if first side 49a of head-mounted kit 40 is configured to face the user with head-mounted kit 40 mounted on the user's head, head-mounted kit 40 can include a light sensor to detect the illumination of light at second side 49b of head-mounted kit 40 opposite first side 49a. Variable dimmer device 46 can be controlled based at least in part on the illumination data in order to adjust the illumination of light transmitted from the second side of head-mounted kit 40 toward the user to improve the visibility of virtual objects displayed by head-mounted kit 40 to the user.

[0081] In Figure 17In the example of FIG. 1, a first lens (push lens 48a) including at least one liquid crystal cell of the examples herein is positioned between the waveguide 50 and the eye when the head-mounted set 40 is in use. Light representing a virtual object is generated and transmitted to the waveguide 50, which directs the light through the push lens 48a and to the eye. The push lens 48a has a focusing effect that focuses the light representing the virtual object so that the object is presented in focus to the user. For example, the virtual object can be generated so that it is in focus at a focal plane at infinity. The push lens 48a can then focus the virtual object at a focal plane closer to the user than infinity to allow the user to focus more comfortably on the virtual object. The focal plane at which the virtual object will be focused and thus the focusing power to be applied by the push lens 48a can be determined based on eye tracking data indicating the direction in which the user's eye is looking, for example, obtained by a suitable sensor as discussed further below.

[0082] Prior to use of the head-mounted set 40, the external environment can be presented in focus to the user. However, in the absence of the pull lens 48b, light from the external environment will at least partially transmit through the waveguide 50 and through the push lens 48a, and thus will be subject to the focusing effect provided by the push lens 48a. This will distort the external environment as viewed by the user through the head-mounted set 40. To compensate for the distortion introduced by the push lens 48a, Figure 17 The head-mounted set 40 of FIG. 1 includes a second lens (pull lens 48b) positioned at the side of the waveguide 50 opposite the push lens 48a. The pull lens 48b applies an appropriate focusing effect to light from the environment that traverses the pull lens 48b to at least partially compensate for or otherwise reduce the focusing effect introduced by the push lens 48a. For example, the push lens 48a and the pull lens 48b can provide focusing effects that are opposite one another, e.g., where the magnitudes are substantially equal but the signs are opposite. As an example, one of the push lens 48a and the pull lens 48b can provide a positive focusing power and the other of the push lens 48a and the pull lens 48b can provide a negative focusing power, which positive focusing power and negative focusing power can be substantially equal in magnitude.

[0083] In examples, at least one lens of the examples herein, such as at least one of the push lens 48a and the pull lens 48b, and in some cases both the push lens 48a and the pull lens 48b, each comprises a so-called doublet lens of a liquid crystal cell according to the examples herein. A doublet lens is a stack of two liquid crystal cells. The focusing effect of a liquid crystal based lens can depend on the polarization of light impinging on the lens. Rather than using a separate polarizer component, using such a doublet lens can provide proper focusing effect with improved light projection; in some examples, this is achieved by configuring one liquid crystal cell of the doublet lens with respect to each liquid crystal cell to modify the respective polarization orientation for which light is directed and the other liquid crystal cell of the doublet lens is positioned orthogonally.

[0084] Figure 17 Examples of the push lens 48a and the pull lens 48b in combination with various other optical components are shown. It will be appreciated that the liquid crystal cells according to the examples herein can be used in combination with optical components different from the ones shown in Figure 17 in order to provide further flexibility in functionality. This can further reduce the size and / or weight of the device comprising the liquid crystal cells and / or improve the optical performance of the device. For example, an assembly comprising liquid crystal cells according to the examples herein, such as a display stack, can comprise a reflection reducing layer, such as an anti-reflective (AR) coating, which can be laminated to another optical component of the assembly, such as the front window / lens 44, and / or a protective layer, such as a hard coating, which serves to protect the assembly from damage due to, for example, abrasion and / or wear due to exposure to environmental conditions.

[0085] In examples, the liquid crystal device comprises electrical terminals electrically connected to the first electrode pattern and the second electrode pattern. The electrical terminals, for example, allow a potential difference to be applied between the first electrode pattern and the second electrode pattern. As explained above, the potential applied to the electrical terminals can be controlled by a suitable control system, for example, such that the liquid crystal device can be switched between activating the first electrode pattern and activating the second electrode pattern. For example, the liquid crystal device can be switched between applying a potential difference across the electrical terminals connected to the first electrode pattern and applying a potential difference across the electrical terminals connected to the second electrode pattern.

[0086] A further example is directed to a system comprising a liquid crystal device according to any of the examples herein, and a driver chip connected to the electrical terminals. Figure 18 A system 55 according to these examples is illustrated. With reference to Figure 18According to these examples, the system 55 includes a processor 51 that operates based on computer program code stored in memory 52 to control an image generation driver chip 53 to cause an image generation system to generate images of left / right perspectives of one or more virtual reality objects (from which a user can perceive 3D images of the virtual reality objects) and to display the images via a waveguide 50. Although not shown in Figure 18 , it will be appreciated that there can be two waveguides: one waveguide displays images of left perspectives of virtual reality objects to a left eye, and another waveguide displays images of right perspectives of virtual reality objects to a right eye, as discussed further with reference to Figure 17 . There can further be two image generation systems: one image generation system generates images of left perspectives of virtual reality objects, and another image generation system generates images of right perspectives of virtual reality objects (although in some cases a single image generation system can generate both images or an image generation system can generate a single image to be displayed to both eyes). The image generation systems are discussed further below with reference to Figure 19 . Input from sensors 54 feeds into the processor 51 to enable the processor 51 to control the position at which virtual reality objects are displayed by the waveguide 50 to seamlessly overlay one or more virtual reality objects into a user’s view of the user’s real environment.

[0087] Based on input into the processor 51 from one or more sensors 54 that sense movement of the user’s eyes and / or based on the content being displayed by the waveguide 50, the processor 51 controls an adaptive lens driver chip 36 to control electrical input to terminals 14a, 14b, 15a, 15b to achieve the optical focusing power (diopters) required for the above-described generation of an optical image of the display output of the waveguide at a distance from the user’s eyes at which the virtual content that the user is determined to be looking at (e.g., by tracking the user’s eyes) is intended to be perceived by the user (through the vergence mechanism described above). The driver chip is an example of a controller, which can be implemented in hardware, e.g., via suitably configured circuitry. In some cases, the driver chip can comprise or be considered to implement at least one processor.

[0088] Figure 19 A hardware architecture of an apparatus 60 according to a further example is schematically illustrated. The apparatus 60 includes at least one liquid crystal cell according to examples herein. In Figure 19 , the apparatus 60 is configured to be mounted in use on a human head, e.g., a user’s head, with the liquid crystal cell positioned in the field of view of the eyes of the head. In Figure 19 , the apparatus 60 is an AR headset for displaying virtual images to a wearer of the headset, and can be similar to or the same as the apparatus 60 of Figure 17The headgear 40. However, in other instances, including with Figure 19 Devices with similar hardware architectures to Device 60 can be assembled for different purposes and may include additional components and / or omissions. Figure 19 At least one of the components shown in the figure.

[0089] Figure 19 The device 60 includes an optical system 62, an image generation system 64, at least one processor 66, a storage device 68, at least one sensor 70, a user input / output interface 72, a communication system 74, and at least one additional hardware system 76. The components of the device 60 are interconnected via at least one bus 78, which may be or include any suitable interface or bus for transmitting data between the illustrated components.

[0090] The optical system 62 includes a first assembly and a second assembly, which in this example are a first display stack 62a and a second display stack 62b, respectively. The first display stack 62a includes, for example, a first set of optical components configured in a layered stack. The device 60 is configured to allow light from the external environment, when in use and mounted on a head, to be at least partially transmitted through the first display stack 62a and toward the user's first eye. In other words, the device 60 has a first side configured to face the user in use (e.g., ...). Figure 17 In the case of the first side 49a), the first display stack 62a is configured to direct light from the second side to the first eye (in this case, via the first display stack 62a). In this case, the first display stack 62a includes Figure 17 The optical components shown herein are, namely, a pushing lens 48a, a waveguide 50, a pulling lens 48b (where the pushing lens 48a and the pulling lens 48b are each examples of a liquid crystal device according to the examples herein), a variable dimmer device 46, and a front window / lens 44. The pushing lens 48a and / or the pulling lens 48b of the first display stack 62a can be considered as a first lens containing at least one first liquid crystal cell among the liquid crystal cells according to the examples herein. The first lens is configured to be positioned in a first field of view of a first eye (e.g., the user's first eye) during use.

[0091] exist Figure 19In this embodiment, the second display stack 62b includes a second set of optical components, which in this example are identical to the first set of optical components but are configured to transmit light toward the user's second eye when using the device 60. In other words, the second display stack 62b is configured to direct light from a second side of the device 60 toward the second eye. Therefore, in this example, the push lens and / or pull lens of the second display stack 62b can be considered as a second lens containing at least one second liquid crystal cell among the liquid crystal cells according to the embodiments herein. The second lens is configured to be positioned in the second field of view of the second eye (e.g., the user's second eye) during use. It should be understood that, in use, the first lens may be visible only to the first eye or to both the first and second eyes, and the second lens may be visible only to the second eye or to both the first and second eyes during use.

[0092] The spatial arrangement of the elements of the second display stack 62b in at least one layer of the stack may be a mirror image of the spatial arrangement of the corresponding elements of the first display stack 62a in the corresponding layer of the stack of the first optical configuration 62a, as reflected in the sagittal plane of the device 60 (which may be referred to as the longitudinal plane of the device 60, and for example, separates the left and right sides of the device in use). However, in other cases, the first display stack 62a and the second display stack 62b may have structures different from each other. It should be understood that the optical system 62 may include additional components, such as Figure 19 Other optical components not shown in the image.

[0093] Device 60 also includes an image generation system 64 for generating images of virtual objects to be displayed to a user of device 60, such that the virtual objects appear to the user as overlaid on top of an external environment that is at least partially visible to the user via optical system 62. Image generation system 64 may be or include a display device for generating images (e.g., images of virtual objects) for device 60 to display to the user. The display device may be a liquid crystal display (LCD), a light-emitting diode (LED) display device (such as an organic light-emitting diode (OLED) display device), an electroluminescent (EL) display device, etc. Figure 19 In this example, the image generation system 64 communicates optically with the optical system 62. For instance, if device 60 is in... Figure 17 In the form of a head-mounted device 40, the image generation system 64 can be housed by a support frame 42. Light representing virtual objects generated by the image generation system 62 can be transmitted directly (e.g., without traversing another optical component) or via at least one additional optical component to the optical system (e.g., transmitted to a device such as...). Figure 17The waveguide 50 can be a waveguide of a waveguide assembly (e.g., a waveguide assembly of a waveguide assembly 50 as shown in FIG. 1). In some cases, the image generation system can include two display devices, a first display device for a first eye and a second display device for a second eye, e.g., in cases where a first image is to be displayed to the first eye and a second image is to be displayed to the second eye. In other examples, a single display device can be used to generate an image to be displayed to both the first eye and the second eye.

[0094] In Figure 19 In examples where the image generation system 64 is shown as a system separate from the optical system 62. However, in other examples, the image generation system can form part of the optical system. For example, an assembly of the optical system, such as a display stack, can include an image generation system, such as a display device.

[0095] The at least one processor 66 of the device 60 can be a single processor or multiple processors of one or more types. Components of the at least one processor 66 can be implemented using suitably programmed hardware, e.g., in the form of circuitry. The at least one processor 66 can include a central processing unit (CPU), a graphics processing unit (GPU), and / or a neural processing unit (NPU), which can be referred to as a neural network accelerator.

[0096] In some examples, such as Figure 19 A device of the device 60 includes drive circuitry connected to at least one electrical connection connected to the first electrode pattern and the second electrode pattern, such as the terminals 14a, 15a, 14b, and 15b discussed above, to apply a potential difference between at least portions of the first electrode pattern and the second electrode pattern. The potential difference applied between at least portions of the first electrode pattern and the second electrode pattern, such as a magnitude and / or timing of the applied potential difference, can be determined by the at least one processor 66 and / or by the drive circuitry, such as by a controller implemented by at least a portion of the drive circuitry, based on instructions stored in the storage.

[0097] If the potential difference is determined by the drive circuitry, the determination of the potential difference can be initiated by instructions received from the at least one processor, such as instructions indicating that a virtual item is to be displayed and at least one of the electrode patterns is to be activated accordingly so that the virtual item is presented in focus to the user. In this way, the drive circuitry can be agnostic to the at least one processor from which the instructions are received. In other words, the operation of the drive circuitry can be independent, e.g., of the at least one processor used to control the drive circuitry, so that the same effect can be achieved regardless of the at least one processor coupled to the drive circuitry, provided that the at least one processor provides appropriate instructions to the drive circuitry for the drive circuitry to determine a suitable potential difference.

[0098] A potential difference can be applied by at least one driver of the drive circuitry to the electrical connections, such as Figure 18 The adaptive lens driver wafer 36 is an example of a driver. The application of a potential difference by the at least one driver can be considered to correspond to a so-called "driving" of the electrode pattern via the electrical connections. The drive circuitry can be in the form of at least one system on a chip (SoC).

[0099] The storage 68 can be or include computer-usable, electrically and / or non-electrically dependent memory. The storage 68 can include random access memory (RAM) and / or read only memory (ROM). The storage 68 can be extractable or non-extractable from the device 60. The storage 68 stores instructions for controlling the device 60 in accordance with the examples herein, for example switching between activation of the first electrode pattern of the at least one liquid crystal cell of the device 60 and activation of the second electrode pattern of the at least one liquid crystal cell of the device 60. Activation of the electrode pattern refers for example to application of a potential difference between at least two connectors connected to the electrode pattern (for example application of a potential difference between the terminals 14a and 15a for the first electrode pattern and / or between the terminals 14b and 15b for the second electrode, for example as shown in Figure 1 Figure 6 Figure 7 and / or Figure 16 The instructions can be in the form of computer-readable and / or executable instructions, for example computer program instructions. Although the storage 68 is shown in Figure 19 as a separate component from the at least one processor 66, in some cases the storage 68 can be or include internal storage of the at least one processor 66, in which case the at least one processor 66 and the storage 68 can be at least partially integrated into the same system or component.

[0100] In this example, the at least one sensor 70 is configured to obtain, in use, eye tracking data of the device, for example indicative of a direction in which at least one eye of the user is looking, as will be appreciated by the person skilled in the art. The eye tracking data can be obtained for each eye, or for a single eye or a combination of both eyes of the user. Suitable sensors for obtaining the eye tracking data include a camera 70a for obtaining an image of at least one eye of the user, an inertial measurement unit (IMU) 70b for determining an orientation of the device 60, and at least one position sensor 70c, such as a global positioning system (GPS) sensor, to determine a position of the device 60. As will be appreciated by the person skilled in the art, the IMU 70b can include at least one accelerometer or gyroscope for determining the orientation of the device 60. The focusing effect of the at least one liquid crystal cell can be controlled based on the eye tracking data, for example in order to reduce eye strain of the user, as further described above. ​​

[0101] The device 60 also includes a user input / output interface 72 via which a user can interact with the device 60 to control the state of the device 60. For example, the user input / output interface 72 can be or include an input device such as a button, touch screen, slider, controller, or any other suitable device for communicating user requests to the device 60 to control the device 60.

[0102] The device 60 includes a communication system 74 for receiving data from a remote system, for example, via a suitable telecommunications network such as a wireless network or via some other type of network or connection. The communication system 74 can include an input / output interface such as a Bluetooth connector, a Universal Serial Bus (USB) connector, or a network connector for receiving data from a remote system.

[0103] Figure 19 The device 60 includes at least one further hardware system 76 for providing electrical power to the electrical components of the device 60, such as a power source, for example, a battery.

[0104] Some examples have been described above in relation to optical focusing devices, but the same techniques have been applied in other fields such as beam steering optics.

[0105] A further example is a method of operating a liquid crystal device according to any of the examples herein, the method comprising switching between (i) applying a potential difference across electrical terminals connected to a first electrode pattern and (ii) applying a potential difference across electrical terminals connected to a second electrode pattern. It will be appreciated that any of the features described in the context of the liquid crystal device herein equally apply to the method of operating the liquid crystal device.

[0106] The term "substantially" as used herein can be taken to mean two elements that are "substantially" the same: the same within manufacturing tolerances, the same within measurement uncertainty, and / or within 5% of each other.

[0107] In addition to any modifications explicitly mentioned above, it will be apparent to those skilled in the art that various other modifications can be made to the described examples within the scope of the appended claims for patent.

[0108] The applicant hereby discloses separately each individual feature or each combination of features described herein and any combination or sub-combination of any of the features or feature combinations disclosed herein. The applicant expressly disclaims any combination of features or feature combinations not expressly disclosed. The scope of the application is not intended to be limited to the foregoing specific illustrative embodiments, but only to be as broad as expressly set forth in the accompanying claims.

Claims

1. A liquid crystal device comprising at least one liquid crystal cell, the liquid crystal cell comprising a first half-cell and a second half-cell and liquid crystal material contained between the first half-cell and the second half-cell; the first half-cell and / or the second half-cell comprising a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern in at least partially the first region of the liquid crystal material; and the liquid crystal device being switchable between activating the first electrode pattern and activating the second electrode pattern.

2. The liquid crystal device of claim 1, wherein the first half-unit includes the first electrode pattern and the second half-unit includes the second electrode pattern.

3. The liquid crystal device as claimed in claim 1 or claim 2, wherein the first electrode pattern and the second electrode pattern are centered on a common axis.

4. The liquid crystal device according to any one of claims 1 to 3, wherein the first electrode pattern comprises a first set of concentric rings and the second electrode pattern comprises a second set of concentric rings.

5. The liquid crystal device of claim 4, wherein the first electrode pattern includes a first set of connectors connecting the first set of concentric rings, and the second electrode pattern includes a second set of connectors connecting the second set of concentric rings.

6. The liquid crystal device of claim 5, wherein the first connector in the first group of connectors has a larger resistance than the second connector in the first group of connectors that is radially outward from the first connector in the first group of connectors, and the first connector in the second group of connectors has a smaller resistance than the second connector in the second group of connectors that is radially outward from the third connector in the second group of connectors.

7. The liquid crystal device according to any one of claims 4 to 6, wherein the first set of concentric rings corresponds to the second set of concentric rings in at least one of the following aspects: the area of ​​each ring, the radius of each ring, the depth of each ring, the material of each ring, the spacing between each pair of adjacent rings, or the number of rings.

8. The liquid crystal device according to any one of claims 4 to 7, wherein the first set of concentric rings is substantially aligned with the second set of concentric rings in a direction parallel to a common axis.

9. The liquid crystal device as claimed in any of the preceding claims, wherein the first electrode pattern and the second electrode pattern have different radial resistance profiles.

10. The liquid crystal device according to any one of claims 1 to 3, wherein the first electrode pattern comprises a plurality of first concentric segments, wherein each first concentric segment comprises a first set of concentric rings and a first set of connectors connecting the first set of concentric rings; and the second electrode pattern comprises a plurality of second concentric segments, wherein each second concentric segment comprises a second set of concentric rings and a second set of connectors connecting the second set of concentric rings; wherein the resistance of each first set of connectors increases radially inward in sequence, and the resistance of each second set of connectors decreases radially inward in sequence.

11. The liquid crystal device of claim 10, wherein the first concentric segment comprises at least one first concentric segment, the innermost radial connector of the at least one first concentric segment exhibiting a higher resistance compared to the outermost radial connector of another radially inwardly adjacent first concentric segment; and wherein the second concentric segment comprises at least one second concentric segment, the innermost radial connector of the at least one second concentric segment exhibiting a lower resistance compared to the outermost radial connector of another radially inwardly adjacent second concentric segment.

12. The liquid crystal device as claimed in any of the preceding claims, wherein the first half-unit comprises at least one support film, and the first electrode pattern is located between an innermost support film of the first half-unit and the liquid crystal material; and wherein the second half-unit comprises at least one support film, and the first electrode pattern is located between an innermost support film of the second half-unit and the liquid crystal material.

13. The liquid crystal device as claimed in any of the preceding claims, wherein the liquid crystal device is switchable between: (i) applying a potential difference across the terminals of the first electrode pattern while keeping the terminals of the second electrode pattern at a common potential; and (ii) applying the potential difference across the terminals of the second electrode pattern while keeping the terminals of the first electrode pattern at a common potential.

14. The liquid crystal device as claimed in any of the preceding claims, operable as an adaptive optical lens.

15. The liquid crystal device as claimed in any of the preceding claims, operable as an optical lens switchable between positive focal length when the first electrode pattern is activated and negative focal length when the second electrode pattern is activated.

16. An assembly comprising: A liquid crystal unit, comprising: The first half-unit and the second half-unit, and the liquid crystal material contained between the first half-unit and the second half-unit; the first half-unit and / or the second half-unit includes a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern in at least partially the first region of the liquid crystal material; the liquid crystal device is switchable between activating the first electrode pattern and activating the second electrode pattern; and At least one additional optical element.

17. The device of claim 16, wherein the at least one additional optical element comprises at least one of the following: a waveguide, an illumination adjustment assembly, a lens, an image generating device, a reflection reduction layer, or a protective layer.

18. An apparatus comprising: A liquid crystal cell includes a first half-cell and a second half-cell and liquid crystal material contained between the first half-cell and the second half-cell, wherein the first half-cell and / or the second half-cell includes a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern in at least part of the first region of the liquid crystal material. At least one processor; and At least one storage device containing instructions configured to use the at least one processor to switch the device between: Activate the first electrode pattern; and Initiate the second electrode pattern.

19. The apparatus of claim 18, comprising: At least one electrical connector is connected to the first electrode pattern and the second electrode pattern; and A drive circuit system connected to the at least one electrical connector to apply a potential difference between at least a portion of the first electrode pattern and at least a portion of the second electrode pattern.

20. The device of claim 18 or claim 19, comprising at least one sensor to acquire eye-tracking data, the instructions being configured to use the at least one processor to cause the device to switch between activating the first electrode pattern and activating the second electrode pattern, at least in part, based on the eye-tracking data.

21. The device of claim 20, wherein the device is configured to be mounted on a human head, wherein the liquid crystal unit is positioned in the field of view of one eye of the human head.

22. The apparatus of claim 21, comprising: A first lens, which includes the first one in the liquid crystal cell; and The second lens contains the second element of the liquid crystal cell.

23. The device of claim 22, wherein the instructions are configured to use the at least one processor to cause the device to switch the first lens to a first focal length and the second lens to a second focal length different from the first focal length.

24. The device of claim 23, wherein the first focal length is a positive focal length and the second focal length is a negative focal length.

25. The device of any one of claims 22 to 24, wherein the field of view of the eye is a first field of view of a first eye, and the first lens is configured to be positioned in the first field of view in use, and the second lens is configured to be positioned in the second field of view of a second eye of the human head in use.

26. The device according to any one of claims 18 to 25, wherein the device is at least one of: an augmented reality display device, a virtual reality display device, or a mixed reality display device.

27. A method of operating a liquid crystal device, the liquid crystal device comprising at least one liquid crystal cell, the liquid crystal cell comprising a first half-cell and a second half-cell and liquid crystal material contained between the first half-cell and the second half-cell; the first half-cell and / or the second half-cell comprising a first electrode pattern for creating a first radial refractive index pattern in a first region of the liquid crystal material, and a second electrode pattern for creating a second radial refractive index pattern in the first region of the liquid crystal material at least partially, the method comprising switching between (i) applying a potential difference across an electrical terminal connected to the first electrode pattern and (ii) applying a potential difference across an electrical terminal connected to the second electrode pattern.

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