Liquid crystal lens and method for preparing the same

Abstract

The present invention provides a liquid crystal lens and a method for preparing the same. The liquid crystal lens has an optical axis, and the liquid crystal lens includes: a first substrate; a second substrate, arranged opposite to the first substrate; a liquid crystal layer, arranged between the first substrate and the second substrate; a common electrode layer, arranged between the second substrate and the liquid crystal layer; and a first electrode layer, arranged between the first substrate and the liquid crystal layer, the first electrode layer including a plurality of first electrodes, the plurality of first electrodes are arranged at intervals from the optical axis to the edge of the liquid crystal lens and divided into a plurality of groups, each group of first electrodes has a preset electrode sampling rate, and the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis. The liquid crystal lens has a simple structure, and the surface of each layer is flat, so it is easy to orient the liquid crystal molecules, easy to process and produce, and can be larger in size.

Description

Technical Field

[0001] The present invention generally relates to the field of lens technology, and in particular to a liquid crystal lens and a preparation method thereof. Background Art

[0002] Liquid crystal lens mainly uses electrodes to be set on two substrates on both sides of the liquid crystal layer, and different driving voltages are applied to different electrodes to form a vertical electric field with different strengths between the two substrates to drive the liquid crystal molecules to arrange and form a variable focus liquid crystal lens. Therefore, only the voltage distribution on the corresponding electrodes needs to be controlled, and the refractive index distribution of the liquid crystal lens will change accordingly, thereby controlling the distribution of the outgoing light passing through the liquid crystal lens. By controlling the voltage distribution on the corresponding electrodes, a non-uniform gradient distribution of the refractive index is formed in the liquid crystal layer of the liquid crystal lens, and the function of the Fresnel liquid crystal lens can be realized.

[0003] Figure 8 FIG. 1 shows an optical path difference distribution curve of an existing equal-height Fresnel liquid crystal lens. The Fresnel liquid crystal lens is generally divided into multiple zones from the center to the edge, and the width of each zone gradually decreases from the center to the edge (i.e. Figure 8 In the figure: W1'>W2'>W3'>…>Wi'), but each zone has the same number of driving electrodes, so the width of the driving electrodes is getting smaller and smaller. For a Fresnel lens, a ring-shaped sawtooth surface (or a central convex surface) is a zone (or a petal of a Fresnel liquid crystal lens is a zone); for a Fresnel liquid crystal lens, a voltage repetition unit can be considered as a zone, that is, there are as many zones as there are voltage repetition units. When the size of a Fresnel liquid crystal lens is large, the line width (width) of the driving electrode at the edge of the lens will be reduced to an unacceptable level. For example, if the line width is too small, it may not be processed, or if the line width is too small, the transition of the electric field cannot effectively control the liquid crystal molecules, etc., thereby limiting the further expansion of the size of the liquid crystal lens and also limiting the application of the liquid crystal lens.

[0004] In order to further expand the size of the liquid crystal lens, an electro-active lens is provided in the prior art, which includes a substrate with a stepped surface, and the stepped surface defines concentric liquid crystal regions whose thickness increases with the radius of the lens. Each region is switched by a different set of ring electrodes, which can be on the stepped surface, below the stepped surface, or opposite to the stepped surface. In each region, the farther the ring electrode is from the center of the lens, the narrower it becomes, but the width of the ring electrode also increases with the thickness of the liquid crystal, thereby offsetting the reduction in width that reduces the performance of the lens. Although the size of this electro-active lens can be made larger, the step difference around the step makes it difficult to orient the nearby liquid crystal molecules, the optical path difference distribution curve changes suddenly at the step position, and multiple liquid crystal devices of different thicknesses are difficult to process.

[0005] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the prior art in the field. Summary of the invention

[0006] In view of one or more defects in the prior art, the present invention provides a liquid crystal lens having an optical axis, the liquid crystal lens comprising:

[0007] a first substrate;

[0008] A second substrate, arranged opposite to the first substrate;

[0009] A liquid crystal layer is disposed between the first substrate and the second substrate;

[0010] a common electrode layer, disposed between the second substrate and the liquid crystal layer; and

[0011] A first electrode layer is arranged between the first substrate and the liquid crystal layer, the first electrode layer includes a plurality of first electrodes, the plurality of first electrodes are arranged at intervals from the optical axis to the edge of the liquid crystal lens and are divided into a plurality of groups, each group of first electrodes has a preset electrode sampling rate, and the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis.

[0012] According to one aspect of the present invention, the plurality of first electrodes are divided into a plurality of regions, each of the regions having a preset width;

[0013] Each of the groups comprises at least one of the regions, and different groups may comprise the same or different numbers of regions;

[0014] In the same group: the electrode sampling rate of each area is the same.

[0015] According to one aspect of the present invention, the width of the zone is

[0016] Wherein, i is the ranking number of the corresponding area in the first electrode layer, and the ranking number is counted from the area closest to the optical axis toward the edge of the liquid crystal lens and starts from 1; W1 is the width of the area closest to the optical axis.

[0017] According to one aspect of the present invention, a second electrode layer is provided between the first electrode layer and the liquid crystal layer, and a dielectric layer is provided between the first electrode layer and the second electrode layer;

[0018] Among the multiple groups: the group closest to the optical axis is the central group, and the other groups are expanded groups;

[0019] The second electrode layer comprises a plurality of second electrodes, the second electrodes are distributed between part of the groups and the liquid crystal layer, the second electrodes between the liquid crystal layer and a group and the first electrodes in the group are alternately arranged in a first direction, the second electrodes partially overlap with the first electrodes adjacent thereto, and the first direction is perpendicular to the optical axis;

[0020] The first electrode is configured to output a driving voltage, and the second electrode is configured to output a coupling voltage through capacitive coupling of two first electrodes partially overlapping with the second electrode.

[0021] According to one aspect of the present invention, the plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer.

[0022] According to one aspect of the present invention, the plurality of second electrodes are distributed between each of the groups and the liquid crystal layer.

[0023] According to one aspect of the present invention, in the central group:

[0024] The overlapping width of each first electrode and the corresponding second electrode is the same; or,

[0025] The overlapping widths of each first electrode and the corresponding second electrode are different, and the overlapping widths of the first electrode close to the optical axis and the corresponding second electrode are greater than the overlapping widths of the first electrode far from the optical axis and the corresponding second electrode; or,

[0026] The overlapping area ratio of each first electrode and the corresponding second electrode is the same.

[0027] According to one aspect of the present invention, the plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer, and the second electrodes and the first electrodes in the enlarged groups have a first spacing in the optical axis direction;

[0028] The first electrodes in the central group are arranged into two layers, and the first electrodes in the two layers are alternately arranged in a first direction, and the projections of the first electrodes of the two layers in the first direction are tangent; a dielectric layer is arranged between the first electrodes of the two layers; the first electrodes in the two layers have a second spacing in the optical axis direction, and the second spacing is greater than the first spacing.

[0029] According to one aspect of the present invention, the plurality of first electrodes are arranged at equal intervals from the optical axis to the edge of the liquid crystal lens.

[0030] According to one aspect of the present invention, the liquid crystal lens further comprises a circuit bus, the circuit bus comprises a plurality of circuit branches, the plurality of circuit branches respectively provide different voltages, and the number of the circuit branches is the same as the number of the first electrodes included in one area of ​​the central group;

[0031] In the central group: the plurality of first electrodes in each of the regions correspond one-to-one to and are electrically connected to the plurality of circuit branches;

[0032] In the expanded group: the first electrode is connected to a corresponding circuit branch according to a target coupling voltage of a second electrode coupled thereto.

[0033] According to one aspect of the present invention, the circuit bus further includes a very large voltage branch and / or a very small voltage branch;

[0034] In the expanded group: the first electrode is connected to a corresponding circuit branch, a maximum voltage branch or a minimum voltage branch according to a target coupling voltage of a second electrode coupled thereto.

[0035] According to one aspect of the present invention, the surface areas of the first electrodes in the same group are the same, the surface areas of the first electrodes in different groups are different, and the surface areas of the first electrodes in the group close to the optical axis are smaller than the surface areas of the first electrodes in the group far from the optical axis.

[0036] According to one aspect of the present invention, in the same group: the line width of the first electrode close to the optical axis is greater than the line width of the first electrode far from the optical axis;

[0037] In two adjacent groups: the line width of the first electrode closest to the optical axis in the group far from the optical axis is greater than the line width of the first electrode farthest from the optical axis in the group close to the optical axis.

[0038] According to one aspect of the present invention, a first liquid crystal alignment layer is provided on the side of the liquid crystal layer close to the first substrate, and a second liquid crystal alignment layer is provided on the side of the liquid crystal layer close to the second substrate. The first liquid crystal alignment layer and the second liquid crystal alignment layer have opposite rubbing directions and are arranged in anti-parallel.

[0039] The present invention also provides a method for preparing a liquid crystal lens, comprising:

[0040] Forming a first electrode layer on the first substrate, the first electrode layer comprising a plurality of first electrodes, the plurality of first electrodes being spaced from the center to the edge of the first substrate and divided into a plurality of groups, each group of first electrodes having a preset electrode sampling rate, and the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis;

[0041] forming a common electrode layer on the second substrate;

[0042] Arranging spacers on the first substrate or the second substrate;

[0043] forming a liquid crystal layer on one of the first substrate and the second substrate;

[0044] forming a plastic frame on the other of the first substrate and the second substrate;

[0045] The first substrate and the second substrate are combined and the glue frame is cured.

[0046] According to one aspect of the present invention, it further includes forming a dielectric layer and a second electrode layer on the first electrode layer;

[0047] Among the multiple groups: the group closest to the optical axis is the central group, and the other groups are expanded groups;

[0048] The second electrode layer comprises a plurality of second electrodes, the second electrodes are distributed between part of the groups and the liquid crystal layer, the second electrodes between the liquid crystal layer and a group and the first electrodes in the group are alternately arranged in a first direction, the second electrodes partially overlap with the first electrodes adjacent thereto, and the first direction is perpendicular to the optical axis;

[0049] The first electrode is configured to output a driving voltage, and the second electrode is configured to output a coupling voltage through capacitive coupling of two first electrodes partially overlapping with the second electrode.

[0050] According to one aspect of the present invention, the plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer.

[0051] According to one aspect of the present invention, the plurality of second electrodes are distributed between each of the groups and the liquid crystal layer.

[0052] According to one aspect of the present invention, the plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer, and the second electrodes and the first electrodes in the enlarged groups have a first spacing in the optical axis direction;

[0053] The first electrodes in the central group are arranged into two layers, and the first electrodes in the two layers are alternately arranged in a first direction, and the projections of the first electrodes of the two layers in the first direction are tangent; a dielectric layer is arranged between the first electrodes of the two layers; the first electrodes in the two layers have a second spacing in the optical axis direction, and the second spacing is greater than the first spacing.

[0054] Compared with the prior art, the embodiments of the present invention provide a liquid crystal lens and a method for preparing the same. The liquid crystal lens has a simple structure, and the surfaces of each layer are flat, so it is easy to orient the liquid crystal molecules and easy to process and produce. By dividing the multiple first electrodes in the first electrode layer into multiple groups, and setting each group of first electrodes to have a preset electrode sampling rate, the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis, so that the size of the liquid crystal lens can be made larger. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0056] Figure 1 shows a cross-sectional view of a liquid crystal lens 100 according to an embodiment of the present invention;

[0057] Figure 2 shows a schematic diagram of a first electrode according to an embodiment of the present invention;

[0058] Figure 3 shows a cross-sectional view of a liquid crystal lens 200 according to an embodiment of the present invention;

[0059] Figure 4 A schematic diagram showing the connection between a first electrode and a circuit bus according to an embodiment of the present invention is shown;

[0060] Figure 5 shows a cross-sectional view of a liquid crystal lens 300 according to an embodiment of the present invention;

[0061] Figure 6 shows a cross-sectional view of a liquid crystal lens 400 according to an embodiment of the present invention;

[0062] Figure 7 A flow chart showing a method for preparing a liquid crystal lens according to an embodiment of the present invention is shown;

[0063] Figure 8 The optical path difference distribution curve of an existing equal-height Fresnel liquid crystal lens is shown. DETAILED DESCRIPTION

[0064] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0065] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0066] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is lower in level than the second feature.

[0068] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0069] The embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0070] Figure 1 A cross-sectional view of a liquid crystal lens 100 according to an embodiment of the present invention is shown. The liquid crystal lens 100 has an optical axis. In some embodiments, the liquid crystal lens can be designed to have different optical path difference distributions such as aspherical surfaces and free-form surfaces according to actual needs. Figure 1 Only the right half of the cross section of the liquid crystal lens 100 is shown. It can be understood that the left half and the right half of the cross section of the liquid crystal lens 100 can be symmetrical about the optical axis. Figure 1 Describe in detail.

[0071] like Figure 1 As shown, the liquid crystal lens 100 includes a first substrate 110, a second substrate 120, a liquid crystal layer 130, a common electrode layer 140 and a first electrode layer 150, wherein the first substrate 110 and the second substrate 120 are arranged opposite to each other, and the first substrate 110 and the second substrate 120 are transparent substrates (for example, they can be glass substrates). The liquid crystal layer 130 is arranged between the first substrate 110 and the second substrate 120. The common electrode layer 140 is arranged between the second substrate 120 and the liquid crystal layer 130, and the common electrode layer 140 can be a surface electrode or can include a plurality of separated electrodes. The first electrode layer 150 is arranged between the first substrate 110 and the liquid crystal layer 130, and the first electrode layer 150 includes a plurality of first electrodes 151, and the plurality of first electrodes 151 are arranged at intervals from the edge of the optical axis to the liquid crystal lens 100 and are divided into a plurality of groups, as shown in FIG. Figure 2 As shown, the first electrode 151 may be a circular electrode. Specifically, the first electrode 151 closest to the optical axis is circular, and the other first electrodes 151 are circular rings, for example, all with the optical axis as the center. Figure 1As shown, each group of first electrodes 151 has a preset electrode sampling rate (the electrode sampling rate refers to the number of first electrodes 151 contained in each wavelength optical path difference provided by the liquid crystal lens, and the electrode sampling rate is greater than zero), and the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis. Figure 1 As shown, the first group has a first electrode sampling rate, the second group has a second electrode sampling rate, and the third group has a third electrode sampling rate, wherein the first electrode sampling rate> the second electrode sampling rate> the third electrode sampling rate, Figure 1 Although only three groups are shown, the present invention is not limited thereto, and two or more groups can be set according to the limit of the processing technology or the actual production needs. By gradually reducing the electrode sampling rate between multiple groups, the width of the first electrode 151 can be controlled within the required range, thereby expanding the processable size range of the liquid crystal lens 100.

[0072] According to one embodiment of the present invention, Figure 1 As shown, the plurality of first electrodes 151 are further divided into a plurality of regions, each region including one or more first electrodes 151 and having a preset width. The width of the region may be, for example, Wherein, i is the ranking number of the corresponding area in the first electrode layer 150, and the ranking number is counted from the area closest to the optical axis to the edge of the liquid crystal lens 100 and starts from 1; W1 is the width of the area closest to the optical axis (that is, the width of the area with a ranking number of 1), and the calculation of W1 is described in detail later. Each group contains at least one area, and different groups contain the same or different numbers of areas. In the same group, the electrode sampling rate of each area is the same. For a zone, different voltages are provided to different first electrodes 151 in the zone, so that the liquid crystal relative to the zone can be deflected at different angles to form a lens area of ​​the Fresnel liquid crystal lens.

[0073] According to one embodiment of the present invention, Figure 1 As shown, the surface areas of the first electrodes 151 in the same group are the same, the surface areas of the first electrodes 151 in different groups are different, and the surface areas of the first electrodes 151 in the group close to the optical axis are smaller than the surface areas of the first electrodes 151 in the group far from the optical axis. Figure 1As shown, the surface area of ​​the first electrode 151 in the first group is less than the surface area of ​​the first electrode 151 in the second group is less than the surface area of ​​the first electrode 151 in the third group. The surface area of ​​the first electrode 151 mentioned here refers to the area including the corresponding first electrode 151 and the gap within a preset range next to the first electrode 151. In this embodiment, the surface area of ​​the first electrode 151 refers to the area including the corresponding first electrode 151 and half of the gap on the inner side of the first electrode 151 and half of the gap on the outer side of the first electrode 151; in other embodiments, the surface area of ​​the first electrode 151 refers to the area including the corresponding first electrode 151 and the gap on the inner side (or outer side) of the first electrode 151.

[0074] According to one embodiment of the present invention, Figure 1 As shown, a plurality of first electrodes 151 in the first electrode layer 150 are arranged at equal intervals from the optical axis to the edge of the liquid crystal lens 100. Regarding the gap between adjacent first electrodes 151: when the gap is small, for example, less than 3 μm, there is no obvious effect on the display effect of the liquid crystal lens 100, but if the gap is further reduced, the improvement of the display effect of the liquid crystal lens 100 is small (or no improvement), and the processing difficulty will be increased; when the gap is large, it will have an adverse effect on the display effect of the liquid crystal lens 100; therefore, the size of the gap is usually selected to be a value that does not affect the effect but can be processed; arranging the first electrodes 151 at equal intervals can facilitate the design and processing of the liquid crystal lens 100.

[0075] According to one embodiment of the present invention, Figure 1 As shown, in the same group: the line width of the first electrode 151 close to the optical axis (i.e., the radial width of the annular electrode) is greater than the line width of the first electrode 151 far from the optical axis. Specifically, in the above preferred embodiment, since the surface areas of the first electrodes 151 in the same group are the same, in the same group: the difference between the outer diameter and the inner diameter of the first electrode 151 closer to the optical axis is greater, and the difference between the outer diameter and the inner diameter of the first electrode 151 farther from the optical axis is smaller, and accordingly, the line width of the first electrode 151 closer to the optical axis is greater, and the line width of the first electrode 151 farther from the optical axis is smaller.

[0076] According to one embodiment of the present invention, Figure 1 As shown in FIG. 1 , in two adjacent groups, the line width of the first electrode 151 closest to the optical axis in the group far from the optical axis is greater than the line width of the first electrode 151 farthest from the optical axis in the group close to the optical axis. The first electrode 151 in the liquid crystal lens 100 is processed as follows: Figure 1For example, within the first group range (1 to m-1 zone), the first electrode sampling rate is used, and the line width of the first electrode 151 gradually decreases along the first direction according to the equal area rule (the surface area of ​​the first electrodes 151 in the same group is the same), until the line width of the first electrode 151 at the edge just meets the design or processing requirements; when the size of the liquid crystal lens 100 is further increased according to this equal area rule, the line width of the first electrode 151 will not meet the design or processing requirements, so the electrode sampling rate is reduced (the second electrode sampling rate is used) within the second group range (m to n-1 zone) to increase the surface area of ​​the first electrode 151, that is, the width of the first electrode 151 is increased; when the second electrode sampling rate is used to a certain size, the line width of the first electrode 151 will not meet the design or processing requirements, so the electrode sampling rate is further reduced (the third electrode sampling rate is used) within the third group range (n to i zone) to further increase the surface area of ​​the first lens, that is, the width of the first electrode 151 is increased, and the lens size can be further expanded. Similarly, by gradually reducing the electrode sampling rate among multiple groups, the width of the first electrode 151 can be controlled within a required range, thereby expanding the processable size range of the liquid crystal lens 100 .

[0077] In the liquid crystal lens 100, since the electrode sampling rate of each group is different, the number of first electrodes 151 contained in the regions in different groups is different. When forming the same focal length, the voltages required to be distributed to the first electrodes 151 in different groups are different. In some embodiments, the power supply circuit can be used to provide each first electrode 151 with the required voltage.

[0078] Figure 3 FIG. 4 shows a cross-sectional view of a liquid crystal lens 200 according to an embodiment of the present invention. Figure 3As shown, the difference between the liquid crystal lens 200 and the liquid crystal lens 100 is that a second electrode layer 160 is arranged between the first electrode layer 150 and the liquid crystal layer 130. For the convenience of explanation, the group closest to the optical axis among the above-mentioned multiple groups is called the central group, and the other groups are called the enlarged groups. The second electrode layer 160 includes a plurality of second electrodes 161, and the second electrodes 161 are arranged between at least part of the groups and the liquid crystal layer 130 (for example, in the liquid crystal lens 200, the plurality of second electrodes 161 are distributed between each enlarged group and the liquid crystal layer 130). The second electrodes 161 located between the liquid crystal layer 130 and a group and the first electrodes 151 in the group are alternately arranged in the first direction, and the second electrodes 161 partially overlap with the first electrodes 151 adjacent to them. The first direction is perpendicular to the optical axis. In this embodiment, the first direction points from the optical axis to the edge of the liquid crystal lens 200. The first electrode 151 is configured to output a driving voltage, and the second electrode 161 is used as a floating electrode. The second electrode 161 can output a coupling voltage through two first electrodes 151 partially overlapping with it through capacitive coupling. The magnitude of the coupling voltage is related to the driving voltage output by the two first electrodes 151 coupled with the corresponding second electrode 161, and is also related to the overlapping area of ​​the corresponding second electrode 161 with the corresponding first electrode 151. A dielectric layer (not shown in the figure) of a certain thickness is provided between the first electrode layer 150 and the second electrode layer 160 to separate and insulate the first electrode 151 from the second electrode 161. In order to ensure the coupling effect between the first electrode 151 and the second electrode 161, the second electrode 161 should be as close to the first electrode 151 as possible, that is, the thickness of the dielectric layer between the first electrode layer 150 and the second electrode layer 160 should be as small as possible. By providing the second electrode layer 160 and using the second electrode 161 as a floating electrode, the driving of the liquid crystal lens 200 can be simplified. By setting the second electrode layer 160, the first electrode 151 and the second electrode 161 can cooperate with the common electrode layer 140 to provide more voltage difference on both sides of the liquid crystal layer 130, thereby improving the display effect of the liquid crystal lens 200; wherein, at the position where the second electrode 161 is set, the second electrode 161 and the common electrode layer 140 provide a voltage difference for the liquid crystal layer 130; at the position where the second electrode 161 is not set (for example: the range where the central group is located, the interval between two adjacent second electrodes 161), the first electrode 151 and the common electrode layer 140 provide a voltage difference for the liquid crystal layer 130.

[0079] in addition, Figure 1 , Figure 3In the description, the left and right halves of the cross-section of the liquid crystal lens 100, 200 are symmetrical about the optical axis. It is easy for those skilled in the art to understand that the left and right halves of the cross-section of the liquid crystal lens 100, 200 may also be asymmetrical about the optical axis, which is also within the principle and protection scope of the present invention.

[0080] According to an embodiment of the present invention, the liquid crystal lens 200 further includes a circuit bus, which includes a plurality of circuit branches, each of which provides a different voltage, and the number of the circuit branches is the same as the number of the first electrodes 151 included in one zone of the central group. In the central group, the plurality of first electrodes 151 in each zone correspond to and are electrically connected to the plurality of circuit branches one by one; in the expanded group, the first electrode 151 is connected to the corresponding circuit branch according to the target coupling voltage of the second electrode 161 coupled thereto.

[0081] Figure 4 FIG. 1 shows a schematic diagram of the connection between the first electrode and the circuit bus according to an embodiment of the present invention. For the convenience of description and understanding, Figure 4 Only three groups are shown, each group contains two regions, and the number of first electrodes contained in each region is at most 10. In fact, the number of groups, the number of regions contained in each group, and the number of first electrodes contained in each region are not limited to this, and are not limited here. Figure 4 As shown, since the electrode sampling rate of the first group (central group) is the highest, the area in the first group contains the largest number of first electrodes, and the number of circuit branches that power the first electrodes in the first group is equal to the number of voltages required to be provided to the first electrodes within the first group (that is, equal to the number of first electrodes in a single area of ​​the first group). Since the electrode sampling rate is reduced, the number of voltages required to be provided to the first electrodes within the second group (expanded group) and the third group (expanded group) are less than the number of voltages required to be provided to the first electrodes within the first group, and the maximum and minimum values ​​of the voltages required to be provided to the first electrodes within the second group and the third group are generally within the maximum and minimum voltages provided for the first electrodes within the first group.

[0082] Suppose the first electrode ( Figure 4 If the number of the first electrodes 151a-151j in the first group is 10, the number of voltages required to be provided by the first electrodes 151a-151j within the first group is 10, and the circuit bus includes 10 circuit branches, and the 10 circuit branches respectively provide voltages

[0083] V1, V2, ..., V9, V10, where V1 is the smallest, V10 is the largest, and the voltage increases monotonically (here only the voltage monotonically increases as an example, but it is not limited to this. In other embodiments, the voltages V1 to V10 may also decrease monotonically). The first electrodes 151a to 151j within the first group are respectively connected to the corresponding circuit branches. The first electrodes ( Figure 4 151a'~151h') is 8, the first electrodes 151a'~151h' within the second group are respectively connected to the corresponding circuit branches, and the first electrodes 151a'~151h' of each zone within the second group are respectively coupled with the corresponding second electrodes 161, so that the 7 second electrodes 161 corresponding to the corresponding zone output coupling voltages V1'~V7' respectively. For example, when the required target coupling voltage V1' is between V1 and V3, the first electrode 151a' is connected to the circuit branch V1, and the first electrode 151b' is connected to the circuit branch V3, and the coupling voltage V1' is obtained by overlapping and coupling the corresponding second electrode 161 with the first electrodes 151a' and 151b' with an appropriate area, wherein V1<V1'<V3. The first electrodes ( Figure 4 The number of the first electrodes 151a"~151e") is 5, the first electrodes 151a"~151e" within the third group are respectively connected to the corresponding circuit branches, and the first electrodes 151a"~151e" of each area within the third group are respectively coupled with the corresponding second electrodes 161, so that the 4 second electrodes 161 corresponding to the corresponding area output coupling voltages V1"~V4". For example, when the coupling voltage V1" is between V3 and V4, the first electrode 151a" is connected to the circuit branch line V3, and the first electrode 151b" is connected to the circuit branch line V4, and the coupling voltage V1" is obtained by overlapping and coupling with the first electrodes 151a" and 151b" with an appropriate area through the corresponding second electrode 161, wherein V3<V1"<V4; for another example, when the coupling voltage V1" is between V4 and V6, the first electrode 151b" is connected to the circuit branch line V4, and the first electrode 151c" is connected to the circuit branch line V6, and the coupling voltage V2" is obtained by overlapping and coupling with the first electrodes 151b" and 151c" with an appropriate area through the corresponding second electrode 161, wherein V4<V2"<V6.

[0084] According to one embodiment of the present invention, Figure 4As shown, the circuit bus may also include a maximum voltage branch Vmax and / or a minimum voltage branch Vmi n. In the expanded group, the first electrode may be connected to the corresponding circuit branch, the maximum voltage branch Vmax or the minimum voltage branch Vmi n according to the target coupling voltage of the second electrode 161 coupled thereto; specifically, when the maximum voltage value required to be provided by the first electrode in an expanded group is greater than the maximum voltage value required to be provided by the first electrode in the central group, the corresponding first electrode in the expanded group may be connected to the maximum voltage branch Vmax; when the minimum voltage value required to be provided by the first electrode in an expanded group is smaller than the minimum voltage value required to be provided by the first electrode in the central group, the corresponding first electrode in the expanded group may be connected to the minimum voltage branch Vmi n.

[0085] Figure 5 FIG. 4 shows a cross-sectional view of a liquid crystal lens 300 according to an embodiment of the present invention. Figure 5 As shown, the difference between the liquid crystal lens 300 and the liquid crystal lens 200 is that the multiple second electrodes 161 in the second electrode layer 160 are distributed between each group and the liquid crystal layer 130, that is, the multiple second electrodes 161 in the second electrode layer 160 are distributed not only between each enlarged group and the liquid crystal layer 130, but also between the central group and the liquid crystal layer 130. By arranging the second electrodes 161 in the range corresponding to the central group, more voltage difference can be provided on both sides of the liquid crystal layer 130, further improving the display effect of the liquid crystal lens.

[0086] According to one embodiment of the present invention, Figure 5As shown, in the central group, each first electrode 151 has the same overlapping width with the corresponding second electrode 161, for example, the overlapping width of the first electrode 151 and the corresponding second electrode 161 may be 5 μm (in other embodiments, it may also be 3 μm, 6 μm, etc., and the present invention is not limited thereto); or, each first electrode 151 has the same overlapping area ratio with the corresponding second electrode 161, for example, the overlapping area ratio of the first electrode 151 and the corresponding second electrode 161 may be 25% (in other embodiments, it may also be 20%, 30%, etc., and the present invention is not limited thereto, and the overlapping area ratio is the overlapping area / the area of ​​the first electrode), or, each first electrode 151 has different overlapping widths with the corresponding second electrode 161, and the overlapping width of the first electrode 151 and the corresponding second electrode 161 close to the optical axis is greater than the overlapping width of the first electrode 151 and the corresponding second electrode 161 away from the optical axis, that is, the overlapping width of the first electrode 151 and the second electrode 161 gradually decreases from the optical axis to the edge of the liquid crystal lens 300. Among them, when the second electrode 151 is set according to the same overlapping width, it is necessary to take all the second electrodes 161 not short-circuiting as the limit / maximum value of the line width (that is, the second electrode 161 cannot be wider, otherwise a short circuit will occur). Therefore, the overlapping width of the second electrode 161 and the first electrode 151 may only occupy a very small part of the corresponding first electrode 151 (for example, the first electrode 151 closest to the optical axis), and the coupling effect between the second electrode 161 and the first electrode 151 is limited; however, when the second electrode 161 is set according to the same overlapping area ratio, there is no such problem, because the overlapping area ratio is the same, the line width of the second electrode 161 may be different (the larger the overlapping area of ​​the second electrode 161 and the first electrode 151, the larger the line width of the corresponding second electrode 161), and the second electrode 161 and the first electrode 151 can have a good coupling effect. Therefore, setting the second electrode 161 according to the same overlapping area ratio has a better effect; similarly, setting the second electrode 151 according to the rule that the overlapping width gradually decreases from the optical axis to the edge of the liquid crystal lens also has a better effect. Within the range corresponding to the central group, the line width of the second electrode 161 is determined according to the overlapping width or overlapping area ratio with the corresponding first electrode 151, which can make the processing of the second electrode layer 160 more convenient. Within the range corresponding to the expanded group, the line width of the second electrode 161 is determined according to the coupling voltage required to be output.

[0087] Figure 6 FIG. 4 shows a cross-sectional view of a liquid crystal lens 400 according to an embodiment of the present invention. Figure 6As shown, the difference between the liquid crystal lens 400 and the liquid crystal lens 200 is that the first electrodes 151 in the central group are arranged in two layers, and the first electrodes 151 in the two layers are alternately arranged in the first direction. Preferably, the projections of the two first electrodes 151 adjacent to each other in the first direction in the central group on the first plane (the first plane is perpendicular to the optical axis) do not overlap, and preferably form a tangent, that is, there is no gap between the two. In the liquid crystal lens 400, the above-mentioned two layers of first electrodes 151 and second electrodes 161 are arranged in different layers, and the layers are separated and insulated by a dielectric layer; preferably, as Figure 6 As shown, the layer where the second electrode 161 is located (the second electrode layer 160) is located between the above two layers of first electrodes 151 (the second electrode 161 and the first electrode 151 in the expanded group have a first spacing in the optical axis direction, and the above two layers of first electrodes 151 have a second spacing, and the second spacing is greater than the first spacing), so that the second electrode 161 is as close as possible to the first electrode 151 coupled thereto. By dividing the first electrode 151 in the central group into two layers, the problem of weak process capability can be well solved. In the case of relatively weak process capability, the gap between adjacent electrodes will be relatively large, thereby affecting the display effect of the liquid crystal lens; if the electrodes are distributed in the same layer with a smaller gap, the risk of short circuit between adjacent electrodes will increase. Dividing the first electrode 151 into two layers can increase the gap between the first electrodes in the same layer, thereby making it less likely for the first electrodes in the same layer to short circuit; at the same time, the upper and lower layers of the first electrodes are separated by a dielectric layer, so they are not easily short-circuited; the electric field is continuously transitioned in the first direction, which can well solve the problem of weak process capability.

[0088] According to one embodiment of the present invention, the liquid crystal lens 100, 200, 300, 400 may further include a first liquid crystal orientation layer and a second liquid crystal orientation layer, wherein the first liquid crystal orientation layer is arranged on a side of the liquid crystal layer 130 close to the first substrate 110, and the second liquid crystal orientation layer is arranged on a side of the liquid crystal layer 130 close to the second substrate 120, and the rubbing directions of the first liquid crystal orientation layer and the second liquid crystal orientation layer are opposite and anti-parallel.

[0089] To intuitively demonstrate the effects of the embodiments of the present invention, examples are given below.

[0090] The basic principle of the Fresnel liquid crystal lens is that, under the action of an external electric field, a non-uniform gradient distribution of refractive index is formed in the liquid crystal layer 130. The focal length f of the Fresnel liquid crystal lens is: Where: r is the radius of the Fresnel liquid crystal lens; Δn is the birefringence coefficient of the liquid crystal material; d is the thickness of the liquid crystal layer 130, and q is the number of Fresnel lens partitions. The optical path difference distribution curve of the Fresnel liquid crystal lens φ = r 2 / (2f*q)=Δn*d, where φ is the optical path difference of the liquid crystal lens. Assuming that the optical path difference provided by the box thickness of the Fresnel liquid crystal lens is pλ (p is the wave number), then pλ=φ=Δn*d.

[0091] [Regarding the calculation of the electrode sampling rate: (1) For a certain liquid crystal lens product, the product of Δn and d (Δn*d) that can be measured by the instrument, λ is known, so p can be calculated according to the above formula; (2) For a certain liquid crystal lens product, the number N of first electrodes (driving electrodes) contained in a certain area can be measured by the equipment, so the electrode sampling rate fs=N / p in the area can be calculated. It should be noted that the electrode sampling rate obtained by this calculation method is obtained by reverse engineering and is not used to limit the electrode sampling rate in this application; the electrode sampling rate in this application is set according to engineering processing limits or actual needs. ]

[0092] The calculation process of the line width of the first electrode 151 in the liquid crystal lenses 100, 200, 300, and 400 is as follows:

[0093] (1) Radius of the central first electrode (the first electrode 151 closest to the optical axis) Where λ is the wavelength of incident light, f is the focal length, and fs1 is the electrode sampling rate of the first group.

[0094] The radius of the x-th first electrode 151 (x is the serial number of the first electrode 151 and is sorted from the optical axis to the edge of the liquid crystal lens) in the first group Thus, the width of each first electrode 151 can be calculated.

[0095] The number of first electrodes 151 in each area of ​​the first group is determined by the electrode sampling rate and the cell thickness of the liquid crystal lens (assuming that the cell thickness of the liquid crystal lens can provide an optical path difference of pλ, where p is the wave number). In the first group: the number of first electrodes 151 in each area is n1=p*fs1;

[0096] The width of the first area (the area with sort number 1) The radius of the first zone R1=W1, the area of ​​the first zone S1=πW12;

[0097] The width of the second area (the area with sort number 2) The outer radius of the second zone The area of ​​the second zone S2 = πW12;

[0098] …

[0099] The width of the i-th area (the area with sorting number i) The outer circle radius of the i-th zone Ri=W1+W2+…+Wi, and the area of ​​the i-th zone Si=πW12.

[0100] The area of ​​each district is equal.

[0101] The electrode sampling rate of the first group is determined, the number of zones contained in the first group is determined by the fact that all electrodes in the zone must meet the processing limit of the minimum width, and the spacing between each first electrode 151 in each group is equal.

[0102] (2) Assume that the first group contains regions 1 to m-1, and the area of ​​the first group is (m-1)πW12. Then the second group starts from region m, and the width of region m is The surface area of ​​the first m regions in the second group is Sm=πW12.

[0103] (3) Determine the electrode sampling rate fs2 of the second group. The number of first electrodes 151 in each zone of the second group is n2=p*fs2.

[0104] (4) Since the surface area of ​​each first electrode 151 in the same group is the same, the surface area of ​​the first first electrode 151 in the second group (the first electrode 151 in the second group closest to the optical axis) = Sm / n2 = πW12 / n2;

[0105] Assuming that the radius of the outer ring of the first first electrode 151 in the second group is r1', the area enclosed by the outer circle of the first first electrode 151 in the second group = (m-1)πW12+Sm / n2=(m-1+1 / n2)πW12=π*r1'2, and then r1' can be calculated; the circular area of ​​the second first electrode 151 in the second group = (m-1)πW12

[0106] +2Sm / n2=π*r2'2, and then r2' can be calculated, and the radius of each first electrode 151 in the first m-region of the second group can be calculated by analogy. The method for calculating the radius of the first first electrode 151 in the region after the second group of m-regions is the same as the method for calculating the ring radius of the first first electrode 151 in the second group of m-regions, which will not be repeated here.

[0107] (5) The electrode sampling rate of the second group is determined. The number of zones contained in the second group is determined by the fact that all electrodes in the zone must meet the processing limit of the minimum width, and the intervals between each first electrode 151 in each group are equal.

[0108] (6) The method for calculating the radius of the first ring of the first electrode 151 in other groups (the third group, the fourth group, etc.) is the same as the method for calculating the radius of the first ring of the first electrode 151 in the second group, and is not described in detail here.

[0109] like Figure 1As shown, assuming that the cell thickness of the liquid crystal lens 100 can provide an optical path difference of 10λ (λ=543.5nm), the focal length f of the liquid crystal lens is 1000mm, and the electrode sampling rate of the first group (first electrode sampling rate) fs1 is 5, then the number of electrodes n1 contained in each zone in the first group is 10*5=50. The radius of the central first electrode (the first electrode 151 closest to the optical axis) The width of the first zone (the zone with a ranking number of 1, the ranking number is counted from the zone closest to the optical axis to the edge of the liquid crystal lens and starts from 1) Assuming that the width of the gap between adjacent first electrodes 151 is 4 μm, the minimum width of the first electrode 151 that can be realized is 10 μm. As shown in Table 1, when the number of first electrodes 151 is 277, the line width of the first electrode 151 reaches the limit value of 10 μm, and the maximum radius of the liquid crystal lens 100 is about 7.7 mm. Obviously, when the electrode sampling rate is 5, the line width of some first electrodes 151 in the sixth zone (the zone with a ranking number of 6) will not be realized, so the first zone to the fifth zone (the zone with a ranking number of 1 to 5) can be regarded as the first group, and the sixth zone can be classified as the second group. The electrode sampling rate of the second group (the second electrode sampling rate) can be reduced to 4 (the electrode sampling rate can also be set to a decimal according to actual needs, such as 4.5), then the number of electrodes n2 contained in each zone in the second group is 10*4=40, and the 40 first electrodes 151 are divided according to the equal area rule, and the line width of all first electrodes 151 in the sixth zone can be adjusted to more than 10. When the first electrode 151 sampling rate is adopted, the line width of part of the first electrode 151 in the sixth area will not meet the design or processing requirements, while when the sixth area is divided into the second group and the second sampling rate is adopted, the line width of the first electrode 151 in the sixth area will meet the requirements and increase the size of the liquid crystal lens to about 8.1 mm. Similarly, the size of the liquid crystal lens can be further increased by further reducing the electrode sampling rate.

[0110]

[0111]

[0112] Table 1

[0113] Compared with the prior art, the liquid crystal lenses 100, 200, 300, and 400 provided in the embodiments of the present invention have a simple structure and are easy to process and produce. By dividing the multiple first electrodes 151 in the first electrode layer 150 into multiple groups, and setting each group of first electrodes 151 to have a preset electrode sampling rate, the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis, so that the size of the liquid crystal lenses 100, 200, 300, and 400 can be made larger.

[0114] Figure 7A flow chart of a method for preparing a liquid crystal lens according to an embodiment of the present invention is shown below. Figure 7 Describe in detail.

[0115] The method for preparing the liquid crystal lens includes the following steps, which are described in detail below.

[0116] Step S410: forming a first electrode layer on a first substrate. The first electrode layer includes a plurality of first electrodes, which are spaced from the optical axis to the edge of the liquid crystal lens and divided into a plurality of groups. The first electrodes may be annular electrodes. Specifically, the first electrode closest to the optical axis is circular, and the other first electrodes are annular, for example, all with the optical axis as the center. Each group of first electrodes has a preset electrode sampling rate (the electrode sampling rate refers to the number of first electrodes contained in each wavelength optical path difference, and the electrode sampling rate is greater than zero), and the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis.

[0117] In step S420 : forming a common electrode layer on the second substrate.

[0118] The formation of the common electrode layer includes arranging a surface electrode on one side of the second substrate. In addition, after the surface electrode is arranged, a second liquid crystal alignment layer can be arranged on the surface of the surface electrode (for example, polyimide can be coated on the surface of the surface electrode and rubbed for alignment).

[0119] In step S430 : spacers are arranged on the first substrate or the second substrate.

[0120] In step S440 : forming a liquid crystal layer on one of the first substrate and the second substrate.

[0121] In step S450 : forming a plastic frame on the other of the first substrate and the second substrate.

[0122] In step S460 : the first substrate and the second substrate are combined and the glue frame is cured.

[0123] The method for preparing the liquid crystal lens may further include step S470: forming a dielectric layer and a second electrode layer on the first electrode layer; step S470 may be performed simultaneously with step S410 according to actual conditions, or may be performed after step S410 is completed. The second electrode layer includes a plurality of second electrodes. After the liquid crystal lens is manufactured, the second electrodes are arranged between at least part of the groups and the liquid crystal layer (preferably, the plurality of second electrodes are distributed between each enlarged group and the liquid crystal layer; or, the plurality of second electrodes are distributed between each group and the liquid crystal layer; or, the plurality of second electrodes are distributed between each enlarged group and the liquid crystal layer, the second electrodes and the first electrodes in the enlarged group have a first spacing in the optical axis direction, and the first electrodes in the central group are arranged in two layers, the first electrodes in the two layers are alternately arranged in the first direction, the projections of the first electrodes in the two layers in the first direction are tangent, a dielectric layer is arranged between the first electrodes in the two layers, the first electrodes in the two layers have a second spacing in the optical axis direction, and the second spacing is greater than the first spacing), the second electrodes between the liquid crystal layer and a group and the first electrodes in the group are alternately arranged in the first direction, the second electrodes partially overlap with the first electrodes adjacent to them, the first direction is perpendicular to the optical axis, and in this embodiment, the first direction is from the optical axis to the edge of the liquid crystal lens. The first electrode is configured to output a driving voltage, and the second electrode is used as a floating electrode. In order to ensure the coupling effect between the first electrode and the second electrode, the second electrode should be as close to the first electrode as possible, that is, the thickness of the dielectric layer between the first electrode layer and the second electrode layer should be as small as possible.

[0124] Finally, it should be noted that the above description is only an embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A liquid crystal lens having an optical axis, the liquid crystal lens comprising: a first substrate; A second substrate, arranged opposite to the first substrate; A liquid crystal layer is disposed between the first substrate and the second substrate; A common electrode layer, disposed between the second substrate and the liquid crystal layer; and a first electrode layer, arranged between the first substrate and the liquid crystal layer, the first electrode layer comprising a plurality of first electrodes, the plurality of first electrodes being arranged at intervals from the optical axis to the edge of the liquid crystal lens and divided into a plurality of groups, each group of first electrodes having a preset electrode sampling rate, and the electrode sampling rate of the group close to the optical axis is greater than the electrode sampling rate of the group far from the optical axis, the electrode sampling rate refers to the number of first electrodes contained in the optical path difference of each wavelength provided by the liquid crystal lens; Wherein, the plurality of first electrodes are divided into a plurality of regions, each of the regions has a preset width, and for a region, different voltages are provided to different first electrodes in the region, so that the liquid crystals corresponding to the region can be deflected at different angles to form a lens region of the Fresnel liquid crystal lens; wherein each of the groups comprises at least one of the regions, and different groups comprise the same or different numbers of regions, wherein at least one of the groups comprises a plurality of the regions; In the same group: the electrode sampling rate of each area is the same.

2. The liquid crystal lens according to claim 1, wherein: The width of the zone is ; Wherein, i is the ranking number of the corresponding area in the first electrode layer, and the ranking number is counted from the area closest to the optical axis toward the edge of the liquid crystal lens and starts from 1; W1 is the width of the area closest to the optical axis.

3. The liquid crystal lens according to claim 1, wherein: A second electrode layer is disposed between the first electrode layer and the liquid crystal layer, and a dielectric layer is disposed between the first electrode layer and the second electrode layer; Among the multiple groups: the group closest to the optical axis is the central group, and the other groups are expanded groups; The second electrode layer comprises a plurality of second electrodes, wherein the second electrodes are distributed between at least part of the groups and the liquid crystal layer, the second electrodes between the liquid crystal layer and a group and the first electrodes in the group are alternately arranged in a first direction, the second electrodes partially overlap with the first electrodes adjacent thereto, and the first direction is perpendicular to the optical axis; The first electrode is configured to output a driving voltage, and the second electrode is configured to output a coupling voltage through capacitive coupling of two first electrodes partially overlapping with the second electrode.

4. The liquid crystal lens according to claim 3, wherein: The plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer.

5. The liquid crystal lens according to claim 3, wherein: The plurality of second electrodes are distributed between each of the groups and the liquid crystal layer.

6. The liquid crystal lens according to claim 5, wherein: In the center group: The overlapping width of each first electrode and the corresponding second electrode is the same; or, The overlapping widths of each first electrode and the corresponding second electrode are different, and the overlapping widths of the first electrode close to the optical axis and the corresponding second electrode are greater than the overlapping widths of the first electrode far from the optical axis and the corresponding second electrode; or, The overlapping area ratio of each first electrode and the corresponding second electrode is the same.

7. The liquid crystal lens according to claim 3, wherein: The plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer; The first electrodes in the central group are arranged in two layers, and the first electrodes in the two layers are arranged alternately in the first direction, and a dielectric layer is arranged between the first electrodes in the two layers.

8. The liquid crystal lens according to claim 7, wherein: The second electrode and the first electrode in the expanded group have a first spacing in the optical axis direction; the first electrodes in the two layers have a second spacing in the optical axis direction, and the second spacing is greater than the first spacing; the projections of the first electrodes of the two layers in the first direction are tangent.

9. The liquid crystal lens according to any one of claims 4 to 6, wherein: The plurality of first electrodes are arranged at equal intervals from the optical axis to the edge of the liquid crystal lens.

10. The liquid crystal lens according to any one of claims 4 to 8, wherein: The liquid crystal lens further comprises a circuit bus, wherein the circuit bus comprises a plurality of circuit branches, wherein the plurality of circuit branches respectively provide different voltages, and the number of the circuit branches is the same as the number of the first electrodes included in one area of ​​the central group; In the central group: the plurality of first electrodes in each of the regions correspond one-to-one to and are electrically connected to the plurality of circuit branches; In the expanded group: the first electrode is connected to a corresponding circuit branch according to a target coupling voltage of a second electrode coupled thereto.

11. The liquid crystal lens according to claim 10, wherein: The circuit bus further includes a very large voltage branch and / or a very small voltage branch; In the expanded group: the first electrode is connected to a corresponding circuit branch, a maximum voltage branch or a minimum voltage branch according to a target coupling voltage of a second electrode coupled thereto.

12. The liquid crystal lens according to claim 1, wherein: The surface areas of the first electrodes in the same group are the same, the surface areas of the first electrodes in different groups are different, and the surface areas of the first electrodes in the group close to the optical axis are smaller than the surface areas of the first electrodes in the group far from the optical axis.

13. The liquid crystal lens according to claim 1, wherein: In the same group: the line width of the first electrode close to the optical axis is greater than the line width of the first electrode far from the optical axis; In two adjacent groups: the line width of the first electrode closest to the optical axis in the group far from the optical axis is greater than the line width of the first electrode farthest from the optical axis in the group close to the optical axis.

14. The liquid crystal lens according to claim 1, wherein: A first liquid crystal alignment layer is disposed on the side of the liquid crystal layer close to the first substrate, and a second liquid crystal alignment layer is disposed on the side of the liquid crystal layer close to the second substrate. The first liquid crystal alignment layer and the second liquid crystal alignment layer have opposite rubbing directions and are arranged antiparallel.

15. A method for preparing a liquid crystal lens, comprising: A first electrode layer is formed on the first substrate, wherein the first electrode layer includes a plurality of first electrodes, the plurality of first electrodes are spaced from the center to the edge of the first substrate and are divided into a plurality of groups, each group of first electrodes has a preset electrode sampling rate, and the electrode sampling rate of the group close to the optical axis of the liquid crystal lens is greater than the electrode sampling rate of the group far from the optical axis, and the electrode sampling rate refers to the number of first electrodes contained in the optical path difference provided by the liquid crystal lens for each wavelength; forming a common electrode layer on the second substrate; Arranging spacers on the first substrate or the second substrate; forming a liquid crystal layer on one of the first substrate and the second substrate; forming a plastic frame on the other of the first substrate and the second substrate; Combining the first substrate with the second substrate and curing the glue frame; Wherein, the plurality of first electrodes are divided into a plurality of regions, each of the regions has a preset width, and for a region, different voltages are provided to different first electrodes in the region, so that the liquid crystals corresponding to the region can be deflected at different angles to form a lens region of the Fresnel liquid crystal lens; wherein each of the groups comprises at least one of the regions, and different groups comprise the same or different numbers of regions, wherein at least one of the groups comprises a plurality of the regions; In the same group: the electrode sampling rate of each area is the same.

16. The preparation method according to claim 15, further comprising forming a dielectric layer and a second electrode layer on the first electrode layer; in, Among the multiple groups: the group closest to the optical axis is the central group, and the other groups are expanded groups; The second electrode layer comprises a plurality of second electrodes, the second electrodes are distributed between part of the groups and the liquid crystal layer, the second electrodes between the liquid crystal layer and a group and the first electrodes in the group are alternately arranged in a first direction, the second electrodes partially overlap with the first electrodes adjacent thereto, and the first direction is perpendicular to the optical axis; The first electrode is configured to output a driving voltage, and the second electrode is configured to output a coupling voltage through capacitive coupling of two first electrodes partially overlapping with the second electrode.

17. The preparation method according to claim 16, wherein: The plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer.

18. The preparation method according to claim 16, wherein: The plurality of second electrodes are distributed between each of the groups and the liquid crystal layer.

19. The preparation method according to claim 16, wherein: The plurality of second electrodes are distributed between each of the enlarged groups and the liquid crystal layer; The first electrodes in the central group are arranged in two layers, and the first electrodes in the two layers are arranged alternately in a first direction, and a dielectric layer is arranged between the first electrodes in the two layers.

20. The preparation method according to claim 19, wherein: The second electrode and the first electrode in the expanded group have a first spacing in the optical axis direction; the first electrodes in the two layers have a second spacing in the optical axis direction, and the second spacing is greater than the first spacing; the projections of the first electrodes of the two layers in the first direction are tangent.

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