Liquid crystal lens, lens module and near-eye display device

Abstract

The present application provides a liquid crystal lens, a lens module and a near-eye display device. The first substrate of the liquid crystal lens is arranged opposite to the second substrate, the liquid crystal layer is located between the first substrate and the second substrate, the first electrode is located on the surface of the first substrate facing the liquid crystal layer, and the second electrode is located on the surface of the second substrate facing the liquid crystal layer. The first electrode includes m electrode units, the m electrode units are arranged at intervals from each other, and the optical path difference of the optical path difference distribution curve of the liquid crystal lens corresponding to the width of each electrode unit is greater than zero and less than or equal to λ / n, wherein λ is the wavelength of the incident light, m ​​is a positive integer greater than or equal to 1, and n is a positive integer greater than or equal to 3, which helps to ensure that the liquid crystal lens has good diffraction efficiency. By changing the voltage value of the electrode unit, the tilt angle of the liquid crystal molecules can be adjusted, thereby changing the refractive index distribution of the liquid crystal lens, and realizing the change of the optical focal length of the liquid crystal lens to change the virtual image distance.

Description

Technical Field

[0001] The present application relates to the field of liquid crystal technology, and in particular to a liquid crystal lens, a lens module and a near-eye display device. Background Art

[0002] Most of the common thin and light augmented reality (AR) display optical systems currently use a folded optical path method, and mechanically adjust the position of the lenses to achieve the effect of adjusting the visual acuity and compensating for the wearer's visual defects. However, the mechanical adjustment method cannot adjust the virtual image distance in real time, resulting in convergence conflict, which can easily cause dizziness and fatigue; and the use of electric mechanical automatic zoom will cause the VR display device to be large in size and have a long zoom time, which cannot meet the reaction time of the human eye. There is currently a plan to use liquid crystal lenses to adjust the virtual image distance, but the optical path difference (OPD) distribution curve generated by the electrodes of the current liquid crystal lenses cannot meet the requirements of optical design well. Summary of the invention

[0003] The embodiments of the present application propose a liquid crystal lens, a lens module and a near-eye display device to solve the above-mentioned technical problems.

[0004] The implementation method of the present application achieves the above-mentioned purpose through the following technical solutions.

[0005] In a first aspect, an embodiment of the present application provides a liquid crystal lens, the liquid crystal lens comprising a first substrate, a second substrate, a liquid crystal layer, a first electrode and a second electrode, the first substrate and the second substrate are arranged opposite to each other, the liquid crystal layer is located between the first substrate and the second substrate, the first electrode is located on the surface of the first substrate facing the liquid crystal layer, and the second electrode is located on the surface of the second substrate facing the liquid crystal layer. The first electrode comprises m electrode units, the m electrode units are arranged at intervals from each other, and the optical path difference of the optical path difference distribution curve of the liquid crystal lens corresponding to the width of each electrode unit is greater than zero and less than or equal to λ / n, wherein m is a positive integer greater than or equal to 1, n is a positive integer greater than or equal to 3, and λ is the wavelength of the incident light.

[0006] In some embodiments, m electrode units are sequentially arranged outward from the optical axis of the liquid crystal lens, the distance between the inner edge line of the mth electrode unit and the optical axis of the liquid crystal lens is greater than or equal to the distance between the outer edge line of the m-1th electrode unit and the optical axis of the liquid crystal lens, and the optical axis of the liquid crystal lens is located at the first electrode unit. The width value of the mth electrode unit along the first direction is x m , the width of the m-1th electrode unit along the first direction is x m-1 , x m With x m-1They respectively correspond to the distances of the optical path difference distribution curve of the liquid crystal lens in the first direction divided into equal parts according to λ / n along the second direction along the first direction, the second direction is perpendicular to the first direction, and m is greater than or equal to 2.

[0007] In some embodiments, the optical path difference distribution curve of the liquid crystal lens in the first direction is an aspherical optical path difference distribution curve.

[0008] In some embodiments, the width of the mth electrode unit along the second direction is y m , the width of the m-1th electrode unit along the second direction is y m-1 ,y m With y m-1 The distances along the second direction respectively correspond to the optical path difference distribution curve of the liquid crystal lens in the second direction after being equally divided by λ / n along the first direction. At least one of the optical path difference distribution curve of the liquid crystal lens in the first direction and the optical path difference distribution curve of the liquid crystal lens in the second direction is a free-form surface optical path difference distribution curve.

[0009] In some embodiments, the optical path difference distribution curve of the liquid crystal lens in the first direction is a free-form surface optical path difference distribution curve, and the optical path difference distribution curve of the liquid crystal lens in the second direction is an aspherical surface optical path difference distribution curve.

[0010] In some embodiments, any two adjacent electrode units are spaced apart along a direction from the first substrate to the second substrate.

[0011] In some embodiments, any two adjacent electrode units are spaced apart and located on the same surface of the first substrate, and the optical path difference of the optical path difference distribution curve of the liquid crystal lens corresponding to the width of each electrode unit is greater than zero and less than λ / n.

[0012] In some embodiments, the electrode units located at the optical axis position of the liquid crystal lens among the m electrode units are surface electrodes, and the remaining electrode units are ring electrodes.

[0013] In a second aspect, an embodiment of the present application further provides a lens module, the lens module comprising a liquid crystal lens of any of the above embodiments and a lens unit, the optical axis of the lens unit coincides with the optical axis of the liquid crystal lens, and the lens unit comprises at least one optical lens.

[0014] In a third aspect, an embodiment of the present application further provides a near-eye display device, which includes a light source and a liquid crystal lens of any of the above embodiments, wherein the liquid crystal lens is used to receive light emitted by the light source.

[0015] In the liquid crystal lens, lens module and near-eye display device provided by the embodiments of the present application, the first substrate and the second substrate of the liquid crystal lens are arranged opposite to each other, the liquid crystal layer is located between the first substrate and the second substrate, the first electrode is located on the surface of the first substrate facing the liquid crystal layer, and the second electrode is located on the surface of the second substrate facing the liquid crystal layer. The first electrode includes m electrode units, and the m electrode units are arranged at intervals from each other. Since the optical path difference of the optical path difference distribution curve of the liquid crystal lens corresponding to the width of each electrode unit is greater than zero and less than or equal to λ / n, m is a positive integer greater than or equal to 1, and n is a positive integer greater than or equal to 3, it helps to ensure that the liquid crystal lens has good diffraction efficiency. By changing the voltage value of the electrode unit, the tilt angle of the liquid crystal molecules can be adjusted, thereby changing the refractive index distribution of the liquid crystal lens, realizing the change of the optical focal length of the liquid crystal lens to change the virtual image distance, and then helping the liquid crystal lens to achieve the effect of being able to form an image more perfectly alone. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the implementation modes of the present application, the drawings required for use in the description of the implementation modes will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 The schematic diagram of the structure of the liquid crystal lens provided by the embodiment of the present application is illustrated.

[0018] Figure 2 A schematic structural diagram of a liquid crystal lens provided in another embodiment of the present application is illustrated.

[0019] Figure 3 A schematic diagram illustrating an optical path difference distribution curve corresponding to an electrode unit of a liquid crystal lens provided in an embodiment of the present application is illustrated.

[0020] Figure 4 A schematic diagram illustrating an electrode unit of a liquid crystal lens provided in another embodiment of the present application corresponding to an optical path difference distribution curve is illustrated.

[0021] Figure 5 A schematic diagram illustrating an optical path difference distribution curve corresponding to an electrode unit of a liquid crystal lens provided in yet another embodiment of the present application is illustrated.

[0022] Figure 6 A schematic diagram of an aspheric lens provided in an embodiment of the present application is illustrated.

[0023] Figure 7 A schematic diagram of a free-form surface lens provided in an embodiment of the present application is illustrated.

[0024] Figure 8 Example Figure 6 Schematic diagram of the dot matrix of an aspheric lens.

[0025] Fig. 9 Example Figure 6 Schematic diagram of the grid distortion of an aspheric lens.

[0026] Fig.10 Example Figure 7 Schematic diagram of the dot matrix of the free-form surface lens.

[0027] Fig.11 Example Figure 7 Schematic diagram of the grid distortion of the free-form surface lens.

[0028] Fig.12 The dot matrix schematic diagram of the parabolic lens provided in the embodiment of the present application is illustrated.

[0029] Fig.13 A schematic diagram of grid distortion of a parabolic lens provided in an embodiment of the present application is illustrated.

[0030] Fig.14 A schematic diagram illustrating the use of a liquid crystal lens and other structures provided in an embodiment of the present application.

[0031] Fig.15 A schematic diagram illustrating the use of a liquid crystal lens and other structures provided in an embodiment of the present application.

[0032] Fig.16 A schematic diagram illustrating the use of a liquid crystal lens and other structural applications provided in an embodiment of the present application.

[0033] Fig.17 The schematic diagram of the structure of the lens module provided by the embodiment of the present application is illustrated.

[0034] Fig.18 A schematic structural diagram of a near-eye display device provided in an embodiment of the present application is illustrated. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the implementation mode of the present application will be clearly and completely described below in conjunction with the drawings in the implementation mode of the present application. Obviously, the described implementation mode is only a part of the implementation mode of the present application, not all the implementation modes. Based on the implementation mode in the present application, all other implementation modes obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0036] See also Figure 1The embodiment of the present application provides a liquid crystal lens 100, which can be applied to display devices such as augmented reality (AR) glasses, virtual reality (VR) glasses, and vehicle-mounted head-up display (HUD).

[0037] When the liquid crystal lens 100 is applied to a near-eye display device, the diameter of the liquid crystal lens 100 may be greater than 20 mm, so as to meet the basic viewing angle requirement of the near-eye display.

[0038] The liquid crystal lens 100 includes a first substrate 10, a second substrate 30, a liquid crystal layer 50, a first electrode 70 and a second electrode 90. The first substrate 10 and the second substrate 30 are arranged opposite to each other, the liquid crystal layer 50 is located between the first substrate 10 and the second substrate 30, the first electrode 70 is located on the surface of the first substrate 10 facing the liquid crystal layer 50, and the second electrode 90 is located on the surface of the second substrate 30 facing the liquid crystal layer 50.

[0039] The width of the liquid crystal layer 50 may be greater than zero and less than 30 μm, which helps to prevent the response time of the liquid crystal lens from being too long.

[0040] The first electrode 70 includes m electrode units 71, and the m electrode units 71 are spaced apart from each other. Wherein, m is a positive integer greater than or equal to 1. The electrode units 71 can be spaced apart from each other by an insulating layer (such as insulating glue). In addition, the first electrode 70 and the liquid crystal layer 50, and the second electrode 90 and the liquid crystal layer 50 can also be spaced apart by an insulating layer.

[0041] The first electrode 70 can be connected to a driving voltage, for example, different electrode units 71 can be connected to the same or different driving voltages. The second electrode 90 can be a surface electrode, and the second electrode 90 can be connected to a common voltage. Under the action of the driving voltage and the common voltage, the tilt angle of the liquid crystal molecules between the first electrode 70 and the second electrode 90 can be adjusted. When different electrode units 71 are connected to driving voltages of different magnitudes, different electric fields are generated between different electrode units 71 and the second electrode 90, which in turn causes different tilt angles of the liquid crystal molecules at different positions.

[0042] Since the refractive index of the liquid crystal lens 100 is related to the tilt angle of the liquid crystal molecules, for example, the relationship between the refractive index of the liquid crystal lens 100 and the tilt angle of the liquid crystal molecules can be obtained by the following calculation formula:

[0043]

[0044] Among them, n eff is the effective refractive index of the liquid crystal, θ is the tilt angle of the liquid crystal molecules, n0 is the ordinary light refractive index of the liquid crystal, ne is the extraordinary refractive index of liquid crystal. Thus, the optical focal length of the liquid crystal lens 100 at different positions can be changed by changing the magnitude of the driving voltage.

[0045] Any two adjacent electrode units 71 may be spaced apart and located on the same surface of the first substrate 10 , which helps to reduce the overall height of the first electrode 70 , and further helps to reduce the height of the liquid crystal lens 100 , thereby facilitating miniaturization of the liquid crystal lens 100 .

[0046] In other embodiments, Figure 2 As shown, any two adjacent electrode units 71 can be spaced in the direction from the first substrate 10 to the second substrate 30. This helps to ensure that there is no gap or the gap is small between the two adjacent electrode units 71 in the positive projection direction of the liquid crystal lens 100 (for example, in the direction from the first substrate 10 to the second substrate 30), thereby helping to minimize the inclination angle of the liquid crystal molecules at the position that cannot be adjusted due to the lack of electrode units 71 in the gap.

[0047] See also Figure 1 , m electrode units 71 may be sequentially arranged in a direction outward from the optical axis 20 of the liquid crystal lens 100. The distance between the inner edge line of the m-th electrode unit 71 and the optical axis 20 of the liquid crystal lens 100 is greater than or equal to the distance between the outer edge line of the m-1-th electrode unit 71 and the optical axis 20 of the liquid crystal lens 100, and the optical axis 20 of the liquid crystal lens 100 is located at the first electrode unit 711.

[0048] The electrode unit 711 located at the optical axis 20 of the liquid crystal lens 100 among the m electrode units 71 is a surface electrode. For example, the first electrode unit 711 is located at the optical axis 20 of the liquid crystal lens 100, and the first electrode unit 711 can be a surface electrode. Since the liquid crystal lens 100 is provided with the electrode unit 71 at the optical axis 20, it helps to avoid the lack of voltage regulation of the liquid crystal lens 100 at the optical axis 20.

[0049] The remaining electrode units 71 except the first electrode unit 711 among the m electrode units 71 are all annular electrodes. For example, when m is 2, the two electrode units 71 are sequentially arranged in the direction outward from the optical axis 20 of the liquid crystal lens 100, and the distance between the second electrode unit 712 and the optical axis 20 of the liquid crystal lens 100 is greater than or equal to the distance between the outer edge line of the first electrode unit 711 and the optical axis 20 of the liquid crystal lens 100. If the second electrode unit 712 is an annular electrode, the second electrode unit 712 and the first electrode unit 711 do not overlap each other in the orthographic projection direction of the liquid crystal lens 100, which helps to avoid the voltage superposition caused by the overlap between the electrode units 71, thereby affecting the adjustment of the tilt angle of the liquid crystal molecules.

[0050] For another example, when m is 3, the three electrode units 71 are sequentially arranged in the direction outward from the optical axis 20 of the liquid crystal lens 100, the distance between the third electrode unit 713 and the optical axis 20 of the liquid crystal lens 100 is greater than or equal to the distance between the outer edge line of the second electrode unit 712 and the optical axis 20 of the liquid crystal lens 100, and the distance between the second electrode unit 712 and the optical axis 20 of the liquid crystal lens 100 is greater than or equal to the distance between the outer edge line of the first electrode unit 711 and the optical axis 20 of the liquid crystal lens 100. The second electrode unit 712 and the third electrode unit 713 are both annular electrodes, and the three electrode units 71 do not overlap each other in the orthographic projection direction of the liquid crystal lens 100, which helps to avoid the voltage superposition caused by the overlap between the electrode units 71, thereby preventing the adjustment of the tilt angle of the liquid crystal molecules from being affected.

[0051] For another example, when m is 4, the four electrode units 71 are sequentially arranged in the direction outward from the optical axis 20 of the liquid crystal lens 100, the distance between the fourth electrode unit 714 and the optical axis 20 of the liquid crystal lens 100 is greater than or equal to the distance between the outer edge line of the third electrode unit 713 and the optical axis 20 of the liquid crystal lens 100, the distance between the third electrode unit 713 and the optical axis 20 of the liquid crystal lens 100 is greater than or equal to the distance between the outer edge line of the second electrode unit 712 and the optical axis 20 of the liquid crystal lens 100, and the distance between the second electrode unit 712 and the optical axis 20 of the liquid crystal lens 100 is greater than or equal to the distance between the outer edge line of the first electrode unit 711 and the optical axis 20 of the liquid crystal lens 100. The second electrode unit 712, the third electrode unit 713 and the fourth electrode unit 714 are all ring electrodes.

[0052] Similarly, when m is 5, 6, 7, 8, 9, 10 or other values, the plurality of electrode units 71 are sequentially arranged along the direction outward from the optical axis 20 of the liquid crystal lens 100 , and the specific arrangement method refers to the arrangement method when m is 2, 3 or 4.

[0053] The optical path difference of the optical path difference distribution curve of the liquid crystal lens 100 corresponding to the width of each electrode unit 71 is greater than zero and less than or equal to λ / n, where λ is the wavelength of the incident light, for example, the incident light can be visible light with a wavelength of 380nm to 760nm. The optical path difference distribution curve of the liquid crystal lens 100 can be an optical path difference of a single wavelength, or an optical path difference greater than a single wavelength, such as 1.5 wavelengths, 2 wavelengths, 2.5 wavelengths, etc. When the total optical path difference of the optical path difference distribution curve of the liquid crystal lens 100 is greater than or equal to the optical path difference of 1 wavelength, m≥n.

[0054] The relationship between the optical path difference corresponding to the width of each electrode unit 71 and the diffraction efficiency of the liquid crystal lens 100 can be obtained according to the following calculation formula: η∝sinc 2 (π / n).

[0055] When n is 2, the corresponding diffraction efficiency is 40.5%.

[0056] When n is 3, the corresponding diffraction efficiency is 68.4%.

[0057] When n is 4, the corresponding diffraction efficiency is 81.1%.

[0058] When n is 5, the corresponding diffraction efficiency is 87.5%.

[0059] When n is 6, the corresponding diffraction efficiency is 91.2%.

[0060] When n is 7, the corresponding diffraction efficiency is 93.5%.

[0061] When n is 8, the corresponding diffraction efficiency is 95.0%.

[0062] When n is 9, the corresponding diffraction efficiency is 96.0%.

[0063] When n is 10, the corresponding diffraction efficiency is 96.8%.

[0064] According to the relationship between the optical path difference corresponding to the width of the electrode unit 71 and the diffraction efficiency, when n is greater than or equal to 3, that is, n is a positive integer greater than or equal to 3, the diffraction efficiency of the liquid crystal lens 100 reaches 68.4%, which helps to ensure that the liquid crystal lens 100 has good diffraction efficiency. By changing the voltage value of the electrode unit 71, the tilt angle of the liquid crystal molecules can be adjusted, thereby changing the refractive index distribution of the liquid crystal lens 100, realizing the change of the optical focal length of the liquid crystal lens 100 to change the virtual image distance, which in turn helps the liquid crystal lens 100 to achieve the effect of being able to form an image more perfectly alone.

[0065] The width of the mth electrode unit 71 along the first direction X is x m , the width of the m-1th electrode unit 71 along the first direction X is x m-1 , x m With x m-1 They respectively correspond to the distances of the optical path difference distribution curve of the liquid crystal lens 100 in the first direction X divided equally into λ / n along the second direction Y along the first direction X. The second direction Y is perpendicular to the first direction X.

[0066] See also Figure 3, if n is 3 and m is 6, then the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is divided equally along the second direction Y by λ / 3, and the distances of the curves after the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is divided equally along the second direction Y by λ / 3 along the first direction X are x6, x5, x4, x3, x2 and x1 respectively. Among them, the optical path differences corresponding to the width value x1 of the first electrode unit 711, the width value x2 of the second electrode unit 712, the width value x3 of the third electrode unit 713, the width value x4 of the fourth electrode unit 714, the width value x5 of the fifth electrode unit 715 and the width value x6 of the sixth electrode unit 716 are all greater than zero and less than or equal to λ / 3. Within the range of assembly error, the optical path differences corresponding to the width value x1 of the first electrode unit 711, the width value x2 of the second electrode unit 712, the width value x3 of the third electrode unit 713, the width value x4 of the fourth electrode unit 714, the width value x5 of the fifth electrode unit 715 and the width value x6 of the sixth electrode unit 716 can all be slightly less than λ / 3 to avoid voltage superposition due to overlap between the electrode units 71.

[0067] See also Figure 4 , if n is 3 and m is 5, then the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is divided equally along the second direction Y by λ / 3, and the distances of the curves after the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is divided equally along the second direction Y by λ / 3 along the first direction X are x5, x4, x3, x2 and x1 respectively. Among them, the optical path differences corresponding to the width value x1 of the first electrode unit 711, the width value x2 of the second electrode unit 712, the width value x3 of the third electrode unit 713, the width value x4 of the fourth electrode unit 714 and the width value x5 of the fifth electrode unit 715 are all greater than zero and less than or equal to λ / 3. Within the range of assembly error, the optical path differences corresponding to the width value x1 of the first electrode unit 711, the width value x2 of the second electrode unit 712, the width value x3 of the third electrode unit 713, the width value x4 of the fourth electrode unit 714 and the width value x5 of the fifth electrode unit 715 can all be slightly less than λ / 3 to avoid voltage superposition due to overlap between the electrode units 71.

[0068] Among them, when any two adjacent electrode units 71 are spaced apart and located on the same surface of the first substrate 10, the optical path difference of the optical path difference distribution curve of the liquid crystal lens 100 corresponding to the width of each electrode unit 71 is greater than zero and less than λ / n, so that the two adjacent electrode units 71 are spaced apart.

[0069] The optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X can be an aspherical optical path difference distribution curve, so that the remaining electrode units 71 except the first electrode unit 711 among the m electrode units 71 are all annular electrodes, which helps to simplify the structure of the electrode unit 71. In addition, since the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is an aspherical optical path difference distribution curve, compared with the parabolic optical path difference distribution curve, it helps the liquid crystal lens 100 to achieve the effect of correcting multiple aberrations such as spherical aberration, coma and distortion of light similar to an aspherical lens, which helps the liquid crystal lens 100 to have clearer imaging and improved aberrations.

[0070] The width of the mth electrode unit 71 along the second direction Y is y m , the width of the m-1th electrode unit 71 along the second direction Y is y m-1 ,y m With y m-1 They respectively correspond to the distances along the second direction Y of the optical path difference distribution curve of the liquid crystal lens 100 in the second direction Y after the curve is equally divided along the first direction X by λ / n.

[0071] See also Figure 5 , if n is 3 and m is 5, then the optical path difference distribution curve 60 of the liquid crystal lens 100 in the second direction Y is equally divided by λ / 3 along the first direction X, and the distances of the curve after the optical path difference distribution curve 60 of the liquid crystal lens 100 in the second direction Y is equally divided by λ / 3 along the first direction X are y5, y4, y3, y2 and y1 respectively along the second direction Y. Among them, the optical path differences corresponding to the width value y1 of the first electrode unit 711, the width value y2 of the second electrode unit 712, the width value y3 of the third electrode unit 713, the width value y4 of the fourth electrode unit 714 and the width value y5 of the fifth electrode unit 715 are all greater than zero and less than or equal to λ / 3. Within the range of assembly error, the optical path differences corresponding to the width value y1 of the first electrode unit 711, the width value y2 of the second electrode unit 712, the width value y3 of the third electrode unit 713, the width value y4 of the fourth electrode unit 714 and the width value y5 of the fifth electrode unit 715 can all be slightly less than λ / 3 to avoid voltage superposition due to overlap between the electrode units 71.

[0072] At least one of the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X and the optical path difference distribution curve 60 of the liquid crystal lens 100 in the second direction Y is a free-form surface optical path difference distribution curve. For example, the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is a free-form surface optical path difference distribution curve, and the optical path difference distribution curve 60 of the liquid crystal lens 100 in the second direction Y is a parabolic optical path difference distribution curve or an aspherical optical path difference distribution curve. For another example, the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is a parabolic optical path difference distribution curve or an aspherical optical path difference distribution curve, and the optical path difference distribution curve 60 of the liquid crystal lens 100 in the second direction Y is a free-form surface optical path difference distribution curve. For another example, the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is a free-form surface optical path difference distribution curve, and the optical path difference distribution curve 60 of the liquid crystal lens 100 in the second direction Y is a free-form surface optical path difference distribution curve. In this way, compared with the existing liquid crystal lens whose optical path difference distribution curve is only a parabolic optical path difference distribution curve, the liquid crystal lens 100 can achieve the effect of correcting various aberrations such as spherical aberration, coma and distortion of light similar to a free-form surface lens, which helps the liquid crystal lens 100 to have clearer imaging and improved aberrations.

[0073] For example Figure 5 In the embodiment, the optical path difference distribution curve 40 of the liquid crystal lens 100 in the first direction X is a free-form surface optical path difference distribution curve, and the optical path difference distribution curve 60 of the liquid crystal lens 100 in the second direction Y is an aspherical surface optical path difference distribution curve.

[0074] In some implementations, the first electrode 70 of the liquid crystal lens 100 of the present application may be designed in the following manners.

[0075] The field of view FOV of the liquid crystal lens 100 is 40 to 120 degrees, the distance from the pupil of the human eye to the electronic zoom lens is 10 to 20 mm, and the exit pupil diameter is 3 to 10 mm. The FOV is set to 80 degrees, the exit pupil distance is 15 mm, and the exit pupil diameter is 5 mm.

[0076] The zoom power is 0.25 diopters to 4 diopters, the relationship between the visual acuity SD and the virtual image distance d is d=1 / SD, and the distance unit is meter.

[0077] After determining the above design function parameters, aspherical lenses and free-form surface lenses can be used to replace the liquid crystal lens 100 during the design process. Through multiple structures of several sets of virtual image distances, the target OPD distribution curve data can be obtained after balancing the aberration.

[0078] The surface profile of an aspheric lens is calculated as follows:

[0079]

[0080] Among them, z is the profile height, r is the radius from the center point, c is the curvature, k is the cone coefficient, and α1~α8 are the aspheric coefficients. The optical path difference distribution curve generated by the aspheric lens is also the aspheric optical path difference distribution curve. According to the above parameters and calculation formula, the data in Table 1 and Figure 6 Aspherical lens 300.

[0081] Table 1

[0082]

[0083] The surface profile of the free-form lens is calculated as follows:

[0084]

[0085] Among them, z is the profile height, r is the radius from the center point, c is the curvature, k is the cone coefficient, A i is the free surface coefficient, x is the x-direction component of r, y is the y-direction component of r, E i (x, y) represents the sum of the power functions of x and y. i The outline of the free-form surface lens is jointly determined, and the optical path difference distribution curve generated by the free-form surface lens is also the free-form surface optical path difference distribution curve.

[0086] According to the above parameters and calculation formula, the data in Table 2 and Table 3 are obtained. Figure 7 The free-form surface lens 400.

[0087] Table 2

[0088]

[0089] Table 3

[0090]

[0091] According to the above Tables 1 to 3, the imaging effect can be simulated, wherein, according to Figure 6 The aspheric lens can be used for imaging simulation to obtain the dot plot and grid distortion plot of the aspheric optical path difference distribution curve, as shown in the figure. Figure 8 and Fig. 9 As shown. Figure 7 The free-form surface lens can be used for imaging simulation to obtain the dot plot and grid distortion plot of the free-form surface optical path difference distribution curve, as shown in the figure. Fig.10 and Fig.11 Then the dot plot and grid distortion plot of the parabola optical path difference distribution curve are shown in Fig.12 and Fig.13 Shown as comparison.

[0092] The point diagram of the aspheric optical path difference distribution curve is smaller than that of the parabolic optical path difference distribution curve, the imaging is clearer, and the grid distortion is reduced (the grid lines are the calculated screen ratio, and the points are the actual imaging positions). The free-form optical path difference distribution curve can further correct the grid distortion, and the effect is better.

[0093] The liquid crystal lens 100 can be used in combination with an aspherical lens, and can correct the human vision while changing the position of the virtual image. Fig.14 As shown, the liquid crystal lens 100 and the aspherical lens 101 can be combined and used with the VR display device 103. Fig.15 and Fig.16 As shown, when the liquid crystal lens 100 and the aspherical lens 101 are combined and matched with the folding system, the diopter adjustment function can be achieved by moving the lens inside the VR display device 103. The combination of the liquid crystal lens 100 and the aspherical lens 101 can be used to adjust the virtual image distance. In addition, according to the requirements of the zoom range, a plurality of liquid crystal lenses 100 are used to increase the ability of the liquid crystal lens 100 to correct aberrations.

[0094] In the liquid crystal lens 100 provided in the embodiment of the present application, the first substrate 10 and the second substrate 30 of the liquid crystal lens 100 are arranged opposite to each other, the liquid crystal layer 50 is located between the first substrate 10 and the second substrate 30, the first electrode 70 is located on the surface of the first substrate 10 facing the liquid crystal layer 50, and the second electrode 90 is located on the surface of the second substrate 30 facing the liquid crystal layer 50. The first electrode 70 includes m electrode units 71, and the m electrode units 71 are arranged at intervals from each other. Since the optical path difference of the optical path difference distribution curve of the liquid crystal lens 100 corresponding to the width of each electrode unit 71 is greater than zero and less than or equal to λ / n, m is a positive integer greater than or equal to 1, and n is a positive integer greater than or equal to 3, it is helpful to ensure that the liquid crystal lens 100 has good diffraction efficiency. By changing the voltage value of the electrode unit 71, the tilt angle of the liquid crystal molecules can be adjusted, thereby changing the refractive index distribution of the liquid crystal lens 100, realizing the change of the optical focal length of the liquid crystal lens 100 to change the virtual image distance, and then helping the liquid crystal lens 100 to achieve the effect of being able to form an image independently and more perfectly.

[0095] See also Fig.17 The embodiment of the present application also provides a lens module 500, which includes the liquid crystal lens 100 of any of the above embodiments and a lens unit 600, wherein the optical axis of the lens unit 600 coincides with the optical axis 20 of the liquid crystal lens 100, and the lens unit 600 includes at least one optical lens. For example, the lens unit 600 includes an aspherical lens, so that the liquid crystal lens 100 can be used in combination with the aspherical lens, which can help correct the human eye's vision on the basis of changing the position of the virtual image.

[0096] In the lens module 500 provided in the embodiment of the present application, the first substrate 10 and the second substrate 30 of the liquid crystal lens 100 are arranged opposite to each other, the liquid crystal layer 50 is located between the first substrate 10 and the second substrate 30, the first electrode 70 is located on the surface of the first substrate 10 facing the liquid crystal layer 50, and the second electrode 90 is located on the surface of the second substrate 30 facing the liquid crystal layer 50. The first electrode 70 includes m electrode units 71, and the m electrode units 71 are arranged at intervals from each other. Since the optical path difference of the optical path difference distribution curve of the liquid crystal lens 100 corresponding to the width of each electrode unit 71 is greater than zero and less than or equal to λ / n, m is a positive integer greater than or equal to 1, and n is a positive integer greater than or equal to 3, it is helpful to ensure that the liquid crystal lens 100 has good diffraction efficiency. By changing the voltage value of the electrode unit 71, the tilt angle of the liquid crystal molecules can be adjusted, thereby changing the refractive index distribution of the liquid crystal lens 100, realizing the change of the optical focal length of the liquid crystal lens 100 to change the virtual image distance, and then helping the liquid crystal lens 100 to achieve the effect of being able to form an image more perfectly alone.

[0097] See also Fig.18 , the embodiment of the present application also provides a near-eye display device 1000, which can be a wearable device such as AR glasses and VR glasses. The near-eye display device 1000 includes a light source 200 and a liquid crystal lens 100 of any of the above embodiments, and the liquid crystal lens 100 is used to receive the light emitted by the light source 200. The light source 200 can be a micro display such as digital light processing (DLP), laser beam scanner (LBS), liquid crystal on silicon (LCOS), digital micro-mirror device (DMD), organic light-emitting diode (OLED), microelectromechanical system (MEMS), etc., and the light emitted by the light source 200 is visible light.

[0098] In the near-eye display device 1000 provided in the embodiment of the present application, the first substrate 10 and the second substrate 30 of the liquid crystal lens 100 are arranged opposite to each other, the liquid crystal layer 50 is located between the first substrate 10 and the second substrate 30, the first electrode 70 is located on the surface of the first substrate 10 facing the liquid crystal layer 50, and the second electrode 90 is located on the surface of the second substrate 30 facing the liquid crystal layer 50. The first electrode 70 includes m electrode units 71, and the m electrode units 71 are arranged at intervals from each other. Since the optical path difference of the optical path difference distribution curve of the liquid crystal lens 100 corresponding to the width of each electrode unit 71 is greater than zero and less than or equal to λ / n, m is a positive integer greater than or equal to 1, and n is a positive integer greater than or equal to 3, it is helpful to ensure that the liquid crystal lens 100 has good diffraction efficiency. By changing the voltage value of the electrode unit 71, the tilt angle of the liquid crystal molecules can be adjusted, thereby changing the refractive index distribution of the liquid crystal lens 100, realizing the change of the optical focal length of the liquid crystal lens 100 to change the virtual image distance, and then helping the liquid crystal lens 100 to achieve the effect of being able to form an image independently and more perfectly.

[0099] In this application, the terms "first", "second", etc. are only used to distinguish descriptions and cannot be understood as specific or special structures. The descriptions of the terms "some embodiments", "other embodiments", etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the utility model. In this application, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this application and the features of the different embodiments or examples without contradiction.

[0100] The above implementation modes are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned implementation modes, a person skilled in the art should understand that the technical solutions described in the aforementioned implementation modes can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various implementation modes of the present application, and should all be included in the protection scope of the present application.

Claims

1. A liquid crystal lens, characterized in that: The liquid crystal lens comprises a first substrate, a second substrate, a liquid crystal layer, a first electrode and a second electrode, wherein the first substrate and the second substrate are arranged opposite to each other, the liquid crystal layer is located between the first substrate and the second substrate, the first electrode is located on a surface of the first substrate facing the liquid crystal layer, and the second electrode is located on a surface of the second substrate facing the liquid crystal layer; The first electrode comprises m electrode units, the m electrode units are arranged at intervals from each other, and the optical path difference of the optical path difference distribution curve of the liquid crystal lens corresponding to the width of each electrode unit is greater than zero and less than or equal to λ / n, wherein m is a positive integer greater than or equal to 1, n is a positive integer greater than or equal to 3, and λ is the wavelength of the incident light; The width values ​​of two adjacent electrode units along the first direction respectively correspond to the distances along the first direction of the curve of the optical path difference distribution curve of the liquid crystal lens in the first direction after being divided into equal parts according to λ / n along the second direction; the width values ​​of two adjacent electrode units along the second direction respectively correspond to the distances along the second direction of the curve of the optical path difference distribution curve of the liquid crystal lens in the second direction after being divided into equal parts according to λ / n along the first direction, and the second direction is perpendicular to the first direction.

2. The liquid crystal lens according to claim 1, characterized in that: The m electrode units are arranged in sequence outward from the optical axis of the liquid crystal lens, the distance between the inner edge line of the m-th electrode unit and the optical axis of the liquid crystal lens is greater than or equal to the distance between the outer edge line of the m-1-th electrode unit and the optical axis of the liquid crystal lens, and the optical axis of the liquid crystal lens is located at the first electrode unit.

3. The liquid crystal lens according to claim 2, characterized in that: The optical path difference distribution curve of the liquid crystal lens in the first direction is an aspherical optical path difference distribution curve.

4. The liquid crystal lens according to claim 2, characterized in that: At least one of the optical path difference distribution curve of the liquid crystal lens in the first direction and the optical path difference distribution curve of the liquid crystal lens in the second direction is a free-form surface optical path difference distribution curve.

5. The liquid crystal lens according to claim 4, characterized in that: The optical path difference distribution curve of the liquid crystal lens in the first direction is a free-form surface optical path difference distribution curve, and the optical path difference distribution curve of the liquid crystal lens in the second direction is an aspherical surface optical path difference distribution curve.

6. The liquid crystal lens according to claim 1, characterized in that: Any two adjacent electrode units are spaced apart along a direction from the first substrate to the second substrate.

7. The liquid crystal lens according to claim 1, characterized in that: Any two adjacent electrode units are spaced apart and located on the same surface of the first substrate, and the optical path difference of the optical path difference distribution curve of the liquid crystal lens corresponding to the width of each electrode unit is greater than zero and less than λ / n.

8. The liquid crystal lens according to claim 1, characterized in that: The electrode unit located at the optical axis position of the liquid crystal lens among the m electrode units is a surface electrode, and the remaining electrode units are all ring electrodes.

9. A lens module, characterized in that: include: The liquid crystal lens according to any one of claims 1 to 8; as well as A lens unit, wherein an optical axis of the lens unit coincides with an optical axis of the liquid crystal lens, and the lens unit comprises at least one optical lens.

10. A near-eye display device, characterized in that: include: light source; as well as The liquid crystal lens according to any one of claims 1 to 8, wherein the liquid crystal lens is used to receive the light emitted by the light source.

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