Birefringent near-to-eye display enhancing lens

Abstract

The invention discloses a birefringence near-to-eye display enhancement lens, the lens at least comprises a birefringence liquid crystal modulator driven by voltage according to a time sequence, the birefringence liquid crystal modulator is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14) and a glass substrate II (12), an included angle alpha is formed between the glass substrate I (11) and the glass substrate II (12), and when an electric field is not applied, the transparent electrode I (13) and the liquid crystal layer (15) are opposite to each other. When an electric field is applied, the refractive index of the wedge-shaped liquid crystal layer (15) is ne, when the electric field is applied, the refractive index of the wedge-shaped liquid crystal layer (15) is no, and the deflection angle theta generated by the emergent light (17) before and after the electric field is applied is approximately equal to (ne-no) * alpha. The enhanced lens is simple and light in structure and high in light transmittance, is externally hung on XR equipment at the near-eye end, is synchronously driven by a host in a wired or wireless manner without changing the original structure, and can improve the angular resolution to 1.4 or 2 times, so that the definition is remarkably improved.

Description

Technical field:

[0001] The present invention relates to a birefringent near-eye display enhancement lens, and more specifically, to an enhancement lens capable of reducing screen window effect and improving display resolution. The birefringent near-eye display enhancement lens can be used as an end near-eye external plug-in component of XR glasses such as VR, AR, and MR, and can also be used as a near-eye enhancement lens for optical components such as Pancake folded optical paths and optical waveguides. Background technology:

[0002] The screen-door effect of VR display affects the user's immersive experience and has always been a problem that needs to be overcome. The screen-door effect is the result of "low fill factor" or "low angular resolution", that is, the proportion of the luminous area of ​​the pixel point in the unit area of ​​the pixel is small, and the display resolution is low. When the display is magnified near the eye, the human eye will directly see the pixel structure of the display screen, making the displayed image unreal, just like looking at something behind a screen. Most VR devices with LCD and OLED displays currently have this problem. Adding an optical diffuser or phase plate between the display screen and the lens, and between the lens and the human eye, so that the light can diffuse to the non-luminous part of the display screen can reduce the screen-door effect. Improving the display resolution can also reduce the screen-door effect.

[0003] The FOV of the current mainstream VR headsets is about 100°, the pixels of a single-eye display are about 2k*2k, and the angular resolution is about 20PPD, which is still a big gap from the 60PPD that the human eye can distinguish. In order to reduce the screen door effect, most VR headsets use LCD displays instead of OLED screens with better color, brightness and energy consumption; the micro OLED single-eye clarity has reached 4K, but it has not been widely used due to its high cost. The more promising micro LED display in the XR field is still in the research and exploration stage, and only monochrome screens are trial-produced. In addition to the technical and cost constraints of micro-pixel displays above 4k, the substantial increase in VR display resolution will put great pressure on the host's rendering computing power, data transmission bandwidth, and battery life. Solving these problems will cost a lot.

[0004] Patent application CN2022108384413 adds an orthogonal phase plate to the lens to precisely control the area and expansion direction of the sub-pixel light-emitting point to reduce the screen window effect. The pixel points diffuse in a diffuse manner with high brightness in the middle and low brightness in the periphery. The screen window effect can only be eliminated when the expansion of adjacent pixels overlaps and penetrates each other. At this time, the image contrast and resolution will decrease to a certain extent; if the expansion of adjacent pixels does not overlap, the original contrast and resolution of the image are maintained, and the screen window effect can only be partially eliminated, that is, the degree of the screen window effect is reduced, and the display resolution cannot be improved. Patent application CN2022219612809 discloses a VR lens structure that can move in a plane translationally. By enhancing the image through pixel jitter, it achieves the purpose of improving the display resolution and reducing the screen window effect. Because it involves mechanical movement, it is difficult to optimize the weight, volume, and power consumption. Patent application CN202310465085 discloses VR display-enhanced lenses, which use synchronous optical switch modulation and pixel jitter technology to stagger and superimpose sub-images displayed sequentially on the screen into a high-resolution image, which can increase the number of displayed pixels to 2 or 4 times, but reduce the image brightness to less than 50% or 25% of the original. Summary of the invention:

[0005] The present invention discloses a birefringent near-eye display enhancement lens, which is intended to be used as an end plug-in or add-on for the XR display optical path. Without substantially changing the original device structure, the display angular resolution is increased to 1.4 or 2 times through a host wired or wireless synchronous voltage drive. The birefringent near-eye display enhancement lens has a simple and light structure, low light attenuation, and good matching compatibility with various types of XR, especially VR head displays, and is particularly suitable for use at the near-eye end.

[0006] The birefringent near-eye display enhancement lens (8) comprises at least one birefringent liquid crystal modulator driven by a voltage in a time sequence. The birefringent liquid crystal modulator is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14), and a glass substrate II (12). The transparent electrode can be an ITO conductive layer attached to the side of the glass substrate close to the liquid crystal. An orientation layer is coated on the transparent electrode. Liquid crystal is encapsulated between the orientation layers. Nematic liquid crystal can be used. The angle between the glass substrate I (11) and the glass substrate II (12) is α. The encapsulated liquid crystal is wedge-shaped. The wedge-shaped liquid crystal can deflect the incident light in a plane direction perpendicular to the intersection line of the wedge. The deflection angle is related to the refractive index of the liquid crystal. When there is no voltage difference between the transparent electrode I (13) and the transparent electrode II (14), and no electric field is applied to the wedge-shaped liquid crystal, the director of the liquid crystal layer (15) is parallel to the glass substrate I (11) and the polarization direction of the incident light (16), and the refractive index of the extraordinary ray e in the wedge-shaped liquid crystal layer (15) is n eWhen an electric field is applied to the wedge-shaped liquid crystal, the director of the liquid crystal layer (15) is perpendicular to the glass substrate I (11), that is, perpendicular to the polarization direction of the incident light (16). The incident light (16) is an ordinary ray o light, and the refractive index in the wedge-shaped liquid crystal layer (15) is n o ,like Figure 1 Before and after the electric field is applied, the angle difference θ≈(n e -n o )*α.

[0007] Through a synchronous voltage controller (10), the birefringent near-eye display enhancement lens (8) can deflect the polarized light emitted by the screen (9) by a small angle θ. When viewed from the human eye, the deflected sub-image A (1) and sub-image B (2) are staggered in a set direction and displayed alternately, filling the non-luminous areas between the pixels, and resynthesizing a frame of high-resolution image with pixel multiplication under the effect of visual persistence, such as Figure 2 As shown. The deflection direction and angle θ of the emitted light (17) correspond to the sub-pixel arrangement of the display screen. Based on the deflection direction and angle, one frame of high-resolution original image is divided into sub-image A (1) and sub-image B (2) at the sub-pixel level. Sub-image A (1) and sub-image B (2) have the same pixels as the screen (9), and the display refresh frame rate is twice that of the original video. The deflection angle θ is set to 0.7 times the reciprocal of the original angular resolution of the near-eye display screen, and the optimal range is 0.015° to 0.06°. When the value of θ is large and exceeds the optimal range, it is necessary to offset and compensate sub-image A (1) relative to sub-image B (2) on the display screen (9). If the frame rate of the alternating sub-images is 100 / 120FPS, the frame rate of the high-resolution image in 2x mode is 50 / 60FPS; according to the screen sub-pixel distribution method, the original image is divided into 4 sub-images, A, B, C, and D. In the 4x pixel enhancement mode, the high-resolution video display frame rate is 25 / 30FPS. Because the actual refresh rate of the display is high, there is no flicker problem in the enhanced mode even though the frame rate of the high-resolution image is lower.

[0008] The above-mentioned enhancement mode requires that the incident light (16) is linearly polarized light. In most cases, the light emitted from the screen (9) is linearly polarized light. When the light emitted from the screen (9) is natural light, it is necessary to add a polarizer in front of the birefringent near-eye display enhancement lens (8) to convert it into linearly polarized light.

[0009] A combination of wedge-shaped birefringent liquid crystal modulators with two wedge-shaped intersection lines (18) perpendicular to each other can form a birefringent near-eye display enhancement lens (8) with 4 times pixel enhancement. The double-layer wedge-shaped birefringent liquid crystal modulator is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14), a glass substrate II (12), a liquid crystal layer II (19), a transparent electrode III (20), and a glass substrate III (21), such as Figure 3 As shown. The transparent electrode II (14) is a common electrode, the wedge angle between the glass substrate I (11) and the glass substrate II (12) is α, and the wedge angle between the glass substrate II (12) and the glass substrate III (21) is also α; the wedge intersection line (18) between the glass substrate I (11) and the glass substrate II (12) is perpendicular to the wedge intersection line between the glass substrate II (12) and the glass substrate III (21); the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are the same, and are parallel to the polarization direction of the glass substrate II (12) and the incident light (16). The voltage difference between the transparent electrode I (13) and the transparent electrode II (14) is V1, and the voltage difference between the transparent electrode II (14) and the transparent electrode III (20) is V2. When V1=V2=0, the refractive index of the incident polarized light in the liquid crystal layer (15) and the liquid crystal layer II (19) is n. e When V1 = 0, V2 = V, the refractive index of the incident polarized light in the liquid crystal layer (15) is n e , the refractive index in the liquid crystal layer II (19) is n o When V1=V2=V, the refractive index of the incident polarized light in the liquid crystal layer (15) and the liquid crystal layer II (19) is n o When V1=V, V2=0, the refractive index of the incident polarized light in the liquid crystal layer (15) is n o , the refractive index in the liquid crystal layer II (19) is n e In one modulation cycle, the emitted light (17) has four deflection angles in the original direction. From the human eye, the image is deflected four times. The lines connecting the deflection positions of the same sub-pixel on the screen form a prismatic quadrilateral ABCD. The deflection position of the sub-pixel is located in the gap between the light-emitting points of the screen pixels. The four sub-images are synthesized into one high-definition image. Figure 4 As shown, in order to simplify the illustration, only monochrome sub-pixels are described.

[0010] The wedge-shaped birefringent liquid crystal modulator used in the above-mentioned birefringent near-eye display enhancement lens (8) can be further optimized.

[0011] The transparent electrode I (13) or the transparent electrode II (14) on the side close to the liquid crystal layer (15) can be configured as a sawtooth prism (3) with a single refractive index n, and the glass substrate I (11) and the glass substrate II (12) are packaged in parallel to replace the wedge-shaped liquid crystal container, so that the liquid crystal layer (15) becomes a double refractive prism with a shape complementary to the sawtooth prism (3), such as Figure 5 The preferred range of the grating pitch of the sawtooth prism (3) is 0.3 to 2 mm. In an extreme case, there is only one grating pitch, that is, the grating pitch is close to the size of the wedge-shaped liquid crystal container. The sawtooth prism (3) can be formed by UV curing glue, and the refractive index n can be set to n e or o , or other refractive index, the short side of the prism is perpendicular to the glass substrate II (12), and the angle between the hypotenuse and the glass substrate II (12) is α. When the refractive index of the liquid crystal layer (15) is the same as the refractive index of the sawtooth prism (3), the outgoing light (17) is not deflected, otherwise the outgoing light (17) is deflected at an angle θ; regardless of whether n is equal to n e or o By properly setting the angle α, the refractive index of the liquid crystal layer (15) under voltage modulation is n e and n o When switching between the two, there is an angle difference θ between the emitted lights (17).

[0012] Two sawtooth prism birefringent liquid crystal modulators can be combined into a birefringent near-eye display enhancement lens (8) with 4 times pixel enhancement. The double-layer sawtooth prism birefringent liquid crystal modulator is composed of a glass substrate I (11), a transparent electrode I (13), a sawtooth prism (3), a liquid crystal layer (15), a transparent electrode II (14), a glass substrate II (12), a liquid crystal layer II (19), a sawtooth prism II (4), a transparent electrode III (20), and a glass substrate III (21), wherein the transparent electrode II (14) is a common electrode. Figure 6 As shown. The angles between the hypotenuses of the sawtooth prism (3) and the two glass substrates are α, and the angle lines of the two are perpendicular to each other; the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are the same, and are parallel to the polarization direction of the glass substrate II (12) and the incident light (16); it is also feasible for the sawtooth prism (3) or the sawtooth prism II (4) to be located in the middle of the two liquid crystal layers. The voltage difference between the transparent electrode I (13) and the transparent electrode II (14) is V1, and the voltage difference between the transparent electrode II (14) and the transparent electrode III (20) is V2. When V1=V2=0, the refractive index of the incident polarized light in the liquid crystal layer (15) and the liquid crystal layer II (19) is n. e When V1 = 0, V2 = V, the refractive index of the incident polarized light in the liquid crystal layer (15) is n e, the refractive index in the liquid crystal layer II (19) is n o When V1=V2=V, the refractive index of the incident polarized light in the liquid crystal layer (15) and the liquid crystal layer II (19) is n o When V1=V, V2=0, the refractive index of the incident polarized light in the liquid crystal layer (15) is n o , the refractive index in the liquid crystal layer II (19) is n e ; Within one modulation cycle, the emitted light (17) has four deflection angles in the original direction.

[0013] The above-mentioned birefringent near-eye display enhancement lens (8) has no obvious light attenuation when the incident light (16) is linearly polarized light. When the screen incident light (16) is natural light, in order not to attenuate the light intensity, it can be decomposed into polarized light I and polarized light II with mutually perpendicular polarization directions through a birefringent crystal sheet, or directly incident on a double-wedge birefringent liquid crystal modulator without passing through a birefringent crystal. The double-wedge birefringent liquid crystal modulator is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14), a glass substrate II (12), a liquid crystal layer II (19), a transparent electrode III (20), and a glass substrate III (21). The transparent electrode II (14) is a common electrode, the wedge angle between the glass substrate I (11) and the glass substrate II (12) is α, and the wedge angle between the glass substrate II (12) and the glass substrate III (21) is also α; the wedge intersection line (18) between the glass substrate I (11) and the glass substrate II (12) is parallel to or coincides with the wedge intersection line between the glass substrate II (12) and the glass substrate III (21); the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are perpendicular to each other and parallel to the glass substrate II (12), such as Figure 7 As shown, the voltage difference between transparent electrode I (13) and transparent electrode II (14) is V1, and the voltage difference between transparent electrode II (14) and transparent electrode III (20) is V2.

[0014] When no voltage is applied, V1=V2=0, the polarization direction of the polarized light I is parallel to the director of the liquid crystal layer (15), and the refractive index is n e , the deflection angle perpendicular to the wedge intersection direction is θ e In the liquid crystal layer II (19), the polarization direction of polarized light I is perpendicular to the director of the liquid crystal, and the refractive index is n o , the deflection angle perpendicular to the wedge intersection direction is θ o , the total deflection angle is θ e +θ o The polarization direction of polarized light II is perpendicular to the director of the liquid crystal layer (15), and the refractive index is n o , the deflection angle is θ oIn the liquid crystal layer II (19), the polarization direction of polarized light II is parallel to the director of the liquid crystal, and the refractive index is n e , the deflection angle is θ e , the total deflection angle is θ e +θ o After the polarized light I and the polarized light II pass through the double-wedge birefringent liquid crystal modulator, the deflection angles of the outgoing light (17) are the same, thus solving the problems of polarized light attenuation and image ghosting.

[0015] When voltage is applied, V1=V2=V, the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are both perpendicular to the glass substrate II (12), the polarization directions of polarized light I and polarized light II are both perpendicular to the directors of the liquid crystal layer (15) and the liquid crystal layer II (19), and their refractive indices are both n o , the total deflection angle perpendicular to the wedge intersection direction is 2θ o Before and after the voltage is applied, the spatial deflection angle θ of sub-image A(1) and sub-image B(2) is (θ e +θ o -2θ o )=θ e -θ o .

[0016] Based on the same idea as the above-mentioned embodiment, two double-wedge birefringent liquid crystal modulators can be combined into a birefringent near-eye display enhancement lens (8) with 4 times pixel enhancement.

[0017] The double wedge birefringent liquid crystal modulator can be optimized into a double sawtooth prism birefringent liquid crystal modulator. The double sawtooth prism birefringent liquid crystal modulator is composed of

[0018] The glass substrate I (11), the transparent electrode I (13), the sawtooth prism (3), the liquid crystal layer (15), the transparent electrode II (14), the glass substrate II (12), the liquid crystal layer II (19), the sawtooth prism II (4), the transparent electrode III (20), and the glass substrate III (21) are composed of: Figure 8 As shown. The transparent electrode II (14) is a common electrode, the structures of the sawtooth prism (3) and the sawtooth prism II (4) are as described above, and the angle lines of the two are parallel to each other; the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are perpendicular to each other and parallel to the glass substrate II (12). Before and after the voltage is applied, the spatial deflection angle θ of the sub-image A (1) and the sub-image B (2) is θ e -θ o .

[0019] According to the same method, two double-sawtooth prism birefringent liquid crystal modulators can be combined into a birefringent near-eye display enhancement lens (8) with 4 times pixel enhancement.

[0020] The birefringent near-eye display enhancement lens (8) can also be composed of a birefringent crystal (5) and a liquid crystal modulator, wherein the liquid crystal modulator is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14), a glass substrate II (12), and a polarizer (6), such as Fig. 9 As shown. An orientation layer I is coated on a transparent electrode I (13), and an orientation layer II is coated on a transparent electrode II (14). The orientation directions of the orientation layer I and the orientation layer II are perpendicular to each other. A twisted nematic liquid crystal layer (15) is encapsulated between the orientation layers, and the transparent electrodes are connected to a power source. Natural light or linearly polarized light incident from the screen direction is decomposed into polarized light I o light and polarized light II e light of equal intensity in the birefringent crystal (5). The polarization directions of the two are perpendicular to each other and are deflected at an angle θ to each other. The polarization directions of the orientation layer I and the polarized light I and the polarizer (6) are consistent. When no voltage is applied, the polarized light I rotates 90° after passing through the liquid crystal layer (15), which is perpendicular to the polarization direction of the polarizer (6) and cannot pass through. The polarized light II rotates 90°, which is consistent with the polarizer (6) and can pass through. When voltage is applied, the polarization directions of the polarized light I and the polarized light II do not rotate, the polarized light I can pass through, and the polarized light II is blocked. The liquid crystal modulator displays the o-light image and the e-light image alternately under the periodic modulation of the voltage controller, and the two are combined into a high-resolution image.

[0021] In pixel enhancement mode, the sub-image display refresh rate is equal to the original video frame rate multiplied by the pixel enhancement multiple. The synchronization voltage settings for 2x enhancement and 4x enhancement display modes are as follows: Fig.10 The display app outputs the synchronization signal of the sub-image via wired or wireless communication, and the voltage controller (10) drives the transparent electrode to alternately control the offset display of the sub-image A (1) and the sub-image B (2), thereby superimposing the sub-image A (1) and the sub-image B (2) into a high-resolution image.

[0022] The video frame rate adaptive display method: when the sub-image frame rate is not higher than the maximum refresh rate of the display screen (9), the high-pixel original image is divided into sub-images and the frame rate is increased and displayed in sequence; when the sub-image frame rate is higher than the maximum refresh rate of the display screen (9), the sub-images A, B, C, and D are displayed in sequence by skipping frames. The sub-images are refreshed at a high frame rate, and adaptive display is achieved between clarity and frame rate, that is, relatively static or slowly moving scenes in the video are displayed at a low frame rate and high definition after the sub-images are synthesized, and scenes with a strong sense of movement in the video are displayed at a high frame rate and low resolution after the sub-images are synthesized. Because the human eye cannot see fast-moving scenes clearly, the display of scenes with a strong sense of movement at a high frame rate and low resolution does not cause negative effects.

[0023] The 4x enhanced mode sub-image frame skipping method as described above is to set 4 frames of the high-definition and high-frame rate original video as a group, and in each group, only sub-image A is retained in the sub-image segmented from the 1st frame image, only sub-image B is retained in the sub-image segmented from the 2nd frame image, only sub-image C is retained in the sub-image segmented from the 3rd frame image, and only sub-image D is retained in the sub-image segmented from the 4th frame image; or, set 2 frames of the high-definition and high-frame rate original video as a group, and in each group, sub-image A and sub-image B are retained in the sub-image segmented from the 1st frame image, and sub-image C and sub-image D are retained in the sub-image segmented from the 2nd frame image. Description of the drawings:

[0024] Figure 1 It is a schematic diagram of the structure and principle of a wedge-shaped birefringent liquid crystal modulator.

[0025] Figure 2 It is a schematic diagram of superimposing 2x enhancement mode sub-images into a high-resolution image.

[0026] Figure 3 It is a schematic diagram of a double-layer wedge-shaped birefringent liquid crystal modulator.

[0027] Figure 4 It is a schematic diagram of the superposition of 4x enhancement mode sub-images into a high-resolution image.

[0028] Figure 5 It is a schematic diagram of a sawtooth prism birefringent liquid crystal modulator.

[0029] Figure 6 It is a schematic diagram of a double-layer sawtooth prism birefringent liquid crystal modulator.

[0030] Figure 7 Schematic diagram of a double-wedge birefringent liquid crystal modulator.

[0031] Figure 8 It is a schematic diagram of a double-sawtooth prism birefringent liquid crystal modulator.

[0032] Fig. 9 It is a schematic diagram of a birefringent crystal liquid crystal modulator.

[0033] Fig.10 This is a schematic diagram of synchronous voltage modulation.

[0034] Fig.11 This is a schematic diagram of VR display using a birefringent near-eye display enhancement lens.

[0035] The diagram numbers in the above-mentioned drawings are:

[0036] 1 sub-image A, 2 sub-image B, 3 sawtooth prism, 4 sawtooth prism II, 5 birefringent crystal, 6 polarizer, 7 VR lens, 8 birefringent near-eye display enhancement lens, 9 screen, 10 voltage controller, 11 glass substrate I, 12 glass substrate II, 13 transparent electrode I, 14 transparent electrode II, 15 liquid crystal layer, 16 incident light, 17 outgoing light, 18 wedge intersection line, 19 liquid crystal layer II, 20 transparent electrode III, 21 glass substrate III. a, b, c, d in the figure indicate the director and refractive index of the liquid crystal layer in a voltage modulation cycle of the birefringent liquid crystal modulator.

[0037] The birefringent near-eye display enhancement lens disclosed in the present invention has a simple and lightweight structure and high light transmittance. It can be mounted on a lower-definition XR device at the near-eye end to significantly improve clarity. Compared with ultra-high-definition XR headsets that directly increase display resolution, it can reduce the requirements for host rendering computing power, data transmission bandwidth, and battery life, and can significantly reduce the cost of XR headsets. In addition, based on the characteristics of low light attenuation, thin structure, and pixel doubling of the birefringent near-eye display enhancement lens, it can also be set in the XR optical module or on the light-emitting side of the display screen to improve the XR display effect. Specific implementation method:

[0038] In implementation example 1, a birefringent liquid crystal modulator constituting a birefringent near-eye display enhanced lens is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14), and a glass substrate II (12). The transparent electrode is made of an ITO conductive layer and is attached to a side of the glass substrate close to the liquid crystal. An orientation layer is coated on the transparent electrode. Nematic liquid crystals are encapsulated between the orientation layers. The angle α between the glass substrate I (11) and the glass substrate II (12) is such that the encapsulated liquid crystal is wedge-shaped, which can deflect the incident light (16). Figure 1 As shown, before and after the electric field is applied, the deflection angle difference θ≈(n e -n o)*α. For near-eye displays with a resolution of 15 to 40 ppd, the value range of θ is 0.015° to 0.06°. Adjust the size of α to make the deflection angle θ close to 0.7 times the inverse of the original angular resolution of the near-eye display. The α value is very small, generally between 0.05° and 1°. When the α value is too large and causes θ to be out of range, the display app offsets the sub-image A (1) relative to the sub-image B (2) on the display screen (9) in units of complete pixels for angle compensation to ensure that the deflection angle θ is 0.7 times the inverse of the original angular resolution of the near-eye display. The frame rate of the alternating sub-images is 50 FPS, and the frame rate of the high-resolution image in 2x mode is 25 FPS; according to the distribution of the sub-pixels on the screen, the original image is divided into sub-image A (1) and sub-pixel B (2) to achieve 2x enhanced mode display. Use the mobile phone screen as the display for the simplest VR display, such as Fig.11 As shown, the light emitted by the mobile phone screen is linearly polarized light, the image resolution is 1080P, the FOV is 80°, the angular resolution is 13.5ppd, and in the 2x enhancement mode, the deflection angle θ=0.05°, the angular resolution is increased to 19ppd, and the light attenuation through the lens is small.

[0039] In implementation example 2, a double-layer wedge-shaped birefringent liquid crystal adjuster is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14), a glass substrate II (12), a liquid crystal layer II (19), a transparent electrode III (20), and a glass substrate III (21), as shown in FIG. Figure 3 As shown, the transparent electrode II (14) is a common electrode, the wedge angle between the glass substrate I (11) and the glass substrate II (12) is α, and the wedge angle between the glass substrate II (12) and the glass substrate III (21) is also α; the wedge intersection line (18) between the glass substrate I (11) and the glass substrate II (12) is perpendicular to the wedge intersection line between the glass substrate II (12) and the glass substrate III (21); the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are the same and are parallel to the polarization direction of the glass substrate II (12) and the incident light (16). The voltage difference between the transparent electrode I (13) and the transparent electrode II (14) is V1, and the voltage difference between the transparent electrode II (14) and the transparent electrode III (20) is V2. A complete voltage modulation cycle includes four equal time periods: at time T1, V1=V2=0; at time T2, V1=0, V2=V; at time T3, V1=V2=V; at time T4, V1=V, V2=0; the deflection direction of the emitted light (17) is modulated four times, completing the alternating display of four sub-images, as shown in FIG. Fig.10The simplest VR display is performed using a 2K screen mobile phone, with a screen resolution of 3200*1440, a horizontal FOV of 80°, a diagonal FOV of 108°, and an angular resolution of 20ppd. In the 4x enhancement mode, the deflection angle θ=0.025°, the angular resolution is increased to 40ppd, and the light attenuation through the lens is small.

[0040] In the third embodiment, the incident light of the screen is natural light, and the double wedge birefringent liquid crystal modulator is composed of a glass substrate I (11), a transparent electrode I (13), a liquid crystal layer (15), a transparent electrode II (14), a glass substrate II (12), a liquid crystal layer II (19), a transparent electrode III (20), and a glass substrate III (21). The transparent electrode II (14) is a common electrode, the wedge angles of the glass substrate I (11) and the glass substrate II (12), and the glass substrate II (12) and the glass substrate III (21) are all α, the intersection line of the wedges of the glass substrate I (11) and the glass substrate II (12) is parallel to the intersection line (18) of the wedges of the glass substrate II (12) and the glass substrate III (21), the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are perpendicular to each other and are parallel to the glass substrate II (12), as shown in FIG. Figure 7 At time T1, V1=V2=0, the polarization direction of polarized light I is parallel to the director of the liquid crystal layer (15), and the refractive index is n e , the polarization direction of polarized light I is perpendicular to the director of liquid crystal layer II (19), and the refractive index is n o The polarization direction of polarized light II is perpendicular to the director of the liquid crystal layer (15), and the refractive index is n o , the polarization direction of polarized light II is parallel to the director of liquid crystal layer II (19), and the refractive index is n e The deflection angles of polarized light I and polarized light II after passing through the double wedge birefringent liquid crystal modulator are the same, which solves the problems of polarized light attenuation and image ghosting. At T2, V1=V2=V, the directors of the liquid crystal layer (15) and the liquid crystal layer II (19) are both perpendicular to the glass substrate II (12), the polarization directions of polarized light I and polarized light II are both perpendicular to the directors of the liquid crystal layer (15) and the liquid crystal layer II (19), and their refractive indices are both n o In this embodiment, the light emitted by the near-eye display screen is natural light, the single-screen resolution is 2160*2160, the horizontal FOV is 100°, the angular resolution is 21.6ppd, and in the 2x enhancement mode, the deflection angle θ between the sub-image A (1) and the sub-image B (2) is 0.032°, the angular resolution is increased to 30ppd, and the light passing through the birefringent near-eye display enhancement lens (8) has no polarization attenuation.

[0041] The present invention is intended to utilize the birefringence effect of liquid crystals, apply a modulation voltage to transparent electrodes, and drive a wedge-shaped or sawtooth-shaped liquid crystal layer to deflect the incident light emitted by the display screen. In view of the wide variety of liquid crystals, the suitable orientation layer direction, the liquid crystal director direction, the voltage modulation method, and the configuration schemes of the glass substrate and transparent electrodes constituting the liquid crystal packaging box are also diverse. The implementation method described in the present invention is only a special case among many feasible schemes and cannot be listed one by one. The claims of the present invention include embodiments that simply adjust some components or the order of components in the implementation scheme and have equivalent effects.

Claims

1. A birefringent near-eye display enhancement lens, characterized in that: Its structure at least includes a birefringent liquid crystal modulator driven by voltage in a time sequence, which is composed of a glass substrate I, a transparent electrode I, a liquid crystal layer, a transparent electrode II, and a glass substrate II. Voltage modulation is applied between the transparent electrode I and the transparent electrode II to change the refractive index of the incident light in the liquid crystal. There is a small deflection angle θ between the outgoing light before and after the electric field is applied. When viewed from the human eye through the birefringent liquid crystal modulator, the deflected sub-images A and B are staggered and displayed alternately, filling the non-luminous areas between the pixels, and resynthesizing a high-resolution image with multiplied pixels under the visual persistence effect.

2. The birefringent near-eye display enhancement lens according to claim 1, further characterized in that: The transparent electrode is attached to the side of the glass substrate close to the liquid crystal. The transparent electrode is coated with an orientation layer. The liquid crystal is encapsulated between the orientation layers. The angle between the glass substrate I and the glass substrate II is α. The encapsulated liquid crystal is wedge-shaped. The wedge-shaped liquid crystal can deflect the incident light on the plane perpendicular to the intersection line of the wedge. When there is no voltage difference between the transparent electrode I and the transparent electrode II, and no electric field is applied to the wedge-shaped liquid crystal, the liquid crystal director is parallel to the glass substrate I and the polarization direction of the incident light. As an extraordinary light ray e-light, the refractive index in the wedge-shaped liquid crystal is n e When an electric field is applied to the wedge-shaped liquid crystal, the liquid crystal director is perpendicular to the glass substrate I, that is, perpendicular to the polarization direction of the incident light. The incident light is an ordinary ray o light, and the refractive index in the wedge-shaped liquid crystal is n o , the deflection angle between the outgoing light passing through the wedge-shaped liquid crystal before and after the electric field is applied is θ≈(n e -n o )*α, the deflection angle θ is equal to 0.7 times the reciprocal of the original angular resolution of the near-eye display.

3. The birefringent near-eye display enhancement lens according to claim 1, further characterized in that: The transparent electrode I or the transparent electrode II is close to the side of the liquid crystal, and a sawtooth prism with a single refractive index n is arranged. The glass substrate I and the glass substrate II are packaged in parallel. The liquid crystal layer is a birefringent prism with a shape complementary to the sawtooth prism. The short side of the sawtooth prism is perpendicular to the glass substrate, and the angle between the hypotenuse and the glass substrate is α. Under synchronous voltage modulation, the refractive index of the liquid crystal is n. e and n o The deflection angle between the outgoing light is θ, which is equal to 0.7 times the reciprocal of the original angular resolution of the near-eye display.

4. The birefringent near-eye display enhancement lens according to claim 2, further characterized in that: A double-layer wedge-shaped birefringent liquid crystal modulator with mutually perpendicular wedge intersection lines is combined to form a birefringent near-eye display enhancement lens with 4 times pixel enhancement. The middle glass substrate and transparent electrode of the double-layer wedge-shaped birefringent liquid crystal modulator are shared. The angles of the two wedge-shaped liquid crystal layers are both α. The two wedge intersection lines are mutually perpendicular. The directors of the liquid crystal layer and the liquid crystal layer II are the same and parallel to the glass substrate and the polarization direction of the incident light. The voltage difference between the transparent electrode I and the transparent electrode II is V1, and the voltage difference between the transparent electrode II and the transparent electrode III is V2. a) When V1 = V2 = 0, the refractive index of the incident polarized light in the liquid crystal layer and liquid crystal layer II is n e ; b) When V1 = 0, V2 = V, the refractive index of the incident polarized light in the liquid crystal layer is n e , the refractive index in the liquid crystal layer II is n o ; c) When V1 = V2 = V, the refractive index of the incident polarized light in the liquid crystal layer and liquid crystal layer II is n o ; d) When V1 = V, V2 = 0, the refractive index of the incident polarized light in the liquid crystal layer is n o , the refractive index in the liquid crystal layer II is n e ; In one voltage modulation cycle, the incident light has four deflection angles in the original direction. The image is deflected four times when viewed from the human eye. The lines connecting the deflection positions of the same sub-pixel on the screen form a prismatic quadrilateral ABCD. The deflection angle θ corresponding to each edge is equal to 0.5 times the inverse of the original angular resolution of the near-eye display. The sub-pixel deflection position is in the gap between the light-emitting points of the screen pixels, and the four sub-images are synthesized into one frame of high-definition image.

5. The birefringent near-eye display enhancement lens according to claim 3, further characterized in that: Two sawtooth prism birefringent liquid crystal modulators are combined to form a birefringent near-eye display enhancement lens with 4 times pixel enhancement. The double-layer sawtooth prism birefringent liquid crystal modulator consists of a glass substrate I, a transparent electrode I, a sawtooth prism I, a liquid crystal layer, a transparent electrode II, a glass substrate II, a liquid crystal layer II, a sawtooth prism II, a transparent electrode III, and a glass substrate III. The transparent electrode II is a common electrode. The angles between the hypotenuses of the sawtooth prism and the sawtooth prism II and the glass substrate are both α, and the angle lines are perpendicular to each other. The directors of the liquid crystal layer and the liquid crystal layer II are the same and are parallel to the glass substrate II and the polarization direction of the incident light. The voltage difference between the transparent electrode I and the transparent electrode II is V1, and the voltage difference between the transparent electrode II and the transparent electrode III is V2. a) When V1 = V2 = 0, the refractive index of the incident polarized light in the liquid crystal layer and liquid crystal layer II is n e ; b) When V1 = 0, V2 = V, the refractive index of the incident polarized light in the liquid crystal layer is n e , the refractive index in the liquid crystal layer II is n o ; c) When V1 = V2 = V, the refractive index of the incident polarized light in the liquid crystal layer and liquid crystal layer II is n o ; d) When V1 = V, V2 = 0, the refractive index of the incident polarized light in the liquid crystal layer is n o , the refractive index in the liquid crystal layer II is n e ; In one voltage modulation cycle, the emitted light has four deflection angles, and the adjacent deflection angles θ are set to 0.5 times the reciprocal of the original angular resolution of the near-eye display screen.

6. The birefringent near-eye display enhancement lens according to claim 2, further characterized in that: The screen output light is natural light, and the birefringent liquid crystal modulator is designed as a double wedge liquid crystal structure, which consists of a glass substrate I, a transparent electrode I, a liquid crystal layer, a transparent electrode II, a glass substrate II, a liquid crystal layer II, a transparent electrode III, and a glass substrate III. The transparent electrode II is a common electrode, and the wedge angles of the glass substrate I and the glass substrate II, and the glass substrate II and the glass substrate III are all α. The wedge intersection line of the glass substrate I and the glass substrate II is parallel to the wedge intersection line of the glass substrate II and the glass substrate III. The directors of the liquid crystal layer and the liquid crystal layer II are perpendicular to each other and are parallel to the glass substrate II. Before and after the voltage is applied, the output light deflection angle θ is equal to 0.7 times the inverse of the original angular resolution of the near-eye display screen. The double wedge birefringent liquid crystal modulator with parallel wedge intersection lines can eliminate polarization attenuation and compensate for image ghosting caused by the birefringence of natural light.

7. The birefringent near-eye display enhancement lens according to claim 3, further characterized in that: The incident light of the screen is natural light, and the birefringent liquid crystal modulator is designed as a double sawtooth prism liquid crystal structure, which is composed of a glass substrate I, a transparent electrode I, a sawtooth prism, a liquid crystal layer, a transparent electrode II, a glass substrate II, a liquid crystal layer II, a sawtooth prism II, a transparent electrode III, and a glass substrate III. The transparent electrode II is a common electrode. The corner lines of the sawtooth prism and the sawtooth prism II are parallel to each other, and the directors of the liquid crystal layer and the liquid crystal layer II are perpendicular to each other and parallel to the glass substrate II. Before and after the voltage is applied, the deflection angle θ of the outgoing light is equal to 0.7 times the inverse of the original angular resolution of the near-eye display screen, which can eliminate polarization attenuation and compensate for image ghosting caused by the birefringence of natural light.

8. The birefringent near-eye display enhancement lens according to claim 6 or 7, further characterized in that: The incident light of the screen is natural light. The birefringent liquid crystal modulator is composed of a double-layer double-wedge liquid crystal structure, or a double-layer double-serrated prism liquid crystal structure. In one voltage modulation cycle, the outgoing light has four deflection angles. The adjacent deflection angle θ is equal to 0.5 times the reciprocal of the original angular resolution of the near-eye display. Under the voltage modulation driven synchronously by the display app, the number of pixels displayed on the screen is increased to 4 times.

9. The birefringent near-eye display enhancement lens according to claim 1, further characterized in that: The birefringent liquid crystal modulator is composed of a birefringent crystal, a glass substrate I, a transparent electrode I, a liquid crystal layer, a transparent electrode II, a glass substrate II, and a polarizer. An orientation layer I is coated on the transparent electrode I, and an orientation layer II is coated on the transparent electrode II. The orientation directions of the orientation layer I and the orientation layer II are perpendicular to each other. Twisted nematic liquid crystals are encapsulated between the orientation layers. Natural light or linearly polarized light incident from the screen direction is decomposed into polarized light I and polarized light II of equal intensity in the birefringent crystal. e light, the polarization directions of the outgoing light are perpendicular to each other, and are deflected at an angle θ to each other. The polarization directions of the orientation layer I, polarized light I and the polarizer are consistent. When no voltage is applied, the polarization direction of polarized light I rotates 90° after passing through the liquid crystal layer, which is perpendicular to the polarization direction of the polarizer and cannot pass through. The polarization direction of polarized light II rotates 90°, and its polarization direction is consistent with the polarizer and can pass through. When voltage is applied, the polarization directions of polarized light I and polarized light II do not rotate, polarized light I can pass through, and polarized light II is blocked. The birefringent liquid crystal modulator alternately displays o photon images and e photon images under periodic voltage modulation, and the two are combined into a high-resolution image.

10. The birefringent near-eye display enhancement lens according to claim 2, further characterized in that: When the deflection angle θ of the output light of the birefringent liquid crystal modulator exceeds the optimal range, the position offset of sub-image A relative to sub-image B on the display screen is compensated; when the sub-image frame rate is not higher than the maximum refresh rate of the display screen, the high-pixel original image is divided into sub-images and the frame rate is increased and displayed in sequence; when the sub-image frame rate is higher than the maximum refresh rate of the display screen, the sub-images A, B, C, and D are displayed in sequence in a skipped frame manner.

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