Double-entrance-pupil waveguide display device
By setting the double-entry pupil area on the optical waveguide plate and using a polarization control unit, combined with a rotatably symmetric waveguide architecture, the problems of poor color uniformity and ghosting in the waveguide display device are solved, and a more uniform image display effect is achieved.
Patent Information
- Application Number
- CN202422012524.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-19
- Publication Date
- 2025-05-23
- Estimated Expiration
- 2034-08-19
Smart Images
Figure CN222896280U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of image display technology, and in particular to a dual-entry-pupil waveguide display device. Background Art
[0002] An optical waveguide is a medium device that guides light waves to propagate in it. The diffraction optical waveguide can utilize the diffraction effect of light and adopt a grating structure to modulate the light beam. At present, the conventional single-layer, single-optical machine, and single-entrance pupil waveguide display device has different intensity distributions of output image lights of different wavelengths due to the different step lengths and diffraction efficiencies of total internal reflection of light of different wavelengths in the waveguide. As a result, the color uniformity of the superimposed image is relatively poor, affecting the viewing effect.
[0003] In addition, the optical waveguide plate will also reflect light toward the light-emitting device. The reflected light is then reflected by the light-emitting device and then irradiates the optical waveguide plate again. It is no longer parallel to the light that initially irradiates the optical waveguide plate, but has a certain angle difference. This will cause the same pixel to have two light rays at different angles entering the entrance pupil area of the optical waveguide plate, so that the output light rays in the exit pupil area also have different angles, which will cause ghosting and affect the viewing experience. Utility Model Content
[0004] The purpose of the embodiments of the present application is to provide a dual-entry-pupil waveguide display device, which can achieve higher color uniformity of superimposed images and solve the ghosting problem.
[0005] In one aspect of an embodiment of the present application, a dual-entry-pupil waveguide display device is provided, comprising a light waveguide unit and a light engine unit, wherein the light waveguide unit comprises a light waveguide plate, at least two entrance pupil areas are arranged on the light waveguide plate, and a polarization control unit is further arranged between the light engine unit and the corresponding entrance pupil areas; image light output by the light engine unit passes through the polarization control unit, is coupled by the entrance pupil areas into the light waveguide plate to form input light, and the polarization control unit is used to block the light reflected from the light waveguide plate back to the light engine unit from irradiating the entrance pupil areas again, or is used to block the light reflected from the light waveguide plate from entering the light engine unit again;
[0006] An exit pupil area is also provided on the optical waveguide plate, and positions of at least two entrance pupil areas are rotationally symmetrical about a geometric center of the exit pupil area.
[0007] Optionally, the grating vectors of at least two of the entrance pupil regions are symmetrical about the geometric center of the exit pupil region.
[0008] Optionally, the exit pupil area receives image light output from the same pixel point of the light engine unit corresponding to at least two entrance pupil areas, and at least two beams of the image light propagate towards each other in the exit pupil area in a manner of total internal reflection.
[0009] Optionally, the exit pupil area receives image light output from the same pixel point of the light engine unit corresponding to at least two entrance pupil areas, and at least two beams of image light formed after coupling output from the exit pupil area have the same propagation direction of output light.
[0010] Optionally, the image light output by the central pixel point of the light engine unit is incident on the corresponding entrance pupil area along the normal direction of the total internal reflection surface of the light waveguide plate.
[0011] Optionally, a pupil expansion area is correspondingly arranged between each of the entrance pupil areas and the exit pupil area.
[0012] Optionally, the light engine unit includes a display chip and a collimating lens group, and the images displayed by the display chips on different light engine units at the same time are the same, or the images displayed by the display chips on different light engine units at the same time are rotationally symmetric.
[0013] Optionally, the polarization control unit includes a polarizer and a quarter wave plate arranged in sequence.
[0014] Optionally, the polarization control unit includes a quarter wave plate and a polarizer arranged in sequence.
[0015] The dual-entry pupil waveguide display device provided in the embodiment of the present application includes an optical waveguide unit and an optical engine unit. The optical waveguide unit includes an optical waveguide plate. At least two entrance pupil areas are arranged on the optical waveguide plate. The optical engine unit is used to output image light. The entrance pupil area couples the image light output by the light engine unit into the optical waveguide plate to form input light. An exit pupil area is also arranged on the optical waveguide plate. The exit pupil area receives the input light coupled into the optical waveguide plate by the at least two entrance pupil areas and forms output light. The positions of the at least two entrance pupil areas are rotationally symmetric about the geometric center of the exit pupil area. The use of this rotationally symmetrically distributed dual light engine unit and dual entrance pupil waveguide architecture can make the light intensity distribution of different color output images more uniform, the consistency of the light intensity distribution of each color is better, and higher color uniformity is achieved; and a polarization control unit is also arranged between the light engine unit and the corresponding entrance pupil area. The image light output by the light engine unit is coupled into the optical waveguide plate by the entrance pupil area after passing through the polarization control unit. The polarization control unit is used to block the light reflected back to the light engine unit through the optical waveguide plate from irradiating the entrance pupil area again, or to block the light reflected by the optical waveguide plate from entering the light engine unit again. The polarization control unit prevents the image light output by the light engine from being irradiated to the optical waveguide plate again after being reflected by the optical waveguide plate, thereby solving the ghosting problem. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0017] Figure 1 This is a schematic diagram of the diffractive light waveguide augmented reality display;
[0018] Figure 2 This is the principle diagram of the uneven brightness and color of the image displayed by the optical waveguide;
[0019] Figure 3 This is the principle diagram of the optical waveguide display image ghosting;
[0020] Figure 4 is a schematic structural diagram of a dual-entry-pupil waveguide display device provided in this embodiment;
[0021] Figure 5 is a grating distribution diagram in a light waveguide plate of a double-entry-pupil waveguide display device provided in this embodiment;
[0022] Figure 6 is one of the waveguide mode diagrams of the grating distribution in the optical waveguide plate of the double-entry-pupil waveguide display device provided in this embodiment;
[0023] Figure 7 This is the second waveguide mode diagram of the grating distribution in the optical waveguide plate of the double-entry-pupil waveguide display device provided in this embodiment;
[0024] Figure 8 This is one of the principle diagrams of the polarization control unit of the dual-entry-pupil waveguide display device provided in this embodiment;
[0025] Fig. 9 This is the second schematic diagram of the polarization control unit of the dual-entry-pupil waveguide display device provided in this embodiment;
[0026] Fig.10 This is the third schematic diagram of the polarization control unit of the dual-entry-pupil waveguide display device provided in this embodiment;
[0027] Fig.11 This is one of the optical path schematic diagrams of the dual-entry-pupil waveguide display device provided in this embodiment;
[0028] Fig.12 This is the second optical path schematic diagram of the dual-entry-pupil waveguide display device provided in this embodiment;
[0029] Fig.13 is a structural schematic diagram of a first embodiment of a dual-entry-pupil waveguide display device provided in this embodiment;
[0030] Fig.14 It is a schematic structural diagram of Example 2 of the dual-entry-pupil waveguide display device provided in this embodiment. DETAILED DESCRIPTION
[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.
[0032] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.
[0033] It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0034] The augmented reality display system based on diffraction optical waveguide is mainly composed of three parts: light engine, optical waveguide plate and human eye. Figure 1 The light engine is used to generate image information, and is mainly composed of a display chip and an imaging lens group, wherein the display chip is located on the rear focal plane of the imaging lens group.
[0035] Each pixel on the display chip emits a corresponding spherical light beam. After passing through the imaging lens group, the spherical light beam forms parallel light and irradiates the entrance pupil area of the optical waveguide plate. The coupling input unit on the entrance pupil area couples the parallel light into the optical waveguide plate and transmits it forward in the optical waveguide plate by total reflection until it encounters the coupling output unit in the exit pupil area. Part of the light beam will be coupled out to the viewer's eyes, and part of the light beam will continue to be transmitted forward by total reflection and the process is repeated continuously. Figure 1 As shown, each time the light beam encounters the coupling-out unit, a portion of the light will be coupled out.
[0036] Each pixel on the display chip emits a composite light composed of different wavelengths mixed in different proportions. The composite light is generally formed by mixing three different wavelengths of light: red, green, and blue. The composite light beam emitted by the same pixel enters the entrance pupil area of the optical waveguide plate at the same angle, while the light of different wavelengths (i.e., different colors) at the same pixel is modulated by the coupling input unit to form different diffraction angles, among which the red light has the largest diffraction angle, the green light has the second largest diffraction angle, and the blue light has the smallest diffraction angle.
[0037] Different diffraction angles will cause different wavelengths of light to have different steps of total reflection in the waveguide plate (i.e., the interval between two total reflections of light at the same side of the waveguide plate). Figure 2 It can be seen that the step length of red light (lr) is the longest, the step length of green light (lg) is the second, and the step length of blue light (lb) is the shortest. The difference in step length will cause the light of different wavelengths at the same pixel to encounter the coupling output unit at different times in the exit pupil area, resulting in inconsistent uniformity of light of different colors in the exit pupil area.
[0038] In order to solve the above problems, based on this, an embodiment of the present application provides a dual-entrance pupil waveguide display device, which uses a rotationally symmetrical waveguide architecture to make the light intensity distribution of different color output images more uniform, and the consistency of the light intensity distribution of each color is better, thereby achieving higher color uniformity. This architecture requires that the images incident by the two entrance pupils are preferably the same, so that the complementary effect of the two image lights can be maximized through rotational symmetry to improve color uniformity. The architecture setting for optimal uniformity requires that the image center light output by the two light engine units illuminate the entrance pupil area in a direction perpendicular to the total internal reflection surface of the light waveguide unit, which will cause the problem of image ghosting. The embodiment of the present application solves the problem of image ghosting by setting a polarization control unit between the light engine and the waveguide entrance pupil area.
[0039] For details, please refer to Figure 4 The dual-entrance pupil waveguide display device provided in the embodiment of the present application includes a light waveguide unit and a light engine unit. The light waveguide unit includes a light waveguide plate 10. At least two entrance pupil areas IE are arranged on the light waveguide plate 10. The present application takes two entrance pupil areas IE as an example, namely, entrance pupil area I-EI and entrance pupil area I-E2, which are used to couple the image light output by the light engine unit 21 and the light engine unit 22 into the light waveguide plate 10. The image light output by the light engine is coupled by the entrance pupil area IE to form an input light propagating in the light waveguide plate 10 in a total internal reflection manner.
[0040] A polarization control unit is also provided between the light engine unit and the corresponding entrance pupil area. The image light output by the light engine unit is coupled into the optical waveguide plate 10 by the coupling input element on the entrance pupil area after passing through the polarization control unit. The polarization control unit is used to block the light reflected by the optical waveguide plate 10 from entering the light engine unit again.
[0041] The optical waveguide plate 10 is also provided with an exit pupil region OE, which receives input light coupled from the two entrance pupil regions IE and forms output light OUT;
[0042] The positions of the two entrance pupil areas IE are rotationally symmetric about the geometric center of the exit pupil area OE.
[0043] Two entrance pupil areas IE and one exit pupil area OE are arranged on the optical waveguide plate 10 , and two light engine units are arranged outside the optical waveguide plate 10 , corresponding to the two entrance pupil areas IE respectively.
[0044] Each light engine unit includes a display chip 201 and a collimating lens group 202. The display chip 201 is used to emit an imaging light beam, that is, each pixel on the display chip 201 will emit a spherical light beam. The collimating lens group 202 is used to change the spherical light beam emitted by the display chip 201 into a plane light beam. Each pixel corresponds to a plane light beam of a different angle.
[0045] Diffraction gratings are set in both the entrance pupil area IE and the exit pupil area OE. After the image light output by the light engine unit is irradiated on the entrance pupil area IE on the optical waveguide plate 10, it is diffracted by the diffraction grating on the entrance pupil area IE to form input light transmitted to the exit pupil area OE. The diffraction grating of the exit pupil area OE diffracts the light coupled input by the entrance pupil area IE from the optical waveguide plate 10 and outputs it to form output light.
[0046] The exit pupil area OE receives image light output from the same pixel point of the light engine unit corresponding to the two entrance pupil areas IE. That is to say, the two input light beams transmitted to the exit pupil area OE by the two entrance pupil areas IE correspond to the light emitted by the same pixel point on the light engine unit. The two input light beams propagate toward each other in the exit pupil area OE by total internal reflection. Correspondingly, the two output light beams OUT formed after being emitted from the exit pupil area OE have the same propagation direction.
[0047] In addition, different light engine units corresponding to at least two entrance pupil areas IE may be located on the same side or different sides of the light waveguide plate 10, depending on actual needs.
[0048] In the present application, the positions of the two entrance pupil areas IE are rotationally symmetric about the geometric center of the exit pupil area OE, that is, after rotating one of the entrance pupil areas IE by a certain angle about the geometric center of the exit pupil area OE, the entrance pupil area IE can overlap with the position of the other entrance pupil area IE. By adopting such a rotationally symmetric dual light engine unit and dual entrance pupil waveguide architecture, the intensity distribution of the output light OUT of different wavelengths can be made more uniform, the light intensity distribution of each wavelength is more consistent, and higher color uniformity can be achieved.
[0049] Correspondingly, the display chips 201 on different light engine units display the same image at the same time, or the images are rotationally symmetric to each other.
[0050] Furthermore, an expansion pupil area can be set between each entrance pupil area IE and exit pupil area OE, which are expansion pupil area R-E1 and expansion pupil area R-E2 respectively. The entrance pupil area I-EI corresponds to the expansion pupil area R-E1, and the entrance pupil area I-E2 corresponds to the expansion pupil area R-E2. Diffraction gratings are set in the entrance pupil area IE, the expansion pupil area RE and the exit pupil area OE. The expansion pupil area expands the input light coupled by the entrance pupil area IE into the waveguide plate 10 and transmits it to the exit pupil area OE.
[0051] The pupil expansion area receives the input light coupled into the corresponding entrance pupil area IE, and forms an expanded light transmitted toward the exit pupil area OE.
[0052] Figure 5It is a specific form of grating distribution in the optical waveguide plate 10, wherein the entrance pupil area I-EI is located at the upper left corner of the optical waveguide plate 10, and a diffraction grating DOE11 is arranged, and DOE11 has a direction V11; the entrance pupil area I-E2 is located at the lower right corner of the optical waveguide plate 10, and a diffraction grating DOE12 is arranged, and DOE12 has a direction V12. The pupil expansion area R-E1 is located to the right of the entrance pupil area I-EI, and a diffraction grating DOE21 is arranged, and DOE21 has a direction V21; the pupil expansion area R-E2 is located to the left of the entrance pupil area I-E2, and a diffraction grating DOE22 is arranged, and DOE22 has a direction V22. The exit pupil area OE is located between the pupil expansion areas R-E1 and R-E2, that is, in the middle of the optical waveguide plate 10, and a diffraction grating DOE3 is arranged, and DOE3 has directions V31 and V32.
[0053] Among them, the positions of the entrance pupil area I-EI and the entrance pupil area I-E2 are rotationally symmetrically distributed about the geometric center position of the exit pupil area OE.
[0054] Figure 6 The waveguide mode diagram of the grating DOE11, DOE21, and DOE3 distribution. The small circle KTIR represents the first wave vector boundary for satisfying the total reflection (TIR) in the optical waveguide plate 10, and the large circle Kmax represents the second wave vector boundary for total reflection in the optical waveguide plate 10. The wave vector boundary can be determined by the refractive index of the optical waveguide plate 10 and the grating period. The specific waveguide process is as follows:
[0055] The incident light IN1 enters the optical waveguide plate 10 from the area BOX0, and the first right-transmitted light B1a is transmitted to the right in the grating direction V11, and its wave vector is in the area BOX1a; the second-transmitted light B2a is transmitted in the grating direction V21, and its wave vector is in the area BOX2a. The first output light OUT1 is transmitted in the grating direction V31, and its wave vector is in the area BOX3. According to the waveguide theory, the wave vector path in the waveguide needs to be a closed loop to ensure the symmetrical relationship between the input and output of the optical waveguide plate 10.
[0056] and Figure 6 Rotationally symmetrical settings Figure 7 middle, Figure 7 The waveguide mode diagram of the grating DOE12, DOE22, and DOE3 distribution. The small circle KTIR represents the first wave vector boundary for satisfying the total reflection (TIR) in the optical waveguide plate 10, and the large circle Kmax represents the second wave vector boundary for total reflection in the optical waveguide plate 10. The wave vector boundary can be determined by the refractive index of the optical waveguide plate 10 and the grating period. The specific waveguide process is as follows:
[0057] The incident light IN1 enters the waveguide from area BOX0, the first left-transmitted light B1b is transmitted to the left in the grating direction V12, and its wave vector is in area BOX1b; the second-transmitted light B2b is transmitted in the grating direction V22, and its wave vector is in area BOX2b. The first output light OUT1 is transmitted in the grating direction V32, and its wave vector is in area BOX3. According to waveguide theory, the wave vector path in the waveguide needs to be a closed loop to ensure the symmetrical relationship between the waveguide input and output.
[0058] On this basis, in order to achieve perfect rotational symmetry, the image center light (i.e., the light output by the central pixel point) output by the two light engine units is required to illuminate the entrance pupil area of the light waveguide plate 10 along the normal direction of the total internal reflection surface of the light waveguide plate 10. Since the light waveguide plate 10 has a certain reflectivity, after the image light output by the light engine unit is irradiated to the light waveguide plate 10, part of the reflected light re-enters the light engine unit and is reflected back by the internal display chip 201 thereof, and then irradiates the light waveguide plate 10 again.
[0059] like Figure 3 As shown, except for the central light (i.e., the light output by the central pixel), the angles of the light output by other pixel points have a certain angle with the normal of the plane of the optical waveguide plate 10 (i.e., the total internal reflection surface of the optical waveguide plate 10). Therefore, the light reflected by the optical waveguide plate 10 back to the light engine unit and reflected by the display chip 201 and then irradiated onto the entrance pupil area IE of the optical waveguide plate 10 again is no longer parallel to the light initially irradiated onto the entrance pupil area IE of the optical waveguide plate 10, but a certain angle difference is generated. This will cause the same pixel point to have two light rays at different angles incident on the entrance pupil area IE of the optical waveguide plate 10, so that the output light in the exit pupil area OE also has different angles, thereby generating ghosting.
[0060] In order to solve the problem of ghosting, a polarization control unit is arranged between each light engine unit and the corresponding entrance pupil area IE to block the light reflected back to the light engine unit through the light waveguide plate 10, so that the image light output by the light engine unit cannot be irradiated to the light waveguide plate 10 again after being reflected by the light waveguide plate 10, thereby solving the problem of ghosting.
[0061] Specifically, Fig.12 and Fig.13 As shown, the polarization control unit may include a polarizer 301 and a quarter wave plate 302. The polarizer 301 is an optical element that can change the polarization state of incident light into linear polarized light, that is, the outgoing light after passing through the polarizer 301 is linear polarized light, and the polarization direction is parallel to the transmission direction of the polarizer 301; the quarter wave plate is also an optical element that can change the polarization state of incident light. The polarization control unit is used to change the polarization state of light transmitted between the light engine unit and the optical waveguide plate 10.
[0062] The light engine unit emits an imaging light beam, which passes through the polarizer 301 in the polarization control unit to form linear polarized light, and then passes through the quarter wave plate 302 to form circular polarized light. After the circular polarized light is irradiated to the entrance pupil area of the optical waveguide plate 10, part of it is coupled to the input grating for diffraction to form the first transmission light T1 transmitted to the pupil expansion area; the diffraction grating in the pupil expansion area diffracts the first transmission light T1 to form the second transmission light T2 transmitted to the exit pupil area OE; the diffraction grating in the exit pupil area OE diffracts the second transmission light T2 and outputs it from the optical waveguide plate 10 to form the output light OUT.
[0063] like Figure 8 As shown, when the transmission direction of the polarizer 301 is the x-axis direction, natural light passes through the polarizer 301 to form linear polarized light Ex with a single vibration direction, and natural light remains natural light after passing through the 1 / 4 wave plate.
[0064] like Fig. 9 As shown, the linear polarized light Ex in the x direction forms circularly polarized light after passing through the quarter wave plate. When the circularly polarized light passes through the quarter wave plate again, the linear polarized light Ey in the y direction is formed. The polarization directions of the linear polarized light Ey and the linear polarized light Ex are perpendicular to each other.
[0065] like Fig.10 As shown, the linear polarized light Ey in the y direction is absorbed by the polarizer 301 and cannot pass through the polarizer 301 , while the linear polarized light Ex in the x direction can pass through the polarizer 301 .
[0066] Based on the above principles, the present application sets a polarization control unit between the light outlet of the light engine unit and the entrance pupil area IE of the light waveguide plate 10, thereby controlling the polarization state of the light reflected by the entrance pupil area IE of the light waveguide plate 10, so that the reflected light can no longer be reflected by the display chip 201, or after being reflected by the display chip 201, it can no longer irradiate the entrance pupil area IE of the light waveguide plate 10, thereby solving the ghosting problem caused by the secondary irradiation light.
[0067] The following two embodiments are used for specific description. In one embodiment, Fig.11 As shown, by controlling the polarization direction of the light emitted by the light engine unit, the light emitted by the light engine unit is linearly polarized light X0 before entering the polarization control unit, and the transmission direction of the polarizer 301 in the polarization control unit is adjusted so that the transmission direction of the polarizer 301 is parallel to the vibration direction of the electric vector of the linear polarized light X0.
[0068] The linearly polarized light X0 passes through the polarizer 301 and the quarter wave plate 302 in sequence to form the first circularly polarized light S1; after the first circularly polarized light S1 is irradiated to the entrance pupil area IE of the optical waveguide plate 10, part of it is reflected by the optical waveguide plate 10 to form the second circularly polarized light S2. Figure 8 , Fig. 9 and Fig.10 From the analysis, it can be seen that the second circularly polarized light S2 is modulated by the 1 / 4 wave plate 302 to form linearly polarized light whose polarization direction is perpendicular to the transmission direction of the polarizer 301, and is then absorbed by the polarizer 301 and cannot pass through the polarizer 301 again, so that the reflected light cannot enter the light engine unit and is reflected by the display chip 201, thereby eliminating the ghosting of the displayed image.
[0069] In another embodiment, Fig.12 As shown, by controlling the polarization direction of the light emitted by the light engine unit, the light emitted by the light engine unit is circularly polarized light S0 before entering the polarization control unit, and adjusting the directions of the 1 / 4 wave plate 302 and the polarizer 301 in the polarization control unit, the circularly polarized light S0 emitted by the light engine unit is modulated by the 1 / 4 wave plate to form a first linear polarized light X1 whose polarization direction is parallel to the transmission direction of the polarizer 301.
[0070] After the first linear polarized light X1 passes through the polarizer 301 and irradiates the entrance pupil area IE of the optical waveguide plate 10, part of it is reflected by the optical waveguide plate 10 to form the second linear polarized light X2; the second linear polarized light X2 passes through the polarizer 301 and the 1 / 4 wave plate 302 in sequence to form the first circular polarized light S1; the first circular polarized light S1 passes through the collimating lens group 202 and is reflected by the display chip 201 to form the second circular polarized light S2. Figure 8 , Fig. 9 and Fig.10 From the analysis, it can be known that after the second circularly polarized light S2 is modulated by the 1 / 4 wave plate 302 to form a linear polarized light whose polarization direction is perpendicular to the transmission direction of the polarizer 301, it is absorbed by the polarizer 301 and can no longer pass through the polarizer 301, so that the light reflected by the display chip 201 can no longer illuminate the entrance pupil area IE of the optical waveguide plate 10, and the ghosting of the displayed image can also be eliminated.
[0071] It can be seen that by setting up the polarization control unit, the image light reflected by the optical waveguide plate 10 is prevented from entering the light engine unit, or the image light reflected by the optical waveguide plate 10 and entering the light engine unit is prevented from being reflected back to the optical waveguide plate 10 by the internal components of the light engine unit, thereby solving the problem of ghosting.
[0072] In summary, the dual-entry pupil waveguide display device provided in the embodiment of the present application solves the problem of uneven brightness and color display caused by the different step sizes and diffraction efficiencies of total reflection of light of different wavelengths in the optical waveguide in the display system based on the diffraction optical waveguide, and the problem of display image ghosting caused by multiple coupling of image light into the optical waveguide.
[0073] By adopting a double light engine unit with rotational symmetry and a waveguide architecture with double entrance pupils, the intensity distribution of the output light OUT of different colors is more uniform, the consistency of the light intensity distribution of each color is better, higher color uniformity is achieved, and a better image display effect can be obtained. In addition, a polarization control unit is set on the transmission light path between the light engine unit and the entrance pupil area IE of the light waveguide plate 10, so that the image light beam emitted by the light engine unit cannot irradiate the light waveguide plate 10 again after being reflected by the light waveguide plate 10, thereby achieving the purpose of eliminating image ghosting.
[0074] by Fig.13 and Fig.14 Taking the embodiment as an example, Fig.13 In the figure, the polarization control unit is composed of a polarizer 301 and a quarter wave plate 302. The light emitted from the light engine unit first passes through the polarizer 301, then passes through the quarter wave plate 302, and then enters the entrance pupil area IE. The polarization control unit includes a polarization control unit 31 and a polarization control unit 32, which correspond to the light engine unit 21 and the light engine unit 22, the entrance pupil area I-EI and the entrance pupil area I-E2, and the pupil expansion area R-E1 and the pupil expansion area R-E2. The polarization control unit changes the polarization state of the light transmitted between the light engine unit and the optical waveguide plate 10, so as to prevent the image light reflected by the optical waveguide plate 10 from entering the light engine unit again.
[0075] The difference is that Fig.14 In the figure, the polarization control unit is composed of a quarter wave plate 302 and a polarizer 301. The light emitted from the light engine unit first passes through the quarter wave plate 302, then passes through the polarizer 301, and then enters the entrance pupil area IE; the polarization control unit includes a polarization control unit 31 and a polarization control unit 32, which correspond to the entrance pupil area I-EI and the entrance pupil area I-E2, the pupil expansion area R-E1 and the pupil expansion area R-E2 respectively. The polarization control unit changes the polarization state of the light transmitted between the light engine unit and the optical waveguide plate 10, so as to prevent the image light reflected from the optical waveguide plate 10 and entering the light engine unit from being reflected back to the optical waveguide plate 10 by the internal components of the light engine unit.
[0076] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A dual-entry-pupil waveguide display device, characterized in that: include: An optical waveguide unit and an optical engine unit, wherein the optical waveguide unit comprises an optical waveguide plate, at least two entrance pupil areas are arranged on the optical waveguide plate, and a polarization control unit is further arranged between the optical engine unit and the corresponding entrance pupil areas; the image light output by the optical engine unit passes through the polarization control unit and is coupled by the entrance pupil area into the optical waveguide plate to form input light, and the polarization control unit is used to block the light reflected back to the optical engine unit through the optical waveguide plate from irradiating the entrance pupil area again, or to block the light reflected by the optical waveguide plate from entering the optical engine unit again; An exit pupil area is also provided on the optical waveguide plate, and positions of at least two entrance pupil areas are rotationally symmetrical about a geometric center of the exit pupil area.
2. The dual-entry-pupil waveguide display device according to claim 1, characterized in that: At least two grating vectors of the entrance pupil area are symmetrical about the geometric center of the exit pupil area.
3. The dual-entry-pupil waveguide display device according to claim 2, characterized in that: The exit pupil area receives image light output from the same pixel point of the light engine unit corresponding to at least two entrance pupil areas, and at least two beams of the image light propagate towards each other in the exit pupil area in a total internal reflection manner.
4. The dual-entry-pupil waveguide display device according to claim 2, characterized in that: The exit pupil area receives image light output from the same pixel point of the light engine unit corresponding to at least two entrance pupil areas, and the propagation direction of at least two beams of image light formed after coupling output from the exit pupil area is the same.
5. The dual-entry-pupil waveguide display device according to claim 2, characterized in that: The image light outputted by the central pixel point of the light engine unit is incident on the corresponding entrance pupil area along the normal direction of the total internal reflection surface of the light waveguide plate.
6. The dual-entry-pupil waveguide display device according to claim 2, characterized in that: A pupil expansion area is correspondingly arranged between each of the entrance pupil areas and the exit pupil area.
7. The dual-entry-pupil waveguide display device according to claim 2, characterized in that: The light engine unit includes a display chip and a collimating lens group. The images displayed by the display chips on different light engine units at the same time are the same, or the images displayed by the display chips on different light engine units at the same time are rotationally symmetric.
8. The dual-entry-pupil waveguide display device according to any one of claims 1 to 7, characterized in that: The polarization control unit includes a polarizing plate and a quarter wave plate which are arranged in sequence.
9. The dual-entry-pupil waveguide display device according to any one of claims 1 to 7, characterized in that: The polarization control unit includes a quarter wave plate and a polarizing plate which are arranged in sequence.