Display module of near-eye display device and near-eye display device

Abstract

This application provides a display module and a near-eye display device. The display module includes an optical waveguide, a projection optical engine, and a cover plate. The cover plate is located between the optical waveguide and the projection optical engine, and is connected to the projection optical engine. The cover plate is parallel or inclined relative to the exit pupil plane of the projection optical engine, and is also parallel or inclined relative to the optical waveguide. The cover plate in the display module can be used to ensure the waterproof and dustproof protection of the projection optical engine. Furthermore, based on the arrangement of the cover plate in the display module, it is not necessary to annularly bond the projection optical engine to the optical waveguide, which helps to reduce the light energy loss of the display module of the near-eye display device.

Description

Technical Field

[0001] This application relates to the field of near-eye display technology, and more particularly to a display module and a near-eye display device. Background Technology

[0002] Near-eye display devices can include augmented reality (AR) devices, mixed reality (MR) devices, and so on. Near-eye display devices can employ various display schemes, such as Bird Bath (semi-reflective), insect-eye (off-axis reflective), freeform prism, and waveguide display schemes. The display module of each scheme can include a projection engine and a transmission medium. The projection engine projects the image, and the transmission medium changes the orientation of the image.

[0003] In related technologies, near-eye display devices typically employ waveguide display solutions. Because waveguides have pupil-expanding capabilities, when the display module of a near-eye display device includes a waveguide, the near-eye display device can have a larger eye box (i.e., the area where the image can be clearly seen) and is also thinner and lighter.

[0004] Assembling the projection optical engine and waveguide in the display module of near-eye display devices is a major challenge. In related technologies, the projection optical engine is typically bonded to the waveguide using a ring-shaped adhesive to achieve waterproofing and dustproofing. Figure 1 a and Figure 1 As shown in b. Figure 1 'a' represents the area before bonding. Figure 1 b represents the bonding process. However, since bonding the projection engine to the optical waveguide requires the use of adhesive, a high-refractive-index medium, the adhesive is introduced into the region where the light propagates in the waveguide during the annular bonding process. This results in a significant proportion of the light transmitted in the total internal reflection region of the waveguide entering the adhesive, leading to light energy loss and stray light. Alternatively, if the adhesive is an absorbing material, stray light will not be introduced, but the light energy loss will be even more severe. Summary of the Invention

[0005] This application provides a display module and a near-eye display device, aiming to reduce the factors that cause light energy loss in the assembly process of the display module of the near-eye display device, thereby reducing the light energy loss of the display module of the near-eye display device.

[0006] In a first aspect, this application provides a display module for a near-eye display device, the display module including an optical waveguide, a projection optical engine, and a cover plate; the cover plate is located between the optical waveguide and the projection optical engine, the cover plate is connected to the projection optical engine, the cover plate is arranged parallel or inclined relative to the exit pupil plane of the projection optical engine, and the cover plate is arranged parallel or inclined relative to the optical waveguide.

[0007] Secondly, this application provides a near-eye display device, which includes the display module of the aforementioned near-eye display device.

[0008] This application provides a display module and a near-eye display device. The display module includes an optical waveguide, a projection optical engine, and a cover plate. The cover plate is located between the optical waveguide and the projection optical engine, and is connected to the projection optical engine. When the cover plate is parallel or inclined relative to the exit pupil plane of the projection optical engine, it can cover the exit pupil plane of the projection optical engine, thus ensuring the waterproof and dustproof protection of the projection optical engine. Furthermore, since the cover plate is located between the optical waveguide and the projection optical engine, and is parallel or inclined relative to the exit pupil plane of the projection optical engine, and is also parallel or inclined relative to the optical waveguide, it is not necessary to annularly bond the projection optical engine to the optical waveguide. This reduces the factors that cause light energy loss during the assembly process of the display module of the near-eye display device, thereby helping to reduce the light energy loss of the display module of the near-eye display device. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 a to Figure 1 b is a schematic diagram of the display module of the near-eye display device involved in the related technology;

[0011] Figure 2 This is a schematic diagram of the structure of a display module of a near-eye display device provided in an embodiment of this application;

[0012] Figure 3 This is a schematic diagram of the connection of a display module according to an embodiment of this application;

[0013] Figure 4 This is a schematic diagram of ghosting offset caused by cover plate tilting according to an embodiment of this application;

[0014] Figure 5 A schematic diagram of the optical waveguide coordinate system corresponding to an embodiment of this application;

[0015] Figure 6 a to Figure 6 b is a schematic diagram of the structure of a display module according to an embodiment of this application;

[0016] Figure 7 a to Figure 7b is a K-vector diagram of a display module according to an embodiment of this application;

[0017] Figure 8 a to Figure 8 b is a K-vector diagram of a display module according to another embodiment of this application;

[0018] Figure 9 a to Figure 9 b is a schematic diagram of the structure of a display module according to another embodiment of this application;

[0019] Figure 10 a to Figure 10 b is a K-vector diagram of a display module according to another embodiment of this application;

[0020] Figure 11 a to Figure 11 b is a schematic diagram of the structure of a display module according to another embodiment of this application;

[0021] Figure 12 This is a K-vector diagram of a display module according to another embodiment of this application;

[0022] Figure 13 This application also provides a schematic diagram of the structure of a display module according to an embodiment;

[0023] Figure 14 This is a schematic diagram of the structure of a near-eye display device provided in an embodiment of this application. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0026] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a display module of a near-eye display device provided in an embodiment of this application.

[0028] like Figure 2 As shown, the display module includes an optical waveguide, a projection optical engine, and a cover plate; the cover plate is located between the optical waveguide and the projection optical engine, the cover plate is connected to the projection optical engine, the cover plate is set parallel or inclined relative to the exit pupil plane of the projection optical engine, and the cover plate is set parallel or inclined relative to the optical waveguide.

[0029] For example, the projection optical engine has an exit pupil. The exit pupil plane of the projection optical engine is used to indicate a virtual plane perpendicular to the main optical axis of the projection optical engine and containing the exit pupil point. The projection optical engine can provide light to the optical waveguide. Since the cover plate is located between the optical waveguide and the projection optical engine, the light provided by the projection optical engine to the optical waveguide can be transmitted to the optical waveguide after the action of the cover plate, and then transmitted to the human eye through the optical waveguide.

[0030] For example, a projection optical engine may include a projection optical system and a projection light source. Accordingly, the projection optical engine may also include a lens barrel, without limitation. The projection optical system may include one or more lenses. The projection light source may include a screen or a light source, without limitation. In an exemplary embodiment, the projection optical engine may include a micro light-emitting diode (microLED) optical engine, a liquid crystal on silicon (LCoS) optical engine, a digital light processing (DLP) optical engine, a fiber scanning display (FSD) optical engine, etc., without limitation.

[0031] For example, an optical waveguide may include one of a geometrical optical waveguide or a diffractive optical waveguide. The optical waveguide includes a waveguide substrate, a light-in coupling region, and a light-out coupling region. The light-in coupling region and the light-out coupling region are disposed on the waveguide substrate. The light-in coupling region can be used to receive light provided by a projection optical engine, thereby coupling the light provided by the projection optical engine into the waveguide substrate. The light provided by the projection optical engine can be transmitted to the light-in coupling region of the optical waveguide after passing through a cover plate. The light coupled into the waveguide substrate is transmitted through the waveguide substrate to the light-out coupling region, and after passing through the light-out coupling region, it exits the waveguide substrate and is then transmitted to the human eye.

[0032] Because the cover plate is located between the optical waveguide and the projection optical engine, and is connected to the projection optical engine, and is positioned parallel or inclined relative to the exit pupil plane of the projection optical engine, the cover plate can cover the exit pupil plane of the projection optical engine. This allows the display module to be protected against water and dust by the cover plate. Furthermore, because the cover plate is positioned between the optical waveguide and the projection optical engine, and is parallel or inclined relative to the exit pupil plane of the projection optical engine, and also parallel or inclined relative to the optical waveguide, it is unnecessary to annularly bond the projection optical engine to the optical waveguide. This reduces factors that cause light energy loss during the assembly process of the display module in near-eye display devices, thus helping to minimize light energy loss in the display module of near-eye display devices.

[0033] For example, the cover plate is detachably connected to the projector. The cover plate can be connected to the projector using detachable connection methods such as adhesive, snap-fit, plug-in, magnetic, or threaded connection. Of course, it is not limited to these methods; a sealing ring can also be provided between the cover plate and the projector to improve the connection stability between the cover plate and the projector.

[0034] Accordingly, when the cover plate is connected to the projection optical engine, the cover plate and the projection optical engine can form a single projection optical engine-cover plate assembly. This single projection optical engine-cover plate assembly can also be detachably connected to areas of the optical waveguide that do not transmit light. For example, the single projection optical engine-cover plate assembly can also use detachable connection methods such as adhesive bonding, snap-fitting, plugging, magnetic attraction, and threaded engagement to connect to areas of the optical waveguide that do not transmit light, thereby achieving stable assembly without loss of light energy. For example, such as... Figure 3 As shown, the projection optical engine-cover plate assembly can connect to areas of the optical waveguide that do not transmit light, such as areas outside the human eye's observation zone within the optical waveguide. Of course, it is not limited to this, and no restrictions are imposed here.

[0035] For example, Figure 2 as well as Figure 3 This can be used to indicate the front view of the display module of a near-eye display device, which is equivalent to indicating the front view shape of the cover plate in the display module. The top view shape of the cover plate can include at least one of a circle, an ellipse, and a polygon, without limitation.

[0036] For example, the cover plate entity can be embodied as a thin sheet. For instance, the cover plate includes a planar cover plate. The cover plate can include a glass plate, a plastic plate, a polarizer, a phase retarder, etc., without limitation. A phase retarder includes, for example, a quarter-wave plate, without limitation. Taking a cover plate entity comprising a circular or elliptical thin sheet as an example, when the cover plate is connected to the projection optical engine, the circular or elliptical thin sheet makes circumferential contact with the projection optical engine, thereby allowing the circular or elliptical thin sheet to connect to the projection optical engine. Of course, this is not limited to this, and no limitation is made here.

[0037] When the cover plate is located between the optical waveguide and the projection optical engine, and the cover plate is set parallel or inclined relative to the optical waveguide, the cover plate can help avoid ghosting and / or image inversion.

[0038] For example, since light is emitted from the projection optical engine, coupled into the optical waveguide after passing through the cover plate, and then transmitted and coupled out to the human eye through the optical waveguide, the transmittance of the cover plate will affect the brightness and clarity of the image viewed by the human eye. In one embodiment, the visible light transmittance of the cover plate is greater than or equal to 80%.

[0039] like Figure 4 As shown, when the cover plate is set parallel or tilted relative to the optical waveguide, if the cover plate is set at an angle δ relative to the optical waveguide, it will cause the image ghosting to shift by an angle of 2δ, that is:

[0040]

[0041] When the cover plate is tilted non-zero relative to the optical waveguide (e.g., δ is not equal to 0), the human eye will observe a ghost image offset by 2δ angles outside the normal image. When δ equals 0, 2δ also equals 0, and the human eye will not see the ghost image. Therefore, no ghost image or image inversion will occur when the cover plate is parallel to the optical waveguide. However, due to the possibility of non-zero deviations during the assembly of the display module in near-eye display devices, the cover plate needs to be tilted relative to the optical waveguide in some cases. The following section discusses in detail the cases where the cover plate is tilted relative to the optical waveguide.

[0042] For example, the image ghosting shift caused by the cover plate can prevent the image ghosting from entering the human eye, thereby avoiding the ghosting effect and improving the display effect of the display module of the near-eye display device.

[0043] In one embodiment, the cover plate is rotated by an angle α about the x-axis of the optical waveguide, and / or the cover plate is rotated by an angle β about the y-axis of the optical waveguide.

[0044] Generally, the x-axis of an optical waveguide is parallel to one side of the smallest external rectangle corresponding to the ray extraction region, and the y-axis is parallel to the other side of the same rectangle. The x-axis is perpendicular to the y-axis. Typically, in a top-view view of the optical waveguide, the x-axis can be horizontal to the right, and the y-axis is in the waveguide plane and perpendicular to the x-axis, for example, it can be positioned from bottom to top. In other cases, the x-axis can be rotated a certain angle relative to the horizontal to the right, while the y-axis remains in the waveguide plane and perpendicular to the x-axis.

[0045] like Figure 5As shown, the optical waveguide coordinate system can include the x-axis, y-axis, and z-axis of the optical waveguide. This coordinate system can also be called the optical waveguide coordinate system xyz. For example, the x-axis of the optical waveguide is parallel to one side of the smallest external rectangle corresponding to the ray detachment region of the optical waveguide; the y-axis is parallel to the other side of the same rectangle, and the x-axis is perpendicular to the y-axis. Similarly, the z-axis is perpendicular to both the x-axis and y-axis of the optical waveguide, and also perpendicular to the waveguide plane. However, the optical waveguide coordinate system xyz is not limited to this specific configuration and is not restricted here.

[0046] When the cover plate is positioned parallel or tilted relative to the optical waveguide, it can rotate by an angle α around the x-axis of the optical waveguide. Correspondingly, the cover plate can also rotate by an angle β around the y-axis of the optical waveguide.

[0047] When the cover plate is set parallel or tilted relative to the optical waveguide, such as rotating by an angle α about the x-axis of the optical waveguide and / or rotating by an angle β about the y-axis of the optical waveguide, the cover plate can help avoid ghosting, which is beneficial to improving the display effect of the display module of the near-eye display device.

[0048] For example, the β angle can include either β1 or β2. In one embodiment, the cover plate rotates clockwise around the y-axis of the optical waveguide by an angle β1, where β1 is greater than or equal to 0° and less than 90°; or, the cover plate rotates counterclockwise around the y-axis of the optical waveguide by an angle β2, where β2 is greater than or equal to 0° and less than 90°. When the cover plate rotates a non-zero β angle around the y-axis of the optical waveguide but not around the x-axis, the rotation angle β is equal to the angle between the side view and the x-axis, or the tilt angle. When the cover plate rotates around both the x-axis and y-axis of the optical waveguide simultaneously, the rotation angle β around the y-axis is not equal to the tilt angle with respect to the x-axis, but can be considered approximately equal. The same applies to other cases. When the cover plate rotates non-zero angles around both the x-axis and y-axis of the optical waveguide simultaneously, different rotation sequences will achieve different final effects, but this paper analyzes this under the assumption that the rotation sequence has little impact and will not delve into the details.

[0049] Taking the positive direction of the y-axis of the optical waveguide as the direction from the bottom to the top of the waveguide from a top-down view as an example. Figure 6 As shown in Figure a, the cover plate is rotated clockwise by an angle β1 around the y-axis of the optical waveguide. The angle β1 is greater than or equal to 0° and less than 90°. Figure 6 As shown in Figure b, the cover plate is rotated counterclockwise by an angle β2 around the y-axis of the optical waveguide. The angle β2 is greater than or equal to 0° and less than 90°.

[0050] In one exemplary embodiment, assuming the aspect ratio of the projection screen corresponding to the display module is greater than 1, the cover plate in the display module is parallel or tilted relative to the optical waveguide, the projection optical engine is not tilted relative to the optical waveguide, the optical waveguide includes a left eye waveguide and a diffraction waveguide, and the coupling is a horizontal pupil with the grating vector pointing horizontally to the right, the cover plate can be rotated clockwise by an angle β1 around the y-axis of the optical waveguide, or the cover plate can be rotated counterclockwise by an angle β2 around the y-axis of the optical waveguide. Both angles β1 and β2 are within the range of 0°-90°, and neither angle β1 nor β2 is equal to 90°.

[0051] Of course, this is not the only possibility; the cover plate can also rotate around the x-axis of the optical waveguide. For the case of horizontal pupil expansion, if the minimum rotation angle corresponding to the cover plate rotating around the y-axis of the optical waveguide is smaller than the minimum rotation angle corresponding to the cover plate rotating around the x-axis of the optical waveguide, then when designing the display module of a near-eye display device, it is preferable to set the cover plate to rotate around the y-axis of the optical waveguide. Correspondingly, the cover plate can also be set to rotate around both the x-axis and y-axis of the optical waveguide simultaneously. For example, the aspect ratio of the projection screen corresponding to the display module can also be less than or equal to 1, without limitation.

[0052] In one embodiment, the angle β1 satisfies the following relationship:

[0053]

[0054] Alternatively, the angle β2 satisfies the following relationship:

[0055]

[0056] Where n indicates the refractive index of the optical waveguide at the analysis wavelength λ, the analysis wavelength λ indicates the wavelength of the light emitted by the projection optical engine, and FOV indicates the diagonal full field of view of the display module. h Used to indicate the horizontal field of view (FOV) of the display module. v Used to indicate the vertical full field of view of the display module.

[0057] When the wavelength λ of the light emitted by the projection optical engine is different, the refractive index of the optical waveguide is different at different analysis wavelengths λ.

[0058] The full field of view of the display module indicates the maximum spatial angle range that the light emitted from the projector can cover, originating from the exit pupil center. The diagonal full field of view of the display module indicates the angle (maximum angle) between the two endpoints of the diagonal of the projected image corresponding to the light emitted from the projector and the exit pupil center. The horizontal full field of view of the display module indicates the angle (width direction) between the two endpoints of the horizontal projection of the projected image corresponding to the projector and the exit pupil center. The vertical full field of view of the display module indicates the angle (height direction) between the two endpoints of the vertical projection of the projected image corresponding to the projector and the exit pupil center.

[0059] In the projection optical engine analysis, the wavelength of the light ray is λ, the refractive index of the waveguide substrate at λ is n, and the period of the light ray coupling region of the light waveguide, such as the period of the coupling grating, is p. in In the case of the coupled grating relative grating vector K in =λ / p in A coupling grating can ensure that the projection k-region corresponding to the projection optical engine falls within the total internal reflection region, such as... Figure 7 a and Figure 7 The annular region shown in b. Based on this, the relative grating vector K coupled into the grating. in The following relationship must be satisfied:

[0060]

[0061] When the relative grating vector K coupled into the grating in The value of is the relative grating vector K of the coupled grating. in When the value of β1 is in the middle of its range, the minimum value of β1 is approximately equal to the minimum value of β2; when the relative grating vector K coupled into the grating... in The value of is close to the relative grating vector K of the coupled grating. in When the range of values ​​is within the upper and lower limits, the minimum value of β1 ≠ the minimum value of β2. The projection k-region of the projection optical engine caused by the clockwise rotation of the cover plate around the y-axis of the optical waveguide is as follows: Figure 7 The dashed area 'a' is shown. The projection region k of the projection optical engine caused by the counterclockwise rotation of the cover plate around the y-axis of the optical waveguide is shown below. Figure 7 The area shown by the dashed line in b is illustrated. Figure 7 For clarity, a slight translation was made relative to the raster vector. Figure 8 , Figure 10 , Figure 12 Similarly, this will not be elaborated further. In the projection k region of the projection optical engine, according to the relative grating vector K of the coupled grating... in In the case of translation, the projected k-region needs to fall outside the total reflection region.

[0062] Based on this, when the cover plate rotates clockwise around the y-axis of the optical waveguide, the rotation angle of the cover plate around the y-axis of the optical waveguide, i.e., the angle β1, satisfies the following relationship:

[0063]

[0064] Correspondingly, when the cover plate rotates counterclockwise around the y-axis of the optical waveguide, the rotation angle of the cover plate around the y-axis of the optical waveguide, i.e., the angle β2, satisfies the following relationship:

[0065]

[0066] Understandably, the rotation angle of the cover plate around the y-axis of the optical waveguide in a clockwise or counterclockwise direction can have a minimum angle. When the rotation angle of the cover plate around the y-axis of the optical waveguide in a clockwise or counterclockwise direction is greater than or equal to the corresponding minimum angle, the cover plate can prevent ghosting between the cover plate and the optical waveguide, which is beneficial for improving the display effect of the display module in near-eye display devices. When the rotation angle of the cover plate around the y-axis of the optical waveguide in a clockwise or counterclockwise direction is equal to the corresponding minimum angle, it is beneficial for achieving a minimum volume of the display module.

[0067] Of course, this is not limited to this. When the cover plate rotates by an angle α around the x-axis of the optical waveguide, the angle α can include angle α1 or angle α2. In one embodiment, the cover plate rotates clockwise by an angle α1 around the x-axis of the optical waveguide, where angle α1 is greater than or equal to 0° and less than 90°; or, the cover plate rotates counterclockwise by an angle α2 around the x-axis of the optical waveguide, where angle α2 is greater than or equal to 0° and less than 90°. The cover plate can have a corresponding minimum rotation angle when rotating around the x-axis of the optical waveguide, and the method for determining the minimum rotation angle when rotating around the x-axis of the optical waveguide can refer to the aforementioned method for determining the minimum rotation angle when rotating around the y-axis of the optical waveguide. For example, it can be determined by combining the diagonal full field of view (FOV) of the display module and the refractive index n of the optical waveguide, which will not be elaborated further here. Correspondingly, the optical waveguide has a corresponding relative grating vector K. in And the relative grating vector K of the optical waveguide in Given the existence of a range of values, the minimum angle of rotation when the cover plate is tilted relative to the optical waveguide has a range of values, which will not be elaborated here.

[0068] Of course, this is not the only possibility. When the optical waveguide includes a geometric waveguide, the minimum rotation angle when the cover plate is tilted relative to the waveguide can also have a corresponding range of values. For example, the minimum rotation angle when the cover plate is tilted relative to the waveguide can still be determined by combining the diagonal full FOV of the display module and the refractive index n of the waveguide. Furthermore, when the optical waveguide includes a geometric waveguide, it is not necessary to consider the relative grating vector K of the waveguide. inFurthermore, in the K-vector diagram corresponding to the geometric waveguide, there are not only translations but also scalings, which are not restricted here.

[0069] In one embodiment, the shortest distance between the optical waveguide and the projection optical engine in the z-axis direction of the optical waveguide is greater than or equal to 0 mm and less than or equal to 10 mm; the z-axis of the optical waveguide is perpendicular to the optical waveguide plane, that is, the z-axis of the optical waveguide is perpendicular to the x-axis and y-axis of the optical waveguide.

[0070] When the cover plate is parallel or inclined relative to the optical waveguide, its placement between the waveguide and the projection optical engine, and its connection to the projection optical engine, may increase the size of the display module in the near-eye display device. To reduce the size of the display module, the shortest distance between the optical waveguide and the projection optical engine along the z-axis of the waveguide can be limited during the design process. For example, the shortest distance between the optical waveguide and the projection optical engine along the z-axis can be greater than or equal to 0 mm and less than or equal to 10 mm. The shortest distance between the optical waveguide and the projection optical engine along the z-axis of the waveguide can be represented as L. Figure 6 As shown in Figure a, the shortest distance L between the optical waveguide and the projection optical engine along the z-axis of the optical waveguide satisfies the following relationship: L ≥ D × tanβ1, where D indicates the diameter of the projection optical engine. Of course, the calculation of the shortest distance L is not limited to this method, and is not restricted here.

[0071] In one embodiment, the optical waveguide includes a left optical waveguide and the cover plate includes a first cover plate, which is arranged parallel or inclined relative to the left optical waveguide; or, the optical waveguide includes a right optical waveguide and the cover plate includes a second cover plate, which is arranged parallel or inclined relative to the right optical waveguide.

[0072] For example, when the display module is applied to a near-eye display device, the left optical waveguide can correspond to the left eye of the user wearing the near-eye display device, and the right optical waveguide can correspond to the right eye of the user wearing the near-eye display device.

[0073] For example, the optical waveguide may include only the left optical waveguide, in which case the projection optical engine includes only the left projection optical engine, and the cover plate includes only the first cover plate. The optical waveguide may also include only the right optical waveguide, in which case the projection optical engine includes only the right projection optical engine, and the cover plate includes only the second cover plate.

[0074] The descriptions related to the left or right optical waveguide can be found in the previous description of the optical waveguide, and the descriptions related to the first and second cover plates can be found in the previous description of the cover plates, and will not be repeated here.

[0075] In one embodiment, the optical waveguide includes a left optical waveguide and a right optical waveguide, and the cover plate includes a first cover plate and a second cover plate; the first cover plate is arranged parallel or inclined relative to the left optical waveguide, and the second cover plate is arranged parallel or inclined relative to the right optical waveguide, the left optical waveguide and the right optical waveguide are mirror images of each other, and the first cover plate and the second cover plate are mirror images of each other.

[0076] For example, when the first cover plate rotates by an angle α around the x-axis of the left optical waveguide, the second cover plate also rotates by an angle α around the x-axis of the right optical waveguide. However, the rotation direction of the first cover plate around the x-axis of the left optical waveguide is a mirror image of the rotation direction of the second cover plate around the x-axis of the right optical waveguide. For instance, when the coordinate systems of the left and right optical waveguides are mirror images, when the first cover plate rotates by an angle α clockwise around the x-axis of the left optical waveguide, the second cover plate rotates by an angle α counterclockwise around the x-axis of the right optical waveguide.

[0077] Correspondingly, when the first cover plate rotates by an angle β around the y-axis of the left optical waveguide, the second cover plate also rotates by an angle β around the y-axis of the right optical waveguide. However, the rotation direction of the first cover plate around the y-axis of the left optical waveguide is a mirror image of the rotation direction of the second cover plate around the y-axis of the right optical waveguide. For example, when the coordinate systems of the left and right optical waveguides are mirror images, when the first cover plate rotates by an angle β counterclockwise around the y-axis of the left optical waveguide, the second cover plate rotates by an angle β clockwise around the y-axis of the right optical waveguide.

[0078] Of course, it is not limited to this, and no restrictions are set here.

[0079] When assembling the left projection optical engine and left waveguide of the display module, the first cover plate can be used to achieve waterproofing and dustproofing for the left projection optical engine. Correspondingly, when assembling the right projection optical engine and right waveguide of the display module, the second cover plate can be used to achieve waterproofing and dustproofing for the right projection optical engine. Based on this, when assembling the projection optical engine and waveguide of the display module, it is not necessary to ring-bond the left projection optical engine to the left waveguide, nor is it necessary to ring-bond the right projection optical engine to the right waveguide, which helps to reduce the light energy loss of the display module.

[0080] In one embodiment, the projection optical engine is arranged parallel to or tilted relative to the optical waveguide.

[0081] For example, the projection optical engine may include a left projection optical engine and a right projection optical engine. The optical waveguide may include a left optical waveguide and a right optical waveguide. The left projection optical engine corresponds to the left optical waveguide, and thus provides light to the left optical waveguide. The right projection optical engine corresponds to the right optical waveguide, and thus provides light to the right optical waveguide. The cover plate includes a first cover plate and a second cover plate. The first cover plate protects the left projection optical engine, and the second cover plate protects the right projection optical engine. The left projection optical engine may be arranged parallel to or tilted relative to the left optical waveguide. Correspondingly, the right projection optical engine may be arranged parallel to or tilted relative to the right optical waveguide. Accordingly, the left and right projection optical engines are mirror images of each other, the left and right optical waveguides are mirror images of each other, and the first and second cover plates are mirror images of each other. In another embodiment, the display module of the near-eye display device may include only a left projection optical engine, a left optical waveguide, and a first cover plate, and the left projection optical engine is arranged parallel to or tilted relative to the left optical waveguide. Of course, this is not the only limitation. The display module of the near-eye display device may also include only the right projection optical engine, the right optical waveguide and the second cover plate, and the right projection optical engine may be set parallel or tilted relative to the right optical waveguide. There are no restrictions here.

[0082] Setting the projection optical engine parallel or tilted relative to the optical waveguide improves the assembly flexibility of the projection optical engine and optical waveguide in the display module of near-eye display devices. Furthermore, setting the projection optical engine parallel or tilted relative to the optical waveguide helps avoid image inversion, thus improving the display performance of the display module.

[0083] In one embodiment, the projection optical engine is rotated by an angle ω about the x-axis of the optical waveguide, and / or the projection optical engine is tilted by an angle γ about the y-axis of the optical waveguide.

[0084] For example, the x-axis of the optical waveguide is parallel to one side of the smallest external rectangle corresponding to the light ray extraction region of the optical waveguide, the y-axis of the optical waveguide is parallel to the other side of the smallest external rectangle corresponding to the light ray extraction region of the optical waveguide, and the x-axis of the optical waveguide is perpendicular to the y-axis of the optical waveguide; of course, it is not limited to this, the x-axis and y-axis of the optical waveguide can also be rotated relative to the smallest external rectangle corresponding to the light ray extraction region, which is not restricted here.

[0085] For example, when the projection optical engine is arranged parallel or tilted relative to the optical waveguide, the projection optical engine can rotate by an angle ω about the x-axis of the optical waveguide, and the projection optical engine can also rotate by an angle γ about the y-axis of the optical waveguide. For instance, when the projection optical engine rotates by an angle ω about the x-axis of the optical waveguide, it can rotate by an angle ω1 clockwise about the x-axis of the optical waveguide, or it can rotate by an angle ω2 counterclockwise about the x-axis of the optical waveguide. Correspondingly, when the projection optical engine rotates by an angle γ about the y-axis of the optical waveguide, it can rotate by an angle γ1 clockwise about the y-axis of the optical waveguide, or it can rotate by an angle γ2 counterclockwise about the y-axis of the optical waveguide; no limitation is made here.

[0086] For example, the angle ω can be smaller than the field of view (FOV). v / 2, or the ω angle can be greater than or equal to FOV. v / 2. For example, the γ angle can be smaller than the field of view (FOV). h / 2, or the γ angle can be greater than or equal to FOV. h / 2, without limitation.

[0087] When the projection optical engine is rotated by an angle ω around the x-axis of the optical waveguide, and / or the projection optical engine is rotated by an angle γ around the y-axis of the optical waveguide, it is beneficial to improve the assembly flexibility of the projection optical engine and the optical waveguide in the display module of the near-eye display device and to improve the display performance of the display module.

[0088] In one embodiment, the angle ω is greater than or equal to the field of view (FOV). v / 2, and / or, the γ angle is greater than or equal to FOV h / 2.

[0089] For example, the projection optical engine rotates by an angle ω around the x-axis of the optical waveguide, and the angle ω is greater than or equal to the field of view (FOV). v In the case of / 2, the cover plate can be tilted relative to the optical axis of the projector, which helps to prevent the cover plate from producing an inverted image. In another embodiment, the cover plate can also be set perpendicular to the optical axis of the projector so that the cover plate does not produce an inverted image.

[0090] For example, the projection optical engine rotates by an angle γ about the y-axis of the optical waveguide, and the angle γ is greater than or equal to the field of view (FOV). h In the case of / 2, the cover plate can be tilted relative to the optical axis of the projector, which helps to prevent the cover plate from producing an inverted image. In another embodiment, the cover plate can also be set perpendicular to the optical axis of the projector so that the cover plate does not produce an inverted image.

[0091] In one exemplary embodiment, for the display module of a near-eye display device, during the design of the optical waveguide and projection optical engine, the projection optical engine can be designed to be tilted relative to the optical waveguide first, and then the cover plate can be designed to be parallel or tilted relative to the optical waveguide. During the assembly of the optical waveguide and projection optical engine, the cover plate and projection optical engine can be assembled first to form an optical engine module, and then the optical engine module and optical waveguide can be assembled. The display module assembled in this way can utilize the cover plate positioned between the projection optical engine and the optical waveguide to avoid ghosting between the cover plate and the optical waveguide, while also preventing the cover plate from producing an inverted image.

[0092] For example, the projection optical engine rotates by an angle ω around the x-axis of the optical waveguide, and the angle ω is greater than or equal to the field of view (FOV). v In the case of / 2, such as Figure 8 a and Figure 8 b shows an equal FOV v In the case of / 2, the relative grating vector K of the optical waveguide. in The following relationship must be satisfied:

[0093]

[0094] At this point, considering both the ghosting between the cover plate and the optical waveguide and the avoidance of image reversal on the cover plate, the cover plate can be rotated clockwise by an angle β3 around the y-axis of the optical waveguide. The angle β3 satisfies the following relationship:

[0095]

[0096] Alternatively, the cover plate can be rotated counterclockwise by an angle β4 about the y-axis of the optical waveguide, where the angle β4 satisfies the following relationship:

[0097]

[0098] It is understandable that the β angle can include the β3 angle, and the β angle can include the β4 angle.

[0099] Accordingly, the projection optical engine is rotated by an angle ω around the x-axis of the optical waveguide, and the angle ω is greater than or equal to the FOV. v In the case of / 2, the projection optical engine can also rotate by an angle γ around the y-axis of the optical waveguide. For example... Figure 9 a or Figure 9 As shown in b, the projection optical engine can also rotate by an angle γ1 around the y-axis of the optical waveguide. Correspondingly, with... Figure 9 a corresponds to the K-vector diagram of the display module, for example, as shown in... Figure 10 a. with Figure 9 b corresponds to the K-vector diagram of the display module, for example, as shown in... Figure 10 As shown in b. Of course, the projection optical engine can be tilted relative to both the x-axis and y-axis of the optical waveguide, but this is not a limitation and will not be discussed here.

[0100] At this point, to avoid ghosting between the cover plate and the optical waveguide, and to prevent the cover plate from producing an inverted image, the cover plate can be rotated clockwise by an angle β5 around the y-axis of the optical waveguide. The angle β5 satisfies the following relationship:

[0101]

[0102] Alternatively, the cover plate can be rotated counterclockwise by an angle β6 about the y-axis of the optical waveguide, where the angle β6 satisfies the following relationship:

[0103]

[0104] Understandably, the β angle can include the β5 angle, and the β angle can include the β6 angle.

[0105] In an exemplary embodiment, when the diagonal field of view (FOV) of the display module is less than or equal to 30°, the angle β1 satisfies the following relationship:

[0106]

[0107] Alternatively, the angle β2 satisfies the following relationship:

[0108]

[0109] When the diagonal full field of view of the display module is greater than 30°, the value range of the angles β1 and β2, such as the calculation method of the upper and lower limits of the angles, still conforms to the aforementioned calculation principle. However, compared with the aforementioned relationship, a corresponding correction coefficient needs to be added for calculation. Furthermore, the angle β1 is still greater than or equal to 0° and less than 90°, and the angle β2 is still greater than or equal to 0° and less than 90°.

[0110] In one embodiment, the optical waveguide is tilted relative to the human eye coordinate system. When the optical waveguide is tilted relative to the human eye coordinate system, i.e., the mirror angle and / or inward angle are not zero, the direction of the human eye's gaze when viewing the image changes accordingly.

[0111] For example, the tilt angle of the optical waveguide coordinate system xyz relative to the human eye coordinate system XYZ can include a mirror angle and / or an inward angle. The optical waveguide can be tilted at an angle ζ relative to the X-axis of the human eye coordinate system, such as... Figure 11 a and Figure 11 As shown in b. Accordingly, as Figure 11 a and Figure 11 As shown in b, the cover plate can still be rotated by an angle γ around the y-axis of the optical waveguide, such as by an angle γ2. Similarly, the cover plate can still be rotated by an angle ω around the x-axis of the optical waveguide, without any restrictions.

[0112] When the optical waveguide is tilted relative to the human eye coordinate system, the human eye coordinate system differs from the optical waveguide coordinate system corresponding to the optical waveguide in the display module. Conversely, when the optical waveguide is not tilted relative to the human eye coordinate system, the human eye coordinate system is the same as the optical waveguide coordinate system corresponding to the optical waveguide in the display module. Regardless of whether the optical waveguide is tilted relative to the human eye coordinate system, the minimum rotation angle of the cover plate when it is tilted relative to the optical waveguide can still be calculated according to the optical waveguide coordinate system corresponding to the optical waveguide. The method for calculating according to the optical waveguide coordinate system corresponding to the optical waveguide can refer to the aforementioned method for calculating the minimum tilt angle when the cover plate is tilted relative to the optical waveguide, and will not be repeated here.

[0113] In one exemplary embodiment, taking an optical waveguide including a left optical waveguide as an example, the light coupling region of the left optical waveguide can expand the pupil to the right, downward, upward to the right, downward to the right, etc., that is, the value range of the ξ angle includes -90° to 90°. When the optical waveguide includes a right optical waveguide, the right optical waveguide is mirrored, i.e., symmetrically arranged, with the left optical waveguide as a mirror image.

[0114] Taking the light coupling area of ​​the left optical waveguide expanding to the right, and the aspect ratio of the projection screen corresponding to the display module being greater than 1 as an example, based on the consideration of avoiding ghosting and inverted images, when the cover plate rotates around the y-axis of the optical waveguide by an angle β, the angle β satisfies the following relationship: max[2°, FOV] v / 2]≤β≤45°, and the shortest distance L between the optical waveguide and the projection optical engine in the z-axis direction of the optical waveguide satisfies the following relationship: 0.5mm≤L≤10mm.

[0115] Taking the downward expansion of the light coupling area of ​​the left optical waveguide as an example, and the aspect ratio of the projection screen corresponding to the display module being less than or equal to 1, based on the consideration of avoiding ghosting and image inversion, the cover plate is rotated by an angle α around the x-axis of the optical waveguide. The angle α satisfies the following relationship: max[2°, FOV] h / 2]≤α≤45°, and the shortest distance L between the optical waveguide and the projection optical engine in the z-axis direction of the optical waveguide satisfies the following relationship: 0.5mm≤L≤10mm.

[0116] Of course, it is not limited to this, and no restrictions are set here.

[0117] In one exemplary embodiment, the pupil expansion method of the light coupling region of the optical waveguide can be diverse. For example, the relative grating vector, i.e., the K vector, of the light coupling region can be non-horizontal, or even vertically downward or vertically upward. Figure 12 As shown. According to K in With k xThe angle ξ between the axes is distinguished as follows: when the absolute value of the angle ξ is less than 45°, the minimum angle required for the cover plate to rotate around the y-axis of the optical waveguide is smaller than the minimum angle required for the cover plate to rotate around the x-axis of the optical waveguide; when the absolute value of the angle ξ is greater than or equal to 45°, the minimum angle required for the cover plate to rotate around the x-axis of the optical waveguide is smaller than the minimum angle required for the cover plate to rotate around the y-axis of the optical waveguide.

[0118] In one embodiment, the display module further includes a light-shielding member, which, together with the cover plate and the projection optical engine, forms a light-shielding cavity.

[0119] For example, in order to reduce the adverse effects of stray light on the display effect of the display module, the space between the projector and the cover plate needs to be shielded. Based on this, if a light shield is provided in the display module, and the light shield, the cover plate, and the projector form a light shield cavity, the light shield cavity can cover the space between the projector and the cover plate, which is beneficial to improving the display effect of the display module.

[0120] like Figure 13 As shown, at least one of the following treatments can be applied to the edge of the cover plate: chamfering, rounding, or polishing, so that the light-shielding component and the cover plate can be tightly connected, thereby forming a sealed light-shielding cavity between the light-shielding component, the cover plate, and the projection optical engine, thus improving the display effect of the display module.

[0121] In one embodiment, the projection area of ​​the cover plate along the optical axis of the projection optical engine is greater than or equal to the exit pupil of the projection optical engine, so as to facilitate processing or assembly and reduce light energy loss.

[0122] For example, a projection engine may include at least one exit pupil. The shape of the exit pupil of the projection engine may include a circle, a quadrilateral, a hexagon, etc., and is not limited thereto.

[0123] When the projected area of ​​the cover plate along the optical axis of the projector is greater than or equal to the exit pupil of the projector, the projected area of ​​the cover plate along the optical axis of the projector can cover the exit pupil of the projector. For example, when the projected area of ​​the cover plate along the optical axis of the projector is greater than or equal to one exit pupil of the projector, the projected area of ​​the cover plate along the optical axis of the projector can cover one exit pupil of the projector. As another example, when the projected area of ​​the cover plate along the optical axis of the projector is greater than or equal to multiple exit pupils of the projector, the projected area of ​​the cover plate along the optical axis of the projector can cover multiple exit pupils of the projector. Based on this, the light provided by the projector can be directed onto the optical waveguide after passing through the cover plate, thereby reducing the light energy loss of the display module.

[0124] In another embodiment, the projection area of ​​the cover plate along the optical axis of the projection optical engine is smaller than the exit pupil of the projection optical engine, so as to act as a physical aperture, in which case there is a loss of light energy.

[0125] The display module of the near-eye display device provided in the above embodiments includes an optical waveguide, a projection optical engine, and a cover plate. The cover plate is located between the optical waveguide and the projection optical engine, and is connected to the projection optical engine. The cover plate is parallel or inclined relative to the exit pupil plane of the projection optical engine, and is also parallel or inclined relative to the optical waveguide. The cover plate in the display module can be used to ensure the waterproof and dustproof protection of the projection optical engine. Furthermore, based on the arrangement of the cover plate in the display module, it is not necessary to annularly bond the projection optical engine to the optical waveguide, which helps to reduce the light energy loss of the display module of the near-eye display device.

[0126] Please see Figure 14 , Figure 14 This is a schematic diagram of the structure of a near-eye display device provided in an embodiment of this application.

[0127] In one embodiment, the near-eye display device is the display module of the near-eye display device provided in any of the embodiments described above.

[0128] It should be understood that the display module provided in any of the above embodiments can provide light to the optical waveguide included in the display module through the projection optical engine included in the display module. Since the cover plate included in the display module is located between the optical waveguide and the projection optical engine, the light provided by the projection optical engine to the optical waveguide can be transmitted to the optical waveguide after the action of the cover plate, and then transmitted to the human eye of the near-eye display device after the action of the optical waveguide, so as to realize the near-eye display function of the near-eye display device. The specific structure and implementation principle of the display module can be referred to the above text, and will not be described again here.

[0129] For example, near-eye display devices include AR devices, such as AR glasses, AR helmets, etc.; near-eye display devices may also include MR devices, such as MR glasses, MR helmets, etc., without limitation.

[0130] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0131] It should also be understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. It should be noted that, herein, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0132] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above descriptions are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A display module for a near-eye display device, characterized in that, The display module includes an optical waveguide, a projection optical engine, and a cover plate; the cover plate is located between the optical waveguide and the projection optical engine, the cover plate is connected to the projection optical engine, the cover plate is parallel or inclined relative to the exit pupil plane of the projection optical engine, and the cover plate is parallel or inclined relative to the optical waveguide.

2. The display module according to claim 1, characterized in that, The cover plate is rotated by an angle α about the x-axis of the optical waveguide, and / or the cover plate is rotated by an angle β about the y-axis of the optical waveguide.

3. The display module according to claim 2, characterized in that, The cover plate is rotated clockwise by an angle β1 about the y-axis of the optical waveguide, where the angle β1 is greater than or equal to 0° and less than 90°; or, The cover plate is rotated counterclockwise by an angle β2 around the y-axis of the optical waveguide, where the angle β2 is greater than or equal to 0° and less than 90°.

4. The display module according to claim 3, characterized in that, The angle β1 satisfies the following relationship: Alternatively, the β2 angle satisfies the following relationship: Wherein, n indicates the refractive index of the optical waveguide at the analysis wavelength λ, the analysis wavelength λ indicates the wavelength of the light emitted by the projection optical engine, and FOV indicates the diagonal full field of view of the display module. h Used to indicate the horizontal field of view (FOV) of the display module. v Used to indicate the vertical full field of view of the display module.

5. The display module according to claim 1, characterized in that, The shortest distance between the optical waveguide and the projection optical engine in the z-axis direction of the optical waveguide is greater than or equal to 0 mm and less than or equal to 10 mm.

6. The display module according to claim 1, characterized in that, The visible light transmittance of the cover plate is greater than or equal to 80%.

7. The display module according to claim 1, characterized in that, The optical waveguide includes a left optical waveguide, and the cover plate includes a first cover plate, which is disposed parallel to or inclined relative to the left optical waveguide; or... The optical waveguide includes a right-side optical waveguide, and the cover plate includes a second cover plate, which is arranged parallel or inclined relative to the right-side optical waveguide.

8. The display module according to claim 1, characterized in that, The optical waveguide includes a left optical waveguide and a right optical waveguide. The cover plate includes a first cover plate and a second cover plate. The first cover plate is arranged parallel or inclined relative to the left optical waveguide, and the second cover plate is arranged parallel or inclined relative to the right optical waveguide. The left optical waveguide and the right optical waveguide are mirror images of each other, and the first cover plate and the second cover plate are mirror images of each other.

9. The display module according to any one of claims 1 to 8, characterized in that, The projection optical engine is arranged parallel to or at an angle relative to the optical waveguide.

10. The display module according to claim 9, characterized in that, The projection optical engine rotates by an angle ω about the x-axis of the optical waveguide, and / or the projection optical engine rotates by an angle γ about the y-axis of the optical waveguide.

11. The display module according to claim 10, characterized in that, The ω angle is greater than or equal to FOV v / 2, and / or, the γ angle is greater than or equal to FOV h / 2.

12. The display module according to any one of claims 1 to 8, characterized in that, The optical waveguide is tilted relative to the human eye coordinate system.

13. The display module according to any one of claims 1 to 8, characterized in that, The projection area of ​​the cover plate along the optical axis of the projection optical engine is greater than or equal to the exit pupil area of ​​the projection optical engine.

14. The display module according to any one of claims 1 to 8, characterized in that, The display module also includes a light-shielding component, which, together with the cover plate and the projection optical engine, forms a light-shielding cavity.

15. A near-eye display device, characterized in that, The near-eye display device includes the display module of the near-eye display device as described in any one of claims 1 to 14.

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