An optical pupil expander, device, method, and display device

Abstract

This application discloses an optical pupil-expanding device, apparatus, method, and display device, relating to the field of optics. It includes: a waveguide plate, a pupil-expanding unit, an exit pupil unit, and an entrance pupil unit with grating grooves arranged in multiple directions. In this device, since the third guided light is diffracted by the pupil-expanding unit, the maximum length of the area occupied by the third guided light in the exit pupil unit is equal to the length of the pupil-expanding unit; the second guided light is diffracted by the entrance pupil unit, therefore, the maximum length of the area occupied by the second guided light in the exit pupil unit is equal to the length of the entrance pupil unit. With previous devices, the maximum length of the exit pupil unit covered by the guided light is only equal to the length of the pupil-expanding unit. However, in the device of this application, the length of the exit pupil area covered by the guided light is greater than the length of the pupil-expanding unit. Therefore, without increasing the size of the pupil-expanding device, it can provide a larger range of eye movement; it is convenient to wear; and it relatively reduces the difficulty and cost of manufacturing.

Description

Technical Field

[0001] This application relates to the field of optics, and in particular to an optical pupil expander, device, method, and display device. Background Technology

[0002] When users observe virtual images displayed on virtual display devices, such as Virtual Reality (VR) devices, Augmented Reality (AR) devices, and in-vehicle head-up displays, they do so through the exit pupil of the virtual display device. However, because the size of the exit pupil of a virtual display device is limited, the virtual image emitted from the exit pupil can only be seen from a specific position. Therefore, a pupil dilator is needed to expand the visual pupil of the virtual display device, allowing the user a larger, more comfortable viewing position relative to the location of the virtual display device, i.e., a wider range of eye movements.

[0003] Currently, pupil dilation devices are used to achieve a larger range of eye movement. Common pupil dilation devices consist of a waveguide plate, an entrance pupil unit, a dilation unit, and an exit pupil unit. The entrance pupil unit is typically a single-wavelength diffraction grating unit, which can only provide light transmission in a single diffraction direction or two opposing ±1st order diffraction directions. Input light is diffracted by the entrance pupil unit to form entrance pupil diffracted light in a single diffraction direction. This entrance pupil diffracted light is then diffracted by the dilation unit to form dilation unit diffracted light. Finally, the exit pupil unit diffracts this diffracted light into output light. In this pupil dilation device, the maximum length of the exit pupil unit that can be covered by the diffracted light from the dilation unit is equal to the length of the dilation unit itself. To provide a larger range of eye movement with existing pupil dilation devices, the exit pupil unit's light-emitting area needs to be as large as possible. Furthermore, the area of ​​the dilation unit needs to be as large as possible to provide light that can cover the entire exit pupil unit. This results in a very large area for the existing dilation unit, increasing the overall area of ​​the pupil dilation device, and increasing manufacturing difficulty and cost.

[0004] Therefore, how to make the pupil dilator provide a larger range of eye movement without increasing the size of the pupil dilator is a technical problem that urgently needs to be solved by those in the field. Summary of the Invention

[0005] The purpose of this application is to provide an optical pupil dilator, device, method, and display device for providing a larger range of eye movement without increasing the size of the pupil dilator.

[0006] To address the aforementioned technical problems, this application provides an optical pupil expanding device, comprising: a waveguide plate, a pupil expanding unit, an exit pupil unit, and an entrance pupil unit, wherein the entrance pupil unit, the pupil expanding unit, and the exit pupil unit are all grating elements, and the entrance pupil unit has grating grooves arranged in multiple directions; the length of the entrance pupil unit is less than the length of the pupil expanding unit, and the length of the exit pupil unit is greater than the length of the pupil expanding unit;

[0007] The entrance pupil unit is used to receive input light and diffract the input light into conductive light that propagates in different directions; wherein, the conductive light includes at least a first conductive light propagating in a first direction and a second conductive light propagating in a second direction;

[0008] The pupil expanding unit is located in the first direction, and the grating groove of the pupil expanding unit is inclined at a first preset angle relative to the first direction, for receiving the first transmitted light and diffracting the first transmitted light into a third transmitted light that propagates along the second direction;

[0009] The exit pupil unit is located in the second direction and is used to receive the third transmitted light and diffract the third transmitted light to form a first output light, and to receive the second transmitted light and diffract the second transmitted light to form a second output light.

[0010] Preferably, the entrance pupil unit has grating grooves arranged in two directions, and is a first region grating with a first grating period and a second region grating with a second grating period, wherein the grooves of the first region grating have the same direction, the grooves of the second region grating have the same direction, and the grooves of the first region grating have different directions from those of the second region grating.

[0011] Preferably, the first region grating is used to diffract the input light into the first guided light that propagates along the first direction, wherein the first direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light and the wave vector of the first region grating;

[0012] The second region grating is used to diffract the input light into the second guided light that propagates along the second direction, wherein the second direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light and the wave vector of the second region grating;

[0013] The pupil expansion unit is used to receive the first guided light and diffract the first guided light to form a third guided light along the fourth direction; wherein, the fourth direction is the direction of the wave vector formed by superimposing the transverse wave vector of the first guided light and the grating wave vector of the pupil expansion unit, and the fourth direction is the same as the second direction;

[0014] The exit pupil unit has the same grating vector as the second region grating.

[0015] Preferably, the vector sum of the grating wave vector of the first region grating, the grating wave vector of the pupil expansion unit, and the grating wave vector of the exit pupil unit is 0, and the vector sum of the grating wave vector of the second region grating and the grating wave vector of the exit pupil unit is 0.

[0016] Preferably, the entrance pupil unit is a two-dimensional grating, wherein the two-dimensional grating is a grating formed by alternating a first one-dimensional grating having a first grating period and a second one-dimensional grating having a second grating period.

[0017] Preferably, it further includes a beam-splitting unit, wherein the beam-splitting unit is the grating element;

[0018] The beam splitting unit is located within the waveguide between the entrance pupil unit and the exit pupil unit, and is located in the second direction. The grating groove line of the beam splitting unit is inclined at a second preset angle relative to the first direction.

[0019] The beam splitting unit is used to receive the second guided light and diffract the second guided light through an even number of times to form a fourth guided light that propagates along the second direction;

[0020] The exit pupil unit is used to receive the fourth transmitted light and diffract the fourth transmitted light to form the third output light.

[0021] Preferably, the grating vector of the beam splitter unit is the same as that of the pupil expander unit.

[0022] To address the aforementioned technical problems, this application also provides an optical pupil-expanding device, including the aforementioned optical pupil-expanding apparatus; wherein each of the optical pupil-expanding apparatuses is staggered or highly aligned.

[0023] To address the aforementioned technical problems, this application also provides a display device, including the aforementioned optical pupil expander.

[0024] To address the aforementioned technical problems, this application also provides an optical pupil expansion method, applied to an optical pupil expansion device comprising a waveguide plate, a pupil expansion unit, an exit pupil unit, and an entrance pupil unit, wherein the entrance pupil unit, the pupil expansion unit, and the exit pupil unit are all grating elements, the entrance pupil unit having grating grooves arranged in multiple directions; the pupil expansion unit is located in the first direction, and the grating grooves of the pupil expansion unit are inclined at a first preset angle relative to the first direction; the length of the entrance pupil unit is less than the length of the pupil expansion unit, and the length of the exit pupil unit is greater than the length of the pupil expansion unit; the exit pupil unit is located in the second direction; the method includes:

[0025] The entrance pupil unit receives input light and diffracts the input light into conductive light that propagates in different directions; wherein the conductive light includes at least a first conductive light propagating in a first direction and a second conductive light propagating in a second direction;

[0026] The pupil expansion unit receives the first transmitted light and diffracts the first transmitted light into a third transmitted light that propagates along the second direction;

[0027] The exit pupil unit receives the third transmitted light and diffracts the third transmitted light to form the first output light, and receives the second transmitted light and diffracts the second transmitted light to form the second output light.

[0028] The optical pupil expanding device provided in this application includes: a waveguide plate, a pupil expanding unit, an exit pupil unit, and an entrance pupil unit. The entrance pupil unit, pupil expanding unit, and exit pupil unit are all grating elements. The entrance pupil unit has grating grooves arranged in multiple directions. The length of the entrance pupil unit is less than the length of the pupil expanding unit, and the length of the exit pupil unit is greater than the length of the pupil expanding unit. The entrance pupil unit is used to receive input light and diffract the input light into guided light propagating in different directions. The guided light includes at least a first guided light propagating in a first direction and a second guided light propagating in a second direction. The pupil expanding unit is located in the first direction, and the grating grooves of the pupil expanding unit are inclined at a first preset angle relative to the first direction. It is used to receive the first guided light and diffract the first guided light into a third guided light propagating in the second direction. The exit pupil unit is located in the second direction and is used to receive the third guided light and diffract the third guided light into a first output light, and to receive the second guided light and diffract the second guided light into a second output light. In the pupil dilator of this application, since the third guided light is formed by diffraction of the pupil dilator unit, the maximum length of the area occupied by the third guided light in the exit pupil unit is the length of the pupil dilator unit; the second guided light is formed by diffraction of the entrance pupil unit, therefore, the maximum length of the area occupied by the second guided light in the exit pupil unit is the length of the entrance pupil unit. If a previous pupil dilator with an entrance pupil unit having a single diffraction direction is used, the maximum length of the exit pupil unit covered by the guided light is only the length of the pupil dilator unit. However, in the pupil dilator of this application, the length of the exit pupil area covered by the guided light is greater than the length of the pupil dilator unit. Thus, without increasing the size of the pupil dilator, the pupil dilator can provide a larger range of eye movement; and it is convenient to wear and relatively reduces the difficulty and cost of manufacturing the pupil dilator.

[0029] In addition, this application also provides an optical pupil-expanding device, a display device, and an optical pupil-expanding method, which have the same or corresponding technical features as the optical pupil-expanding device mentioned above, and have the same effect. Attached Figure Description

[0030] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A front view of a pupil expansion device that divides the entrance pupil unit into two grating regions, provided in an embodiment of this application;

[0032] Figure 2 This is a schematic diagram showing the magnitude and direction of the grating vectors of each grating unit on the pupil dilator;

[0033] Figure 3(a) is a schematic diagram of the beam propagation process of the first path provided in the embodiment of this application;

[0034] Figure 3(b) is a wave vector diagram of a beam propagating along the first path according to an embodiment of this application;

[0035] Figure 3(c) is a schematic diagram of the beam propagation process of the second path provided in the embodiment of this application;

[0036] Figure 3(d) is a wave vector diagram of a beam propagating along a second path according to an embodiment of this application;

[0037] Figure 4 A front view of a pupil dilator that uses a two-dimensional grating as the entrance pupil unit, provided in an embodiment of this application;

[0038] Figure 5 A front view of a pupil expansion device with the entrance pupil unit divided into two grating regions and a beam splitting unit added, provided in an embodiment of this application;

[0039] Figure 6 A schematic diagram showing the magnitude and direction of the grating vectors of each grating unit in another pupil expanding device provided in this application embodiment;

[0040] Figure 7(a) is a schematic diagram of the beam propagation process of the third path provided in the embodiment of this application;

[0041] Figure 7(b) is a wave vector diagram of a beam propagating along the third path according to an embodiment of this application;

[0042] Figure 8(a) is a schematic diagram of a lateral misaligned splicing provided in an embodiment of this application;

[0043] Figure 8(b) is a schematic diagram of a horizontal height alignment splicing provided in an embodiment of this application;

[0044] Figure 9(a) is a schematic diagram of a display device provided in an embodiment of this application;

[0045] Figure 9(b) is a schematic diagram of another display device provided in an embodiment of this application. Detailed Implementation

[0046] 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, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0047] The core of this application is to provide an optical pupil dilator, device, method, and display device for providing a larger range of eye movement without increasing the size of the pupil dilator.

[0048] Conventional diffractive waveguide pupil expanders typically use an entrance pupil unit with a single wave vector diffraction grating. This unit can only provide light transmission in a single diffraction direction or in two opposing ±1st order diffraction directions. The image light coupled into the entrance pupil unit is typically expanded in at least one direction by the pupil expander before being coupled out by the exit pupil unit. The beam expansion capability of a pupil expander can be represented by the eye movement range it provides. When the field of view (FOV) of the input image is fixed, the size of the eye movement range is determined by the area of ​​the exit pupil unit's grating region. A larger exit pupil unit grating region requires a larger pupil expander unit grating region to provide an expanded beam sufficient to cover the entire exit pupil unit grating region, further increasing the size of the beam expander. A large beam expander size is detrimental to wearing comfort and increases material and manufacturing costs. In certain special scenarios, the size of the waveguide plate available for fabrication is limited by process technology. For example, in semiconductor manufacturing, the maximum current size can only support 12-inch substrate wafers. Fabricating a pupil expander capable of supporting a larger eye movement range within this limited substrate size presents certain technological challenges and increases manufacturing costs. Therefore, this application employs an entrance pupil unit with at least two diffraction grating wave vectors, allowing the image beam coupled through the entrance pupil unit to propagate within the waveguide plate in at least two different directions. Through beam transmission path design, the transmitted light in both directions can collectively cover a larger exit pupil unit grating area, thereby achieving a compact waveguide pupil expander design with a larger eye movement range. It should be noted that the pupil expander of this application can be applied to virtual reality displays, augmented reality displays, or automotive head-up displays, etc.

[0049] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. An embodiment of the present application provides an optical pupil expanding device, which includes: a waveguide plate, a pupil expanding unit, an exit pupil unit, and an entrance pupil unit. The entrance pupil unit, pupil expanding unit, and exit pupil unit are all grating elements. The entrance pupil unit has grating grooves arranged in multiple directions. The length of the entrance pupil unit is less than the length of the pupil expanding unit, and the length of the exit pupil unit is greater than the length of the pupil expanding unit.

[0050] The entrance pupil unit is used to receive input light and diffract the input light into guided light that propagates in different directions; wherein, the guided light includes at least a first guided light propagating in a first direction and a second guided light propagating in a second direction;

[0051] The pupil expansion unit is located in the first direction, and the grating groove of the pupil expansion unit is tilted at a first preset angle relative to the first direction, for receiving the first transmitted light and diffracting the first transmitted light into a third transmitted light that propagates along the second direction;

[0052] The exit pupil unit is located in the second direction and is used to receive the third transmitted light and diffract the third transmitted light to form the first output light, and to receive the second transmitted light and diffract the second transmitted light to form the second output light.

[0053] In the pupil-expanding device of this application embodiment, the entrance pupil unit, the pupil-expanding unit, and the exit pupil unit are located in a waveguide plate. The waveguide plate can be a flat glass plate. Input light is emitted from an optical engine and enters the entrance pupil unit in the waveguide plate, propagating in at least two different directions within the waveguide plate. Since the propagation direction of the light path needs to be changed in the waveguide plate, the entrance pupil unit, the pupil-expanding unit, and the exit pupil unit can be mirrors, gratings, etc., as long as the propagation direction of the light can be changed. In this application embodiment, grating elements are used. The size, grating vector, number, etc. of each grating element are not limited and are determined according to the actual situation. For example, if the entrance pupil unit receives the input light emitted from the optical engine, the optical engine can be a projector, etc., and the exit pupil of the projector is generally circular. Therefore, the shape of the entrance pupil unit can be circular. If only one grating element is used, the entire pupil-expanding device can be easier to manufacture and the structure can be more compact.

[0054] To increase the eye movement range of the pupil dilator without increasing the size of the pupil dilator unit or the overall pupil dilator, this embodiment uses an entrance pupil unit with at least two diffraction grating wave vectors, thus having grating grooves arranged in multiple directions. To ensure a relatively uniform optical path for the guided light formed by the diffraction of the input light through the entrance pupil unit, the entrance pupil unit can be divided into sections, with the same grating wave vector in the same area; alternatively, a multidimensional grating can be used directly. The input light, after diffraction by the entrance pupil unit, forms at least a first guided light propagating along a first direction and a second guided light propagating along a second direction.

[0055] The pupil dilation unit is located in the first direction, i.e., in the direction of propagation of the first guided light. To ensure that the propagation direction of the first guided light changes after passing through the pupil dilation unit, the grating grooves of the pupil dilation unit are oriented in the same direction and tilted at a preset angle relative to the first direction; this preset angle is not limited. Since the goal is to increase the range of motion, i.e., to increase the area covered by the guided light in the exit pupil unit, the directions of the guided light incident on the exit pupil unit must be the same after the direction of the guided light changes through the entrance pupil unit and exit pupil unit. Therefore, based on the input light being diffracted by the entrance pupil unit to form a second guided light propagating in the second direction, the first guided light, after being diffracted by the pupil dilation unit, needs to be diffracted again to form a third guided light propagating in the second direction.

[0056] The grating grooves of the pupil expanding unit are oriented in the same direction. The pupil expanding unit is located in the second direction, thereby receiving the third transmitted light and diffracting the third transmitted light to form the first output light, and receiving the first transmitted light and diffracting the first transmitted light to form the second output light. The propagation directions of the first output light and the second output light are the same.

[0057] It should be noted that the angles at which the first, second, and third guided light rays are incident in the waveguide plate are greater than the critical angle for total internal reflection, meaning that they propagate within the waveguide plate in a manner of total internal reflection.

[0058] The optical pupil-expanding device provided in this embodiment includes: a waveguide plate, a pupil-expanding unit, an exit pupil unit, and an entrance pupil unit with grating grooves arranged in multiple directions. In the pupil-expanding device of this application, since the third guided light is formed by diffraction of the pupil-expanding unit, the maximum length of the area occupied by the third guided light in the exit pupil unit is the length of the pupil-expanding unit; the second guided light is formed by diffraction of the entrance pupil unit, therefore, the maximum length of the area occupied by the second guided light in the exit pupil unit is the length of the entrance pupil unit. If a previous pupil-expanding device with an entrance pupil unit having a single diffraction direction is used, the maximum length of the exit pupil unit covered by the guided light is only the length of the pupil-expanding unit. However, in the pupil-expanding device of this embodiment, the length of the exit pupil area covered by the guided light is greater than the length of the pupil-expanding unit. Therefore, without increasing the size of the pupil-expanding device, the pupil-expanding device can provide a larger range of eye movement; and it is convenient to wear and relatively reduces the difficulty and cost of manufacturing the pupil-expanding device.

[0059] To ensure a neat optical path for the transmitted light formed by the diffraction of the input light through the entrance pupil unit, a preferred embodiment is that the entrance pupil unit has grating grooves arranged in two directions, namely a first region grating with a first grating period and a second region grating with a second grating period. The grooves of the first region grating are in the same direction, the grooves of the second region grating are in the same direction, and the grooves of the first region grating are in different directions from those of the second region grating.

[0060] There are no restrictions on the grating period or grating size of the first and second region gratings. Figure 1 This is a front view of a pupil dilator that divides the entrance pupil unit into two grating regions, as provided in an embodiment of this application. It should be noted that the lengths of the entrance pupil unit, pupil dilator unit, and exit pupil unit mentioned in this application refer to the lengths along... Figure 1 The length in the SX direction. Figure 1In this process, the pupil expanding device 1 includes an entrance pupil unit 2, a pupil expanding unit 3, and an exit pupil unit 4, all of which are located within the waveguide plate 5. The entrance pupil unit 2 includes a first region grating and a second region grating. The first region grating is used to diffract the input light IN1 into a first guided light B1a propagating along a first direction, wherein the first direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light IN1 and the wave vector of the first region grating, i.e., the propagation direction of the first guided light B1a. The second region grating is used to diffract the input light IN1 into a second guided light B1b propagating along a second direction, wherein the second direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light IN1 and the wave vector of the second region grating, i.e., the propagation direction of the second guided light B1b. The expanding pupil unit 3 is used to receive the first guided light B1a and diffract the first guided light B1a into a third guided light B2a along a fourth direction, wherein the fourth direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the first guided light B1a and the grating wave vector of the expanding pupil unit 3, and the fourth direction is the same as the second direction. The exit pupil unit 4 is located in the second direction and is used to receive the third guided light B2a and diffract it to form the first output light OB3a, and to receive the second guided light B1b and diffract it to form the second output light OB3b. The first output light OB3a and the second output light OB3b are combined to form the output light OUT1. In order to reduce the processing difficulty, in this embodiment, the exit pupil unit 4 has the same grating vector as the second region grating, that is, the grating period of the exit pupil unit 4 is the same as the grating period of the second region grating, and the grating direction of the exit pupil unit 4 is the same as the grating direction of the second region grating.

[0061] The entrance pupil unit provided in this embodiment is divided into two regions, and the grating grooves of the grating in the same region are in the same direction, so that the light path when the input light is transmitted in two directions after passing through the entrance pupil unit is more orderly, rather than an intersecting light path.

[0062] To minimize chromatic aberration in the image formed by the pupil dilator and thus improve user experience, a preferred implementation is that the vector sum of the grating wave vectors of the first region grating, the pupil dilator unit, and the exit pupil unit is 0, and the vector sum of the grating wave vectors of the second region grating and the exit pupil unit is also 0.

[0063] The pupil-expanding device in this application embodiment is based on grating diffraction to couple the beam into and out of the waveguide plate, and to change the propagation direction of the beam and expand the beam within the waveguide plate through grating diffraction. Grating diffraction can be understood as loading a grating vector onto the propagation wave vector of the light, the magnitude of which is inversely proportional to the grating period, and the direction of which is perpendicular to the direction of the grating groove / ridge lines. For Figure 1 The pupil dilator shown Figure 2 This is a schematic diagram showing the magnitude and direction of the grating vectors of each grating unit on the pupil expander. Figure 2 The central pupil expansion device 1 achieves a first grating period d by dividing the entrance pupil unit 2 into sections. 1a and the second grating period d 1b The grating vector direction of all functional units is represented by the angle with the SX direction, and the entrance pupil unit 2 has a size of 1 / d. 1a , direction β 1a grating vector V 1a and a size of 1 / d 1b , direction β 1b grating vector V 1b The pupil expanding unit 3 has a grating vector V2 with a size of 1 / d2 and a direction of β2, where d2 is the grating period of the pupil expanding unit 3; the exit pupil unit 4 has a grating vector V3 with a size of 1 / d3 and a direction of β3, where d3 is the grating period of the exit pupil unit 4.

[0064] Figure 2 The input light IN1 of the pupil expansion device 1 can form input light (OUT1) through two paths. Figure 3(a) is a schematic diagram of the beam propagation process of the first path provided in the embodiment of this application. The first path is IN1→B1a→B2a→OB3a. Figure 3(b) is the wave vector diagram of the beam propagating along the first path provided in the embodiment of this application. In Figure 3(b), BND1 represents the total internal reflection angle spectrum line, and BND2 represents the maximum wave vector that the waveguide plate can support. The beam angle spectrum between BND1 and BND2 exists in the form of waveguide light (B1a, B2a) propagating through total internal reflection within the waveguide plate, while the beam within BND1 exists in the form of free-space light (IN1, OUT1). For diffraction beam expansion devices, it is generally required that the sum of the grating wave vectors experienced by the beam along a complete propagation path is 0, that is, V in Figure 3(b). 1a +V2+V3=0, otherwise the final image will exhibit chromatic aberration. Figure 3(c) is a schematic diagram of the beam propagation process of the second path provided in the embodiment of this application, the second path IN1→B1b→OB3b, and Figure 3(d) is the wave vector diagram of the beam propagated by the second path provided in the embodiment of this application. As can be seen from Figure 3(c), after the image light is coupled into the waveguide plate by the entrance pupil unit, it is directly transmitted to the exit pupil unit and coupled out to form the observable output light (OUT1). In order to minimize the occurrence of chromatic aberration, V2+V3=0 is required. 1b +V3=0, which means the second grating period d of the entrance pupil unit 1b It is equal to the grating period d3 of the exit pupil unit.

[0065] The sum of the grating wave vectors experienced by the light beam along a complete propagation path provided in this embodiment is 0, which can minimize the occurrence of dispersion and enable users to observe a clearer image, thereby improving the user experience.

[0066] In the above embodiments, the entrance pupil unit is divided into two regions of grating, so that the input light, after passing through the two gratings, forms guided light that travels in two directions. However, dividing the entrance pupil unit into sections cannot maintain its integrity, resulting in a weakened pupil-dilating effect of the pupil-dilating device. Therefore, in practice, a preferred embodiment is that the entrance pupil unit is a two-dimensional grating, wherein the two-dimensional grating is a grating formed by alternating a first one-dimensional grating with a first grating period and a second one-dimensional grating with a second grating period.

[0067] Figure 4 This is a front view of a pupil expanding device using a two-dimensional grating as the entrance pupil unit, provided as an embodiment of this application. It can be seen that the exit pupil unit, implemented using a two-dimensional grating, has two grating vectors V. 1a and V 1b The technical effect, specific implementation method and principle of the pupil expansion device that divides the entrance pupil unit into two grating regions as described above are the same, and will not be repeated here.

[0068] The two-dimensional grating used in this embodiment as the entrance pupil unit, compared to the method of dividing the entrance pupil unit into sections, can maintain the integrity of the entrance pupil unit, which facilitates subsequent pupil dilation.

[0069] In practice, in order to make the transmitted light cover the exit pupil unit more evenly, a preferred embodiment is that the pupil dilator further includes a beam splitting unit, which is a grating element;

[0070] The beam splitting unit is located in the waveguide between the entrance pupil unit and the exit pupil unit, and is located in the second direction. The grating groove line of the beam splitting unit is tilted at a second preset angle relative to the first direction.

[0071] The beam splitter is used to receive the second guided light and diffract the second guided light through an even number of times to form a fourth guided light that propagates along the second direction;

[0072] The exit pupil unit is used to receive the fourth transmitted light and diffract the fourth transmitted light to form the third output light.

[0073] Based on the above embodiments, a beam splitting unit is added between the entrance pupil unit and the exit pupil unit. Figure 5 This is a front view of a pupil dilator with the entrance pupil unit divided into two grating regions and a beam splitter added, as provided in an embodiment of this application. Figure 5 As shown, the beam-splitting unit 6 at least partially receives the second guided light B1b diffracted from the second region grating of the entrance pupil unit 2, and after an even number of diffractions, the first diffraction forms from the second guided light B1b. Figure 5 The light is transmitted through B2s, and the second diffraction is formed from B2s. Figure 5The fourth guided light B2b shown has the same propagation direction as the second guided light B1b, both being the second direction. The exit pupil unit 4 receives the fourth guided light B2b and diffracts it to form the third output light OB3c. It should be noted that the first output light OB3a, the second output light OB3b, and the third output light OB3c have the same propagation direction, and ultimately, the first output light OB3a, the second output light OB3b, and the third output light OB3c form the output light OUT1.

[0074] Figure 6 This is a schematic diagram showing the magnitude and direction of the grating vectors of each grating unit in another pupil-expanding device provided in an embodiment of this application. Compared to Figure 1 In this embodiment, a beam splitting unit 6 is added, such as... Figure 6 As shown, the beam-splitting unit 6 has a size of 1 / d 2s , direction β 2s grating vector V 2s , where d 2s The grating period of beam splitting unit 6 is shown in Figure 7(a). Figure 7(a) is a schematic diagram of the beam propagation process of the third path provided in the embodiment of this application, which adds a beam propagation path IN1→B1b→B2s→B2b→OB3c, and can be called the third path. Figure 7(b) is the wave vector diagram of the beam propagated by the third path provided in the embodiment of this application. The second region grating of entrance pupil unit 2 forms the second guided light B1b, and beam splitting unit 6 receives the second guided light B1b and forms the fourth guided light B2b after an even number of diffractions.

[0075] It should be noted that even-numbered diffraction refers to the number of diffractions the image light undergoes from its propagation into the beam-splitting unit region to its exit from the beam-splitting unit region. Figure 7(b) shows the case where two diffractions occur in the beam-splitting unit region. The fourth guided light formed by the diffraction of the beam-splitting unit is received by the exit pupil unit and diffracted out to form the third output light. The entire process satisfies the condition that the superposition of the grating wave vectors equals 0. That is, V 1b +n·(V 2s -V 2s +V3=0. Where n is the even-number of diffractions the beam undergoes in the beam splitting unit region. From this equation, we can find that V 2s The effects of even-numbered diffractions cancel each other out. Therefore, the wave vector of the fourth guided light formed by even-numbered diffractions of the beam splitter is the same as the wave vector of the second guided light that has not been diffracted by the beam splitter. At the same time, the wave vector V of the beam splitter... 2s The size and direction do not need to be strictly limited, as long as it is ensured that B2b can propagate within the waveguide plate in a manner of total internal reflection.

[0076] In practice, considering ease of processing, the wave vector V of the beam splitter unit can be... 2sThe wave vector V2 of the pupil expansion unit is set to be equal to that of the beam splitting unit and the pupil expansion unit. The grating vectors of the beam splitting unit and the pupil expansion unit are the same, that is, the grating period of the beam splitting unit is equal to that of the pupil expansion unit and the grating direction is the same.

[0077] The pupil expansion device including a beam-splitting unit provided in this embodiment expands the second transmitted light to a certain extent, allowing it to cover the exit pupil unit area more evenly, thereby improving the light emission uniformity of the exit pupil unit.

[0078] Based on the above embodiments, this embodiment also provides an optical pupil expanding device, including the optical pupil expanding device described above; wherein, each optical pupil expanding device is spliced ​​in a staggered manner or in a height-aligned manner.

[0079] In practice, to obtain a larger eye movement range, the pupil dilators described above can be spliced ​​together. Figure 8(a) is a schematic diagram of a horizontally staggered splicing according to an embodiment of this application. The advantage of staggered splicing is that there is no need to cut the entrance pupil unit, thus allowing more image light to be coupled into the waveguide plate. Figure 8(b) is a schematic diagram of a horizontally height-aligned splicing according to an embodiment of this application. The advantage of height-aligned splicing is that the structure is simpler and flatter, but it requires cutting the entrance pupil unit, thereby reducing the light coupling efficiency.

[0080] The method of splicing multiple pupil dilators provided in this embodiment can achieve a larger eye movement range and improve the user experience compared to using a single pupil dilator.

[0081] Since pupil-expanding devices can be applied to virtual display devices such as VR devices and AR devices, this embodiment also provides a display device, including the aforementioned optical pupil-expanding device, based on the pupil-expanding device described above.

[0082] exist Figure 1 Based on the pupil-expanding device, this embodiment provides a display device. Figure 9(a) is a schematic diagram of a display device provided in this application embodiment. As shown in Figure 9(a), the display device 7 consists of an optical engine 8 and a pupil-expanding device 1. The pupil-expanding device 1 of the display device 7 includes an entrance pupil unit 2, a pupil-expanding unit 3, and an exit pupil unit 4. The optical engine 8 includes a display screen 9 and a collimating lens 10. The display screen 8 loads the image source IMG0 to be displayed. The collimating lens 10 collimates the light emitted by each pixel P0 on the image source IMG0 into parallel light, forming the input beam IN1 of the pupil-expanding device 1 and transmitting it to the entrance pupil unit 2 of the pupil-expanding device 1. The entrance pupil unit 2 couples the input light IN1 into the waveguide plate 5 and forms waveguide light that propagates in the waveguide plate 5 in a total internal reflection manner. The pupil-expanding unit 3 and the exit pupil unit 4 realize the expansion and coupling output of the waveguide light, and finally form the output light OUT1 that can be observed by the human eye (EYE1), i.e., the image light.

[0083] exist Figure 5 Based on the pupil-expanding device, this embodiment provides another display device. Figure 9(b) is a schematic diagram of another display device provided in this application embodiment. As shown in Figure 9(b), the display device 7 is composed of an optical engine 8 and a pupil-expanding device 1. The pupil-expanding device 1 of this display device includes an entrance pupil unit 2, a pupil-expanding unit 3, an exit pupil unit 4, and a beam-splitting unit 6. The exit pupil unit 4 can receive the third conductive light B2a formed by the expansion of the pupil-expanding unit 3, the second conductive light B1b directly formed by the entrance pupil unit 2, and the fourth conductive light B2b formed by the beam splitting unit 6, respectively forming the first output light OB3a, the second output light OB3b, and the third output light OB3c. The first output light OB3a, the second output light OB3b, and the third output light OB3c together constitute the output light OUT1, i.e., the image light.

[0084] The display device provided in this embodiment can improve the pupil size of the virtual display device, expand the eye movement range, and enhance the user experience.

[0085] Furthermore, this embodiment provides an optical pupil expansion method applied to an optical pupil expansion device comprising a waveguide plate, a pupil expansion unit, an exit pupil unit, and an entrance pupil unit. The entrance pupil unit, pupil expansion unit, and exit pupil unit are all grating elements. The entrance pupil unit has grating grooves arranged in multiple directions. The pupil expansion unit is located in a first direction, and the grating grooves of the pupil expansion unit are inclined at a first preset angle relative to the first direction. The length of the entrance pupil unit is less than the length of the pupil expansion unit, and the length of the exit pupil unit is greater than the length of the pupil expansion unit. The exit pupil unit is located in a second direction. The optical pupil expansion method includes:

[0086] The input light is received by the entrance pupil unit and diffracted to form guided light that propagates in different directions; wherein the guided light includes at least a first guided light propagating in a first direction and a second guided light propagating in a second direction;

[0087] The pupil expansion unit receives the first transmitted light and diffracts it to form a third transmitted light that propagates along the second direction;

[0088] The exit pupil unit receives the third transmitted light and diffracts the third transmitted light to form the first output light, and receives the second transmitted light and diffracts the second transmitted light to form the second output light.

[0089] The optical pupil dilation method provided in this embodiment has the same technical features as the optical pupil dilation device mentioned above. The embodiments of the optical pupil dilation device have been described in detail above, so the embodiments of the optical pupil dilation method will not be repeated here. It has the same beneficial effects as the optical pupil dilation device mentioned above.

[0090] The foregoing has provided a detailed description of an optical pupil-expanding device, apparatus, method, and display device provided in this application. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0091] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus 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 apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. An optical pupil dilator, comprising: The waveguide plate, the pupil expanding unit, and the exit pupil unit are characterized in that they further include an entrance pupil unit, wherein the entrance pupil unit, the pupil expanding unit, and the exit pupil unit are all grating elements, the entrance pupil unit has grating grooves arranged in multiple directions; the length of the entrance pupil unit is less than the length of the pupil expanding unit, and the length of the exit pupil unit is greater than the length of the pupil expanding unit; The entrance pupil unit is used to receive input light and diffract the input light into conductive light that propagates in different directions; wherein, the conductive light includes at least a first conductive light propagating in a first direction and a second conductive light propagating in a second direction; The pupil expanding unit is located in the first direction, and the grating groove of the pupil expanding unit is inclined at a first preset angle relative to the first direction, for receiving the first transmitted light and diffracting the first transmitted light into a third transmitted light that propagates along the second direction; The exit pupil unit is located in the second direction and is used to receive the third transmitted light and diffract the third transmitted light to form a first output light, and to receive the second transmitted light and diffract the second transmitted light to form a second output light; The entrance pupil unit has grating grooves arranged in two directions, and consists of a first region grating with a first grating period and a second region grating with a second grating period. The grooves of the first region grating are in the same direction, the grooves of the second region grating are in the same direction, and the grooves of the first region grating are in different directions from those of the second region grating. The first region grating is used to diffract the input light into the first guided light that propagates along the first direction, wherein the first direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light and the wave vector of the first region grating; The second region grating is used to diffract the input light into the second guided light that propagates along the second direction, wherein the second direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light and the wave vector of the second region grating; The pupil expanding unit is used to receive the first guided light and diffract the first guided light to form a third guided light along the fourth direction; wherein, the fourth direction is the direction of the wave vector formed by superimposing the transverse wave vector of the first guided light and the grating wave vector of the pupil expanding unit, and the fourth direction is the same as the second direction; The exit pupil unit has the same grating vector as the second region grating.

2. The optical pupil dilator according to claim 1, characterized in that, The vector sum of the grating wave vector of the first region grating, the grating wave vector of the pupil expansion unit, and the grating wave vector of the exit pupil unit is 0, and the vector sum of the grating wave vector of the second region grating and the grating wave vector of the exit pupil unit is 0.

3. The optical pupil dilator according to claim 1, characterized in that, The entrance pupil unit is a two-dimensional grating, wherein the two-dimensional grating is a grating formed by alternating a first one-dimensional grating with a first grating period and a second one-dimensional grating with a second grating period.

4. The optical pupil dilator according to any one of claims 1 to 3, characterized in that, It also includes a beam-splitting unit, which is the grating element; The beam splitting unit is located within the waveguide between the entrance pupil unit and the exit pupil unit, and is located in the second direction. The grating groove line of the beam splitting unit is inclined at a second preset angle relative to the first direction. The beam splitting unit is used to receive the second guided light and diffract the second guided light through an even number of times to form a fourth guided light that propagates along the second direction; The exit pupil unit is used to receive the fourth transmitted light and diffract the fourth transmitted light to form the third output light.

5. The optical pupil dilator according to claim 4, characterized in that, The grating vector of the beam splitter unit is the same as that of the pupil expander unit.

6. An optical pupil dilator, characterized in that, It includes the optical pupil expanding device according to any one of claims 1 to 5; wherein each of the optical pupil expanding devices is staggered or highly aligned.

7. A display device, characterized in that, Includes the optical pupil dilator as described in any one of claims 1 to 5.

8. An optical pupil dilation method, characterized in that, An optical pupil-expanding device comprising a waveguide plate, a pupil-expanding unit, an exit pupil unit, and an entrance pupil unit, wherein the entrance pupil unit, the pupil-expanding unit, and the exit pupil unit are all grating elements, the entrance pupil unit having grating grooves arranged in multiple directions; the pupil-expanding unit is located in a first direction, and the grating grooves of the pupil-expanding unit are inclined at a first preset angle relative to the first direction; the length of the entrance pupil unit is less than the length of the pupil-expanding unit, and the length of the exit pupil unit is greater than the length of the pupil-expanding unit; the exit pupil unit is located in a second direction; the method includes: The entrance pupil unit receives input light and diffracts the input light into conductive light that propagates in different directions; wherein the conductive light includes at least a first conductive light propagating in a first direction and a second conductive light propagating in a second direction; The pupil expansion unit receives the first transmitted light and diffracts the first transmitted light into a third transmitted light that propagates along the second direction; The exit pupil unit receives the third transmitted light and diffracts the third transmitted light to form the first output light, and receives the second transmitted light and diffracts the second transmitted light to form the second output light; The entrance pupil unit has grating grooves arranged in two directions, and consists of a first region grating with a first grating period and a second region grating with a second grating period. The grooves of the first region grating are in the same direction, the grooves of the second region grating are in the same direction, and the grooves of the first region grating are in different directions from those of the second region grating. The first region grating is used to diffract the input light into the first guided light that propagates along the first direction, wherein the first direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light and the wave vector of the first region grating; The second region grating is used to diffract the input light into the second guided light that propagates along the second direction, wherein the second direction is the direction of the wave vector formed by the superposition of the transverse wave vector of the input light and the wave vector of the second region grating; The pupil expanding unit is used to receive the first guided light and diffract the first guided light to form a third guided light along the fourth direction; wherein, the fourth direction is the direction of the wave vector formed by superimposing the transverse wave vector of the first guided light and the grating wave vector of the pupil expanding unit, and the fourth direction is the same as the second direction; The exit pupil unit has the same grating vector as the second region grating.

Images