Near-to-eye display device

Abstract

A near-to-eye display device includes a waveguide, an image generation device, a light input coupling element, a light output coupling element, and a light leakage suppression element. The waveguide is provided with a first surface and a second surface which are opposite, and the first surface further comprises a light-in area and a light-out area. The image generating device is used for emitting an image light beam towards the light incident area. The light input coupling element is arranged in the light-in area, and the light output coupling element is arranged in the light-out area. The light leakage suppression element is arranged on the second surface and is opposite to the light emitting area. According to the near-to-eye display device, light leakage of the near-to-eye display device can be effectively reduced, privacy of a user can be effectively protected, and the influence on a non-user can be reduced when the near-to-eye display device is worn.

Description

TECHNICAL FIELD

[0001] The present application relates to a display device, and in particular to a near-eye display device. BACKGROUND

[0002] In the application of near-eye display devices, such as Augmented Reality (AR) devices, Mixed Reality (MR) devices or smart glasses, a coupling-in grating is usually used to refract the image beam of an incident light waveguide to an angle greater than the critical angle, so that the image beam is transmitted in the light waveguide in a manner of Total Internal Reflection (TIR) to the coupling-out grating to expand the pupil, and the image beam is transmitted to the user's eyes.

[0003] However, in the process of the image beam irradiating the coupling-out grating, the image beam transmitted to the unexpected direction becomes a leakage light or stray light due to the multi-order diffraction. The aforementioned leakage light can cause the non-user located in front of the user to clearly see the same picture, which not only hinders the privacy of the user, but also easily affects the non-user when using the near-eye display device, thereby reducing the product value and experience of the near-eye display device. SUMMARY

[0004] The present application provides a near-eye display device, which can effectively reduce the leakage light of the near-eye display device, protect the privacy of the user, and reduce the impact on the non-user when wearing.

[0005] An embodiment of the present application provides a near-eye display device, which comprises a waveguide, an image generating device, a light input coupling element, a light output coupling element and a leakage light suppression element. The waveguide has opposite first and second surfaces, and the first surface further comprises a light input area and a light output area. The image generating device is used to emit an image beam towards the light input area. The light input coupling element is arranged in the light input area, and the light output coupling element is arranged in the light output area. The leakage light suppression element is arranged on the second surface and is arranged opposite to the light output area.

[0006] Based on the above, the near-eye display device of the present application arranges the leakage light suppression element and the light output coupling element on the opposite sides of the waveguide. Through the effect of the leakage light suppression element, the leakage light originally directed to the front of the near-eye display device can be transmitted to other directions. Therefore, it is difficult for the onlooker located in front of the near-eye display device to observe the display image of the user, which is beneficial to improve the privacy of the user, and can further optimize the appearance of the near-eye display device and improve the product competitiveness.

[0007] For the above features and advantages of the present application to be more apparent and understandable, the following embodiments are described in detail below, and the detailed description is made in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a schematic view of a near-eye display device according to a first embodiment of the present application.

[0009] Figure 2A and Figure 2B is Figure 1 is a light leakage suppression effect spectrum diagram of the light leakage suppression element of the embodiment.

[0010] Figure 3 is a schematic view of a near-eye display device according to a second embodiment of the present application.

[0011] Figure 4 is a schematic view of a near-eye display device according to a third embodiment of the present application.

[0012] Figure 5 is a partial schematic view of a near-eye display device according to a fourth embodiment of the present application.

[0013] BRIEF DESCRIPTION OF DRAWINGS

[0014] 1A, 1B, 1C: near-eye display device

[0015] 10: waveguide

[0016] 11: first surface

[0017] 12: second surface

[0018] 20: image generation device

[0019] 30A: light input coupling element

[0020] 30B: light output coupling element

[0021] 40: light leakage suppression element

[0022] 41: first side

[0023] 42: second side

[0024] 50: light guide layer

[0025] 60: beam turning element

[0026] 70: fixing member

[0027] AIR: air layer

[0028] DG: grating arrangement direction

[0029] EB: eyebox

[0030] EYE: eye

[0031] FOV1, FOV2: field of view

[0032] G: gap

[0033] IL: image light

[0034] OS: output spectrum

[0035] IR: input region

[0036] IS: input spectrum

[0037] LL: light leakage

[0038] OR: output region

[0039] X, Y, Z: directions DETAILED DESCRIPTION

[0040] The above and other technical contents, features and effects of the present application will be apparent from the following detailed description of a preferred embodiment, taken in conjunction with the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only the directions of the accompanying drawings. Therefore, the directional terms are used for illustration, not for limitation of the present application.

[0041] Figure 1 is a schematic view of a near-eye display device according to a first embodiment of the present application. Please refer to Figure 1 The near-eye display device 1A is configured to provide image light IL to the eye EYE of a user. The near-eye display device 1A includes a waveguide 10, an image generation device 20, a light input coupling element 30A, a light output coupling element 30B and a light leakage suppression element 40. The waveguide 10 has opposite first and second surfaces 11 and 12, the first surface 11 is located at a side of the waveguide 10 close to the eye EYE, and the first surface 11 further includes an input region IR and an output region OR. The image generation device 20 is configured to emit image light IL towards the input region IR. The light input coupling element 30A is disposed at the input region IR, and the light output coupling element 30B is disposed at the output region OR. The light leakage suppression element 40 is disposed on the second surface 12 and opposite to the output region OR.

[0042] The waveguide 10 can serve as a main channel for the image light IL to travel. In some embodiments, the material of the waveguide 10 can be glass or transparent high molecular polymer, and a material with appropriate refractive index is selected to provide total internal reflection of the image light IL in the waveguide 10. In some embodiments, the waveguide 10 can be a planar waveguide, a slab waveguide, a cylindrical waveguide, a spherical waveguide, a curved waveguide, a prism waveguide, a fiber waveguide, or a combination thereof. Figure 1The first surface 11 and the second surface 12 of the waveguide 10 are illustrated as planar, but the present disclosure is not limited thereto. In other embodiments, the first surface 11 and the second surface 12 can also have corresponding curvatures. In other words, the waveguide 10 can also be a curved waveguide. After the image light beams IL exit the waveguide 10, the image light beams IL can enter an eye box EB of the user EYE on the side of the first surface 11 to be received by the user. The waveguide 10 is also configured to pass ambient light from the side of the second surface 12 and allow the eye EYE to see both the image light beams IL and the ambient light. In other words, the image light beams IL can form an augmented reality image after exiting the waveguide 10 to be viewed by the user.

[0043] On the other hand, in some embodiments, the entrance region IR and the exit region OR of the waveguide 10 can both be arranged along the direction X. In other words, the waveguide 10 can be a one-dimensional exit pupil expansion (EPE). However, the present disclosure is not limited thereto.

[0044] The image generation device 20 is configured to emit the image light beams IL toward the entrance region IR. For example, the image generation device 20 can include a liquid crystal display (LCD), a digital light processing (DLP) projector, a liquid crystal on silicon (LCOS) display, a laser scanning system, or any combination thereof, but is not limited thereto. In some embodiments, the near-eye display device 1A can be in the form of glasses, in which the image generation device 20 can be fixed on the temples and the waveguide 10 can be mounted in the frame. Depending on different requirements, the near-eye display device 1A can be in other forms and / or include other elements.

[0045] The light input coupling element 30A and the light output coupling element 30B can both be gratings. The types of gratings can include Surface Relief Gratings (SRG), Holographic Polymer Dispersed Liquid Crystal (HPDLC) gratings, Volume Holographic Grating (VHG), or other suitable types of gratings. The light input coupling element 30A can be used to couple the image light beam IL of the incident waveguide 10 into the waveguide 10, and the light output coupling element 30B can be used to couple the image light beam IL of the outgoing waveguide 10 into the eyebox EYE, both of which can expand the field of view FOV1 of the image light beam IL. The light input coupling element 30A and the light output coupling element 30B can adjust the pitch, period, and refractive index of the grating arrangement to control the diffraction direction of the image light beam IL, to control the coupling efficiency, and to improve the pupil expansion effect. In some embodiments, the materials of the light input coupling element 30A and the light output coupling element 30B can be dielectric materials with low absorption and low loss to visible light and near-infrared light, and the present application is not limited thereto.

[0046] The light leakage suppression element 40 has a first side 41 close to the waveguide 10 and a second side 42 away from the waveguide 10. The light leakage suppression element 40 is configured to diffract the light beam incident on the first side 41, so that the light beam changes its direction after exiting the second side 42. In detail, the light leakage suppression element 40 can be at least one of a transmissive grating and a reflective grating, or include one or more optical structures or materials. The light leakage suppression element 40 can be directly disposed on the second surface 12, or there can be a gap between the first side 41 of the light leakage suppression element 40 and the second surface 12 of the waveguide 10 (described later), and the present application is not limited thereto.

[0047] When the image light beams IL impinge on the light out-coupling element 30B, part of the image light beams IL can be reflected or diffracted on the light out-coupling element 30B and / or the first surface 11, such that part of the image light beams IL can be transmitted towards the direction of the second surface 12 and exit the second surface 12 in the direction Z to form the leakage light LL. The leakage light LL can be further diffracted (e.g. +1st order to +Nth order diffraction or -1st order to -Nth order diffraction) when passing through the leakage light suppressing element 40, such that the direction of the leakage light LL originally transmitted towards the direction Z is changed. For example, in some embodiments, the leakage light suppressing element 40 is configured to transmit part of the display light beams IL (which can be defined as the leakage light LL) exiting the second surface 12 towards the planar direction of the second surface 12. For example, the leakage light suppressing element 40 can be configured to deflect the leakage light LL towards the direction X, towards the negative direction X, towards the direction Y or towards the negative direction Y; or be configured to deflect the leakage light LL towards both the direction X and the negative direction X, or be configured to deflect the leakage light LL towards both the direction Y and the negative direction Y. In other words, the entrance light region IR and the exit light region OR can be arranged along the direction X, and the planar direction of the second surface 12 can be substantially parallel to the direction X, or the planar direction of the second surface 12 can be substantially perpendicular to the direction X, without being limited thereto. In this way, the leakage light suppressing element 40 can avoid the person facing the user (e.g. the non-user in the direction Z) from seeing the image light beams IL at the same horizontal position. Accordingly, when the user wears the near-eye display device 1A, the user's viewing privacy can be ensured, and the near-eye display device 1A can be further optimized in appearance, thereby improving the product competitiveness.

[0048] On the other hand, compared with the prior art which tilts the waveguide to deflect the direction of the leakage light LL to avoid the leakage light LL affecting the non-user, the method can cause the accommodation space for placing the waveguide to be larger, which is not conducive to the lightweight and miniaturization of the near-eye display device; the design of the present embodiment, in which the leakage light suppressing element 40 is disposed on the second surface 12, is also conducive to reducing the overall thickness of the near-eye display device 1A. Compared with the prior art which filters out the leakage light LL by using a polarizer, the embodiment using the leakage light suppressing element 40 has a lower absorption rate of ambient light, which means that the user wearing the near-eye display device 1A can more easily receive light from the outside, and the interactivity and safety with the environment are better.

[0049] Figure 2A and Figure 2B is Figure 1 The leakage light suppression effect spectrum diagram of the leakage light suppressing element of the embodiment. Please refer to Figures 1 to 2B In Figure 2AIn the embodiment, the light leakage suppression element 40 is configured to deflect the light leakage LL towards the direction X or the direction Y. With the input spectrum IS having the maximum red light flux of 0.2 lumem (lm), the maximum green light flux of 0.75 (lm), and the maximum blue light flux of 0.05 (lm) in the image light beam IL, it is found through simulation experiment that, when the image light beam IL is transmitted to the first side 41 of the light leakage suppression element 40 at a normal angle (i.e. towards the direction Z) and the field of view FOV2 of the light leakage LL is about 16 degrees, the output spectrum OS received at the second side 42 of the light leakage suppression element 40 in the direction X or the direction Y has almost the same spectrum as the input spectrum IS. That is, the theoretical efficiency of the light leakage suppression element 40 can be 100% in practice.

[0050] On the other hand, in the embodiment, Figure 2B In the embodiment, the light leakage suppression element 40 is configured to deflect the light leakage LL towards the direction Y or the negative direction of the direction Y. With the input spectrum IS having the maximum red light flux of 0.20 (lm), the maximum green light flux of 0.75 (lm), and the maximum blue light flux of 0.05 (lm) in the image light beam IL, it is found through simulation experiment that, when the image light beam IL is transmitted to the first side 41 of the light leakage suppression element 40 at a normal angle (i.e. towards the direction Z) and the field of view FOV2 of the light leakage LL is about 24 degrees, the output spectrum OS received at the second side 42 of the light leakage suppression element 40 in the direction Y or the negative direction of the direction Y has the maximum red light flux of 0.20 (lm), the maximum green light flux of 0.57 (lm), and the maximum blue light flux of 0.032 (lm). That is, the suppression efficiency of the light leakage suppression element 40 for red light, green light, and blue light can be about 100%, 89%, and 65% in theory. Therefore, the near-eye display device 1A according to the embodiment can effectively reduce the brightness of the image light beam IL received by the non-user in front of the near-eye display device 1A during use.

[0051] Some other embodiments will be described below to further illustrate the present application, in which the same components will be denoted by the same reference numerals, and the description of the same technical content will be omitted. Please refer to the foregoing embodiments for the omitted parts, which will not be described again.

[0052] Figure 3 is a schematic view of a near-eye display device according to a second embodiment of the present application. Please refer to Figure 3 , the near-eye display device 1B is similar to the near-eye display device 1A of Figure 1 , and the main difference is that the near-eye display device 1B further comprises a spacer 70 configured to maintain a distance G between the light leakage suppression element 40 and the second surface 12 of the waveguide 10 to form an air layer AIR.

[0053] In detail, the spacer 70 can include a fixing structure (e.g. a screw) or a bonding agent (e.g. an optically clear adhesive) to prevent the light leakage suppression element 40 from directly contacting the second surface 12. In some embodiments, the spacer 70 can be disposed around the perimeter of the light leakage suppression element 40, that is, the air layer AIR can be a closed air gap to prevent dust or foreign matter from falling into the air layer AIR to affect the viewing experience. In other embodiments, the space of the gap G (i.e. the space in which the air layer AIR is located) can also include a refractive index matching medium (not shown). The refractive index of the refractive index matching medium can be less than the refractive index of the waveguide 10 and greater than the refractive index of the light leakage suppression element 40. The refractive index matching medium can further increase the refraction angle of the light leakage LL transmitted to the light leakage suppression element 40, so that the effect of the light leakage suppression element 40 is improved.

[0054] Figure 4 is a schematic diagram of a near-eye display device according to a third embodiment of the present application. Please refer to Figure 4 The near-eye display device 1C is similar to the near-eye display device 1B of Figure 3 The main difference between the near-eye display device 1C and the near-eye display device 1B is that the near-eye display device 1C further includes a light guide layer 50 disposed on the side of the light leakage suppression element 40 opposite to the waveguide 10, that is, the light guide layer 50 is disposed on the second side 42 of the light leakage suppression element 40. The material of the light guide layer 50 can include a polymer or glass with high light transmittance. When the light leakage LL enters the light guide layer 50 from the second side 42 after diffraction at the light leakage suppression element 40, the light guide layer 50 can facilitate total reflection of the light leakage LL in the light guide layer 50 and transmission of the light leakage LL within the light guide layer 50, so that the light leakage LL can be transmitted in the parallel direction X or the parallel direction Y after leaving the light guide layer 50, which can further avoid the light leakage LL being transmitted to the non-user in the direction Z. In another embodiment not shown, the near-eye display device 1C can further omit the presence of the spacer 70, and directly dispose the light leakage suppression element 40 with the light guide layer 50 on the second surface 12 of the waveguide 10 to achieve the purpose of thinning the near-eye display device 1C.

[0055] Figure 5 is a partial schematic diagram of a near-eye display device according to a fourth embodiment of the present application. Please refer to Figure 5 In the above embodiments, the near-eye display device 1A, the near-eye display device 1B and the near-eye display device 1C can further include a beam turning element 60. The beam turning element 60 is disposed on the first surface 11 and adjacent to the light output coupling element 30B in the direction X and adjacent to the light input coupling element 30A in the negative direction Y. When the image light beam IL is emitted from the image generation device 20 to the eye, the image light beam IL can sequentially pass through the light input coupling element 30A, the beam turning element 60 and the light output coupling element 30B.

[0056] The beam turning element 60 can be a grating to achieve two-dimensional expansion (2D EPE) and to deliver the image light beam IL to the eye EYE of the user. Figure 5 For example, the grating arrangement direction DG of the light input coupling element 30A can be the parallel direction Y, the grating arrangement direction DG of the light output coupling element 30B can be the parallel direction X, and the grating arrangement direction DG of the beam turning element 60 can be neither the parallel direction X nor the parallel direction Y (for example, the grating arrangement direction DG of the beam turning element 60 can be at an angle of 45 degrees with respect to the opposite direction of the direction X and the direction Y, and the utility model is not limited thereto). The beam turning element 60 can achieve expansion in the direction Y and can be used to deliver the image light beam IL from the light input coupling element 30A to the light output coupling element 30B, and the light output coupling element 30B can achieve expansion in the direction X and can be used to deliver the image light from the beam turning element 60 to the eye. It should be understood that the grating of any embodiment of the utility model can use other known gratings in addition to the grating structure of the example. Figure 5

[0057] In summary, the near-eye display device of the utility model sets the light leakage suppression element and the light output coupling element on the opposite sides of the waveguide. Via the effect of the light leakage suppression element, the light leakage originally towards the front of the near-eye display device can be changed to be delivered towards other directions. Therefore, it is more difficult for the onlooker located in front of the near-eye display device to observe the display image of the user, which is beneficial to improve the privacy of the user, and can further optimize the appearance of the near-eye display device and improve the product competitiveness.

[0058] The above-mentioned is only the preferred embodiment of the utility model, and cannot limit the scope of the utility model. Any simple equivalent change and modification made according to the claims and contents of the utility model still falls within the scope of the utility model. In addition, any embodiment or claim of the utility model does not need to achieve all the purposes or advantages or characteristics disclosed in the utility model. Furthermore, the abstract and title (utility model name) are only used to assist the patent document retrieval, and are not used to limit the scope of the utility model. In addition, the terms "first", "second", etc. mentioned in the specification or claims are only used to name the elements or distinguish different embodiments or ranges, and are not used to limit the upper or lower limit of the number of elements.​

Claims

1. A near-eye display device, comprising: The near-eye display device includes a waveguide, an image generation device, a light input-coupling element, a light output-coupling element, and a light leakage suppression element, wherein: the waveguide has opposite first and second surfaces, the first surface further includes an in-coupling region and an out-coupling region; the image generation device is configured to emit an image beam toward the in-coupling region; the light input-coupling element is disposed at the in-coupling region; the light output-coupling element is disposed at the out-coupling region; and the light leakage suppression element is disposed on the second surface and opposite the out-coupling region.

2. The near-eye display device of claim 1, wherein, The near-eye display device further includes a light guide layer disposed on a side of the light leakage suppression element distal to the waveguide.

3. The near-eye display device of claim 2, wherein, The light guide layer is made of glass.

4. The near-eye display device of claim 1, wherein, The light leakage suppression element is configured to cause a portion of the display beam to exit the second surface to propagate toward a planar direction of the second surface.

5. The near-eye display device of claim 4, wherein, The in-coupling region and the out-coupling region are arranged along a first direction, and the planar direction is parallel to the first direction.

6. The near-eye display apparatus of claim 4, wherein, The in-coupling region and the out-coupling region are arranged along a first direction, and the planar direction is perpendicular to the first direction.

7. The near-eye display device of claim 1, wherein, The light leakage suppression element is at least one of a transmissive grating and a reflective grating.

8. The near-eye display device of claim 1, wherein, The near-eye display device further includes a beam turning element disposed on the first surface, wherein the image beam propagates from the image generation device, through the light input-coupling element, the beam turning element, and the light output-coupling element.

9. The near-eye display device of claim 1, wherein, The light leakage suppression element and the second surface further include an air layer or a refractive index matching medium.

10. The near-eye display device of claim 9, wherein, The near-eye display device further includes a spacer configured to maintain a distance between the light leakage suppression element and the second surface to form the air layer.

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