Reflection-type naked-eye 3D display device

Abstract

The utility model discloses a reflective naked-eye 3D display device, and relates to the technical field of projection display. The reflective naked-eye 3D display device comprises an image source used for emitting image light; the Fresnel lens is located on an emergent light path of the image light, and when the image light passes through the Fresnel lens, useful image light penetrating through the Fresnel lens and stray light reflected by the Fresnel lens can be generated; the reflection unit is located behind the Fresnel lens along an emergent light path of the image light, and the useful image light penetrating through the Fresnel lens is reflected by the reflection unit, then penetrates through the Fresnel lens again and enters a human eye view field; and the light path regulation and control unit is located between the image source and the reflection unit and used for carrying out optical processing on the stray light or the useful image light so as to prevent the stray light from entering the field of view of human eyes. Therefore, stray light which is formed by surface reflection of the Fresnel lens and enters human eyes can be greatly reduced or even eliminated, so that the use experience of a user is improved.

Description

Technical Field

[0001] This application relates to the field of projection display technology, and particularly to a reflective autostereoscopic 3D display device. Background Art

[0002] With the rapid development of current technology, the traditional two-dimensional planar display technology has far been unable to meet the current demand of various industries for the perception of depth data and spatial information. In more and more application fields, such as remote meetings, intelligent cockpits, medical imaging, etc., the reconstruction of 3D scenes is desired. Among them, the autostereoscopic 3D display technology can achieve 3D functions without additional glasses.

[0003] Since the structure of the reflective 3D display system is more compact, the reflective 3D display system is more preferred in certain scenarios. However, stray light is formed by reflection on the surface of the optical devices of the reflective autostereoscopic 3D system. The reflection path of the stray light often coincides with or overlaps the reflection path of the image light, thereby affecting the contrast of the image and further affecting the user experience of the observer for the 3D display system. Summary of the Utility Model

[0004] This application provides a reflective autostereoscopic 3D display device, including: an image source for emitting image light; a Fresnel lens located on the outgoing light path of the image light, where the image light generates useful image light transmitted through the Fresnel lens and stray light reflected by the Fresnel lens when passing through the Fresnel lens; a reflection unit located behind the Fresnel lens along the outgoing light path of the image light, and the useful image light transmitted through the Fresnel lens enters the human eye field of view after being reflected by the reflection unit and then passing through the Fresnel lens again; and an optical path control unit located between the image source and the reflection unit for optically processing the stray light or the useful image light to prevent the stray light from entering the human eye field of view.

[0005] Optionally, the optical path control unit includes a quarter-wave plate and a polarizer, the polarizer is arranged between the image source and the Fresnel lens, and the quarter-wave plate is arranged between the polarizer and the Fresnel lens.

[0006] Optionally, the polarizer is used to convert the image light into linearly polarized light, and the quarter-wave plate is used to convert the linearly polarized light into circularly polarized light for output.

[0007] Optionally, the polarizer is an absorption polarizer, the circularly polarized light is left-handed circularly polarized light, and the Fresnel lens reflects a part of the polarized light in the left-handed circularly polarized light to form right-handed polarized stray light to the quarter-wave plate; the quarter-wave plate is used to convert the right-handed polarized stray light into target polarized light orthogonal to the transmission axis of the polarizer, and the absorption polarizer is used to absorb the target polarized light to prevent the right-handed polarized stray light from entering the human eye field of view.

[0008] Optionally, the target polarized light is S-polarized light.

[0009] Optionally, the reflective autostereoscopic 3D display further includes a diffuser disposed between the reflection unit and the Fresnel lens, and the diffuser is used for homogenizing the useful image light transmitted by the Fresnel lens.

[0010] Optionally, the reflective autostereoscopic 3D display device further includes a phase compensation film disposed between the reflection unit and the diffuser; the phase compensation film is used for performing phase compensation on the useful image light after homogenization processing, so that after the phase-compensated useful image light is reflected by the reflection unit, it can be transmitted by the optical path control unit to the human eye field of view.

[0011] Optionally, the quarter-wave plate is disposed parallel to the polarizer, and there is a set angle between the quarter-wave plate and the Fresnel lens.

[0012] Optionally, the optical path control unit is a holographic grating formed on the optical surface of the reflection unit, and is used for controlling the reflection angle of the useful image light at the reflection unit, so that the reflection direction of the useful image light is different from the reflection direction of the stray light, to prevent the stray light from entering the human eye field of view.

[0013] Optionally, the image light is unpolarized light or polarized light.

[0014] In the solution provided by this application, an image source is used to emit image light; a Fresnel lens is located on the outgoing light path of the image light. When the image light passes through the Fresnel lens, useful image light that passes through the Fresnel lens and stray light that is reflected by the Fresnel lens will be generated; a reflection unit is located behind the Fresnel lens along the outgoing light path of the image light. The useful image light that passes through the Fresnel lens enters the human eye field of view after being reflected by the reflection unit and then passing through the Fresnel lens again; and an optical path control unit is located between the image source and the reflection unit, and is used for performing optical processing on the stray light or the useful image light to prevent the stray light from entering the human eye field of view. In this way, the stray light formed by the surface reflection of the Fresnel lens entering the human eye can be greatly reduced or even eliminated, thereby improving the user experience. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It shows a schematic structural diagram of a reflective autostereoscopic 3D display device provided by an embodiment of the present application.

[0017] Figure 2 It shows a schematic structural diagram of another reflective autostereoscopic 3D display device provided by an embodiment of the present application.

[0018] Figure 3 It shows a schematic structural diagram of yet another reflective autostereoscopic 3D display device provided by an embodiment of the present application.

[0019] Figure 4 It shows a schematic structural diagram of still another reflective autostereoscopic 3D display device provided by an embodiment of the present application. Detailed implementation manners

[0020] In order to enable those skilled in the art to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0021] The terms "first", "second", etc. in the present application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0022] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0023] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a reflective autostereoscopic 3D display device provided by an embodiment of the present application. The following will be combined with Figure 1 to elaborate in detail on the reflective autostereoscopic 3D display device provided by the embodiments of the present application. As Figure 1 shown, the reflective autostereoscopic 3D display device 10 may include an image source 110, a Fresnel lens 120, a reflection unit 130, and an optical path adjustment unit 140.

[0024] In this embodiment, the image source 110 may be used to emit image light. Among them, the image light is the image light to be projected and displayed. When the reflective autostereoscopic 3D display device 10 is applied to different scenarios, the output image light is also different; for example, when the reflective autostereoscopic 3D display device 10 is applied to a remote meeting scenario, the image source 110 may output image light related to the meeting content. Another example is that when the reflective autostereoscopic 3D display device 10 is applied to an intelligent cockpit, the image source 110 may output image light of parameters related to driving. Among them, the image source 110 may be a projector, and the image light emitted by the projector may be polarized light or non-polarized light, and the present application does not limit this.

[0025] The Fresnel lens 120 (Fresnel lens), which is located on the outgoing optical path of the image light. When the image light passes through the Fresnel lens 120, useful image light that passes through the Fresnel lens 120 and stray light that is reflected by the Fresnel lens 120 will be generated. Specifically, in practical applications, the curved surface and the flat surface of the Fresnel lens 120 facing the light-emitting side of the image source 110 will reflect part of the circularly polarized light, thereby reflecting and forming polarized stray light. At the same time, the Fresnel lens 120 can also transmit part of the useful image light.

[0026] The reflection unit 130, which is located behind the Fresnel lens 120 along the outgoing optical path of the image light. The useful image light that passes through the Fresnel lens 120 is reflected by the reflection unit 130 and then passes through the Fresnel lens 120 again and enters the human eye's field of view.

[0027] The optical path adjustment unit 140, which is located between the image source 110 and the reflection unit 130, is used to perform optical processing on the stray light or the useful image light to prevent the stray light from entering the human eye's field of view.

[0028] In some embodiments, the optical path adjustment unit 140 may include a polarizer 141 and a quarter-wave plate 142, as Figure 2As shown, the polarizer 141 is arranged between the image source 110 and the Fresnel lens 120, and the quarter wave plate 142 is arranged between the polarizer 141 and the Fresnel lens 120, and the quarter wave plate 142 is arranged in parallel with the polarizer 141. Among them, the polarizer 141 is used to convert the image light into linear polarized light, and the quarter wave plate 142 is used to convert the linear polarized light into circular polarized light for output. Among them, the polarizer 141 only allows a light beam in a certain direction to pass through, and filters out light beams in other directions, so that the output light beam is changed into linear polarized light. When the linear polarized light is vertically incident on the quarter wave plate 142, and the polarization of the light and the optical axis plane of the quarter wave plate (i.e., the vertical natural split plane) form an angle θ, it becomes elliptically polarized light after being emitted. It should be noted that when θ=45°, the emitted light is circularly polarized light.

[0029] Optionally, considering that interference-type polarizers often have a narrow wavelength range and a high requirement for the incident angle, the polarizer 141 is often preferably an absorption-type polarizer. Based on this, the quarter-wave plate 142 converts the linearly polarized light output by the polarizer 141 into a circularly polarized light output, and the plane and curved surface of the Fresnel lens 120 will reflect part of the circularly polarized light, and the rotation direction of the circularly polarized light after reflection will change. For example, taking the circularly polarized light as left-handed circularly polarized light as an example, the rotation direction of the left-handed circularly polarized light reflected by the Fresnel lens 120 will change and become right-handed circularly polarized light, and the right-handed circularly polarized light is the polarized stray light caused by the reflection of the Fresnel lens 120. Further, the circularly polarized light whose rotation direction is changed after being reflected by the Fresnel lens 120 will be transmitted to the quarter-wave plate 142 again, and the quarter-wave plate 142 can convert the right-handed polarized stray light into a target polarized light, such as S-polarized light, which is orthogonal to the transmission axis of the polarizer 141. Since the absorbing polarizer 141 only allows light beams that are consistent with the direction of the transmission axis to pass through, it will absorb light beams in other directions, and the right-handed polarized stray light is orthogonal to the projection axis of the absorbing polarizer 141. Therefore, the absorbing polarizer 141 can absorb the target polarized light, thereby preventing the target polarized light from being transmitted through the absorbing polarizer 141 to the human eye, affecting the user's viewing experience.

[0030] It can be seen that the stray light formed by the reflection on the surface of the Fresnel lens 120 has been absorbed by the light path control unit 140; however, considering that the light path control unit 140 may also have a plane reflection to form some stray light, and because the stray light path reflected by the plane interface has a clear directionality, the angle between the light path control unit 140 and the Fresnel lens 120 can be adjusted to stagger the stray light path of the light path control unit 140 and the image light path. Specifically, Figure 1As shown, the optical path adjustment unit 140 is not parallel to the Fresnel lens 120, and a set angle, such as 1 to 2 degrees, can be set between the two, so as to stagger the paths of the stray light reflected by the optical path adjustment unit 140 and the transmitted image light, thereby avoiding the problem that the stray light is reflected into the human eye and causing a bad viewing experience. Or, the human eye can be slightly deviated from the path of the image light, so as to stagger the path of the stray light of the optical path adjustment unit 140.

[0031] Optionally, as Figure 2 shown, the reflective autostereoscopic 3D display device 10 may further include a diffuser 150, and the diffuser 150 is disposed between the reflection unit 130 and the Fresnel lens 120. The diffuser 150 can uniformly scatter the incident circularly polarized light, making the distribution of the circularly polarized light more uniform, that is, performing light homogenization processing on the circularly polarized light transmitted by the Fresnel lens 120. Thus, since the diffuser 150 can scatter the circularly polarized light, finally a larger eyebox can be obtained at the human eye; based on this, even if the human eye is slightly deviated from the path of the image light, the image light can still be observed.

[0032] Since the Fresnel lens 120 is often an injection molded part, its birefringence coefficient is relatively large, and the polarization of the left-handed circularly polarized light has changed after passing through the Fresnel lens 120. Based on this, please refer to Figure 3 , Figure 3 which is a schematic structural diagram of a reflective autostereoscopic 3D display device provided in another embodiment of the present application. Figure 3 In this reflective autostereoscopic 3D display device 10, in addition to including the image source 110, the optical path adjustment unit 140, the Fresnel lens 120, the reflection unit 130, and the diffuser 150 in the foregoing content, it may further include a phase compensation film 160. Among them, the phase compensation film is an optical element for changing the phase of light waves, and can cause a phase delay when light waves pass through it.

[0033] Among them, the phase compensation film 160 is disposed between the reflection unit 130 and the diffuser 150, and the phase compensation film 160 is used to perform phase compensation on the circularly polarized light after light homogenization processing, so that after the useful image light after phase compensation is reflected by the reflection unit 130, it can be transmitted by the polarizer 141 in the optical path adjustment unit 140 to the human eye field of view. Specifically, the phase compensation film 160 can compensate the phase of the circularly polarized light, so that after the circularly polarized light after compensated phase passes through the quarter-wave plate 142 for the second time, it can pass through the transmission axis of the polarizer 141 and thus be transmitted to the human eye.

[0034] In this embodiment, the stray light caused by the reflection of image light by the plane and curved surface of the Fresnel lens changes its polarization state after passing through the quarter-wave plate of the present application, and thus is absorbed by the polarizer; while the image light transmitted by the Fresnel lens passes through optical devices such as a diffusion sheet and a phase compensation sheet during the transmission process, so that the polarization state of this part of the image light is different from that of the stray light. Therefore, it will not be absorbed by the polarizer during the transmission process of being reflected by the reflection unit and can directly pass through the polarizer and be transmitted to the human eye. It can be seen that the problem of stray light formed by the surface reflection of the Fresnel lens entering the human eye is avoided, thereby greatly improving the user experience of the reflective naked-eye 3D display device.

[0035] In some other embodiments, as Figure 4 shown, the reflective naked-eye 3D display device 10 may include an image source 110, a Fresnel lens 120, a reflection unit 130, an optical path control unit 140, and a diffusion sheet 150. Among them, the optical path control unit 140 is a holographic grating 143, which is formed on the optical surface of the reflection unit 130 and is used to control the reflection angle of the useful image light at the reflection unit 130, so that the reflection direction of the useful image light is different from the reflection direction of the stray light, so as to prevent the stray light from entering the human eye field of view.

[0036] Specifically, the holographic grating 143 is used to reflect the evenly illuminated image light back to the human eye. Since the holographic grating 143 can make the incident angle not equal to the reflection angle when reflecting the light beam. Therefore, the image light beam reflected by the holographic grating 143 has a different optical path from the image light transmitted by the Fresnel lens 220, that is, the optical paths of the image light and the stray light are effectively separated, thus effectively avoiding the problem of stray light being reflected into the human eye and greatly improving the user experience of the reflective naked-eye 3D display device 20.

[0037] In this embodiment, the holographic grating is formed on the optical surface of the reflection unit in a conventional reflective projection naked-eye display system to avoid the problem that the incident light and the reflected light have equal angles, that is, to avoid the problem that stray light (unnecessary light) may also coincide with the optical path of the reflected image light, affecting the quality of the image seen by the human eye. Since the holographic grating allows different angular relationships between the incident light and the reflected light, that is, the incident angle does not need to be equal to the reflection angle, the optical path of the image light and the optical path of the stray light can be designed not to coincide, that is, the stray light and the image light are effectively separated, reducing the influence of the stray light on the quality of the image finally entering the human eye.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A reflective naked-eye 3D display device, characterized in that, The device includes: an image source for emitting image light; a Fresnel lens located on the outgoing light path of the image light, where the image light generates useful image light passing through the Fresnel lens and stray light reflected by the Fresnel lens when passing through the Fresnel lens; a reflection unit located behind the Fresnel lens along the outgoing light path of the image light, and the useful image light passing through the Fresnel lens enters the human eye field of view after being reflected by the reflection unit and then passing through the Fresnel lens again; and an optical path adjustment unit located between the image source and the reflection unit for optically processing the stray light or the useful image light to prevent the stray light from entering the human eye field of view.

2. The reflective autostereoscopic 3D display device according to claim 1, characterized in that, The optical path adjustment unit includes a quarter-wave plate and a polarizer. The polarizer is disposed between the image source and the Fresnel lens, and the quarter-wave plate is disposed between the polarizer and the Fresnel lens.

3. The reflective autostereoscopic 3D display device according to claim 2, wherein The polarizer is used to convert the image light into linearly polarized light, and the quarter-wave plate is used to convert the linearly polarized light into circularly polarized light for output.

4. The reflective autostereoscopic 3D display device according to claim 3, wherein The polarizer is an absorption-type polarizer, the circularly polarized light is left-handed circularly polarized light, and the Fresnel lens reflects a part of the polarized light in the left-handed circularly polarized light to form right-handed polarized stray light to the quarter-wave plate; The quarter-wave plate is used to convert the right-handed polarized stray light into target polarized light orthogonal to the transmission axis of the polarizer, and the absorption-type polarizer is used to absorb the target polarized light to prevent the right-handed polarized stray light from entering the human eye field of view.

5. The reflective autostereoscopic 3D display device according to claim 4, wherein, The target polarized light is S-polarized light.

6. The reflective naked-eye 3D display device according to claim 2, wherein, The reflective autostereoscopic 3D display device further includes a diffuser disposed between the reflection unit and the Fresnel lens, and the diffuser is used to evenly distribute the useful image light transmitted by the Fresnel lens.

7. The reflective autostereoscopic 3D display device according to claim 6, wherein, The reflective autostereoscopic 3D display device further includes a phase compensation film disposed between the reflection unit and the diffuser; The phase compensation film is used to perform phase compensation on the useful image light after the even light distribution process, so that the useful image light after phase compensation can be transmitted by the optical path adjustment unit to the human eye field of view after being reflected by the reflection unit.

8. The reflective naked-eye 3D display device according to claim 2, wherein The quarter-wave plate and the polarizer are arranged in parallel, and there is a set angle between the quarter-wave plate and the Fresnel lens.

9. The reflective naked-eye 3D display device according to claim 1, wherein The optical path adjustment unit is a holographic grating formed on the optical surface of the reflection unit for adjusting the reflection angle of the useful image light at the reflection unit, so that the reflection direction of the useful image light is different from the reflection direction of the stray light to prevent the stray light from entering the human eye field of view.

10. The reflective autostereoscopic 3D display device according to any one of claims 1-9, characterized in that, The image light is unpolarized light or polarized light.

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