Suspended display device and multi-layer display apparatus including the same

Abstract

The present invention relates to a suspension display device and a multi-layer display device including the same. The suspension display device comprises: an image display unit, the image display unit has a display surface of an image and emits display light constituting an initial image from the display surface; and an optical system, the optical system defines an object plane and an image plane, the optical system is arranged to receive the display light emitted from the display surface at the object plane, wherein the optical system comprises a plurality of light groups, the plurality of light groups are configured to have different abilities of converging light in a first direction and a second direction, the first direction and the second direction are respectively orthogonal to the optical axis of the suspension display device, wherein the optical system has an aperture stop for constraining light from the object plane in the second direction, wherein the display light forms a suspension image at the image plane in the air after propagating through the optical system, wherein the image side aperture angle in the first direction is greater than the image side aperture angle in the second direction.

Description

Technical Field

[0001] The embodiments described herein generally relate to light field three-dimensional display technology, and more particularly to a suspension display device and a multi-layer display apparatus including the suspension display device. Background Art

[0002] Among the many display technologies, the mid-air floating display technology has attracted the attention of many researchers because it can present images in the air, bringing strong visual impact and real and fake sensory experience to viewers.

[0003] Conventional suspension display technologies include the use of retroreflective screens, double-layer plane mirror arrays, concave mirrors or integrated imaging to achieve suspension display. However, for the retroreflective screen or double-layer plane mirror array method, the advantage is that a large field of view and aberration-free suspended display image can be achieved. The disadvantage is that the processing technology of the retroreflective screen or double-layer plane mirror array is complicated and the cost is very high. In addition, due to the need for multiple reflections, there are ghost image problems at certain observation angles. The main problem with the concave mirror to achieve a suspended image is that it is difficult to eliminate aberrations such as field curvature and distortion under the condition of a large field of view, and the imaging quality is poor. For the integrated imaging method, many micro-display units are required to project in space to form a suspended image, which makes it difficult to achieve a high resolution, and the screen cost is too high.

[0004] Therefore, a new technical solution for floating display is needed in the art. Summary of the invention

[0005] The purpose of the exemplary embodiments of the present invention is to provide such a floating display device, which can form a floating image in the air and has a lower manufacturing cost and a more flexible optical layout.

[0006] Specifically, an exemplary embodiment of the present invention provides a suspended display device, which includes: an image display unit, the image display unit having a display surface of an image and emitting display light constituting an initial image from the display surface; and an optical system, the optical system defining an object plane and an image plane, the optical system being arranged to receive the display light emitted from the display surface at the object plane, wherein the optical system includes a plurality of light groups, the plurality of light groups being configured to have different abilities to converge light in a first direction and a second direction, the first direction and the second direction being orthogonal to an optical axis of the suspended display device, respectively, wherein the optical system has an aperture stop for constraining light from the object plane in the second direction, wherein the display light forms a suspended image at the image plane in the air after propagating through the optical system, wherein the image-side aperture angle of the first direction is greater than the image-side aperture angle of the second direction.

[0007] In the above-mentioned exemplary embodiment of the suspended display device, the image side aperture angle of the point on the object plane through the multiple light groups along the first direction is relatively large to meet the binocular parallax condition, thereby forming a suspended image at the image plane. The image side aperture angle of the point on the object plane through the multiple light groups along the second direction is relatively small.

[0008] Preferably, in the suspended display device of the above exemplary embodiment, the multiple light groups include: a first light group, which is arranged optically downstream of the aperture stop and includes a one-dimensional optical element with positive optical power for converging light in the second direction; and a second light group, which includes a conjugate imaging element with a one-dimensional grating structure for converging light in the first direction.

[0009] Preferably, in the floating display device of the exemplary embodiment, the distance between the aperture stop and the focal plane of the first light group is d, and the light passing size in the second direction is Dy, and the light passing size Dy satisfies the following conditions:

[0010]

[0011] Wherein, h is the length of the suspended image in the second direction, and f is the focal length of the first light group.

[0012] Preferably, in the suspension display device of the above exemplary embodiment, the aperture stop is set within a range of ±f centered on the focal plane of the first light group.

[0013] Preferably, in the suspended display device of the above exemplary embodiment, the one-dimensional optical element and the conjugate imaging element are integrally formed as a cylindrical sawtooth grating; and the optical system also includes a beam splitter, which is arranged to reflect light from the object plane that passes through the aperture stop onto the one-dimensional sawtooth structure of the cylindrical sawtooth grating, and transmit the light reflected back from the one-dimensional sawtooth structure to the image plane.

[0014] Preferably, in the suspension display device of the above exemplary embodiment, the one-dimensional optical element is a cylindrical lens, the conjugate imaging element is a one-dimensional grid transmission array structure, wherein the distance between the cylindrical lens and the object plane is set within the range of f to 2f of the cylindrical lens.

[0015] Preferably, in the suspended display device of the above exemplary embodiment, the optical system further comprises a third optical group, which is arranged optically upstream of the second optical group and comprises a one-dimensional optical element with positive optical power for modulating light from the object plane in the second direction.

[0016] Preferably, in the floating display device of the above exemplary embodiment, in the second direction, the light transmission size D1 of the first light group is greater than or equal to the light transmission size D3 of the third light group, and the focal length f1 of the first light group is greater than or equal to the focal length f3 of the third light group.

[0017] Preferably, in the suspension display device of the above exemplary embodiment, the distance between the image plane and the first light group is within one focal length of the first light group, that is, d1≤f1, d1 is the distance between the image plane and the first light group.

[0018] Preferably, in the suspension display device of the above exemplary embodiment, the conjugate imaging element having a one-dimensional grating structure and the aperture stop are integrated into a single component.

[0019] Preferably, in the suspended display device of the above exemplary embodiment, the one-dimensional optical element in the first optical group is a free-form surface mirror, which is arranged optically downstream of the conjugate imaging element and arranged to reflect light emitted from the conjugate imaging element to the image plane.

[0020] Preferably, in the suspension display device of the above exemplary embodiment, the first light group and the third light group are substantially symmetrically arranged along the optical axis relative to the conjugate imaging element, and the focal length of the first light group is substantially equal to the focal length of the third light group.

[0021] Preferably, in the floating display device of the above exemplary embodiment, the aperture stop is located at the image-side focal plane of the third light group and at the object-side focal plane of the first light group.

[0022] Preferably, in the suspended display device of the above exemplary embodiment, the conjugate imaging element is a one-dimensional retroreflective screen, the one-dimensional optical element in the first light group is a first concave mirror arranged between the object plane and the image plane, the concave surface of the first concave mirror faces the image plane, and the one-dimensional optical element in the third light group is a second concave mirror with a concave surface facing the one-dimensional retroreflective screen, wherein the optical imaging system further includes: a first beam splitter plate, obliquely arranged between the object plane and the first concave mirror and between the one-dimensional retroreflective screen and the second concave mirror; a second beam splitter plate, arranged between the first concave mirror and the image plane. Preferably, the first beam splitter plate is a polarization beam splitter film for reflecting s-polarized light and transmitting p-polarized light, the second beam splitter plate is a polarization beam splitter plate for reflecting s-polarized light and transmitting p-polarized light, and the optical imaging system further comprises: a first 1 / 4 wave plate, arranged between the second concave mirror and the polarization beam splitter film; a second 1 / 4 wave plate, arranged between the one-dimensional retroreflective screen and the polarization beam splitter film; and a third 1 / 4 wave plate, arranged between the first concave mirror and the polarization beam splitter plate.

[0023] Preferably, in the suspension display device of the above exemplary embodiment, the conjugate imaging element is a one-dimensional retroreflective screen, the one-dimensional optical element in the first optical group is a convex lens arranged between the object plane and the image plane, the convex surface of the convex lens faces the object plane, and the one-dimensional optical element in the third optical group is a concave mirror with a concave surface facing the one-dimensional retroreflective screen, wherein the optical imaging system further includes: a beam splitter, obliquely arranged between the object plane and the convex lens and between the one-dimensional retroreflective screen and the concave mirror; a correction lens, arranged between the beam splitter and the one-dimensional retroreflective screen, for correcting the aberration of the optical system. Preferably, the beam splitter is a polarization beam splitting film for reflecting s-polarized light and transmitting p-polarized light, and the optical imaging system further includes: a first 1 / 4 wave plate, arranged between the concave mirror and the polarization beam splitting film; and a second 1 / 4 wave plate, arranged between the polarization beam splitting film and the correction lens.

[0024] Preferably, in the floating display device of the above exemplary embodiment, the one-dimensional optical element in the third optical group and the aperture stop are integrated into a single component.

[0025] Preferably, in the suspended display device of the above exemplary embodiment, the single component is a cylindrical concave mirror and the concave surface of the cylindrical concave mirror faces the object plane, the conjugate imaging element with a one-dimensional grating structure is a one-dimensional retroreflective screen, and the one-dimensional optical element in the first optical group is a plano-convex cylindrical mirror, the planar side of the plano-convex cylindrical mirror faces the image plane, wherein the suspended display device also includes: a beam splitter, obliquely arranged between the object plane and the cylindrical concave mirror, for transmitting light from the object plane to the cylindrical concave mirror and reflecting light reflected from the cylindrical concave mirror onto the one-dimensional retroreflective screen; a polarization beam splitter film, obliquely arranged between the beam splitter and the one-dimensional retroreflective screen, for reflecting s-polarized light through p-polarized light, wherein the polarization beam splitter film reflects the s-polarized light reflected from the one-dimensional retroreflective screen to the plano-convex cylindrical mirror; and a 1 / 4 wave plate, arranged between the polarization beam splitter film and the one-dimensional retroreflective screen for converting the light reflected from the one-dimensional retroreflective screen into s-polarized light.

[0026] Preferably, in the suspension display device of the above exemplary embodiment, the single component is a cylindrical concave mirror and the concave surface of the cylindrical concave mirror faces the object plane, the conjugate imaging element is a one-dimensional retroreflective screen, and the one-dimensional optical element in the first optical group is a beam splitter concave mirror and the concave surface of the beam splitter concave mirror faces the image plane, wherein the suspension display device further comprises: a beam splitter plate obliquely arranged between the object plane and the cylindrical concave mirror, for transmitting light from the object plane to the cylindrical concave mirror and reflecting light reflected from the cylindrical concave mirror. to the beam splitter concave mirror; a polarization beam splitter plate obliquely arranged between the beam splitter concave mirror and the image plane, for reflecting s-polarized light through p-polarized light, wherein the polarization beam splitter plate reflects the s-polarized light reflected from the one-dimensional retroreflective screen to the beam splitter concave mirror; a first polarizer, arranged between the beam splitter plate and the object plane, for converting light from the object plane into p-polarized light; a first 1 / 4 wave plate, arranged between the beam splitter plate and the beam splitter concave mirror; and a second 1 / 4 wave plate, arranged between the polarization beam splitter plate and the beam splitter concave mirror.

[0027] Preferably, in the suspension display device of the above exemplary embodiment, the length of the suspension image in the second direction is greater than or equal to the length of the initial image in the second direction.

[0028] Preferably, in the floating display device of the above exemplary embodiment, the object plane is configured as a curved surface in the second direction.

[0029] Preferably, in the suspension display device of the above exemplary embodiment, the optical path between the conjugate imaging element and the object point at the optical axis on the object plane is substantially equal to the optical path between the conjugate imaging element and the image point at the optical axis on the image plane.

[0030] According to another exemplary embodiment of the present invention, a multi-layer display device is also provided, which includes: the suspended display device of the above exemplary embodiment; and a transparent display component, which is arranged optically downstream of the suspended display device, wherein the display surface of the transparent display component is located at a different position from the image plane.

[0031] Other features and aspects will become apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention may be better understood by describing exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0033] Figure 1 A schematic block diagram of a suspension display device 100 according to an embodiment of the present invention is shown;

[0034] Figure 2 Schematic diagram showing the principle of light propagation in the horizontal direction and the vertical direction of the optical system 110 in the floating display device 100 according to an embodiment of the present invention;

[0035] Figure 3 Schematic diagrams showing component arrangement and light propagation of the optical system 110 in the floating display device 100 according to an embodiment of the present invention in the horizontal direction and the vertical direction respectively;

[0036] Figure 4 A schematic diagram showing the arrangement of components and light propagation of the optical system 210 according to this optional embodiment in a first direction and a second direction, respectively;

[0037] Figure 5 Schematic diagrams showing component arrangement and light propagation of an optical system 310 according to a further embodiment in a first direction and a second direction, respectively;

[0038] Figure 6 A schematic diagram showing an optical system 610 according to a first example of the present invention and light propagation in the yz plane;

[0039] Figure 7 An example structure in which a one-dimensional optical element and a one-dimensional retroreflective screen are integrated is shown;

[0040] Figure 8 A schematic diagram showing an optical system 810 according to a second example of the present invention and light propagation in the yz plane;

[0041] Fig. 9 An example of a one-dimensional grid transmission array structure 802 is shown;

[0042] Fig.10 A schematic diagram showing an optical system 1010 according to a third example of the present invention and light propagation in the yz plane;

[0043] Fig.11 An optical system 1110 according to a fourth example of the present invention and a schematic diagram of light propagation in the yz plane are shown.

[0044] Fig.12 An example structure of a one-dimensional retroreflective screen is shown;

[0045] Fig.13 A schematic diagram showing an optical system 1310 according to a fifth example of the present invention and light propagation in the yz plane;

[0046] Fig.14 A schematic diagram showing an optical system 1410 according to a sixth example of the present invention and light propagation in the yz plane;

[0047] Fig.15 A schematic diagram showing an optical system 1510 according to a seventh example of the present invention and light propagation in the yz plane;

[0048] Fig.16 A schematic diagram showing an optical system 1610 according to an eighth example of the present invention and light propagation in the yz plane;

[0049] Fig.17 A schematic diagram showing an optical system 1710 according to a ninth example of the present invention and light propagation in the yz plane; and

[0050] Fig.18 A schematic diagram of a multi-layer display device 1800 according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0051] The specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual embodiments. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present invention, some changes such as design, manufacturing or production based on the technical content disclosed in this disclosure are just conventional technical means, and should not be understood as insufficient content of this disclosure.

[0052] Unless otherwise defined, the technical or scientific terms used in the claims and the specification shall have the usual meanings understood by persons with ordinary skills in the technical field to which the invention belongs. The words "first", "second" and similar words used in the patent application specification and the claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "one" or "one" do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalent elements, and do not exclude other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections. The phrase "A is substantially equal to B" is intended to take into account the tolerances in process manufacturing, that is, the values ​​of A and B can be within ±10% of each other.

[0053] Figure 1 A schematic block diagram of a floating display device 100 according to an embodiment of the present invention is shown.

[0054] See also Figure 1, the floating display device 100 according to an embodiment of the present invention may include an image display unit 120 and an optical system 110. The image display unit 120 has a display surface for an image and emits display light constituting an initial image from the display surface. The image display unit 120 may adopt a direct light emitting display method, or may also adopt an indirect projection method to display or project an image on the display surface. The optical system 110 is arranged optically downstream of the image display unit 120 to receive the display light, and has an object plane and an image plane. The object plane may be arranged at the display surface of the image display unit 120 to receive the original light constituting the initial image at the object plane, and then the original light is modulated by the optical system 110 to form a floating image (also referred to as an aerial image) at the image plane in the air. Alternatively, it is conceived that there may be one or more relay optical systems between the image display unit 120 and the optical system 110, which may image the display surface of the image display unit 120 at the object plane of the optical system 110; in this case, the object plane of the optical system 110 may be located at the image plane where the display surface of the image display unit 120 is imaged by one or more relay optical systems.

[0055] Figure 2 Schematic diagrams showing the principle of light propagation in the horizontal direction and the vertical direction of the optical system 110 in the floating display device 100 according to an embodiment of the present invention.

[0056] For ease of description, light can be considered to propagate along the optical path from an optically "upstream" position to an optically "downstream" position in the beam. Therefore, the relative position of an optical element in the optical path can also be described using these two terms. For example, in Figure 2 In the embodiment, the object plane 10 is located optically upstream of the aperture stop and at the same time is located optically upstream of the optical group 101 or 102 , while the aperture stop is located optically upstream of the first optical group 101 .

[0057] See also Figure 2 , the optical system 110 may include a plurality of optical groups. The plurality of optical groups are configured to have different abilities to converge light in a first direction and a second direction. The first direction and the second direction may be orthogonal to the optical axis of the optical system 110, respectively. The first direction and the second direction may be orthogonal to each other. As an example, the first direction may be a horizontal direction (x direction), the second direction may be a vertical direction (y direction), and the optical axis is along the z direction, as shown in the figure.

[0058] In particular, the optical system 110 has an aperture stop for constraining light from the object plane 10 in the vertical direction (y direction). In some embodiments of the present invention, the aperture stop may refer to the place in the optical system 110 where the light passing size in the y direction is the smallest. In the horizontal direction (x direction), the aperture stop may basically have no effect, or constrain the light from the object plane 10 to a lesser extent. In other words, the aperture stop has a relatively small light passing size in the y direction and a relatively large light passing size in the x direction. Those skilled in the art will appreciate that the role of the aperture stop may be achieved by an optical element in a plurality of optical groups, as long as the optical element is able to constrain light in the y direction; in this case, there may be no separate aperture stop in the optical system 110. Therefore, in Figure 2 The aperture stop is shown separately in the figure to more clearly explain the principle of the present invention, but it is not restrictive, so it is represented by a dotted frame.

[0059] The display light from the image display unit 120 forms a suspended image at the image plane 20 in the air after propagating through the aperture stop and a plurality of light groups, wherein the image side aperture angle α in the x direction is greater than the image side aperture angle β in the y direction.

[0060] The plurality of optical groups may include at least a first optical group 101 and a second optical group 102. The first optical group 101 may be disposed optically downstream of the aforementioned aperture stop and include a one-dimensional optical element with positive optical power for converging light in the y direction. The second optical group 102 may include a conjugate imaging element with a one-dimensional grating structure for converging light in the x direction. As an example, the conjugate imaging element with a one-dimensional grating structure may be a one-dimensional retroreflective screen, a one-dimensional grid transmission array, a one-dimensional holographic grating, etc. The benefit of using such a conjugate imaging element is that the positional relationship (object and image) is conjugate, the image is not magnified, and there is no aberration.

[0061] The second light group 102 can be arranged between the first light group 101 and the object plane 10, or between the first light group 101 and the image plane 20. The present invention is not intended to limit the positional relationship between the first light group 101 and the second light group 102. Figure 2 Only an example case where the second light group is arranged between the first light group 101 and the image plane 20 is shown.

[0062] The optical system 110 in the suspension display device 100 according to an exemplary embodiment of the present invention is described above. In the optical system 110, the image-side aperture angle of the point on the object plane 10 through the multiple light groups along the x direction is relatively large (preferably greater than 30 degrees) to meet the binocular parallax condition, thereby forming a suspension image at the image plane 20. The image-side aperture angle of the point on the object plane 10 through the multiple light groups along the y direction is relatively small, preferably within 30 degrees.

[0063] Figure 3 Schematic diagrams showing component arrangement and light propagation of the optical system 110 in the floating display device 100 according to an embodiment of the present invention are shown in the horizontal direction and the vertical direction respectively.

[0064] The aperture stop may have a larger clear aperture Dx in the x direction so as not to restrict light in the x direction, thereby obtaining a sufficiently large x-direction aperture angle to meet the binocular parallax condition to achieve floating display.

[0065] The aperture stop may have a smaller clear aperture Dy in the y direction to limit the light in the y direction, thereby selecting different parts of the light beam to participate in imaging and improving the imaging quality of off-axis points.

[0066] In some embodiments of the present invention, the clear aperture Dx of the aperture stop may be greater than the height A of the object plane (i.e., the display surface) in the x direction, i.e., Dx>A. In this way, it is ensured that the light rays parallel to the principal optical axis of the image plane can pass through the aperture stop, otherwise the complete suspended image cannot be observed because the edge image rays in the x direction cannot enter the human eye.

[0067] The distance between the aperture stop and the focal plane of the first optical group 101 is d, and the clear light size in the y direction is Dy, which is smaller than the clear light size in the y direction of any other optical element in the optical system 110 and satisfies the following conditions:

[0068]

[0069] Wherein, h is the length of the suspended image in the y direction, and f is the focal length of the first optical group 101. In this way, it can be ensured that the light parallel to the main optical axis of the image plane can pass through the aperture stop, otherwise the complete suspended image cannot be observed because the edge image light in the y direction will not enter the human eye.

[0070] In some embodiments of the present invention, the aperture stop can be placed between the first optical group 101 and the object plane 10. Optionally, the aperture stop can be set within the range of ±f centered on the focal plane of the first optical group 101, because the y-direction dimension of the aperture stop will not be higher than the y-direction image height of the suspended image.

[0071] In some embodiments of the present invention, the vertical axis magnification βx of the optical system 110 in the x direction is 1, and the vertical axis magnification βy in the y direction is ≥ 1, but this is not limiting. The advantage of this configuration is that if the vertical axis magnification βy in the y direction is greater than 1, that is, the optical system 110 has a magnifying effect on the object plane in the y direction, so the object plane can be set to be relatively small, thereby reducing the volume of the entire device.

[0072] Optionally, in some embodiments, the optical system 110 may further include a third optical group. The third optical group may be disposed optically upstream of the first optical group 101 (i.e., between the first optical group 101 and the object plane 10) and include a one-dimensional optical element with positive optical power for modulating light from the display surface (i.e., the object plane 10 of the optical system 110) in the second direction (y direction).

[0073] Figure 4 Schematic diagrams showing the arrangement of components and light propagation of the optical system 210 according to this optional embodiment in the first direction and the second direction, respectively. Several details of the optical system 210 are similar to those described above with respect to Figure 1-3 The optical system 110 described is the same and will not be described again. The following mainly describes the differences of the optical system 210.

[0074] like Figure 4 As shown, the third optical group 103 can be arranged between the second optical group 102 and the object plane 10, and includes at least one one-dimensional optical element to modulate the light in the y direction. The third optical group 103 is designed to balance the optical power distribution of the optical system, making the layout of the optical system more flexible, while further reducing aberrations and improving imaging quality.

[0075] In the y direction, the light clearance size D1 of the first light group 101 may be greater than or equal to the light clearance size D3 of the third light group 103. The focal length f1 of the first light group 101 may be greater than or equal to the focal length f3 of the third light group 103. Optionally, the distance between the image plane 20 and the first light group 101 may be within one focal length of the first light group 101, that is, d1≤f1, d1 is the distance between the image plane 20 and the first light group 101. Optionally, the role of the aperture stop may be achieved by a conjugate imaging element having a one-dimensional grating structure in the second light group 102.

[0076] Optionally, in some further embodiments, the one-dimensional optical element in the third optical group 103 can play the role of the aforementioned aperture stop, so the third optical group 103 (especially the one-dimensional optical element) can be integrated with the aperture stop as a single optical component. Figure 5 , wherein a schematic diagram of the component arrangement and light propagation of the optical system 310 according to a further embodiment is shown in the first direction and the second direction respectively. Figure 5As shown, the one-dimensional optical element of the third optical group 103 is an aperture stop. The clear aperture Dx of the one-dimensional optical element of the third optical group 103 can be greater than the height A of the object plane (i.e., the display surface) in the x direction, i.e., Dx>A. In this way, it can be ensured that the light parallel to the main optical axis of the image plane can pass through the aperture stop, otherwise the complete suspended image cannot be observed because the edge image light in the x direction will not be able to enter the human eye. The distance between the one-dimensional optical element of the third optical group 103 and the focal plane of the first optical group 101 is d, and the clear light size in the y direction is Dy, which satisfies the following equation:

[0077]

[0078] Wherein, h is the length of the suspended image in the y direction, and f is the focal length of the first optical group 101. In this way, it can be ensured that the light parallel to the main optical axis of the image plane can pass through the aperture stop, otherwise the complete suspended image cannot be observed because the edge image light in the y direction will not enter the human eye.

[0079] Optionally, the one-dimensional optical element of the third optical group 103 may be disposed within a range of ±f centered at the focal plane of the first optical group 101 .

[0080] In some embodiments of the present invention, the first optical group 101 and the third optical group 103 may be substantially symmetrically arranged along the optical axis relative to the conjugate imaging element, and the focal length of the first optical group 101 may be substantially equal to the focal length of the third optical group 103. Preferably, the optical path between the conjugate imaging element and the object point at the optical axis on the object plane 10 is substantially equal to the optical path between the conjugate imaging element and the image point at the optical axis on the image plane 20.

[0081] Optionally, the aperture stop may be located at the image-side focal plane of the third optical group 103 and at the object-side focal plane of the first optical group 101 .

[0082] Hereinafter, several examples of an optical system in a suspension display device according to an embodiment of the present invention will be described.

[0083] First example

[0084] Figure 6 FIG. 6 is a schematic diagram showing an optical system 610 according to a first example of the present invention and the propagation of light in the yz plane. Figure 2-3 The optical system 110 described is the same and will not be described again. The following mainly describes the differences of the optical system 610 of the first example.

[0085] In this example, the optical system 610 may include an aperture stop 601, a beam splitter 602, and an imaging unit 603. In particular, the one-dimensional optical element (e.g., a lens) in the first optical group and the conjugate imaging element (e.g., a one-dimensional retroreflective screen) having a one-dimensional grating structure in the second optical group are integrally formed into a cylindrical sawtooth grating, i.e., the imaging unit 603. One direction of the imaging unit 603 is a curved surface, and the other direction is a one-dimensional sawtooth structure, and the sawtooth structure is an isosceles triangle structure with a vertex angle of 90 degrees, such as Figure 7 shown.

[0086] like Figure 6 As shown, the light beam emitted from the object plane 10 is filtered by the aperture stop and incident on the beam splitter 602, part of the light used for imaging is reflected by the beam splitter 602 to the one-dimensional sawtooth structure of the imaging unit 603, and the light reflected from the one-dimensional sawtooth structure is transmitted to the image plane 20 via the beam splitter 602 to form a suspended image. Optionally, the object plane 10 and the image plane 20 are both at 2f (twice the focal length) of the imaging unit 603, where f is the focal length of the imaging unit 603 in the second direction (y direction).

[0087] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 610 along the x direction is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20. The image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 610 along the y direction is relatively small to obtain high imaging quality.

[0088] Second example

[0089] Figure 8 FIG. 8 is a schematic diagram showing an optical system 810 according to a second example of the present invention and the propagation of light in the yz plane. Figure 2-3 The optical system 110 described is the same and will not be described again. The following mainly describes the differences of the optical system 810 of the second example.

[0090] In this example, the optical system 810 may include a cylindrical lens 801 (first optical group), a one-dimensional grid transmission array structure 802 (second optical group), and an aperture stop 803. The distance between the cylindrical lens and the object plane may be set within a range of f (one focal length) to 2f (twice focal length) of the cylindrical lens, so that the optical system 810 may form an enlarged suspended image in the y direction. An example of the one-dimensional grid transmission array structure 802 is shown in FIG. Fig. 9As shown, the one-dimensional grid transmission array structure can be formed by laminating a number of parallel glass plates, wherein the laminating surfaces are coated with a metal reflective film, wherein the object point o is optically conjugate with the image point o', the object plane and the image plane of the structure are equal in size, and there is no aberration.

[0091] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 810 along the x direction is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20. The image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 810 along the y direction is relatively small to obtain high imaging quality.

[0092] Third Example

[0093] Fig.10 FIG. 1 is a schematic diagram showing an optical system 1010 according to a third example of the present invention and the propagation of light in the yz plane. Figure 4 The optical system 210 described is the same and will not be described in detail here. The following mainly describes the differences of the optical system 1010 of the third example.

[0094] In this example, the optical system 1010 may include a free-form surface mirror 1001 (first optical group), a one-dimensional grid transmission array structure 1002 (second optical group), a one-dimensional optical element 1003 (third optical group), and an aperture stop 1004. As shown in the figure, the free-form surface mirror 1001 may be arranged optically downstream of the transmissive one-dimensional phase conjugate element 1002 and arranged to reflect the light transmitted from the one-dimensional grid transmission array structure 1002 to the image plane 20.

[0095] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 imaged along the x direction through the optical system 1010 is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20, which has x-direction parallax and produces a technical effect that the suspended image forms a certain angle with the optical system 1010.

[0096] Fourth Example

[0097] Fig.11 FIG. 1 is a schematic diagram showing an optical system 1110 according to a fourth example of the present invention and the propagation of light in the yz plane. Figure 2-4 The optical systems 110 or 210 described are the same and will not be described in detail. The following mainly describes the differences of the optical system 1110 of the fourth example.

[0098] In this example, the conjugate imaging element in the second optical group 102 can play the role of the aforementioned aperture stop, so the second optical group (especially the conjugate imaging element) 102 can be integrated with the aperture stop as a single optical component. Fig.11 , the optical system 1110 may include a free-form mirror 1101 (first optical group), a one-dimensional retroreflective screen 1102 (second optical group and aperture stop), a one-dimensional optical element 1103 (third optical group) and a semi-reflective mirror 1004. The semi-reflective mirror 1004 may be disposed optically downstream of the one-dimensional optical element 1103 and arranged to reflect light from the one-dimensional optical element 1103 to a conjugate imaging element (one-dimensional retroreflective screen 1102) and to transmit light reflected from the one-dimensional retroreflective screen 1102 to the free-form mirror 1101. The free-form mirror 1101 may be disposed optically downstream of the semi-reflective mirror 1104 and configured to reflect light transmitted from the semi-reflective mirror 1104 to the image plane 20. An example of the one-dimensional retroreflective screen 1102 is shown in FIG. Fig.12 As shown, for any light irradiated on the surface of a one-dimensional retroreflective screen, a portion of the light is reflected at the original angle.

[0099] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 1110 along the x direction is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20. The image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 1110 along the y direction is relatively small to obtain high imaging quality.

[0100] Fifth example

[0101] Fig.13 FIG. 1 is a schematic diagram showing an optical system 1310 according to a fifth example of the present invention and the propagation of light in the yz plane. Figure 2-4 The optical systems 110 or 210 described are the same and will not be described in detail. The following mainly describes the differences of the optical system 1310 of the fifth example.

[0102] In this example, the optical system 1310 may include a first concave mirror 1301 (first light group), a one-dimensional retroreflective screen 1302 (second light group and aperture stop), a second concave mirror 1303 (third light group), a first spectroscopic plate 1304, and a second spectroscopic plate 1305. The first concave mirror 1301 is arranged between the object plane 10 and the image plane 20, and its concave surface faces the image plane 20. The first concave mirror may be an equal-thickness structure coated with a 50 / 50 spectroscopic film. The concave surface of the second concave mirror 1303 faces the one-dimensional retroreflective screen 1302. The first spectroscopic plate 1304 is tiltedly arranged between the object plane 10 and the first concave mirror 1301 and between the one-dimensional retroreflective screen 1302 and the second concave mirror 1303. The spectroscopic plate is arranged between the first concave mirror 1301 and the image plane 20.

[0103] Optionally, the first beam splitter plate 1304 may be a polarization beam splitter film, and the second beam splitter plate 1305 may be a polarization beam splitter plate; in this case, the optical system 1310 may further include a first quarter wave plate 1306, a second quarter wave plate 1307, and a third quarter wave plate 1308. In particular, the second optical group (the conjugate imaging element therein) and the aperture stop are integrated into a single component, namely the one-dimensional retroreflective screen 1302. That is, the one-dimensional retroreflective screen 1302 also plays the role of the aperture stop described above. The first quarter wave plate 1306 may be arranged between the second concave mirror 1303 and the polarization beam splitter film, the second quarter wave plate 1307 may be arranged between the one-dimensional retroreflective screen 1302 and the polarization beam splitter film, and the third quarter wave plate 1308 may be arranged between the first concave mirror 1301 and the polarization beam splitter plate. The second quarter wave plate 1307 may be arranged in the same tilting manner as the first beam splitter plate 1304. The optical axes of the second 1 / 4 wave plate 1307 and the third 1 / 4 wave plate 1308 are arranged to be orthogonal.

[0104] When the display surface of the image display unit 120 is set at or relayed to the object plane of the optical system 1310, the s-polarized light emitted from the display surface is reflected by the polarization splitting film and irradiates the second concave mirror 1303. Then, the light reflected by the second concave mirror 1303 is converted into p-polarized light through the first 1 / 4 wave plate 1306, and is transmitted to the one-dimensional retroreflective screen 1302 through the polarization splitting film and the second 1 / 4 wave plate 1307. The light is reflected by the one-dimensional retroreflective screen 1302 and is converted into s-polarized light again through the second 1 / 4 wave plate 1307, and is reflected by the polarization splitting film. The light reflected by the polarization splitting film is irradiated onto the first concave mirror 1301 again through the second quarter wave plate 1307, and a part of the light is irradiated onto the third quarter wave plate 1308 through the first concave mirror 1301. After passing through the third quarter wave plate 1308, the light is still s-polarized light and is reflected by the polarization splitting plate. The light reflected by the polarization splitting plate is irradiated onto the first concave mirror 1301 and is reflected again. After passing through the third quarter wave plate 1308, it becomes p-polarized light and is emitted through the polarization splitting plate to form a suspended image at the image plane 20 in the air.

[0105] Note that the use of the polarization splitter film, the polarization splitter plate, the first 1 / 4 wave plate 1306, the second 1 / 4 wave plate 1307 and the third 1 / 4 wave plate 1308 is to improve the optical efficiency of the optical system while eliminating the influence of unwanted light (for example, external light), but it is not necessary because those skilled in the art can understand that an optical system without using these optical elements is sufficient to achieve the purpose of forming a suspended image.

[0106] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 along the x direction through the optical system 1310 is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20. The image-side aperture angle of the point on the display surface of the image display unit 120 along the y direction through the optical system 1310 is relatively small to obtain high imaging quality. The optical system 1310 is a pure reflection structure, has no chromatic aberration, and is easy to achieve large-scale production.

[0107] Sixth Example

[0108] Fig.14 FIG. 1 shows a schematic diagram of an optical system 1410 and light propagation in the yz plane according to a sixth example of the present invention. Figure 2-4 The optical system 110 or 210 described and the Fig.13 The optical system 1310 described is the same and will not be described again. The following mainly describes the differences of the optical system 1410 of the sixth example.

[0109] In this example, the optical system 1410 may include a convex lens 1401, a one-dimensional retroreflective screen 1402 (a second light group and an aperture stop), a concave mirror 1403, a beam splitter 1404, and a correction lens 1405. The convex lens 1401 is arranged between the object plane 10 and the image plane 20, and its convex surface faces the object plane 10. The concave surface of the concave mirror 1403 faces the one-dimensional retroreflective screen 1402. The beam splitter 1404 is obliquely arranged between the object plane 10 and the convex lens 1401 and between the one-dimensional retroreflective screen 1402 and the concave mirror 1403. The correction lens 1405 is arranged between the beam splitter 1404 and the one-dimensional retroreflective screen 1402 for correcting the aberration of the optical system 1410. The correction lens 1405 may be a positive lens or a negative lens. In this example, the convex lens 1401 and the correction lens 1405 constitute a first optical group, while the concave mirror 1403 and the correction lens 1405 constitute a third optical group. In other words, in this example, the correction lens 1405 can be used as an optical element in the first optical group and an optical element in the third optical group at the same time.

[0110] Optionally, the beam splitter 1404 may be a polarization beam splitting film; in this case, the optical system 1410 may further include a first 1 / 4 wave plate 1406 and a second 1 / 4 wave plate 1407. In particular, the second optical group (the conjugate imaging element therein) and the aperture stop are integrated into a single component, namely the one-dimensional retroreflective screen 1402. In other words, the one-dimensional retroreflective screen 1402 also plays the role of the aperture stop described above.

[0111] When the display surface of the image display unit 120 is set at or relayed to the object plane of the optical system 1310, the s-polarized light emitted by the display surface is reflected by the polarization splitter film and irradiates the concave mirror 1403; the light reflected by the concave mirror 1403 passes through the first 1 / 4 wave plate 1406 for the second time and is converted into p-polarized light, which is transmitted to the correction lens 1405 through the polarization splitter film and the second 1 / 4 wave plate 1407; the light passing through the correction lens 1405 is reflected by the one-dimensional retroreflective screen 1402 and passes through the correction lens 1405 again, is converted into s-polarized light through the second 1 / 4 wave plate 1407, and is reflected by the polarization splitter film; the light reflected by the polarization splitter film converges at the image plane 20 in the air through the convex lens 1401 to form a suspended image.

[0112] Note that the use of the polarization splitter film, the first quarter wave plate 1406 and the second quarter wave plate 1407 is to improve the optical efficiency of the optical system while eliminating the influence of unwanted light (e.g., external light), but it is not necessary because those skilled in the art will understand that an optical system without using these optical elements is sufficient to achieve the purpose of forming a suspended image.

[0113] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 1410 along the x direction is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20. The image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 1410 along the y direction is relatively small to obtain high imaging quality.

[0114] In the fifth and sixth examples above, the optical system 1310 or 1410 may be a symmetrical structure, and the one-dimensional retroreflective screen 1302 or 1402 in the second optical group is at the middle position of the optical system 1310 or 1410, that is, the optical path between the conjugate imaging element and the object plane is substantially equal to the optical path between the conjugate imaging element and the image plane. In addition, the focal length of the first optical group is substantially equal to the focal length of the third optical group, and the object plane 10 and the image plane 20 are substantially equal in size.

[0115] Example 7

[0116] Fig.15 FIG. 1 shows a schematic diagram of an optical system 1510 according to a seventh example of the present invention and light propagation in the yz plane. Figure 5 The optical system 310 described is the same and will not be described again. The following mainly describes the differences of the optical system 1510 of the seventh example.

[0117] In this example, the optical system 1510 may include a plano-convex cylindrical mirror 1501 (first light group), a sawtooth grating 1502 (second light group), a cylindrical concave mirror 1503 (third light group and aperture stop), a polarization beam splitter plate 1504, a first polarizer 1505, a second polarizer 1506, a first 1 / 4 wave plate 1507, and a second 1 / 4 wave plate 1508. In particular, the third light group (i.e., the one-dimensional optical element therein) and the aperture stop are integrated into a single component, i.e., the cylindrical concave mirror 1503, and its concave surface faces the object plane 10. That is, the cylindrical concave mirror 1503 also plays the role of the aperture stop in the y direction. The conjugate imaging element is a sawtooth grating 1502 arranged to face the image plane 20, and the one-dimensional optical element in the first optical group is a plano-convex cylindrical mirror 1501 arranged between the image plane 20 and the sawtooth grating 1502, the plano-convex cylindrical mirror 1501 has its plano-side facing the image plane 20, and the convex side of the plano-convex cylindrical mirror 1501 faces the sawtooth grating 1502. A polarization beam splitter plate 1504 is obliquely arranged between the object plane 10 and the cylindrical concave mirror 1503 and between the sawtooth grating 1502 and the plano-convex cylindrical mirror 1506. A first polarizer 1505 is arranged between the object plane 10 and the polarization beam splitter plate 1504 to convert light from the object plane 10 into p-polarized light. A second polarizer 1506 is arranged optically downstream of the plano-convex cylindrical mirror 1501 to block the transmission of s-polarized light. The first 1 / 4 wave plate 1507 is disposed between the cylindrical concave mirror 1503 and the polarization beam splitter plate 1504 to convert the light reflected from the cylindrical concave mirror 1503 into s-polarized light. The second 1 / 4 wave plate 1508 is disposed between the polarization beam splitter plate 1504 and the sawtooth grating 1502 to convert the light reflected from the sawtooth grating 1502 into p-polarized light.

[0118] When the display surface of the image display unit is arranged at or relayed to the object plane of the optical system 1510, the light emitted from the display surface passes through the first polarizer 1505, is converted into p-polarized light, passes through the polarization beam splitter plate 1504, and the polarization beam splitter plate 1504 transmits the p-polarized light and reflects the s-polarized light. Therefore, the light emitted from the display surface passes through the polarization beam splitter plate 1504, passes through the first 1 / 4 wave plate 1507, and irradiates the cylindrical concave mirror 1503. The light returning from the cylindrical concave mirror 1503 passes through the first 1 / 4 wave plate 1507 again, is converted into s-polarized light, is reflected by the polarization beam splitter plate 1504, passes through the second 1 / 4 wave plate, and irradiates the sawtooth grating 1502. The light reflected from the sawtooth grating 1502 passes through the second 1 / 4 wave plate 1508 again, is converted into p-polarized light, passes through the polarization beam splitter plate 1504, and irradiates the plano-convex cylindrical mirror 1506. Finally, the light passes through the plano-convex cylindrical mirror 1501 to form a suspended image at the aerial image plane 20. The second polarizer 1506 allows only p-polarized light to pass through and filters out s-polarized stray light. At the same time, when external light is incident on the sawtooth grating 1502, it cooperates with the second 1 / 4 wave plate 1508 to eliminate the influence of external light.

[0119] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 1510 along the x direction is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20. The image-side aperture angle of the point on the display surface of the image display unit 120 formed by the optical system 1510 along the y direction is relatively small to obtain high imaging quality.

[0120] Example 8

[0121] Fig.16 FIG. 1 shows a schematic diagram of an optical system 1610 according to an eighth example of the present invention and light propagation in the yz plane. Figure 5 The optical system 310 described is the same and will not be described in detail here. The following mainly describes the differences of the optical system 1610 of the eighth example.

[0122] In this example, the optical system 1610 may include a plano-convex cylindrical mirror 1601 (first light group), a one-dimensional retroreflective screen 1602 (second light group), a cylindrical concave mirror 1603 (third light group and aperture stop), a polarization beam splitter film 1604, a beam splitter 1605, a first polarizer 1606, a second polarizer 1607, and a quarter wave plate 1608. In particular, the third light group (i.e., the one-dimensional optical element therein) and the aperture stop are integrated into a single component, i.e., the cylindrical concave mirror 1603, and its concave surface faces the object plane 10. That is, the cylindrical concave mirror 1603 also plays the role of the aperture stop in the y direction. The conjugate imaging element with a one-dimensional grating structure is a one-dimensional retroreflective screen 1602, and the one-dimensional optical element in the first optical group is a plano-convex cylindrical mirror 1601 arranged between the image plane 20 and the polarization beam splitter film 1604, the plano-convex cylindrical mirror 1601 has its planar side facing the image plane 20, and the convex side facing the polarization beam splitter film 1604. The beam splitter 1605 is obliquely arranged between the object plane 10 and the cylindrical concave mirror 1603, for transmitting the light from the object plane 10 to the cylindrical concave mirror 1603 and reflecting the light reflected from the cylindrical concave mirror 1603 onto the one-dimensional retroreflective screen 1602. The polarization beam splitter film 1604 is obliquely arranged between the beam splitter 1605 and the one-dimensional retroreflective screen 1602, for reflecting the s-polarized light through the p-polarized light. The polarization beam splitter film 1604 reflects the s-polarized light reflected from the one-dimensional retroreflective screen 1602 to the plano-convex cylindrical mirror 1601. The first polarizer 1606 is disposed between the beam splitter 1605 and the polarization beam splitter film 1604 to convert the light from the object plane 10 into p-polarized light. The 1 / 4 wave plate 1608 is disposed between the polarization beam splitter film 1604 and the one-dimensional retroreflective screen 1602 to convert the light reflected from the one-dimensional retroreflective screen 1602 into s-polarized light. The second polarizer 1607 is disposed optically downstream of the plano-convex cylindrical mirror 1601 to pass the s-polarized light.

[0123] When the display surface of the image display unit is set at the object plane 10 of the optical system 1610, the light emitted from the display surface passes through the beam splitter 1605 and is irradiated onto the cylindrical concave mirror 1603 and reflected by the concave mirror 1603, and then irradiates the beam splitter 1605 again and is reflected onto 1606, which is a polarizer for passing light in the p-polarized state; the p-polarized light further passes through the polarization beam splitter film (passing P light and reflecting s light) and irradiates the 1 / 4 wave plate 1608, and the light is reflected by the one-dimensional retroreflective screen 1602 and then passes through the 1 / 4 wave plate 1608 again to become s-polarized light; the s-polarized light is reflected by the polarization beam splitter film 1604, irradiates onto the lens 1601, and is emitted through the second polarizer 1607 to form a suspended image in space. The second polarizer 1607 can pass s-polarized light. The absorption axes of the second polarizer 1607 and the first polarizer 1606 are orthogonal to each other, which can prevent large-angle light emitted from the display surface from directly passing through the second polarizer 1607 and the first polarizer 1606 and entering the human eye to form ghost images.

[0124] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 through the optical system 1610 along the x direction is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20, and the image-side aperture angle of the point on the display surface of the image display unit 120 through the optical system 1610 along the y direction is relatively small, so as to obtain high imaging quality.

[0125] Example 9

[0126] Fig.17 FIG. 1 shows a schematic diagram of an optical system 1710 according to a ninth example of the present invention and light propagation in the yz plane. Figure 5 The optical system 310 described is the same and will not be described in detail here. The following mainly describes the differences of the optical system 1710 of the ninth example.

[0127] In this example, the optical system 1710 may include a beam splitter concave mirror 1701 (first light group), a one-dimensional retroreflective screen 1702 (second light group), a cylindrical concave mirror 1703 (third light group and aperture stop), a beam splitter plate 1704, a polarization beam splitter plate 1705, a first polarizer 1706, a first 1 / 4 wave plate 1707, and a second 1 / 4 wave plate 1708. In particular, the third light group (i.e., the one-dimensional optical element therein) and the aperture stop are integrated into a single component, i.e., the cylindrical concave mirror 1703, and its concave surface faces the object plane 10. That is, the cylindrical concave mirror 1703 also plays the role of the aperture stop in the y direction. The phase conjugate optical element is a one-dimensional retroreflective screen 1702 , and the one-dimensional optical element in the first optical group is a beam splitter concave mirror 1701 arranged between a beam splitter plate 1704 and a polarization beam splitter plate 1705 , the concave surface of the beam splitter concave mirror 1701 faces the image plane 20 .

[0128] The beam splitter plate 1704 is disposed obliquely between the object plane 10 and the cylindrical concave mirror 1703, and is used to transmit the light from the object plane 10 to the cylindrical concave mirror 1703 and reflect the light reflected from the cylindrical concave mirror 1703 to the beam splitter concave mirror 1701. The polarization beam splitter plate 1705 is disposed obliquely between the beam splitter concave mirror 1701 and the image plane 20, and is used to reflect the s-polarized light through the p-polarized light, and the polarization beam splitter plate 1705 reflects the s-polarized light reflected from the one-dimensional retroreflective screen 1702 to the beam splitter concave mirror 1701. The first polarizer 1706 is disposed between the beam splitter plate 1704 and the object plane 10, and is used to convert the light from the object plane 10 into p-polarized light. The first 1 / 4 wave plate 1707 is disposed between the beam splitter plate 1704 and the beam splitter concave mirror 1701. The second 1 / 4 wave plate 1708 is disposed between the polarization beam splitter plate 1705 and the beam splitter concave mirror 1701.

[0129] When the display surface of the image display unit is set at the object plane 10 of the optical system 1410, the light emitted from the display surface passes through 1706 (1 / 4 wave plate + polarizer), and the outgoing light is p-polarized light, which passes through the beam splitter plate 1704 and irradiates the cylindrical concave reflector 1703. The light is reflected by the cylindrical concave reflector 1703, and then reflected by the beam splitter plate 1704, irradiates the first 1 / 4 wave plate 1707, converts the p-polarized light into circularly polarized light, and then irradiates the beam splitter concave mirror 1701. The beam splitter concave mirror 1701 is a flat plate structure of equal thickness with a certain curvature, and the surface is coated with a semi-reflective and semi-transparent film. After passing through the beam splitting concave mirror 1701, the light is irradiated onto the second 1 / 4 wave plate 1708, which converts the circularly polarized light into s-polarized light, which is reflected by the polarization beam splitting plate 1705, and is irradiated onto the one-dimensional retroreflective screen 1702 and reflected. After being reflected by the polarization beam splitting plate for the second time, the light passes through the second 1 / 4 wave plate 1708 and is converted into circularly polarized light. A portion of the light is reflected by the beam splitting concave mirror 1701, and is converted into p-polarized light again through the second 1 / 4 wave plate 1708, which is emitted through the polarization beam splitting plate 1705 to form a suspended image in the air.

[0130] In this way, the image-side aperture angle of the point on the display surface of the image display unit 120 imaged along the x direction by the optical system 1710 is relatively large, satisfying the binocular parallax condition, thereby forming a suspended image at the image plane 20 .

[0131] Optionally, in the above-mentioned exemplary embodiments and examples, when the object plane of the optical system 110 is a plane, since the optical system may have field curvature in the y direction, the suspended image may be formed to be curved. Therefore, in order to correct the field curvature in the y direction, the object plane of the optical system 110 may be set as a curved surface in the y direction. For example, if the display surface of the image display unit 120 coincides with the object plane of the optical system 110, the display surface may be set as a curved surface. Alternatively, the display surface may form a curved image at the object plane of the optical system 110 through a relay imaging unit.

[0132] According to another exemplary embodiment of the present invention, a multi-layer display device is also provided.

[0133] Fig.18 A schematic diagram of a multi-layer display device 1800 according to an embodiment of the present invention is shown.

[0134] The multi-layer display device 1800 may include any of the above-described suspended display devices 1810 and a transparent display 1820. The transparent display component 1820 may be disposed optically downstream of the suspended display device 1810. The display surface 30 of the transparent display component 1820 is located at a different position from the image plane 20. The transparent display component 1820 may have a high transmittance, such as a transparent OLED / LED / LCD display or a film (slide).

[0135] The above describes the multi-layer display device 1800 according to an exemplary embodiment of the present invention. Using the multi-layer display device 1800, the suspension display device 1810 can form a suspension image at the image plane 20, and the transparent display 1820 can display different information at the display surface 30. In this way, the secondary information can be displayed on the display surface 30, and the important information can be presented at the image plane 20, thereby improving the efficiency and experience of people in obtaining information.

[0136] The above describes in detail the suspension display device, the optical system used therein, and the multi-layer display device according to an exemplary embodiment of the present invention. The optical system in the suspension display device is easy to process, which can effectively reduce costs, while eliminating the ghost image problem existing in the prior art, and has a more flexible optical layout. The suspension display device is used to realize the light field reconstruction of the display surface in the air, which is a light field three-dimensional display technology. The image side aperture angle of the light beam on the display surface through the optical system along the first direction is relatively large, which meets the binocular parallax condition, thereby realizing the floating display of the image. In particular, for the optical system in the suspension display device of the present invention, the aperture stop mentioned in this article only plays the role of limiting the light in the second direction, while the role of limiting the light in the first direction can be assumed by the first light group or a conjugate imaging element with a one-dimensional grating structure. Compared with the traditional optical system, the optical element that plays the role of the aperture stop in the first and second directions may not be the same optical element.

[0137] It should be understood that the above description is illustrative and not restrictive. For example, the above embodiments (and / or their various aspects) can be used in combination with each other. In addition, without departing from the scope of the present invention, many modifications can be made to adapt specific conditions or materials to the teachings of the various embodiments of the present invention. Although the size and type of the material described herein are used to define the parameters of the various embodiments of the present invention, the various embodiments are not meant to be restrictive, but exemplary embodiments. In the case of reading the above description, many other embodiments are obvious to those skilled in the art. Therefore, the scope of the various embodiments of the present invention should be determined with reference to the attached claims, and the full range of equivalent forms claimed by these claims.

Claims

1. A suspension display device, comprising: an image display unit having an image display surface and emitting display light constituting an initial image from the display surface; as well as an optical system, the optical system defining an object plane and an image plane, the optical system being arranged to receive the display light emitted from the display surface at the object plane, wherein the optical system comprises a plurality of light groups, the plurality of light groups being configured to have different abilities of converging light in a first direction and a second direction, the first direction and the second direction being orthogonal to the optical axis of the suspended display device, respectively, wherein the optical system has an aperture stop for constraining the light from the object plane in the second direction, wherein the display light forms a suspended image at the image plane in the air after propagating through the optical system, and the image side aperture angle in the first direction is greater than the image side aperture angle in the second direction, The plurality of light groups include: a first optical group, the first optical group comprising an optical element for modulating light in the second direction; and A second light group, wherein the second light group comprises a conjugate imaging element having a one-dimensional grating structure, for converging light in the first direction.

2. The suspension display device according to claim 1, characterized in that: The distance between the aperture stop and the focal plane of the first light group is d, and the light clearance size in the second direction is Dy, and the light clearance size Dy satisfies the following conditions: Wherein, h is the length of the suspended image in the second direction, and f is the focal length of the first light group.

3. The suspension display device according to claim 1, characterized in that: The optical element is a one-dimensional optical element, and the one-dimensional optical element and the conjugate imaging element are integrally formed as a cylindrical sawtooth grating.

4. The suspension display device according to claim 1, characterized in that: The optical element is a one-dimensional optical element, the one-dimensional optical element is a cylindrical lens, and the conjugate imaging element is a one-dimensional grating transmission array structure.

5. The suspension display device according to claim 1, characterized in that: The optical system further includes a third optical group including a one-dimensional optical element for modulating the light from the object plane in the second direction.

6. The suspension display device according to claim 5, characterized in that: The one-dimensional optical element in the third optical group and the aperture stop are integrated into a single component.

7. The suspension display device according to claim 1, characterized in that: The conjugate imaging element having a one-dimensional grating structure and the aperture stop are integrated into a single component.

8. The suspension display device according to claim 5, characterized in that: The first light group and the third light group are substantially symmetrically arranged along the optical axis relative to the conjugate imaging element.

9. The suspension display device according to claim 1, characterized in that: The optical system further comprises: A beam splitter is arranged along the optical path between the conjugate imaging element and the image display unit.

10. The suspension display device according to claim 9, characterized in that: The optical system further comprises: a phase delay film, arranged along the optical path between the conjugate imaging element and the beam splitter; and / or The beam splitter has polarization splitting capability.

11. The suspension display device according to claim 1, characterized in that: The length of the suspended image in the second direction is greater than or equal to the length of the initial image in the second direction.

12. The suspension display device according to any one of claims 2 to 10, characterized in that: The optical path between the conjugate imaging element and the object point at the optical axis on the object plane is substantially equal to the optical path between the conjugate imaging element and the image point at the optical axis on the image plane.

13. The suspension display device according to any one of claims 1 to 11, characterized in that: The object plane is configured as a curved surface in the second direction.

14. A multi-layer display device comprising: The suspended display device according to any one of claims 1 to 13; as well as A transparent display component is arranged at the optical downstream of the suspension display device, wherein a display surface of the transparent display component and the image plane are located at different positions.

Images