Patent Description:
The present disclosure relates to AR, and more particularly, to a prismatic AR display device.

The augmented reality (referred as "AR" hereafter) is a technique that calculates the positions and angles of camera images in real time and incorporates corresponding images, videos or 3D models. This kind of technology superimposes virtual information onto real-world scenes so as to achieve the "seamless" integration of the real-world information with the virtual-world one.

In order to ensure that a user can see superimposed virtual images and real-world scene images, the AR technology is required to use the imaging technology and the beam-splitting and combining technology. In the prior prismatic AR display device, the imaging optical path and the beam-splitting and combining optical path are realized by a single one beam splitting prism. With this kind of display device, virtual images seen by human eyes may have a relatively large color difference and a poor definition. Prior art document D1 (<CIT>) discloses an intelligent helmet binocular display system for electric power inspection and a realization method of intelligent helmet binocular display system, where, according to the method, a binocular imaging optical subsystem and a sequential logical circuit based on an FPGA (Field Programmable Gate Array) are designed; an invented intelligent helmet binocular enhanced reality display system comprises image acquisition, data conversion, caching, storage, protocol conversion and an interface; intelligent helmet binocular imaging enhanced reality display for the electric power inspection is realized (see ABSTRACT of D1).

A plurality of aspects of the present disclosure provide a prismatic AR display device for reducing the color difference of virtual images and improving the definition of aliased images viewed by human eyes.

The present invention provides a prismatic AR display device as defined in claim <NUM>.

Further alternatively, the first single lens is a positive lens.

Further alternatively, the first light incident surface and/or the second light incident surface are/is plated with an anti-reflection film.

Further alternatively, the display device further comprises a polarization element,
wherein the polarization element is located on a light emergent side of a second light emergent surface of the beam splitting prism, and a polarization direction of the polarization element is perpendicular to the polarization direction of the PBS; the second light emergent surface is opposite to the first light incident surface.

Further alternatively, the first light incident surface and/or the second light incident surface are/is a concave surface.

Further alternatively, the beam splitting prism comprises a first prism and a second prism that are sequentially arranged,.

Further alternatively, the beam splitting prism comprises a second prism and a first prism that are sequentially arranged,.

Further alternatively, the first light emergent surface is a concave surface that is concentric with the second light incident surface and has the same curvature radius as the latter.

Further alternatively, the LCOS lighting apparatus comprises a concavo-convex lens and a light source device that are sequentially arranged along the second axis, wherein a first surface of the concavo-convex lens close to the light source device is a concave spherical surface, and a second surface of the concavo-convex lens close to the PBS is a convex spherical surface; light emitted by the light source device is converged to the PBS via the concavo-convex lens, and polarized by the PBS, and then enters the LCOS display chip in the form of an orthogonal linearly polarized light.

Further alternatively, the LCOS lighting apparatus comprises an aspherical positive lens arranged on the second axis and located between the concavo-convex lens and the PBS, wherein the aspherical positive lens is used for uniformly refracting the light emitted from the light source device and refracted by the concavo-convex lens to the PBS so that the refracted light is polarized by the PBS and then enters the LCOS display chip.

In the prismatic AR display device according to the claimed invention, the imaging optical path comprises the double cemented lens and the first single lens that are coaxially arranged in order, and the beam-splitting and combining optical path is realized by the beam splitting prism. In such optical path design, the double cemented lens can correct the color difference generated by the imaging optical path and the beam-splitting and combining optical path while conducting imaging on the virtual image light emitted by the LCOS display chip, and thus the color difference of the virtual images may be reduced and the definition of the aliased images viewed by human eyes may be improved.

The drawings described herein are used for providing a further understanding of the present disclosure, and constitute part of the present disclosure. The exemplary embodiments of the present disclosure and description thereof are used for explaining the present disclosure, and do not constitute improper limitations thereon. In the drawings:.

To make the object, technical solutions and advantages of the present disclosure clearer, the technical solutions of the present disclosure will be described below in combination with the some embodiments of the present disclosure and corresponding accompanying drawings. It is obvious that the described embodiments only constitute some of the embodiments of the present disclosure, instead of all of the embodiments thereof. Based on the embodiments in the present disclosure, all the other embodiments obtained by those of ordinary skill in the within the scope of the claims.

In the imaging optical path of prior prismatic AR, as shown in <FIG>, virtual image light reflected by an LCOS (Liquid Crystal on Silicon) display chip passes through a PBS (polarization beam splitter) and enters a beam splitting prism; then, is transmitted through a transflective medium film of the beam splitting prism, and subjected to imaging by a reflecting surface of the beam splitting prism; thereafter, the light is reflected by the transflective medium film and aliased with ambient light to be presented to human eyes. In the above optical path, the imaging optical path and the beam-splitting and combining optical path are realized by a single one beam splitting prism. Since in the virtual image light, beams of light of different wavelengths are different from one another in chromatic dispersion and refractive coefficients in the beam splitting prism. Therefore, they will have different imaging positions. As a result, the virtual images viewed by human eyes have serious color difference and poor definition. In order to solve the above problems, some of the embodiments of the present disclosure provide a prismatic AR display device as shown in the following drawings.

<FIG> is a schematic diagram illustrating the structure of a prismatic AR display device provided by some embodiments of the present disclosure. As shown in <FIG>, the prismatic AR display device comprises:
an LCOS display chip <NUM>, a polarization beam splitter (PBS) <NUM>, a double cemented lens <NUM>, a first single lens <NUM> and a beam splitting prism <NUM> which are sequentially arranged along a first axis, and LCOS lighting apparatus <NUM> which is arranged on a second axis perpendicular to the first axis and close to the PBS <NUM>. In some embodiments, both the first axis and the second axis may be perpendicular to a light incident surface of the PBS <NUM> and pass through the geometric center point of the PBS <NUM>, and the two are perpendicular to each other.

In some embodiments, the double cemented lens <NUM> may be formed by bonding a low-dispersion crown glass positive lens with a high-dispersion flint glass negative lens, and the negative lens in the double cemented lens <NUM> is close to the PBS <NUM>, and the positive lens is close to the first single lens <NUM>. The double cemented lens <NUM> can not only eliminate the color difference generated in optical paths, but also deflect light of large divergence angle transmitted by the PBS <NUM> into that of small divergence angle to be propagated, which can improve the light collecting efficiency of the AR display device.

In some embodiments, the first single lens <NUM> may be a positive lens. The first single lens <NUM> is used to cooperate with the double cemented lens <NUM> to conduct imaging, and share focal power in the optical path system to optimize the optical path structure. Optionally, the material of the first single lens <NUM> may be different from that of the double cemented lens <NUM>. In other words, the first single lens <NUM> is neither a flint glass lens nor a crown glass lens. As such, it can further eliminate the color difference produced in optical paths, which can improve the definition of virtual images viewed by human eyes in the end.

The beam splitting prism <NUM> comprises two light incident surfaces, two light emergent surfaces and one beam splitting surface, and the beam splitting surface may be realized by the transflective medium film.

As shown in <FIG>, a first light incident surface Si1 of the beam splitting prism <NUM> is close to the first single lens <NUM>, and its optical axis coincides with that of the first single lens <NUM>; an optical axis of a second light incident surface Si2 of the beam splitting prism <NUM> is perpendicular to that of the first light incident surface Si1, and the second light incident surface Si2 is opposite to a first light emergent surface Se1.

It should be noted that in the above or following embodiments of the present disclosure, the LCOS display chip <NUM> cited herein is a kind of display chip that can't emit light independently, which needs to be illuminated by polarized light to exhibit pictures of different gray scales and colors. In some embodiments of the present disclosure, the PBS <NUM> is used to cooperate with the LCOS lighting apparatus <NUM> to generate linearly polarized light to achieve illumination of the LCOS display chip <NUM>. In the display device shown in <FIG>, upon transmission by the PBS <NUM> and refraction by the double cemented lens <NUM>, the virtual image light emitted by the LCOS display chip <NUM> enters the first single lens <NUM> where it is refracted to the beam splitting prism <NUM> by the first single lens <NUM>; then, it is combined, on a beam splitting surface of the beam splitting prism <NUM>, with ambient light from the second light incident surface Si2 of the beam splitting prism <NUM>; thereafter, the combined light is transmitted to human eyes from the first light emergent surface Se1 of the beam splitting prism <NUM>. As such, the virtual images superimposed with real ambient images can be viewed by human eyes from the light emergent side of the first light emergent surface Se1.

In the prismatic AR display device provided by some embodiments of the present disclosure, the imaging optical path comprises the double cemented lens <NUM> and the first single lens <NUM> that are coaxially arranged in order, and the beam-splitting and combining optical path is realized by the beam splitting prism <NUM>. On one hand, in such optical path design, the double cemented lens <NUM> can correct the color difference generated by the imaging optical path and the beam-splitting and combining optical path while conducting imaging on the virtual image light emitted by the LCOS display chip <NUM>, which reduces the color difference of virtual images, which can improve the definition of aliased images viewed by human eyes. On the other hand, the imaging optical path formed by the double cemented lens <NUM> and the first single lens <NUM> comprises, in total, five optical surfaces having certain curvature radiuses. This ensures that the imaging optical path has a sufficiently large field angle, and that this field angle may be adjusted according to imaging requirements. Besides, without the functions of beam splitting and beam combining, the beam splitting prism <NUM> may be equivalently regarded as a parallel plate glass having a certain thickness for shortening optical paths to optimize the structure of the display device.

In some embodiments, as shown in <FIG>, the beam splitting prism <NUM> comprises a first prism <NUM> and a second prism <NUM> that are sequentially arranged, wherein a slant facet of the first prism <NUM> is cemented to that of the second prism <NUM>, and a cemented surface is plated thereon with a transflective medium film to form a beam splitting surface of the beam splitting prism <NUM>.

In such structure, the first light incident surface Si1 may be a surface on the first prism <NUM> which is close to the first single lens <NUM> and whose optical axis coincides with that of the first single lens <NUM>; the first light emergent surface Se1 may be a surface on the first prism <NUM> whose optical axis is perpendicular to that of the first single lens <NUM>; the second light incident surface Si2 may be a surface on the second prism <NUM> whose optical axis is perpendicular to that of the first single lens <NUM>.

Virtual image light refracted by the first single lens <NUM> is incident on the beam splitting surface through the first light incident surface Si1 on the first prism <NUM>, which is then reflected to the first light emergent surface Se1 on the first prism <NUM> via the beam splitting surface; at the same time, ambient light is incident on the beam splitting surface through the second light incident surface Si2 on the second prism <NUM>, which is then transmitted to the first light emergent surface Se1 on the first prism <NUM> via the beam splitting surface. As such, virtual-real aliasing images can be viewed by human eyes from the light emergent side of the first light emergent surface Se1.

In the above process, the virtual image light refracted by the first single lens <NUM> is required to pass through the beam splitting surface of the beam splitting prism <NUM> only once before it reaches human eyes, and thus, its optical efficiency is <NUM>%. In the optical paths shown in <FIG>, the virtual image light passes through the beam splitting surface of the beam splitting prism twice, and thus, its optical efficiency is only <NUM>%. Therefore, with respect to the related art, the present disclosure can greatly improve the optical efficiency of virtual images during their imaging, which, under the condition of enabling human eyes to view virtual images of equal brightness, reduces the power consumption required by the LCOS lighting apparatus for illuminating the LCOS display chip <NUM>.

In some embodiments, as shown in <FIG>, the beam splitting prism <NUM> comprises a second prism <NUM> and a first prism <NUM> that are sequentially arranged, wherein a slant facet of the second prism <NUM> is cemented to that of the first prism <NUM>, and a cemented surface is plated thereon with a transflective medium film for forming a beam splitting surface of the beam splitting prism <NUM>.

The first light incident surface Si1 may be a surface on the second prism <NUM> which is close to the first single lens <NUM> and whose optical axis coincides with that of the first single lens <NUM>; the second light incident surface Si2 may be a surface on the second prism <NUM> whose optical axis is perpendicular to that of the first single lens <NUM>, and the second light incident surface Si2 is a convex surface and plated with the transflective medium film; the first light emergent surface Se1 may be a surface on the first prism <NUM> whose optical axis is perpendicular to that of the first single lens <NUM>.

In this kind of structure, virtual image light refracted by the first single lens <NUM> is incident on the beam splitting surface through the first light incident surface Si1 on the second prism <NUM>; then, it is reflected to the second light incident surface Si2 on the second prism <NUM> via the beam splitting surface; thereafter, this light is reflected to the beam splitting surface by the second light incident surface Si2, and then transmitted to the first light emergent surface Se1 on the first prism <NUM> via the beam splitting surface. At the same time, ambient light is incident on the beam splitting surface through the second light incident surface Si2 on the second prism <NUM>, which is then transmitted to the first light emergent surface Se1 on the first prism <NUM> via the beam splitting surface. As such, virtual-real aliasing images can be viewed by human eyes from the light emergent side of the first light emergent surface Se1.

In the above process, the second light incident surface Si2 is a convex surface and plated with the transflective medium film, which can collimate light incident thereon to form amplified images. The virtual image light after collimation is more concentrated in energy, which can improve the definition of virtual images viewed by a user.

As shown in <FIG>, in some embodiments, the first light emergent surface Se1 is a concave surface concentric with the second light incident surface Si2, and its curvature radius is the same as that of the second light incident surface Si2, such that effective regions of the beam splitting prism <NUM> are equal in thickness. As such, the distortion of ambient light is reduced, and the quality of ambient light viewed by human eyes is improved.

In some embodiments, the PBS <NUM> may be cemented by a pair of high-precision rectangular prisms. A ramped surface of one of the rectangular prisms is plated thereon with a polarization beam splitting medium film capable of splitting an incident non-polarized light into two linearly polarized light beams perpendicular to each other. Here, the horizontally polarized light (P light) passes through the film completely, while the vertically polarized light (S light) is reflected out at an angle of <NUM> degrees. In other words, the emergent directions of the S polarized light and the P polarized light form an angle of <NUM> degrees.

As shown in <FIG> and <FIG>, the LCOS display chip <NUM> and the LCOS lighting apparatus <NUM> may be arranged on two adjacent sides of the PBS <NUM>. For example, the LCOS display chip <NUM> is arranged on the first axis, and the LCOS lighting apparatus <NUM> is arranged on the second axis. Here, the LCOS lighting apparatus <NUM> comprises a concavo-convex lens <NUM> and a light source device <NUM> that are sequentially arranged along the second axis.

Non-polarized light of large divergence angle emitted by the light source device <NUM> first enters the concavo-convex lens <NUM> where it is refracted, via the concavo-convex lens <NUM>, into light with small divergence angle; then, such light with small divergence angle enters the PBS <NUM>, and is polarized by the polarization beam splitting medium film of the PBS <NUM>; thereafter, one of the linearly polarized light beams may illuminate the LCOS display chip <NUM> so that the LCOS display chip <NUM> may exhibit pictures of different gray scales and colors. In the above or following embodiments of the present disclosure, the virtual image light emitted by the LCOS display chip <NUM> should be construed as the light reflected by the LCOS display chip <NUM> through the above illumination process, and detailed description thereof will be omitted.

Here, a first surface S11 of the concavo-convex lens <NUM> close to the light source device <NUM> is a concave spherical surface, and a second surface S12 away from the light source device <NUM> is a convex spherical surface. After light emitted by the light source device <NUM> is incident on the first surface S11, the light is deflected into small-angled light to be incident on the second surface S12. In order to ensure light collecting efficiency, the second surface S12 is a convex spherical surface in the shape of nearly a semi-spherical surface, such that when the curvature radius is determined, the second surface S12 has a maximum numerical aperture. As such, the light flux of the second surface S12 is increased so as to propagate light refracted thereon by the first surface S11 as much as possible. In addition, as a convex spherical surface, the second surface S12 can endow light emitted out of the concavo-convex lens <NUM> with a smaller divergence angle to control the angle of the illuminative light spot reaching the LCOS display chip <NUM> to be within a reasonable range. Alternatively, when the concavo-convex lens <NUM> is determined, the curvature radius of the second surface S12 may be designed to be twice that of the first surface S11.

In the LCOS lighting apparatus <NUM> provided in the above embodiments, the adoption of the concavo-convex lens <NUM> can achieve a high lighting efficiency. However, in some possible cases, as limited by the encapsulation structure of the light source device <NUM>, the light source device <NUM> gives out light inhomogeneously, thus leading to poor uniformity in the light illuminated on the display area of the LCOS display chip <NUM>. In order to improve the uniformity of illumination for the LCOS display chip <NUM>, the present disclosure also sets forth an LCOS lighting apparatus as shown in <FIG>. As shown in <FIG>, this apparatus further comprises an aspherical positive lens <NUM>.

The aspherical positive lens <NUM> is located between the concavo-convex lens <NUM> and the PBS <NUM>, and coaxial with the concavo-convex lens <NUM>. In some embodiments, the light emitted by the light source device <NUM> may be deflected, by the concavo-convex lens <NUM>, into that of small divergence angle before it is incident on the aspherical positive lens <NUM>. The aspherical positive lens <NUM> can uniformly refract the light emitted by the light source device <NUM> and refracted thereon by the concavo-convex lens <NUM> to the PBS <NUM> where it is polarized by the PBS <NUM> and then enters the LCOS display chip <NUM>.

Here, the aspherical positive lens <NUM> has a curvature radius continuously changes from the center to the edge, and its focal power is positive. As such, the direction of each emergent light ray can be accurately controlled, such that light may reach specified positions on the target plane upon being deflected. In this manner, illuminative light spots are ensured to be distributed fairly uniformly on the LCOS display chip.

In the above or following embodiments of the present disclosure, the first light incident surface Si1 and/or the second light incident surface Si2 may be plated with an anti-reflection film. If the first light incident surface Si1 is plated thereon with an anti-reflection film, the intensity of the virtual image light incident on the first light incident surface Si1 can be increased, such that the virtual images viewed by human eyes are clearer. Similarly, if the second light incident surface Si2 is plated thereon with an anti-reflection film, the intensity of ambient light incident on the second light incident surface Si2 can be increased, such that the true ambient images viewed by human eyes are clearer.

In some embodiments of the present disclosure, the first light incident surface Si1 and/or the second light incident surface Si2 may be a concave surface to enhance its light collecting capability. For example, if the first light incident surface Si1 is a concave surface, the first light incident surface Si1 can propagate the virtual image light emitted by the LCOS display chip <NUM> at a high light collecting efficiency even though the display area of the LCOS display chip <NUM> is augmented.

In the above or following embodiments of the present disclosure, the transflective medium film in the beam splitting prism <NUM> can transmit part of the virtual image light incident through the first light incident surface Si1 to the second light emergent surface Se2 of the beam splitting prism <NUM>, wherein the second light emergent surface Se2 is the surface in the beam splitting prism <NUM> opposite to the first light incident surface Si1. In some possible cases, the light emergent side of the second light emergent surface Se2 is unobstructed, which is likely to let out virtual images, thus undermining privacy of a user.

Therefore, as shown in <FIG>, the prismatic AR display device provided by the present disclosure may further comprise a polarization element <NUM>. The polarization element <NUM> is located on the light emergent side of the second light emergent surface Se2, and the polarization direction of the polarization element <NUM> is perpendicular to that of the PBS <NUM>. As such, the polarization element <NUM> may eliminate the polarized virtual image light transmitted out of the second light emergent surface Se2, which avoids letting out virtual images viewed by a user, thus protecting the privacy of the user and improving user experience.

In some embodiments, the polarization element <NUM> may be an optical element separate from the beam splitting prism <NUM>, e.g., a polarization plate. In some embodiments, the polarization element <NUM> may be designed integrally with the beam splitting prism. For example, the second light emergent surface Se2 of the beam splitting prism <NUM> may be plated with a polarization medium film to further optimize the volume of the display device while achieving light elimination.

With the above embodiments, some embodiments of the present disclosure provides prismatic AR display apparatus comprising any one of the prismatic AR display devices described in the above embodiments. Accordingly, this apparatus has such advantages as small imaging color difference, large field angle and high optical efficiency.

It should be noted that such descriptions as "first" and "second" in this document are used to distinguish between different optical elements and the like. They do not represent the sequential order of the optical elements in optical paths, nor do they define that "first" and "second" are different types.

Claim 1:
A prismatic AR display device, comprising:
an LCOS display chip (<NUM>), a polarization beam splitter, PBS, (<NUM>), a double cemented lens (<NUM>), a first single lens (<NUM>) and a beam splitting prism (<NUM>) which are sequentially arranged along a first axis, and LCOS lighting apparatus (<NUM>) which is arranged on a second axis perpendicular to the first axis and is close to the PBS (<NUM>),
the double cemented lens (<NUM>) comprises a positive lens and a negative lens, the negative lens is close to the PBS, and the positive lens is close to the first single lens;
a first light incident surface (Si1) of the beam splitting prism (<NUM>) is close to the first single lens (<NUM>), and an optical axis of the first light incident surface (Si1) coincides with an optical axis of the first single lens (<NUM>); an optical axis of a second light incident surface (Si2) of the beam splitting prism (<NUM>) is perpendicular to the optical axis of the first light incident surface (Si1), and the second light incident surface (Si2) is opposite to a first light emergent surface (Se1);
the LCOS lighting apparatus (<NUM>) is used for illuminating the LCOS display chip (<NUM>), such that the LCOS display chip (<NUM>) emits virtual image light; after being transmitted by the PBS (<NUM>), the virtual image light emitted by the LCOS display chip (<NUM>) directly enters the double cemented lens (<NUM>), and after being refracted by the double cemented lens (<NUM>), the virtual image light enters the first single lens (<NUM>), and is refracted to the beam splitting prism (<NUM>) by the first single lens(<NUM>); then, on a beam splitting surface of the beam splitting prism (<NUM>), the refracted light is combined with ambient light from the second light incident surface (Si2) of the beam splitting prism (<NUM>) and the combined light is transmitted to human eyes from the first light emergent surface (Se1) of the beam splitting prism (<NUM>),
wherein the virtual image light transmitted by the PBS (<NUM>) enters the beam splitting prism (<NUM>) after passing through five optical surfaces having certain curvature radiuses.