A miniature projection system and near-eye display device

Abstract

The application discloses a kind of micro projection system and near-eye display equipment, for being placed in the non-self-luminous image of image source surface to projection surface projection, comprising: first prism, second prism and PBS prism;Wherein, illumination light, after being injected into PBS prism, is reflected by polarized light splitting surface, and is propagated in second prism and first prism, and is emitted from incident surface, and is shot to image source surface;Image light is configured as linearly polarized light, which is converted after being reflected by image source surface illumination light polarized direction, image light enters first prism by incident surface, is reflected by second surface, is reflected by third surface or other surface adjacent to third surface, then transmits second surface, then enters PBS prism after transmitting second prism, and image light is emitted from PBS prism after transmitting polarized light splitting surface, and is shot to projection surface.The micro projection system, imaging light path and illumination light path share first prism, second prism and PBS prism, realize light path folding, greatly reduce the volume of projection system.

Description

TECHNICAL FIELD

[0001] The present application relates to a micro-projection system, and relates to a near-eye display device using the micro-projection system. BACKGROUND

[0002] Since the concept of virtual reality (VR) and augmented reality (AR) was proposed, the market of near-eye display devices based on VR or AR mode has made great progress. Among many hardware implementation modes of AR or VR technology, the near-to-eye display (NED) is the most effective and can bring the best experience to the user. Because the near-to-eye display needs to be worn on the head of a person, its small size and good display effect are particularly important.

[0003] The waveguide system is a representative of the light and thin scheme in the current near-eye display scheme, and the thickness of the waveguide is relatively light and thin, generally within 3 mm; the waveguide needs to be used with a projection system, however, the volume of the existing projection system is usually large, and the size of the projection system directly restricts the overall volume size of the display module. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a micro-projection system.

[0005] Another technical problem to be solved by the present application is to provide a near-eye display device using the micro-projection system.

[0006] In order to achieve the above technical purpose, the present application adopts the following technical scheme:

[0007] According to a first aspect of an embodiment of the present application, a micro-projection system is provided for projecting a non-self-luminous image placed on an image source surface to a projection surface, comprising:

[0008] A first prism includes an incident surface close to the image source surface, a second surface close to the projection surface, and a third surface away from the projection surface;

[0009] A second prism is arranged between the first prism and the projection surface;

[0010] A PBS prism is arranged between the second prism and the projection surface; the PBS prism is provided with a polarization beam splitting surface;

[0011] The illumination light is linearly polarized light, after the illumination light enters the PBS prism, it is reflected by the polarization beam splitting surface, then it is directed to the second prism, then it propagates in the second prism and the first prism, and is emitted from the incident surface to the image source surface

[0012] The image light is configured as linear polarized light whose polarization direction is changed after the illumination light is reflected by the image source surface, the image light enters the first prism through the incidence surface, is reflected by the second surface, is reflected by the third surface or other surface adjacent to the third surface, transmits through the second surface, then enters the PBS prism after transmitting through the second prism, and is emitted from the PBS prism after transmitting through the polarization beam splitting surface, and is directed to the projection surface.

[0013] According to a preferred embodiment of the present application, preferably, the first prism and the second prism are wedge prisms, and a gap is arranged between the first prism and the second prism.

[0014] Preferably, the first prism and the second prism are free-form prisms, and the incidence angle of the image light when the image light is emitted from the incidence surface to the second surface satisfies the total reflection condition.

[0015] According to another preferred embodiment of the present application, preferably, the first prism and the second prism are triangular prisms, a polarization beam splitting film is arranged between the first prism and the second prism, and the first prism and the second prism are pasted to form another PBS prism.

[0016] Preferably, the third surface of the first prism is provided with a 1 / 4 wave plate, and a first curved mirror is arranged on the side of the third surface.

[0017] The second prism has a fourth surface opposite to the incidence surface, the fourth surface is provided with a 1 / 4 wave plate, and a second curved mirror is arranged on the side of the fourth surface.

[0018] Preferably, a first lens group is arranged between the first curved mirror and the first prism, and a second lens group is arranged between the second curved mirror and the second prism.

[0019] Preferably, the first curved mirror is realized by attaching a total reflection film to the surface of the first prism away from the first lens group, and the second curved mirror is realized by attaching a total reflection film to the surface of the second prism away from the second lens group.

[0020] Preferably, the micro projection system further comprises:

[0021] a micro display screen for providing image light to the first prism, the micro display screen reflects light and changes the polarization direction of linear polarized light at the same time;

[0022] an illumination light source for providing illumination light to the PBS prism, and a linear polarized plate is arranged between the illumination light source and the PBS prism.

[0023] Preferably, an illumination homogenization and collimation system is further arranged between the illumination light source and the PBS prism.

[0024] According to a second aspect of the embodiments of the present application, a near-eye display device is provided, comprising the above-mentioned micro-projection system, and further comprising a waveguide system, a coupling-in end of the waveguide system being arranged at a position of the projection surface of the micro-projection system.

[0025] The present application discloses a micro-projection system and a near-eye display device, comprising an imaging system and an illumination system sharing a first prism, a second prism and a PBS prism, wherein image light enters the first prism through an incident surface, is reflected by a second surface, is reflected by a third surface or another surface adjacent to the third surface, then transmits through the second surface, then transmits through the second prism, and then enters the PBS prism, and the image light transmits through a polarization beam splitting surface of the PBS prism and is emitted from the PBS prism to a projection surface; illumination light is emitted into the PBS prism, is reflected by the polarization beam splitting surface, is emitted to the second prism, then propagates in the second prism and the first prism, and is emitted from the incident surface. The micro-projection system shares the first prism, the second prism and the PBS prism for the imaging light path and the illumination light path, realizes light path folding, and greatly reduces the volume of the projection system. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the overall light path of the micro-projection system in the first embodiment;

[0027] Figure 2 is a schematic diagram of the imaging light path in the micro-projection system in the first embodiment;

[0028] Figure 3 is a light path diagram of part of the elements in the imaging light path in the first embodiment;

[0029] Figure 4 is a schematic diagram of the illumination light path in the micro-projection system in the first embodiment;

[0030] Figure 5 is a schematic diagram of the near-eye display device composed of the micro-projection system shown in the first embodiment and a waveguide system;

[0031] Figure 6 is a schematic diagram of the overall light path of the micro-projection system in the second embodiment;

[0032] Figure 7 is a light path diagram of part of the elements in the imaging light path in the second embodiment;

[0033] Figure 8 is a schematic diagram of the illumination light path in the micro-projection system in the second embodiment;

[0034] Figure 9This is a schematic diagram of the imaging optical path in the micro-projection system in the second embodiment. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0036] This invention discloses a micro-projection system and a near-eye display device using the micro-projection system and waveguide system. The micro-projection system projects a non-self-emissive image placed on an image source surface onto a projection surface. The micro-projection system includes an illumination system and an imaging system. The illumination system provides illumination light to the image source surface; the illumination light is linearly polarized. The imaging system outputs image light from the image source surface to the projection surface; the image light is configured as linearly polarized light whose polarization direction is changed after reflection from the image source surface. The imaging system and the illumination system share a first prism, a second prism, and a PBS prism, thereby achieving optical path folding and significantly reducing the size of the projection system.

[0037] First Embodiment

[0038] like Figures 1 to 4 As shown, the micro-projection system provided in this embodiment includes a micro-display screen 108, an LED light source 201, a PBS prism 102, a second prism 104, and a first prism 105. The surface where the display screen 108 is located is the image source surface 203, and the surface where the aperture 109 is located is the projection surface. The imaging system consists of the micro-display screen 108, the first prism 105, the second prism 104, the PBS prism 102, and auxiliary lenses 107, 106, and 101. The illumination light route consists of the illumination light source 201, the illumination homogenizing and collimating system 202, the PBS prism 102, the second prism 104, the first prism 105, and auxiliary lenses 204, 106, and 107. The imaging system and the illumination system share the first prism 105, the second prism 104, and the PBS prism 102.

[0039] Specifically, the microdisplay 108 is a non-self-emissive display such as Liquid Crystal on Silicon (LCOS) or Digital Micromirror Devices (DMD). The microdisplay 108 can change the polarization direction of linearly polarized light while reflecting light.

[0040] like Figure 3As shown, the first prism 105 includes an incident surface S6 close to the image source surface 203, and a second surface S4 close to the projection surface and a third surface S5 away from the projection surface. The first prism 105 is a wedge prism or a triangular prism, and a wedge prism is used in this embodiment. The surface types of the incident surface S6, the second surface S4 and the third surface S5 of the first prism 105 are spherical, aspherical or free-form surface; preferably, the incident surface S6 of the first prism 105 is aspherical or free-form surface, and the surface types of the second surface S4 and the third surface S5 are free-form surface to correct system aberration. The surface of the third surface S5 is provided with a total reflection film. The image light emitted by the micro display screen 108 enters the first prism 105 through the incident surface S6, and the incident angle of the image light to the second surface S4 for the first time satisfies the total reflection condition. After the image light is totally reflected by the second surface S4, the image light reaches the third surface S5 and is reflected to the second surface S4. At this time, the total reflection condition is not satisfied, and the image light transmits through the second surface S4 to reach the second prism 104.

[0041] A lens group including a positive lens 107 and a negative lens 106 is further arranged between the first prism 105 and the micro display screen 108, for adjusting the focal power and magnification of the imaging system. The lens group can also be a positive-negative cemented lens, which is not limited herein.

[0042] The second prism 104 is arranged between the first prism 105 and the projection surface 109. The second prism 104 is a wedge prism or a triangular prism, and a wedge prism is used in this embodiment. There is a gap between the second prism 104 and the first prism 105 to ensure the total reflection effect of the second surface S4. The second prism 104 includes a surface S3 close to the first prism, a surface S1 facing the projection surface, and a non-optical surface S2 between S3 and S1. The surface types of the surface S3 close to the first prism and the surface S1 facing the projection surface can be spherical, aspherical or free-form surface. Among them, the surface types of the surface S3 close to the first prism and the second surface S4 are consistent, and preferably the gap between them is less than 1 mm.

[0043] The PBS prism 102 is arranged between the second prism 104 and the projection surface 109; the PBS prism 102 is provided with a polarization splitting surface 103, which can be a film-coated splitting film layer or a film-pasted splitting film layer. The film system is characterized by transmitting P-polarized light and reflecting S-polarized light. In this embodiment, the image light reaching the polarization splitting surface 103 is P-type polarized light, and the image light transmits through the polarization splitting surface 103 to the projection surface 109.

[0044] A plano-convex lens 101 is arranged on the side of the PBS prism 102 facing the projection surface 109, and the plane of the plano-convex lens 101 is pasted on the surface of the PBS prism 102.

[0045] As Figure 2As shown in the figure, it is the schematic diagram of the imaging light path of the micro projection system. In the imaging process, linearly polarized light is emitted from the micro display screen 108, and after refraction by the lenses 107 and 106, it enters the wedge prism 105 through the incident surface S6. At this time, the schematic diagram of the light propagation in the wedge prism 105 is as shown in the figure Figure 3 As shown in the figure, due to the air gap between the surface S3 of the wedge prism 104 and the second surface S4 of the wedge prism 105, the light will be incident to the third surface S5 after total reflection at the surface S4. The surface of the third surface S5 is coated or attached with a total reflection film. After reflection by the third surface S5, the light is incident to the second surface S4 again. At this time, the light no longer satisfies the total reflection condition, and thus is emitted from the second surface S4 and enters the wedge prism 104. After the image light transmits through the surface S3 adjacent to the first prism 105 and the surface S1 facing the projection surface, it is emitted from the wedge prism 104 and enters the PBS prism 102. At this time, the polarization state of the image light satisfies the transmission polarization state of the beam splitter prism, and the image light is transmitted and propagated from the polarization beam splitting surface 103 and then transmits through the lens 101 to the stop position 109 of the image light, i.e. the position of the projection surface.

[0046] In this experimental example, a set of optical related parameters are provided according to the above system, which are shown in Table 1 and Table 2.

[0047] Table 1: Parameters of each optical surface in the imaging system provided by the first embodiment

[0048]

[0049]

[0050] Table 2: Eccentricity data of the optical surfaces of the wedge prisms 104 and 105 (relative to the projection surface 109)

[0051] X eccentricity Y eccentricity Z eccentricity Alpha tilt S1 0 0 7.5403 0 S3 0 1.293456 8.51253 27.36136 S5 0 0.491254 11.68895 -9.96077 S6 0 4.212386 9.747441 79.00855

[0052] The micro projection system provided by the present application comprises an illumination system for providing illumination light to the image source surface 203. The schematic diagram of the illumination system is as shown in the figure Figure 4As shown, the illumination system comprises an illumination light source and an illumination homogenization and collimation system, wherein the illumination light source is an LED light source 201, which is a self-luminous high-brightness LED lamp, and the illumination homogenization and collimation system is an optional element, which comprises a collimation element, a filter element and a homogenization element, the collimation element can be a lens group or a TIR lens and the like optical element having a receiving effect on the angle of light, and the homogenization element can be a microlens array or a light rod and the like differential optical device.

[0053] Figure 5 is the optical principle diagram of the near-eye display device composed of the micro projection system and the waveguide system provided by the present application. Wherein the coupling-in end of the waveguide system 20 is arranged at the projection surface position of the micro projection system 10, so that the image light enters the waveguide system 20 through the coupling-in end and then undergoes multiple total reflections, and finally exits through the coupling-out element and enters the human eye. The waveguide system can be a geometric waveguide, a diffractive waveguide or other optical systems with pupil expansion characteristics.

[0054] Here, the typical data of the micro projection system provided by the above embodiment is given, the field of view angle is 40°, the optical volume is 13mmx15mmx8mm, about 1.56cc. As can be seen, the volume of the micro projection system is small, which can thin the thickness of the entire near-eye display device, so that the near-eye display device is made into the form of glasses.

[0055] Second embodiment

[0056] As Figures 6 to 9As shown, the micro projection system provided by the embodiment includes a micro display screen 316, an LED light source 308, a PBS prism 302, a second PBS prism 312 composed of a second prism and a first prism, a first curved mirror 315, a second curved mirror 309, an illumination homogenization collimation system, and other auxiliary lenses. Among them, the plane where the light-emitting surface of the display screen 316 is located is the image source plane, and the plane where the diaphragm 304 is located is the projection plane; the imaging system is composed of the micro display screen 316, the second PBS prism 312 composed of the first prism and the second prism, the first curved mirror 315, the PBS prism 302, and the lenses 304, 313, and 314; the illumination light path is composed of the illumination light source 308, the illumination relay system, the PBS prism 302, the second PBS prism 312 composed of the second prism and the first prism, the second curved mirror 309, and other lenses 303, 310, and 311; the imaging system and the illumination system share the PBS prism 302 and the second PBS prism 312 composed of the first prism and the second prism.

[0057] Specifically, the micro display screen 316 is a non-self-luminous display screen such as a Liquid Crystal on Silicon (LCOS) or a Digtial Micromirror Device (DMD). The micro display screen 316 reflects light and changes the polarization direction of linearly polarized light at the same time.

[0058] In this embodiment, the first prism and the second prism are triangular prisms, and a polarization beam splitter film 319 is arranged between the first prism and the second prism. The film is characterized by transmitting P-polarized light and reflecting S-polarized light. The first prism and the second prism are glued to form the second PBS prism 312.

[0059] As shown in FIG. 3, Figure 7 In the PBS prism 312, the triangular prism close to the projection plane 304 is defined as the second prism 312B, and the triangular prism away from the projection plane 304 is defined as the first prism 312A. The face of the first prism 312A facing the micro display 316 is defined as the incident face S6, the face of the first prism 312A close to the second prism 312B is defined as the second face S4, and the face of the first prism 312A away from the second prism 312B is defined as the third face S5. The face of the second prism 312B opposite to the incident face S6 is defined as the fourth face S2. Each face of the first prism 312A and the second prism 312B is a plane.

[0060] As shown in FIG. 3, Figure 6 and 8 A quarter-wave plate 321 is pasted on the third face S5 of the first prism 312A, and a lens 313, a lens 314, and a first curved mirror 315 are arranged outside the third face S5 for correcting the aberration of the imaging system.

[0061] As Figure 6 and 9 As shown in the fourth surface S2 of the second prism 312B, a quarter wave plate 320 is pasted, and a lens 311, a lens 312 and a second curved mirror 309 are arranged outside the fourth surface S2 for correcting the aberration of the illumination system.

[0062] In this embodiment, the parameters of the lens 311 and the lens 312 arranged outside the third surface S5 are the same as the parameters of the lens 313 and the lens 314 arranged outside the fourth surface S2. The lens 311 and the lens 312 are preferably positive-negative cemented lenses.

[0063] In this embodiment, the parameters of the second curved mirror 309 and the first curved mirror 315 are the same, and the first curved mirror 315 and the second curved mirror 309 are independent mirrors. In other embodiments, the parameters of the first curved mirror 315 and the second curved mirror 309 can be different, and the first curved mirror 315 and the second curved mirror 309 can also be realized by attaching a total reflection film to the surface of the lens 314 and the lens 310 farthest from the PBS prism 312.

[0064] A PBS prism 302 is arranged between the second PBS prism 312 and the projection surface 304. A polarization splitting surface 318 is arranged in the PBS prism 302, which can be a film-coated splitting film layer or a film-pasted splitting film. The film system is characterized by transmitting P-polarized light and reflecting S-polarized light.

[0065] On the side of the PBS prism 302 facing the projection surface 304, a plano-convex lens 301 is arranged, and the plane of the plano-convex lens 301 is pasted on the surface of the PBS prism 302.

[0066] In this embodiment, the illumination system includes an illumination light source and an illumination uniformity collimation system; wherein the illumination light source 308 is an LED light source, and the illumination uniformity collimation system is an optional element including a TIR lens 307, a dichroic sheet 306 and a microlens array 305. The TIR lens 307 is a collimation element, the dichroic sheet 306 is a filtering element, and the microlens array 305 is a uniformity element.

[0067] In the illumination system, a plano-convex lens 303 is further included, and the plane of the plano-convex lens 303 is pasted on the surface of the PBS prism 302 facing the illumination light source 308. A linear polarizer 317 is also arranged on the surface of the PBS prism 302 facing the illumination light source (see Figure 8 ), so as to convert the illumination light into linearly polarized light.

[0068] The embodiment provides a set of optical correlation parameters according to the system. The lens 301 and the lens 303 are glass spherical lenses, the lens 301 and the lens 303 are cemented on adjacent surfaces of the same PBS prism 302; the lens 310 and the lens 311 are spherical lenses, the lens 310 and the lens 311 form a positive-negative cemented lens, the second curved mirror 309 is an aspherical mirror; the lens 313 and the lens 314 are spherical lenses, the lens 313 and the lens 314 form a positive-negative cemented lens, the first curved mirror 315 is an aspherical mirror; wherein the optical parameters of the lens 313, the lens 314, the lens 310 and the lens 311 are the same, the optical parameters of the first curved mirror 315 and the second curved mirror 309 are the same. The specific parameters of the optical lens or prism are shown in Table 3 and Table 4.

[0069] Table 3: Parameters of each optical surface in the micro projection system provided by the second embodiment

[0070]

[0071] Table 4: Optical parameters of the aspherical curved mirror 315

[0072]

[0073]

[0074] In the embodiment, the light path diagram of the illumination system is shown in Figure 8 The illumination light is emitted by the LED light source 308, and the light needs to be collimated by the TIR lens 307 due to the large divergence angle of the LED light source. The light passes through the relay system 306 to play a filtering role, and the light forms a beam splitting and uniform light function after passing through the microlens array 305. The light enters the prism 302 after passing through the lens 303, and the middle of 302 and 303 is a plane cemented. The cemented middle has a linear polarizer 317, which can form S polarized light from the light emitted by the LED. The light is reflected after being converted into S polarized light and being incident on the PBS polarizing film 318, so as to be emitted from the PBS prism 302 and enter the second prism 312B. The image light is reflected by the polarization beam splitting film 319 between the first prism 312A and the second prism 312B. The S polarized light passing through the 1 / 4 wave plate 320 of the fourth surface S2 of the second prism 312B is converted into left-handed polarized light. The illumination light emitted from the PBS prism 312 is incident downward on the cemented lens group 311, 310, and then enters 310, 311 again after being reflected by the aspherical mirror. The reflected light is converted into right-handed polarized light, and the polarized light is converted into P polarized light again after passing through the 1 / 4 wave plate 320. The P polarized light is transmitted to the LCOS panel 316 after being incident on the PBS polarizing film 319.

[0075] The imaging system light path diagram is shown as follows Figure 9 After the illumination light is reflected by the LCOS 316, the polarization state of the image light is converted from P-type polarized light to S-type polarized state. After the image light is reflected by the PBS polarizing film 319, the image light penetrates the cemented prism group through the 1 / 4 wave plate 321, and is reflected by the aspheric mirror 315 again through the 1 / 4 wave plate. At this time, the S-type polarized light is converted into P-type polarized light. After the image light penetrates the two PBS prisms, the image light is emitted from the diaphragm position 304.

[0076] In summary, the micro projection system and the near-eye display device provided by the present application, wherein the imaging light path and the illumination light path share a plurality of elements such as the first prism, the second prism and the PBS prism, the illumination light path and the imaging light path are folded multiple times, the volume of the projection system is greatly reduced, the miniaturization of the projection system is realized, and finally the volume of the near-eye display device is reduced.

[0077] The micro projection system and the near-eye display device provided by the present application are described in detail above. Any obvious modification made by the person skilled in the art without departing from the essential content of the present application will constitute an infringement of the patent right of the present application, and the corresponding legal responsibility will be borne.

Claims

1. A micro projection system for projecting a non-self-luminous image placed on an image source plane to a projection plane, characterized by, Comprise: A first prism, including an incident surface close to the image source surface, and a second surface close to the projection surface and a third surface away from the projection surface; the third surface of the first prism is provided with a 1 / 4 wave plate; A first curved mirror is provided on the side of the third surface; A second prism is provided between the first prism and the projection surface; a polarization beam splitter film is provided between the first prism and the second prism; the second prism has a fourth surface opposite to the incident surface; the fourth surface is provided with a 1 / 4 wave plate; a second curved mirror is provided on the side of the fourth surface; A PBS prism is provided between the second prism and the projection surface; a polarization beam splitter surface is provided in the PBS prism; The illumination light is linearly polarized light, after the illumination light enters the PBS prism, it is reflected by the polarization beam splitter surface, then enters the second prism, is reflected by the second surface, is reflected by the second curved mirror adjacent to the fourth surface, transmits through the second surface, enters the first prism, and is emitted from the incident surface to the image source surface; The image light is configured as linearly polarized light whose polarization direction is changed after the illumination light is reflected by the image source surface, the image light enters the first prism through the incident surface, is reflected by the second surface, is reflected by the first curved mirror adjacent to the third surface, transmits through the second surface, then transmits through the second prism to enter the PBS prism, and is emitted from the PBS prism to the projection surface after transmitting through the polarization beam splitter surface.

2. The micro projection system according to claim 1, wherein: The first prism and the second prism are triangular prisms, and the first prism and the second prism are pasted to form another PBS prism.

3. The micro projection system according to claim 2, wherein: A first lens group is provided between the first curved mirror and the first prism; A second lens group is provided between the second curved mirror and the second prism.

4. The micro projection system according to claim 3, wherein: The first lens group and the second lens group are positive-negative double cemented lenses respectively.

5. The micro projection system according to claim 3, wherein: The first curved mirror is implemented by attaching a total reflection film to the surface of the first prism away from the first lens group through the first lens group; The second curved mirror is implemented by attaching a total reflection film to the surface of the second prism away from the second lens group through the second lens group.

6. The micro projection system according to claim 2 or 3, wherein: The surface types of the first curved mirror and the second curved mirror are aspherical surfaces.

7. The micro -projection system of claim 2, wherein the light source is a light emitting diode (LED). Further comprising: A micro display screen for providing image light to the first prism; the micro display screen reflects light and changes the polarization direction of linearly polarized light at the same time; An illumination light source for providing illumination light to the PBS prism, and a linear polarizer is provided between the illumination light source and the PBS prism.

8. The micro projection system according to claim 7, wherein: An illumination homogenization and collimation system is further provided between the illumination light source and the PBS prism.

9. A near-eye display device comprising the micro-projection system of any of claims 1-8, further comprising a waveguide system, an in-coupling end of the waveguide system being disposed at a location of the projection face of the micro-projection system.

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