Projection ray machine module and near-to-eye display system using same

Abstract

The invention discloses a projection light machine module, which comprises a lens group and an image rotation prism arranged from an image source to an exit pupil position, and is characterized in that the lens group comprises a plurality of lenses coaxially arranged along the optical axis of the image source, and the lens group is used for receiving image light emitted by the image source; the image rotation prism is arranged between the lens group and the exit pupil position, and the bottom surface of the image rotation prism is parallel to the optical axis; the driving mechanism is used for driving the image rotation prism to rotate around an optical axis, so that the image rotation prism is switched between two states that the bottom surface of the image rotation prism is parallel to the long side or the short side of the image source and the bottom surface of the image rotation prism is obliquely intersected with the long side or the short side of the image source by 45 degrees; therefore, the image at the exit pupil position is switched between a horizontal screen display state and a vertical screen display state. The invention further discloses a near-to-eye display system comprising the projection light machine module, the image at the exit pupil position can rotate by 90 degrees, the size of the image observed by human eyes is not changed during horizontal screen display and vertical screen display, and a good display effect is achieved.

Description

Technical Field

[0001] The present invention relates to a projection optical machine module and also to a near-eye display system using the projection optical machine module. Background Art

[0002] Since the concepts of virtual reality (VR) and augmented reality (AR) were introduced, the market for near-eye display devices based on VR and AR models has seen significant growth. Among the many hardware implementations for AR or VR technology, near-eye displays (NEDs) are the most effective and offer the best user experience available.

[0003] A near-eye display (NED) is a head-mounted display that projects images directly into the viewer's eyes. The NED's display is held so close to the human eye, below the visual distance, that the human eye cannot directly discern the image content. However, the NED's optical system magnifies the image on the display and refocuses it onto the retina, making the magnified image appear as if it were several meters away, thus enabling the display effects of AR and VR technologies.

[0004] At the same time, when using mobile devices, people typically use a vertical screen for streaming media and a horizontal screen for video viewing to adapt to different development applications. However, in currently designed near-eye display systems, the image source displayed can only be rotated to accommodate horizontal and vertical screens through software control. When displayed in vertical mode, the size of the image source displayed by the image source is significantly reduced, and it cannot be displayed full screen. As a result, the image displayed in vertical mode appears significantly smaller than the image displayed in horizontal mode, affecting the viewing experience. Summary of the Invention

[0005] In view of this, the primary technical problem to be solved by the present invention is to provide a projection optical machine module that can achieve a 90° rotation of the image at the exit pupil position while keeping the image displayed by the image source unchanged.

[0006] Another technical problem to be solved by the present invention is to provide a near-eye display system using the above-mentioned projection optical module, which can achieve a 90° rotation of the image observed by the human eye while keeping the image displayed by the image source unchanged.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A projection optical module includes a lens assembly and an image transfer prism arranged in sequence from an image source to an exit pupil position, wherein:

[0009] The lens assembly includes multiple lenses coaxially arranged along the optical axis of the image source. The lens assembly is used to receive the image light emitted by the image source; the focal length of the lens assembly is: 8mm <f<13mm;

[0010] The image-transmitting prism is located between the lens assembly and the exit pupil. The cross-section of the image-transmitting prism is an isosceles trapezoid with an angle of 45°. The bottom surface of the image-transmitting prism is parallel to the optical axis. Image light enters the image-transmitting prism from the light-entering surface, is reflected by the bottom surface, and is emitted from the light-exiting surface to form an image at the exit pupil.

[0011] The projection optical module also includes a driving mechanism for driving the image relay prism to rotate 45° clockwise or counterclockwise around the optical axis, so that the image relay prism switches between a first usage state in which its bottom surface is parallel to the long side or short side of the image source and a second usage state in which its bottom surface is obliquely intersected with the long side or short side of the image source at 45°, thereby rotating the image obtained from the pupil position by 90° and switching between horizontal and vertical display states.

[0012] Preferably, the exit pupil diameter of the projection optical module is:

[0013] Preferably, the lens assembly includes at least three lenses, and the total system length of the projection optical module is less than 50 mm.

[0014] Preferably, the lens assembly includes at least one positive-negative doublet lens, and the positive-negative doublet lens is arranged close to the exit pupil position.

[0015] Preferably, the lens assembly includes a plurality of aspheric lenses, and the number of aspheric optical surfaces is 2 to 6.

[0016] Preferably, in the lens assembly, the lens close to the image relay prism is a positive lens, and the lens close to the image source is a negative lens.

[0017] Preferably, in the image relay prism, the light exit surface and the light incident surface are aspherical surfaces.

[0018] A near-eye display system comprises a waveguide with a two-dimensional pupil expansion function that is perpendicular to the user's visual axis, and the above-mentioned projection optical module.

[0019] Preferably, the horizontal field of view angle and the vertical field of view angle of the waveguide are equal.

[0020] Preferably, the waveguide is a two-dimensional array waveguide or a diffraction waveguide.

[0021] The projection optical module disclosed in the present invention includes a lens assembly and a rotating prism arranged sequentially from the image source to the exit pupil. A drive mechanism drives the rotating prism to rotate 45° about the optical axis, allowing the rotating prism to switch between two states: one in which its bottom surface is parallel to the long side of the image source, and the other in which its bottom surface is tilted and intersected by 45° with the long side of the image source. This allows the image obtained at the pupil position to switch between horizontal and vertical display states. The near-eye display system disclosed in the present invention, including the aforementioned projection optical module, enables 90° rotation of the image at the exit pupil position. Furthermore, after the pupil is expanded by a waveguide, the size of the image observed by the human eye remains unchanged in both horizontal and vertical display modes, achieving excellent display effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of the projection optical machine module provided by the present invention;

[0023] FIG2( a ) is a schematic diagram of a first usage state of a projection optical module, wherein the wide field angle direction of an image at an exit pupil position is parallel to the long side direction of an image source;

[0024] FIG2( b ) is a schematic diagram of a second usage state of the projection optical module, wherein the wide field angle direction of the image at the exit pupil position is perpendicular to the long side direction of the image source;

[0025] Figure 3 Schematic diagram of a two-dimensional array waveguide near-eye display system using the above-mentioned projection optical module;

[0026] Figure 4 Schematic diagram of a diffraction waveguide near-eye display system using the above-mentioned projection optical module;

[0027] Figure 5(a) and Figure 5(b) are Figure 3 Schematic diagram of two display states of the two-dimensional array waveguide near-eye display system shown;

[0028] Figure 6 Schematic diagram of the optical path of the projection optical module in the first embodiment of the present invention;

[0029] Figure 7 Schematic diagram of the optical surface of the projection optical engine module in the first embodiment of the present invention;

[0030] Figure 8 The MTF curve of the projection optical module provided by the first embodiment of the present invention;

[0031] Figure 9 The distortion grid of the projection optical engine module provided by the first embodiment of the present invention;

[0032] Figure 10Schematic diagram of the optical path of the projection optical module in the second embodiment of the present invention;

[0033] Figure 11 Schematic diagram of the optical surface of the projection optical engine module in the second embodiment of the present invention;

[0034] Figure 12 This is the MTF curve of the projection optical module provided by the second embodiment of the present invention;

[0035] Figure 13 The distortion grid of the projection optical engine module provided by the second embodiment of the present invention;

[0036] Figure 14 Schematic diagram of the optical path of the projection optical module in the third embodiment of the present invention;

[0037] Figure 15 Schematic diagram of the optical surface of the projection optical engine module in the third embodiment of the present invention;

[0038] Figure 16 This is the MTF curve of the projection optical module provided by the third embodiment of the present invention;

[0039] Figure 17 The distortion grid of the projection optical engine module provided by the third embodiment of the present invention;

[0040] Figure 18 Schematic diagram of the optical path of the projection optical module in the fourth embodiment of the present invention;

[0041] Figure 19 Schematic diagram of the optical surface of the projection optical engine module in the fourth embodiment of the present invention;

[0042] Figure 20 This is the MTF curve of the projection optical engine module provided by the fourth embodiment of the present invention;

[0043] Figure 21 The distortion grid of the projection optical engine module provided by the fourth embodiment of the present invention;

[0044] Figure 22 Schematic diagram of the optical path of the projection optical module in the fifth embodiment of the present invention;

[0045] Figure 23 Schematic diagram of the optical surface of the projection light engine module in the fifth embodiment of the present invention;

[0046] Figure 24 This is the MTF curve of the projection optical engine module provided by the fifth embodiment of the present invention;

[0047] Figure 25 This is the distortion grid of the projection optical engine module provided by the fifth embodiment of the present invention. Detailed implementation manners

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0049] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not limited to the present invention.

[0051] The present invention provides a projection optical machine module as Figure 1 shown, which includes a lens lens group 30 and an image rotation prism 40 arranged in sequence from an image source 10 to an exit pupil position 20; the lens lens group 30 includes a plurality of lenses coaxially arranged along the optical axis of the image source, and the lens lens group 30 is used to receive the image light emitted by the image source, and the focal length range of the lens lens group is 8mm < f < 13mm; the image rotation prism 40 is arranged between the lens lens group and the exit pupil position, and the cross-section of the image rotation prism is an isosceles trapezoid with an included angle equal to 45°, including a top surface, a bottom surface, an incident light surface inclinedly arranged and an exit light surface inclinedly arranged. The bottom surface of the image rotation prism is parallel to the optical axis. The image light enters the image rotation prism from the incident light surface, is reflected by the bottom surface, and then exits from the exit light surface, and forms an image at the exit pupil position 20; the above projection optical machine module further includes a driving mechanism for driving the image rotation prism 40 to rotate 45° clockwise and counterclockwise around the optical axis, so that the image rotation prism 40 is in a first use state where its bottom surface is parallel to the long side or short side of the image source 10 and a second use state where its bottom surface is inclined and intersects the long side or short side of the image source 10 at 45°, so as to rotate the image at the exit pupil position by 90° and switch between two states of horizontal screen display and vertical screen display.

[0052] Figures 2(a) and 2(b) schematically illustrate the long side direction of the image source and the long side direction of the image at the exit pupil position of the projection optical system. For ease of description, this will be referred to as the wide field angle direction in the following description. As shown in Figures 2(a) and 2(b), the projection optical module can rotate the image at the exit pupil position by 90° by rotating the image relay prism 40, thereby changing the wide field angle direction of the projection optical module. Figure 2(a) illustrates the first usage state of the projection optical module. In this state, the bottom surface of the image relay prism 40 is parallel to the long side of the image source 10, and the wide field angle direction of the image at the exit pupil position is parallel to the long side of the image source 10. Figure 2(b) illustrates the second usage state of the projection optical module. In this state, the bottom surface of the image relay prism 40 intersects the long side of the image source 10 at an oblique angle of 45°, and the wide field angle direction of the image at the exit pupil position is perpendicular to the long side of the image source 10.

[0053] When it is necessary to switch from the horizontal screen display state shown in Figure 2(a) to the vertical screen display, the image relay prism 40 is rotated 45° counterclockwise around the optical axis to the position shown in Figure 2(b). At this time, the bottom surface of the image relay prism 40 obliquely intersects with the long side of the image source 10 at an angle of 45°. The wide field angle direction of the image at the exit pupil position is perpendicular to the long side direction of the image source 10, thereby achieving a 90° rotation of the image at the exit pupil position.

[0054] When it is necessary to switch from the portrait display state shown in Figure 2(b) to the landscape display state, the image relay prism 40 is rotated 45° clockwise around the optical axis to the position shown in Figure 2(a). At this time, the bottom surface of the image relay prism 40 is parallel to the long side of the image source 10, and the wide field angle direction of the image at the exit pupil position is parallel to the long side direction of the image source 10.

[0055] In this projection optical module, the use of a rotating image-transmitting prism 40 reduces the rotational accuracy requirements. Rotation is equivalent to rotating a parallel plate, introducing no additional aberrations. Furthermore, the position of the exit pupil remains unchanged before and after rotation, enabling the projection optical module to switch between horizontal and vertical display fields without changing the structure of other components. Furthermore, by rotating the image-transmitting prism 40, the image at the exit pupil position switches between horizontal and vertical display modes. In both display modes, the size of the image at the exit pupil remains unchanged, unaffecting the display quality.

[0056] In the aforementioned projection optical module, when the light-entry and light-exit surfaces of the image-relay prism 40 are both flat and the image-relay prism has no optical power, the lens assembly 30 includes at least three lenses. In some implementations, the lens assembly 30 includes at least one positive-negative doublet lens, which is positioned near the exit pupil, with the positive lens positioned near the exit pupil and the negative lens positioned away. In some implementations, the lens assembly 30 includes only a plurality of spherical lenses, which may be five, six, or seven in number, with the lens closest to the image-relay prism being a positive lens and the lens closest to the image source being a negative lens. In some implementations, lens assembly 30 includes one, two, or three aspheric lenses. Accordingly, the number of aspheric lenses can range from two to six. When lens assembly 30 includes one or two aspheric lenses, multiple spherical lenses must be used in conjunction with each other to achieve a desired focal length and exit pupil. One or more aspheric lenses are positioned relative to the multiple spherical lenses, closer to the image source. By including aspheric lenses in the lens assembly, the number of lenses can be reduced, shortening the overall length of the optical system. Furthermore, an image-converting prism with optical power can be used to further reduce the number of lenses in the lens assembly and the overall length of the optical system.

[0057] The exit pupil diameter of the above-mentioned projection optical module is: In addition, the total length of the optical system is less than 50 mm, and the total length of the optical system refers to the distance from the image source plane to the exit pupil plane.

[0058] The present invention also provides a near-eye display system using the above-mentioned projection optical module, including a waveguide perpendicular to the visual axis and the above-mentioned projection optical module. Among them, the waveguide uses a waveguide with a two-dimensional pupil expansion function and is adapted to the above-mentioned projection optical module with a circular exit pupil. For example, the waveguide uses a two-dimensional array waveguide or a diffraction waveguide. The exit pupil diameter of the projection optical module of the two-dimensional array waveguide is required to be larger, and the exit pupil diameter of the projection optical module of the diffraction waveguide is required to be smaller. The exit pupil diameter of 2mm to 6mm can cover the use range of the two-dimensional array waveguide and the diffraction waveguide.

[0059] Figure 3A two-dimensional array waveguide near-eye display system using the above-mentioned projection optical module is provided, comprising a two-dimensional array waveguide 51 perpendicular to the user's visual axis, and a projection optical module disposed at the waveguide coupling end 53. The projection optical module is disposed in a manner that ensures that image light entering the waveguide undergoes total internal reflection. The projection optical module is disposed with the optical axis perpendicular to the coupling surface of the coupling end, and preferably, the long side of the image source is parallel to the long side of the coupling end. Of course, it is also possible to dispose the long side of the image source perpendicular to the long side of the coupling end. Preferably, during installation, the bottom surface of the image transfer prism is parallel to the long side of the image source and the long side of the coupling end, which serves as the initial state of use. In this state, the image is displayed in landscape mode. By rotating the image transfer prism 40 clockwise or counterclockwise, the image at the exit pupil position of the projection optical module is converted from landscape mode to portrait mode. The clockwise or counterclockwise rotation direction depends on whether the waveguide optical system is configured for the left or right eye. Then, by rotating the image-transmitting prism in the opposite direction to return it to its original position, the image is restored to horizontal display.

[0060] Figure 4 A diffraction waveguide near-eye display system using the aforementioned projection optical module is provided, comprising a diffraction waveguide 52 perpendicular to the user's visual axis and a projection optical module positioned adjacent to the waveguide coupling grating 54. The projection optical module is configured to ensure that image light entering the waveguide undergoes a predetermined diffraction. During installation, the diffraction waveguide is configured to present a horizontal screen display as the initial state of use. By rotating the image transfer prism 40 clockwise or counterclockwise, the image at the exit pupil of the projection optical module is converted from a horizontal screen display to a vertical screen display. The clockwise or counterclockwise rotation direction depends on whether the waveguide optical system is configured for the left or right eye. The image transfer prism is then rotated in the opposite direction to return to its initial position, restoring the image to a horizontal screen display.

[0061] Figures 5(a) and 5(b) illustrate a 2D array waveguide near-eye display system using the aforementioned projection optical module. The image source is a 0.25-inch display screen with a 4:3 aspect ratio. The projection optical module's exit pupil diameter ranges from 4mm to 6mm. The 2D array waveguide has a diagonal field of view of 30°, with horizontal and vertical fields of view of 24.1°, respectively.

[0062] As shown in Figure 5(a), horizontal screen display is used as the initial state. At this time, the wide field angle direction of the image at the exit pupil position of the projection optical module is parallel to the long side direction of the display screen (image source). The light in the long side direction propagates through the path shown in the figure and reaches the exit pupil position of the waveguide. The human eye can observe the image displayed in horizontal screen. At this time, the field angle of the long side of the image observed by the human eye is 24.1°, and the aspect ratio is 4:3.

[0063] As shown in Figure 5(b), with other components remaining unchanged, the image-relay prism 40 is rotated 45° around the optical axis. At this time, the wide field angle direction of the image at the exit pupil position of the projection optical module is perpendicular to the long side of the display screen. The light in the long side direction propagates along the path shown in the figure and reaches the exit pupil position of the waveguide. The human eye can observe the image displayed in portrait mode. At this time, the field angle of the long side of the image observed by the human eye is 24.1°, and the aspect ratio becomes 3:4.

[0064] The switching process between horizontal screen display and vertical screen display of the diffraction waveguide near-eye display system using the projection optical module provided by the present invention is the same as the above process and will not be repeated here.

[0065] In the following embodiments, projection optical modules with different exit pupil diameters are provided as examples for use with two-dimensional array waveguides and diffraction waveguides.

[0066] First embodiment

[0067] like Figure 6 The projection optical module shown includes a prism 10, a positive-negative doublet lens 11, lens 12, lens 13, lens 14, lens 15, and lens 16, arranged in order from the exit pupil toward the image source (display screen 18). In positive-negative doublet prism 11, the lens closest to the exit pupil is a positive lens, while the lens further away is a negative lens. Lenses 12 and 14 are positive lenses, while lenses 13, 15, and 16 are negative lenses.

[0068] The surface markings of each optical surface of the projection optical module provided in the first embodiment are as follows: Figure 7 As shown, all optical surfaces of the lens assembly are spherical, and the surface parameters of each optical surface are shown in Table 1. The optical surfaces 101, 102, and 103 of the image relay prism and the leftmost surface 104 of the lens assembly use global coordinates to describe the surface position and orientation. The global coordinate reference is the aperture set at the exit pupil position. The specific parameters are shown in Table 2.

[0069] Table 1 Surface parameters of each surface in the first embodiment

[0070]

[0071] Table 2 Coordinates of the global coordinate surface used in the first embodiment

[0072]

[0073]

[0074] The above-mentioned projection optical module uses a 0.25-inch display screen with an aspect ratio of 4:3, an exit pupil diameter of 4mm, and a diagonal field of view of 30°; the focal length of the lens group is 11.9mm, and the total length of the projection optical system is 48.5mm.

[0075] The MTF of the projection optical module is as follows Figure 8 As shown in the figure, when the exit pupil diameter is 4mm, the transfer function value of all fields of view is not less than 0.5 at 120 line pairs / mm, which fully meets the needs of the human eye. Figure 9 As shown, the system distortion rate is about 3%. The system distortion can be pre-distorted and corrected by electronic correction when the image is displayed, and it does not affect the final viewing effect.

[0076] Second embodiment

[0077] like Figure 10 and Figure 11 The lens optical module shown is different from the first embodiment, in that the lens group adopts a combination of two aspherical lenses and two spherical lenses. While the image quality is not significantly reduced, the number of lenses is reduced, the length of the lens group along the optical axis is shortened, and the total length of the optical system is reduced.

[0078] Specifically, if Figure 10 The projection optical module shown includes a prism 20, lenses 21, 22, 23, and 24 arranged in order from the exit pupil toward the image source (display screen 25). Lenses 21 and 23 are positive lenses, while lenses 22 and 24 are negative lenses. In this lens assembly, lenses 21 and 22 near the exit pupil are spherical lenses, while lenses 23 and 24 near display screen 25 are aspherical lenses.

[0079] The surface markings of each optical surface of the projection optical module provided in the second embodiment are shown in FIG. Figure 11 The surface data of each optical surface are shown in Table 3. Surfaces 201, 202, 203, and 204 use global coordinates to describe their position and orientation, with the global coordinate reference being the aperture. Their specific parameters are shown in Table 4. Surfaces 208, 209, 210, and 211 are aspherical, with their coefficients shown in Table 5.

[0080] Table 3 Surface parameters of each surface in the second embodiment

[0081]

[0082]

[0083] Table 4 Coordinates of the global coordinate surface used in the second embodiment

[0084] Surface marking x y z α β γ 201 0 0 3.12 -45 0 0 202 0 -4.73 13.83 -90 0 0 203 0 0 24.54 225 0 0 204 0 0 28.83 0 0 0

[0085] Table 5 Surface parameters of the aspheric surface used in the second embodiment

[0086]

[0087] The equation of the aspheric surface is:

[0088]

[0089] Where c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, and Ai is the coefficient of the higher-order term.

[0090] The above-mentioned projection optical module uses a 0.25-inch display screen with an aspect ratio of 4:3, an exit pupil diameter of 4mm, and a diagonal field of view of 30°; the focal length of the lens group is 11.9mm, and the total length of the optical system is 46mm.

[0091] The MTF of the projection optical module is as follows Figure 12 As shown in the figure, when the exit pupil diameter is 4mm, the transfer function value of all fields of view is greater than 0.4 at 120 line pairs / mm, which fully meets the needs of the human eye. Figure 13 As shown, the system distortion rate is about 3%. The system distortion can be pre-distorted and corrected by electronic correction when the image is displayed, and it does not affect the final viewing effect.

[0092] Third embodiment

[0093] like Figure 14 and Figure 15 The lens optical module shown uses a combination of two aspherical lenses and three spherical lenses.

[0094] Specifically, if Figure 14 The projection optical module shown includes a prism 30, lens 31, lens 32, lens 33, lens 34, and lens 35, arranged in sequence from the exit pupil toward the image source (display screen 36). Lenses 31, 32, and 34 are positive lenses, while lenses 33 and 35 are negative lenses. In this lens assembly, lenses 31, 32, and 33 near the exit pupil are spherical lenses, while lenses 34 and 35 near display screen 36 are aspherical lenses.

[0095] The surface markings of each optical surface of the projection optical module provided in the third embodiment are shown in FIG. Figure 15 The surface data of each optical surface are shown in Table 6. Surfaces 301, 302, 303, and 304 use global coordinates to describe their position and orientation, with the global coordinate reference being the aperture. Their specific parameters are shown in Table 7. Surfaces 310, 311, 312, and 313 are aspherical, with the various aspherical coefficients shown in Table 8.

[0096] Table 6 Surface parameters of each surface in the third embodiment

[0097]

[0098]

[0099] Table 7 Coordinates of the global coordinate surface used in the third embodiment

[0100] Surface marking x y z α β γ 301 0 0 4.10 -45 0 0 302 0 -5.59 16.74 -90 0 0 303 0 0 29.39 225 0 0 304 0 0 34.19 0 0 0

[0101] Table 8 Surface parameters of the aspherical surface used in the third embodiment

[0102]

[0103] The equation of the aspheric surface is:

[0104]

[0105] Where c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, and Ai is the coefficient of the higher-order term.

[0106] The display screen size of this projection optical module is: 0.19 inches, the aspect ratio of the screen is 16:9, the exit pupil diameter is 6mm, the diagonal field of view angle is 25°; the focal length of the lens group is: 10.88mm, and the total length of the system is 50mm.

[0107] The MTF of the projection optical module is as follows Figure 16 As shown in Figure 1, the transfer function value of all viewing fields is greater than 0.2 at 120 line pairs / mm, which can meet the needs of the human eye. Figure 17 As shown, the system distortion rate is about 3%. The system distortion can be pre-distorted and corrected by electronic correction when the image is displayed, and it does not affect the final viewing effect.

[0108] Fourth embodiment

[0109] like Figure 18 and Figure 19 The lens optical module shown uses three aspherical lenses as a lens group and is used in combination with an image-transmitting prism.

[0110] Specifically, if Figure 18 The projection optical module shown includes a prism 40, lens 41, lens 42, and lens 43, arranged in order from the exit pupil toward the image source. Lenses 41 and 42 are positive lenses, while lens 43 is a negative lens. In this lens assembly, all three lenses are aspherical.

[0111] The surface markings of each optical surface of the projection optical module provided in the fourth embodiment are shown in FIG. Figure 19 The surface data of each optical surface are shown in Table 9. Surfaces 401, 402, 403, and 404 use global coordinates to describe their position and orientation, with the global coordinate reference being the aperture. Their specific parameters are shown in Table 10. Surfaces 404, 405, 406, 407, 408, and 409 are aspherical, and their coefficients are shown in Table 11.

[0112] Table 9 Surface parameters of each surface in the fourth embodiment

[0113]

[0114] Table 10 Coordinates of the global coordinate surface used in the fourth embodiment

[0115] Surface marking x y z α β γ 401 0 0 2.16 -45 0 0 402 0 -4.13 11.5 -90 0 0 403 0 0 20.83 225 0 0 404 0 0 24.88 0 0 0

[0116] Table 11 Surface parameters of the aspheric surface used in the fourth embodiment

[0117]

[0118] The equation of the aspheric surface is:

[0119]

[0120] Where c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, and Ai is the coefficient of the higher-order term.

[0121] The projection optical module uses a 0.35-inch display screen with an aspect ratio of 16:9, a diagonal field of view of 40°, an exit pupil diameter of 2mm, a focal length of 12.10mm, and a total system length of 42.2mm.

[0122] The MTF of the projection optical module is as follows Figure 20 As shown in Figure 1, the transfer function value of all viewing fields is greater than 0.2 at 120 line pairs / mm, which meets the needs of the human eye. Figure 21As shown, the system distortion rate is about 2%. The system distortion can be pre-distorted and corrected by electronic correction when the image is displayed, and does not affect the final viewing effect.

[0123] Fifth embodiment:

[0124] Furthermore, in order to reduce the volume, the design freedom is given to the surface of the image-relay prism, such as Figure 22 and Figure 23 As shown, at this time, the two transmission surfaces of the image-relay prism become aspherical surfaces, and the lens assembly can be composed of only two aspherical lenses, and the overall size of the optical machine is further reduced.

[0125] Specifically, if Figure 22 The projection optical module shown includes a prism 50, lens 51, and lens 52, arranged in sequence from the exit pupil toward the image source. Lens 51 is a positive lens, and lens 52 is a negative lens. Both lenses 51 and 52 are aspherical lenses. In this embodiment, the light entrance surface 503 and light exit surface 501 of the prism 50 have optical power, enabling further amplification and aberration correction of light passing through the lens assembly.

[0126] The surface markings of each optical surface of the projection optical module provided in the fifth embodiment are shown in FIG. Figure 23 The specific surface parameters of each optical surface are shown in Table 12. Surfaces 501, 502, 503, and 504 use global coordinates to describe their position and orientation, with the global coordinate reference being the aperture. Their specific parameters are shown in Table 13. Surfaces 501, 503, 504, 505, 506, and 507 are aspherical, and their coefficients are shown in Table 14.

[0127] Table 12 Surface parameters of each surface in the fifth embodiment

[0128]

[0129] Table 13 Coordinates of the global coordinate surface used in the fifth embodiment

[0130]

[0131]

[0132] Table 14 Surface parameters of the aspherical surface used in the fifth embodiment

[0133]

[0134] The equation of the aspheric surface is:

[0135]

[0136] Where c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, and Ai is the coefficient of the higher-order term.

[0137] The display screen size of this projection optical module is: 0.25 inches, the aspect ratio of the screen is 4:3, the exit pupil diameter is 4mm, the diagonal field of view is 30°; the focal length of the lens group is: 11.9mm, and the total length of the system is 43.7mm.

[0138] The MTF of the projection optical module is as follows Figure 24 As shown in Figure 2, the transfer function value of all viewing fields is greater than 0.2 at 70 line pairs / mm, which can meet the needs of the human eye. Figure 25 As shown, the system distortion rate is about 1%. The system distortion can be pre-distorted and corrected by electronic correction when the image is displayed, and does not affect the final viewing effect.

[0139] In summary, the projection optical module provided by the present invention includes a lens assembly and a rotating prism arranged in sequence from the image source to the exit pupil position. The rotating prism is driven by a driving mechanism to rotate 45° around the optical axis, so that the rotating prism switches between a first usage state in which its bottom surface is parallel to the long side of the image source and a second usage state in which its bottom surface is obliquely intersected with the long side of the image source at 45°, thereby enabling the image obtained at the pupil position to be rotated 90°, thereby switching between the two states of horizontal and vertical display. The near-eye display system provided by the present invention, including the above-mentioned projection optical module, adopts the above-mentioned projection optical module to enable the image at the exit pupil position to be rotated 90°, and then enter the human eye through a waveguide. The human eye can view the image displayed in both horizontal and vertical modes. The image size of the two display modes remains unchanged, and only the aspect ratio changes, thereby achieving a good display effect.

[0140] The above description is only a preferred embodiment of the present invention and does not limit the implementation mode and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A projection optical module, characterized in that It includes a lens group and an image-transmitting prism arranged in sequence from the image source to the exit pupil position, wherein: The lens assembly includes multiple lenses coaxially arranged along the optical axis of the image source. The lens assembly is used to receive the image light emitted by the image source; the focal length of the lens assembly is: 8mm <f<13mm; The image-transmitting prism is located between the lens assembly and the exit pupil. The cross-section of the image-transmitting prism is an isosceles trapezoid with an angle of 45°. The bottom surface of the image-transmitting prism is parallel to the optical axis. Image light enters the image-transmitting prism from the light-entering surface, is reflected by the bottom surface, and is emitted from the light-exiting surface to form an image at the exit pupil. The projection optical module also includes a driving mechanism for driving the image relay prism to rotate 45° clockwise or counterclockwise around the optical axis, so that the image relay prism switches between a first usage state in which its bottom surface is parallel to the long side or short side of the image source and a second usage state in which its bottom surface is obliquely intersected with the long side or short side of the image source at 45°, thereby rotating the image obtained from the pupil position by 90° and switching between horizontal and vertical display states.

2. The projection optical module according to claim 1, wherein: The exit pupil diameter of the projection optical module is: 2mm≤φ≤6mm.

3. The projection optical module according to claim 1, wherein: The lens assembly includes at least three lenses, and the total system length of the projection optical module is less than 50 mm.

4. The projection optical module according to claim 3, wherein: The lens assembly includes at least one positive-negative doublet lens, and the positive-negative doublet lens is arranged near the exit pupil position.

5. The projection optical module according to claim 3, wherein: The lens assembly includes a plurality of aspheric lenses, and the number of the aspheric optical surfaces is 2 to 6.

6. The projection optical module according to claim 3, wherein: In the lens assembly, the lens close to the image relay prism is a positive lens, and the lens close to the image source is a negative lens.

7. The projection optical module according to claim 2, wherein: In the image relay prism, the light exiting surface and the light incident surface are aspherical surfaces.

8. A near-eye display system, characterized in that: It comprises a waveguide which is perpendicular to the visual axis of the user and has a two-dimensional pupil expansion function, and a projection optical module as described in any one of claims 1 to 7.

9. The near-eye display system according to claim 8, wherein: The horizontal field of view angle and the vertical field of view angle of the waveguide are equal.

10. The near-eye display system according to claim 8, wherein: The waveguide is a two-dimensional array waveguide or a diffraction waveguide.

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