Optical systems and head mounted display devices

Abstract

The embodiments of the present disclosure provide an optical system and a head-mounted display device. The optical system of the embodiments of the present disclosure may include: a display element, a lens, a beam splitter, and a reflector arranged in sequence along the optical axis of the system; the lens can magnify the image displayed by the display element; wherein the light from the display element passes through the lens, the beam splitter, and the reflector in sequence, and after passing through the beam splitter again, enters the eye box of the optical system, and the eye box is set at a preset eye distance; the optical system meets any of the following dimensions: the height of the optical system is less than or equal to 27mm, and the thickness is less than or equal to 20mm; the height of the optical system is less than or equal to 24mm, and the thickness is less than or equal to 16mm.

Description

[0001] The present disclosure is a divisional application of a utility model patent application with an application date of September 12, 2023, an application number of 202322476849.3, and an invention name of “Optical system and head-mounted display device”. Technical Field

[0002] The embodiments of the present disclosure relate to the field of augmented reality technology, and in particular to an optical system and a head-mounted display device. Background Art

[0003] Augmented reality technology is a technology that presents and interacts virtual scenes with real scenes. By projecting virtual images and real scenes into the user's eyes at the same time, it can provide users with a visual experience that integrates virtual and real scenes. Wearing devices that implement augmented reality, such as head-mounted display devices and AR glasses, is a common way for users to experience the integration.

[0004] As application requirements increase, the overall structure of head-mounted display devices is required to be more compact. However, it is difficult to balance the volume of the optical system, the field of view, and the eye box (i.e., the area where the human eye can move and within which the human eye can see the entire displayed image) in design. Utility Model Content

[0005] In view of this, an embodiment of the present disclosure provides an optical system and a head-mounted display device.

[0006] According to a first aspect of an embodiment of the present disclosure, an optical system is provided, comprising: a display element, a lens, a beam splitter, and a reflector arranged in sequence along an optical axis of the system; the lens can magnify the image displayed by the display element; wherein light from the display element passes through the lens, the beam splitter, and the reflector in sequence, and after passing through the beam splitter again, enters an eye box of the optical system, and the eye box is set at a preset eye-adaptive distance; the optical system satisfies any of the following dimensions: the height of the optical system is less than or equal to 27 mm, and the thickness is less than or equal to 20 mm; the height of the optical system is less than or equal to 24 mm, and the thickness is less than or equal to 16 mm.

[0007] According to a second aspect of an embodiment of the present disclosure, a head-mounted display device is provided, wherein the head-mounted display device includes the above-mentioned optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present disclosure. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0009] Figure 1A schematic diagram of the structure of an optical system provided in an embodiment of the present disclosure.

[0010] Figure 2 A schematic diagram of another optical system structure provided in an embodiment of the present disclosure.

[0011] Figure 3 for Figure 1 An imaging light path diagram of an optical system of the type shown.

[0012] Figure 4 A schematic diagram of an optical transfer function (MTF) curve of an optical system provided in an embodiment of the present disclosure.

[0013] Figure 5 It is a schematic structural diagram of a head mounted display device according to an exemplary embodiment of the present disclosure.

[0014] Description of reference numerals:

[0015] 100: Optical system

[0016] 101: Display components

[0017] 102: Lens

[0018] 103: Spectroscope

[0019] 104: Reflector

[0020] 500: Head-mounted display device DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in the field should belong to the scope of protection of the embodiments of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0022] The specific implementation of the embodiment of the present disclosure is further explained below in conjunction with the accompanying drawings of the embodiment of the present disclosure.

[0023] Figure 1 shows a schematic diagram of the structure of an optical system provided by some embodiments of the present disclosure, Figure 2 Another structural schematic diagram of the optical system provided by some embodiments of the present disclosure is shown.

[0024] See also Figure 1 , Figure 2, the optical system 100 includes: a display element 101, a lens 102, a beam splitter 103 and a reflector 104 arranged in sequence along the optical axis of the system. The light emitted by the display element 101 passes through the lens 102, the beam splitter 103 and the reflector 104 in sequence and then passes through the beam splitter 103 again before entering the eye box of the optical system 100, so that the human eye located in the eye box can see the image displayed by the display element 101.

[0025] The display element 101 is used to display the image that needs to be projected into the human eye. The display element 101 can be, but is not limited to, a relatively small display to minimize the overall volume of the optical system 100. For example, the display element 101 can be an organic light-emitting diode (OLED) image source, a liquid crystal on silicon (LCOS) image source, a liquid crystal (LCD) image source, a micro-electro-mechanical system (MEMS) image source, or a digital micromirror device (DMD) image source. The image displayed by the display element 101 can be, but is not limited to, various types such as 2D images, 3D images, static images, and dynamic images.

[0026] The lens 102 is used to provide a diopter for the optical system 100 , and can magnify the image displayed by the display element 101 . When the image displayed by the display element 101 is relatively small, the image displayed by the display element 101 can be magnified.

[0027] The beam splitter 103 is used to split the incident light. The beam splitter 103 has a first surface and a second surface, and either the first surface or the second surface can be used as the beam splitting surface of the beam splitter 103. The beam splitting surface is partially transmissive and partially reflective.

[0028] The reflector 104 is used to reflect the incident light so that the light is deflected and enters the eye box. The reflector 104 can be partially transmissive, partially reflective, or fully reflective.

[0029] It should be noted that, for the entire optical system, the system optical axis is the line connecting the optical centers of the optical elements in the optical system, and the optical elements are arranged along the system optical axis; for a single optical element (for example, the optical axis of a reflector), the optical axis of the optical element passes through the optical center of the optical element, and no deflection occurs between the incident light and the outgoing light. It is understandable that due to manufacturing and assembly errors, the system optical axis and the optical axis of a single optical element may not be a perfect straight line.

[0030] In some possible implementations, see Figure 1 , the display element 101, the lens 102 and the reflector 104 are located on the same side of the beam splitter 103. The normal direction of the display element 101 is consistent with or parallel to the optical axis of the lens 102. The lens 102 has a first surface close to the beam splitter 103 and a second surface close to the display element 101. The beam splitter 103 has a second surface close to the lens 102 and a first surface away from the lens 102. The second surface of the beam splitter 103 is a beam splitting surface. The beam splitting surface of the beam splitter 103 is inclined at a certain angle to the optical axis of the lens 102. The optical axis of the reflector 104 is inclined at a certain angle to the beam splitting surface of the beam splitter 103. The reflector 104 can be a semi-transparent and semi-reflective lens.

[0031] like Figure 1 As shown, the light emitted by the display element 101 enters the lens 102, passes through the second surface and the first surface of the lens 102, and then enters the second surface of the beam splitter 103. Part of the light is transmitted through the second surface and the first surface of the beam splitter 103, and part of the light is reflected by the second surface (i.e., the beam splitting surface) of the beam splitter 103 to the reflective surface of the reflector 104. The light reflected by the reflective surface of the reflector 104 passes through the beam splitter 103 again, and then enters the eye box. Natural light from the real world can enter the eye box after passing through the reflector 104 and the beam splitter 103, so that the human eye in the eye box can see the clear image displayed by the enlarged display element 101 and the real world at the same time.

[0032] In some possible implementations, see Figure 2 , the display element 101, the lens 102 and the reflector 104 can be arranged on both sides of the beam splitter 103. In other words, the display element 101 and the lens 102 can be arranged on one side of the beam splitter 103, and the reflector 104 can be arranged on the other side of the beam splitter 103. The normal direction of the display element 101 is consistent with or parallel to the optical axis of the lens 102. The lens 102 has a second surface close to the display element 101 and a first surface close to the beam splitter 103. The beam splitter 103 has a second surface close to the lens 102 and a first surface close to the reflector 104. The second surface of the beam splitter 103 is a transmission surface, and the first surface of the beam splitter 103 is a beam splitting surface. The beam splitting surface of the beam splitter 103 is at a certain inclination angle with the optical axis of the lens 102. The optical axis of the reflector 104 is at a certain inclination angle with the beam splitting surface of the beam splitter 103.

[0033] like Figure 2As shown, the light emitted by the display element 101 enters the lens 102, passes through the second surface and the first surface of the lens 102, and then enters the beam splitter 103. After being transmitted by the second surface and the first surface of the beam splitter 103, it enters the reflection surface of the reflector 104, and then is reflected by the reflection surface of the reflector 104 to the first surface of the beam splitter 103, wherein part of the light is reflected by the first surface (i.e., the beam splitting surface) of the beam splitter 103, and finally enters the eye box. Natural light from the real world can enter the eye box after passing through the beam splitter 103, so that the human eye in the eye box can simultaneously see the clear image displayed by the magnified display element 101 and the real world.

[0034] Figure 3 Shows Figure 1 An imaging optical path diagram of the optical system 100 of the type shown. The light emitted by the display element 101 enters the lens 102, and is incident on the second surface of the beam splitter 103 after being refracted by the second surface and the first surface of the lens 102, wherein part of the light is reflected by the second surface of the beam splitter 103 (i.e., the beam splitting surface of the beam splitter 103) to the reflecting surface of the reflector 104, and the light reflected by the reflecting surface of the reflector 104 passes through the beam splitter 103 and finally enters the eye box, so that the human eye located in the eye box can see the clear image displayed by the magnified display element 101.

[0035] Figure 2 The imaging principle of an optical system 100 of the type shown is similar to Figure 1 The optical system shown is approximate and will not be described in detail here.

[0036] In some embodiments of the present disclosure, the first ratio of the optical system 100 is greater than or equal to 1 and less than or equal to 1.3, and the first ratio refers to the ratio between the square root of the product of the focal length of the lens 102 and the focal length of the reflector 104 and the system focal length of the optical system 100; the optical system 100 has a field of view angle greater than or equal to 35° and less than or equal to 55°. In other words, the optical system 100 satisfies the relationship shown in the following formula (1). As a result, the human eye can view a clear image with a field of view range greater than or equal to 35° and less than or equal to 55° within a set eye box.

[0037]

[0038] Among them, f L represents the focal length of the lens 102, f R represents the focal length of the reflecting surface of the reflector 104, f represents the system focal length of the optical system 100, and the value range of the first ratio s1 is [1, 1.3]. That is, the first ratio s1 can be greater than or equal to 1 and less than or equal to 1.3.

[0039] In this way, the optical system 100 can have a compact system volume while having a field angle of greater than or equal to 35° and less than or equal to 55°.

[0040] Optionally, the first ratio s1 may also be set to be greater than or equal to 1.05 and less than or equal to 1.2. In this way, the optical system 100 can have a field of view greater than or equal to 35° and less than or equal to 55° while further reducing the volume of the system.

[0041] In some embodiments of the present disclosure, the height of the optical system 100 is less than or equal to 27 mm, and the thickness is less than or equal to 20 mm. As a result, the optical system 100 in the embodiments of the present disclosure is compact and can meet the requirements of wearing comfort of the head-mounted display device. Optionally, the height of the optical system 100 can also be less than or equal to 24 mm, and the thickness can be less than or equal to 16 mm. The volume of the optical system 100 can be further reduced, so as to better meet the requirements of wearing comfort of the head-mounted display device.

[0042] In some embodiments of the present disclosure, the second ratio of the optical system 100 is greater than or equal to 0.75 and less than or equal to 0.985, and the second ratio refers to the ratio of the sum of the spacing between the reflector 104 and the beam splitter 103 along the system optical axis and the spacing between the lens 102 and the beam splitter 103 along the system optical axis to the system focal length of the optical system 100. In other words, the optical system 100 can satisfy the relationship shown in the following formula (2):

[0043] (L1+L2) / f=s2 (2)

[0044] Wherein, L1 represents the distance between the reflector 104 and the beam splitter 103 along the system optical axis, L2 represents the distance between the lens 102 and the beam splitter 103 along the system optical axis, and the second ratio s2 is greater than or equal to 0.75 and less than or equal to 0.985.

[0045] It can be understood that the spacing between the reflector 104 and the beam splitter 103 along the system optical axis may refer to the distance between the optical center of the reflector 104 and the optical center of the beam splitter 103 on the system optical axis, and the spacing between the lens 102 and the beam splitter 103 in the optical axis direction may refer to the distance between the optical center of the lens 102 and the optical center of the beam splitter 103 in the system optical axis direction.

[0046] Optionally, the second ratio s2 may be greater than or equal to 0.825 and less than or equal to 0.925.

[0047] Since the optical system 100 with a large field of view usually corresponds to a small system focal length, the small system focal length requires that the reflector 104 and the lens 102 in the optical system 100 have a small spacing. Figure 1For an optical system of the type shown, if a large field of view is achieved, it means that the spatial distance between the reflector 104 and the lens 102 is small. When the spatial distance is too close, interference between the optical elements is likely to occur (i.e., when the distance is too close, the edge of the reflector 104 and the edge of the lens 102 interfere with each other). Figure 2 For the optical system shown in the figure, if a large field of view is achieved, it means that the spatial distance between the reflector 104 and the lens 102 is small, then the spatial distance between the reflector 104 and the beam splitter 103, and the spatial distance between the beam splitter 103 and the lens 102 should also be small. When the spatial distance between the reflector 104 and the beam splitter 103, and the spatial distance between the beam splitter 103 and the lens 102 are too close, interference between the optical elements is likely to occur. The spacing between the reflector 104 and the beam splitter 103, and the spacing between the lens 102 and the beam splitter 103 can be optimized by formula (2), so that when the focal length of the optical system 100 is f, the spatial distance between the reflector 104 and the lens 102 is more reasonable, thereby avoiding interference between the optical elements.

[0048] In some embodiments of the present disclosure, the lens 102 may be an aspheric lens satisfying the equation shown in the following formula (3). The aspheric lens can perform spherical aberration correction, which can improve the imaging quality of the optical system 100 in a set eye box.

[0049]

[0050] Among them, r represents the distance vector height of the aspheric surface from the fixed point of the aspheric surface when the aspheric surface is at a height of h along the optical axis, c represents the curvature of the aspheric surface, that is, c = 1 / R (R is the curvature radius of the aspheric surface), k represents the cone coefficient, and Ai represents the coefficient of the i-th order of the aspheric surface.

[0051] In some embodiments of the present disclosure, the third ratio of the optical system 100 may be greater than or equal to 0.2 and less than 1, and the third ratio refers to the ratio between the difference between the sag of the first surface of the lens 102 (i.e., the surface close to the beam splitter 103) at the maximum effective aperture and the sag of the second surface of the lens 102 (i.e., the surface close to the display element 101) at the maximum effective aperture and the sum of the sag of the first surface of the lens 102 at the maximum effective aperture and the sag of the second surface of the lens 102 at the maximum effective aperture. In other words, the optical system 100 may satisfy the relationship shown in the following formula (4):

[0052] (SGL1-SG□2) / (SGL1+SGL2)=s3 (4)

[0053] Wherein, SGL1 represents the sag of the surface of the lens 102 close to the beam splitter 103 at the maximum effective aperture, SGL2 represents the sag of the surface of the lens 102 close to the display element 101 at the maximum effective aperture, and the third ratio s3 is greater than or equal to 0.2 and less than 1.

[0054] Optionally, the third ratio s3 of the optical system 100 may be greater than or equal to 0.4 and less than or equal to 0.8.

[0055] It should be noted that the lens 102 generally includes an effective aperture portion and an edge portion used for installation and fixing, wherein the effective aperture portion participates in imaging.

[0056] Formula (4) can take into account both the central field of view and the peripheral field of view of the optical system 100, better balance the resolution and field curvature of the central field of view and the peripheral field of view of the optical system 100, and effectively reduce the difficulty of lens processing and manufacturing.

[0057] In some embodiments of the present disclosure, the fourth ratio of the optical system 100 may be greater than or equal to 5 and less than or equal to 7, and the fourth ratio refers to the ratio of the product of the center thickness of the lens 102 and the focal length of the lens 102 to the system focal length of the optical system 100. In other words, the optical system 100 may also satisfy the relationship shown in the following formula (5):

[0058] T×f L / f=s4 (5)

[0059] Wherein, T represents the central thickness of the lens 102 , and the fourth ratio s4 is greater than or equal to 5 and less than or equal to 7.

[0060] Optionally, the fourth ratio may be greater than or equal to 5.5 and less than or equal to 6.5.

[0061] Formula (5) can effectively reduce the difficulty of processing and manufacturing the lens 102, and can also adjust the volume of the lens, thereby reducing the weight and size of the entire system.

[0062] In addition, by reasonably optimizing the center thickness of the lens 102 and the focal length of the lens 102, the size of the lens 102 of the optical system 100 can be made more reasonable when the system focal length is f, which is beneficial to improving the imaging quality of the optical system 100 within the set eye box and the specified field of view, thereby facilitating a better balance between the volume, field of view and eye box range of the optical system 100.

[0063] In some embodiments of the present disclosure, the fifth ratio of the optical system 100 may be greater than or equal to 0.02 and less than or equal to 0.2, and the fifth ratio refers to the ratio of the distance between the second surface of the lens 102 (i.e., the surface close to the display element 101) and the display surface of the display element 101 to the system focal length of the optical system 100. In other words, the optical system 100 may also satisfy the relationship shown in the following formula (6):

[0064] BFL / f=s5 (6)

[0065] Wherein, BFL represents the distance between the second surface of the lens 102 and the display surface of the display element 101 along the system optical axis, and the fifth ratio s5 is greater than or equal to 0.02 and less than or equal to 0.2.

[0066] It should be noted that, in the embodiment of the present disclosure, the distance BFL between the surface of the lens 102 close to the display element 101 and the display element 101 is calculated as an equivalent distance in the air.

[0067] By rationally designing the system focal length of the optical system 100 and the distance from the second surface of the lens to the display element 101 according to formula (6), the CRA (Chief Ray Angle) of the optical system 100 can be better matched with the CRA of the display element.

[0068] In some embodiments of the present disclosure, the refractive index of the lens 102 may be greater than or equal to 1.4 and less than or equal to 1.7. Optionally, the refractive index of the lens 102 may be greater than or equal to 1.4 and less than or equal to 1.6.

[0069] In some embodiments of the present disclosure, the Abbe number of the lens 102 may be greater than or equal to 18 and less than or equal to 65. Optionally, the Abbe number of the lens 102 may be greater than or equal to 30 and less than or equal to 60.

[0070] Selecting a lens 102 with a reasonable refractive index and Abbe number can help improve the imaging quality of the optical system 100 within a set eye box and a specified field of view, while balancing the volume, field of view, and eye box range of the optical system 100.

[0071] See also Figure 1 and Figure 2 , the beam splitter 103 may be tilted relative to the lens 102. In some possible implementations, the angle between the normal of the display element 101 and the beam splitter surface of the beam splitter 103 is β, the angle between the beam splitter surface of the beam splitter 103 and the optical axis of the reflector 104 is α, and the beam splitter 103 may be tilted relative to the lens 102 such that: β is greater than or equal to 40° and less than or equal to 50°, and α is greater than or equal to β-10° and less than or equal to β+10°, thereby ensuring that the optical system 100 can achieve the designed field of view angle and eye box, and ensuring the imaging quality of the optical system 100.

[0072] In some embodiments of the present disclosure, the sixth ratio of the optical system 100 may be greater than or equal to 0.2 and less than or equal to 0.385, and the sixth ratio refers to the ratio of the distance between the reflector 104 and the beam splitter 103 along the system optical axis to the focal length of the reflector 104. In other words, the optical system 100 satisfies the relationship shown in the following formula (7):

[0073] L1 / f R =s6 (7)

[0074] Wherein, L1 represents the spacing between the reflector 104 and the beam splitter 103 along the optical axis of the system, and the sixth ratio s6 is greater than or equal to 0.2 and less than or equal to 0.385. The spacing between the reflector 104 and the beam splitter 103 can be controlled by formula (7), so that the spacing between the reflector 104 and the beam splitter 103 is more reasonable, which is beneficial to improving the imaging quality of the optical system 100 at a set eye box and a specified field of view angle, and is beneficial to adjusting the size of the eye box.

[0075] Optionally, the sixth ratio s6 may be greater than or equal to 0.3 and less than or equal to 0.35.

[0076] In some embodiments of the present disclosure, the size of the eye box at a preset eye relief (ER) satisfies: the length of the eye box is greater than or equal to 8 mm and less than or equal to 25 mm, and the height of the eye box is greater than or equal to 3 mm and less than or equal to 10 mm, that is, the eye box can be set to a size that satisfies the relationship shown in the following formula (8).

[0077] 8mm*3mm<EB<25mm*10mm (8)

[0078] Wherein, EB represents eye box, mm represents millimeter, * represents multiplication, length refers to the dimension along the left and right eye direction, and height refers to the dimension perpendicular to the left and right eye direction.

[0079] In some embodiments of the present disclosure, the diameter of the eye box at a preset eye relief may be greater than or equal to 6 mm.

[0080] In some embodiments of the present disclosure, the field of view angle of the optical system 100 can also reach greater than or equal to 40° and less than or equal to 55°. Therefore, the optical system 100 of the embodiment of the present disclosure can perform high-quality imaging of the image displayed by the display element 101 within a larger field of view, so that the human eye located in the set eye box can see a clear image of the image displayed by the display element 101.

[0081] Table 1 shows a reference table of optical parameters of each optical element in the optical system 100 of some embodiments of the present disclosure, and Table 2 shows an example of aspheric coefficients of the lens 102 in the optical system 100 shown in Table 1. The field angle of the optical system 100 is 43°, the system focal length f is 16.75 mm, the first ratio is 1.16, the second ratio is 0.896, the third ratio is 0.44, the fourth ratio is 5.97, the fifth ratio is 0.09, and the sixth ratio is 0.36.

[0082]

[0083] Table 1

[0084] parameter S5 S7 S8 K 1.29 -22.50 2.97 A 2.21E-06 5.34E-04 2.63E-04 B 3.45E-09 -7.34E-06 -4.87E-06 C -4.34E-12 8.18E-08 6.70E-08 D 5.93E-14 -4.63E-10 -5.06E-10 E -1.15E-17 8.88E-13 1.58E-12

[0085] Table 2

[0086] Figure 4 Schematic diagram of a modulation transfer function (MTF) curve of the optical system 100 is shown. MTF is a way to describe the performance of an optical system and can be used to judge the ability of the optical system to restore contrast. Figure 4 The horizontal axis represents spatial frequency, the vertical axis represents contrast, the solid line represents the meridian direction, and the dotted line represents the sagittal direction. Figure 4 As shown, the optical system 100 has good resolution in different field of view directions, and the overall imaging quality is high, meeting the requirements of human eye resolution clarity.

[0087] Reference Figure 5 , shows a schematic diagram of the structure of a head mounted display device 500 according to an embodiment of the present disclosure. Figure 5 As shown, the head mounted display device 500 of this embodiment includes: a frame and the aforementioned optical system 100.

[0088] The frame is used to fix the optical system 100. The frame can be, for example but not limited to, a headband or a glasses frame.

[0089] In some optional embodiments, the head-mounted display device 500 includes but is not limited to: VR smart glasses, AR smart glasses, XR smart glasses, MR smart glasses, etc.

[0090] In some optional embodiments, the head-mounted display device 500 includes an integrated head-mounted display device or a split head-mounted display device. The split head-mounted display device may include a head-mounted display device and a terminal device, wherein the head-mounted display device is, for example, AR glasses, VR glasses, MR glasses, etc. The terminal device is, for example, a mobile phone, a tablet, a computer, etc.

[0091] It should be pointed out that, according to the needs of implementation, the various components / steps described in the embodiments of the present disclosure can be split into more components / steps, or two or more components / steps or partial operations of components / steps can be combined into new components / steps to achieve the purpose of the embodiments of the present disclosure.

[0092] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of the present disclosure.

[0093] The above implementation methods are only used to illustrate the embodiments of the present disclosure, and are not limitations of the embodiments of the present disclosure. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, all equivalent technical solutions also belong to the scope of the embodiments of the present disclosure. The scope of patent protection of the embodiments of the present disclosure should be defined by the claims.

Claims

1. An optical system for a head mounted display device, comprising: Display elements, lenses, beam splitters, and reflectors are sequentially arranged along the optical axis of the system; The lens is capable of magnifying the image displayed by the display element; Wherein, the light from the display element passes through the lens, the beam splitter, the reflector in sequence, and then passes through the beam splitter again before entering the eye box of the optical system, and the eye box is set at a preset eye distance; Wherein, the optical system meets any of the following dimensions: The height of the optical system is less than or equal to 27 mm, and the thickness is less than or equal to 20 mm; The height of the optical system is less than or equal to 24 mm, and the thickness is less than or equal to 16 mm.

2. The optical system according to claim 1, wherein: The field of view angle of the optical system is greater than or equal to 35° and less than or equal to 55°; the optical system satisfies the following relationship: Among them, f L represents the focal length of the lens, f R represents the focal length of the reflecting surface of the reflector, f represents the system focal length of the optical system, and the first ratio s1 satisfies any of the following conditions: The first ratio s1 is greater than or equal to 1 and less than or equal to 1.3; The first ratio s1 is greater than or equal to 1.05 and less than or equal to 1.

2.

3. The optical system according to claim 1, wherein: The optical system also satisfies the following relationship: (L1+L2) / f=s2 Wherein, L1 represents the distance between the reflector and the beam splitter along the optical axis of the system, L2 represents the distance between the lens and the beam splitter along the optical axis of the system, and the second ratio s2 satisfies any of the following conditions: The second ratio s2 is greater than or equal to 0.75 and less than or equal to 0.985; The second ratio s2 is greater than or equal to 0.825 and less than or equal to 0.

925.

4. The optical system according to claim 1, wherein: The lens satisfies the following relationship: (SGL1-SGL2) / (SGL1+SGL2)=s3 Wherein, SGL1 represents the sag of the surface of the lens close to the beam splitter at the maximum effective aperture, SGL2 represents the sag of the surface of the lens close to the display element at the maximum effective aperture, and the third ratio s3 satisfies any of the following conditions: The third ratio s3 is greater than or equal to 0.2 and less than 1; The third ratio s3 is greater than or equal to 0.4 and less than or equal to 0.

8.

5. The optical system according to claim 1, wherein: The lens satisfies the following relationship: T×f L / f=s4 Wherein, T represents the central thickness of the lens, and the fourth ratio s4 satisfies any of the following conditions: The fourth ratio s4 is greater than or equal to 5 and less than or equal to 7; The fourth ratio s4 is greater than or equal to 5.5 and less than or equal to 6.

5.

6. The optical system according to claim 1, wherein: The lens satisfies the following relationship: BFL / f=s5 Wherein, BFL represents the distance between the surface of the lens close to the display element and the display surface of the display element along the system optical axis, and the BFL is calculated as an equivalent distance in the air, and the fifth ratio s5 is greater than or equal to 0.02 and less than or equal to 0.

2.

7. The optical system according to claim 1, wherein: The reflector satisfies the following relationship: L1 / f R =s6 Wherein, L1 represents the distance between the reflector and the beam splitter along the optical axis of the system, and the sixth ratio s6 satisfies any of the following conditions: The sixth ratio s6 is greater than or equal to 0.2 and less than or equal to 0.385; The sixth ratio s6 is greater than or equal to 0.3 and less than or equal to 0.

35.

8. The optical system according to claim 1, wherein: The refractive index of the lens is greater than or equal to 1.4 and less than or equal to 1.7; the Abbe number of the lens is greater than or equal to 18 and less than or equal to 65.

9. The optical system according to claim 1, wherein: The eye box meets any of the following dimensions at the preset eye relief: The length of the eye box is greater than or equal to 8 mm and less than or equal to 25 mm, and the height of the eye box is greater than or equal to 3 mm and less than or equal to 10 mm; The diameter of the eye box is greater than 6mm.

10. A head mounted display device, comprising: A frame for fixing the optical system; The optical system is the optical system according to any one of claims 1 to 9.

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