Near-to-eye display equipment, ray machine and eyepiece thereof

Abstract

The invention discloses a near-to-eye display device, an optical machine and an eyepiece thereof, relates to the technical field of optics, and is used for solving the problem that the weight of the optical machine of the existing near-to-eye display device is too heavy. The eyepiece is used for projecting light of an image source and comprises a first lens and a second lens which are sequentially arranged, the second lens is closer to the image source than the first lens along the optical axis of the eyepiece, the object side face of the first lens is a concave face, the image side face of the first lens is a convex face, and the object side face of the second lens is a convex face. Light emitted by the image source sequentially passes through the second lens and the first lens and then is projected out. The eyepiece uses a small number of lenses and is light in weight, so that an optical machine and a near-to-eye display device are light in weight.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular to a near-eye display device, an optical engine and an ocular lens thereof. BACKGROUND

[0002] Augmented Reality (AR) technology is to integrate the virtual environment generated by computer with the real environment around the user by means of photoelectric display technology, interactive technology, various sensor technologies and computer graphics and multimedia technology, so that the user believes that the virtual environment is a part of the real environment around him from the sensory effect.

[0003] The trend of the near-eye display device is light weight, which can meet the needs of daily long-time wearing. However, the optical engine of the existing near-eye display device is heavy, and the monocular optical engine is usually more than 5g, so the weight of the entire near-eye display device also increases, which cannot meet the needs of consumers. SUMMARY

[0004] The purpose of the present application is to provide a near-eye display device, an optical engine and an ocular lens thereof, which are light in weight.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] An ocular lens for projecting light rays of an image source, comprising a first lens and a second lens arranged in sequence, the second lens being closer to the image source than the first lens along an optical axis of the ocular lens, each lens comprising an object side close to the image source and an image side away from the image source, the object side of the first lens being concave and the image side being convex, and the object side of the second lens being convex and the image side being convex.

[0007] In some embodiments, the following condition is met: -1.3 < f1 / f < -1.0;

[0008] Wherein, f1 represents the focal length of the first lens, and f represents the focal length of the ocular lens.

[0009] In some embodiments, the following condition is met: 0.5 < f2 / f < 0.7;

[0010] Wherein, f2 represents the focal length of the second lens, and f represents the focal length of the ocular lens.

[0011] In some embodiments, the following condition is met: 0.25 ≤ (image height / 2) / EFFL ≤ 0.3; wherein, EFFL represents the effective focal length of the ocular lens.

[0012] In some embodiments, the object side and the image side of the first lens are both aspherical surfaces, and the following condition is met:

[0013] R 110 =R 11 / (1 + (T1 - T0) * tce1);

[0014] A 110i =A 11i / (1 + (T1 - T0) * tce1);

[0015] R 120 =R 12 / (1 + (T1 - T0) * tce1);

[0016] A 120i =A 12i / (1 + (T1 - T0) * tce1);

[0017] wherein R 110 represents a design radius of curvature of an image side of the first lens, R 11 represents a radius of curvature of the image side of the first lens at an operating temperature, A 110i represents an i-th order design aspheric coefficient of the image side of the first lens, A 11i represents an i-th order aspheric coefficient of the image side of the first lens at the operating temperature;

[0018] R 120 represents a design radius of curvature of an object side of the first lens, R 12 represents a radius of curvature of the object side of the first lens at the operating temperature, A 120i represents an i-th order design aspheric coefficient of the object side of the first lens, A 12i represents an i-th order aspheric coefficient of the object side of the first lens at the operating temperature;

[0019] T1 represents the operating temperature, T0 represents an original temperature, and tce1 represents a thermal expansion coefficient of the first lens.

[0020] In some embodiments, the object side and the image side of the second lens are both aspheric and satisfy the following conditional expressions:

[0021] R 210 =R 21 / (1 + (T1 - T0) * tce2);

[0022] A 210i =A 21i / (1 + (T1 - T0) * tce2);

[0023] R 220 =R 22(1 + (T1 - T0) * tce2);

[0024] A 220i =A 22i (1 + (T1 - T0) * tce2);

[0025] wherein R 210 represents a design curvature radius of an image side surface of the second lens, R 21 represents a curvature radius of the image side surface of the second lens at an operating temperature, A 210i represents an i-th order design aspheric coefficient of the image side surface of the second lens, A 21i represents an i-th order aspheric coefficient of the image side surface of the second lens at the operating temperature;

[0026] R 220 represents a design curvature radius of an object side surface of the second lens, R 22 represents a curvature radius of the object side surface of the second lens at the operating temperature, A 220i represents an i-th order design aspheric coefficient of the object side surface of the second lens, A 22i represents an i-th order aspheric coefficient of the object side surface of the second lens at the operating temperature;

[0027] T1 represents the operating temperature, T0 represents an original temperature, and tce2 represents a thermal expansion coefficient of the second lens.

[0028] In some embodiments, the density of the first lens is 1 / 5-1 / 2 of the density of a glass lens, and the density of the second lens is 1 / 5-1 / 2 of the density of a glass lens.

[0029] In some embodiments, the eyepiece further comprises:

[0030] a reflecting element disposed between the image source and the second lens, configured to reflect light rays from the image source to the second lens.

[0031] An optical engine, comprising:

[0032] an image source configured to emit light rays;

[0033] the eyepiece of any of the above, configured to project the light rays from the image source.

[0034] A near-eye display device, comprising:

[0035] the optical engine of the above;

[0036] a waveguide disposed on an output side of the optical engine, configured to transmit the light rays from the optical engine.

[0037] The eyepiece is used for projecting light rays of an image source, and the eyepiece comprises a first lens and a second lens arranged in sequence, and the light rays emitted by the image source are projected out after passing through the second lens and the first lens in sequence. The object side surface of the second lens is a convex surface, and the image side surface of the second lens is a convex surface, so that the light rays emitted by the image source are deflected in a converging manner when passing through the second lens. The object side surface of the first lens is a concave surface, so that the field angle of the light rays collected by the first lens from the second lens is increased, and the image side surface of the first lens is a convex surface, so that the light rays passing through the first lens are deflected in a converging manner. The eyepiece uses a small number of lenses, and the weight of the eyepiece is relatively light.

[0038] The optical-mechanical device and the near-eye display device are relatively light in weight. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0040] Figure 1 A side view of an eyepiece and an image source arrangement provided for the first embodiment;

[0041] Figure 2 A side view of an eyepiece and an image source arrangement provided for the second embodiment;

[0042] Figure 3 An MTF graph of the eyepiece provided for the first embodiment;

[0043] Figure 4 A point spread function graph of the eyepiece provided for the first embodiment;

[0044] Figure 5 A field curvature graph and a distortion graph of the full field of view and the full wavelength range of the eyepiece provided for the first embodiment;

[0045] Figure 6 An axial chromatic aberration curve graph of the eyepiece provided for the first embodiment;

[0046] Figure 7-1 An MTF graph of the eyepiece provided for the first embodiment at 0℃;

[0047] Figure 7-2 An MTF graph of the eyepiece provided for the first embodiment at 20℃;

[0048] Figure 7-3 An MTF graph of the eyepiece provided for the first embodiment at 70℃.

[0049] The reference signs in the drawings accompanying the specification comprise:

[0050] 1 - first lens, 2 - second lens, 3 - reflecting element, 4 - image source, 11 - image side of the first lens, 12 - object side of the first lens, 21 - image side of the second lens, 22 - object side of the second lens. DETAILED DESCRIPTION

[0051] In order to make the technical solutions in the present application better understood to those skilled in the art, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings accompanying the specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should belong to the scope of protection of the present application.

[0052] The present embodiment provides an eyepiece for projecting light from an image source, comprising a first lens and a second lens arranged in sequence, the second lens is closer to the image source than the first lens along the optical axis of the eyepiece, each lens comprises an object side close to the image source and an image side away from the image source, the object side of the first lens is concave and the image side is convex, the object side of the second lens is convex and the image side is convex.

[0053] The light emitted by the image source is projected out after passing through the second lens and the first lens in sequence. The object side of the second lens is convex and the image side is convex, the light emitted by the image source is deflected with converging property when passing through the second lens. The object side of the first lens is concave, which can increase the field angle of the first lens for collecting light from the second lens, and the image side of the first lens is convex, which makes the light passing through the first lens deflected with converging property. The light emitted by the image source becomes parallel light after passing through the second lens and the first lens in sequence and is projected out, and the image source is located on the focal plane of the eyepiece. The eyepiece of the present embodiment uses fewer lenses, so the weight of the eyepiece is lighter.

[0054] Exemplarily, reference can be made to Figure 1 Or Figure 2 , Figure 1 A side view of an eyepiece and an image source arrangement provided for the first embodiment, Figure 2 A side view of an eyepiece and an image source arrangement provided for the second embodiment, wherein both show the light propagation. For example Figure 1 Or Figure 2As shown, the eyepiece comprises a first lens 1 and a second lens 2 arranged in sequence, the object side surface 12 of the first lens is concave, the image side surface 11 of the first lens is convex, the object side surface 22 of the second lens is convex, and the image side surface 21 of the second lens is convex. The light emitted by the image source 4 becomes parallel light after passing through the second lens 2 and the first lens 1 in sequence, and the image source 4 is located on the focal plane of the eyepiece.

[0055] In some embodiments, the eyepiece satisfies the following conditional expression: -1.3 < f1 / f < -1.0; wherein f1 represents the focal length of the first lens, and f represents the focal length of the eyepiece. The ratio of the focal length of the first lens 1 to the focal length of the eyepiece satisfies -1.3 < f1 / f < -1.0, which can reduce the tolerance sensitivity of the first lens 1 under the condition that the first lens 1 has sufficient deflection ability for light. If f1 / f is less than -1.3, the deflection ability of the eyepiece for light will be weakened, the total length of the eyepiece will be increased, and the total length of the eyepiece refers to the distance along the optical axis from the image side surface of the first lens 1 to the image source 4; if f1 / f is greater than -1.0, the tolerance sensitivity of the first lens 1 will be increased, and the light will be deviated greatly under the condition that the deviation is designed to be very small, which is more sensitive to processing and assembly.

[0056] In some embodiments, the eyepiece satisfies the following conditional expression: 0.5 < f2 / f < 0.7; wherein f2 represents the focal length of the second lens, and f represents the focal length of the eyepiece. The ratio of the focal length of the second lens 2 to the focal length of the eyepiece satisfies 0.5 < f2 / f < 0.7, which can avoid increasing the thickness of the second lens 2, avoiding increasing the weight of the second lens 2, and avoiding increasing the tolerance sensitivity under the condition that the second lens 2 has sufficient deflection ability for light. If f2 / f is less than 0.5, the installation tolerance of the second lens 2 will be more sensitive, which will reduce the yield of assembly; if f2 / f is greater than 0.7, the thickness of the second lens 2 will be further increased, which is not conducive to processing, will increase the cost, and will also increase the weight of the second lens 2.

[0057] In some embodiments, the eyepiece satisfies the following conditional expression: 0.25 ≤ (image height / 2) / EFFL ≤ 0.3; wherein EFFL represents the effective focal length of the eyepiece. The effective focal length EFFL of the eyepiece is the same optical parameter as the focal length f of the eyepiece. The image height refers to the diagonal length of the entire rectangular picture after the object is imaged by the optical system. According to the formula tan(FOV / 2) = (image height / 2) / EFFL, 0.25 ≤ tan(FOV / 2) ≤ 0.3, 28° ≤ FOV ≤ 33.4°, and FOV represents the field of view angle of the eyepiece. Therefore, the eyepiece can be compatible with a field of view angle of 28°~33.4°.

[0058] The object side surface 12 of the first lens can be spherical, and the image side surface 11 of the first lens can be spherical, which is convenient for processing and can reduce the cost. Alternatively, the object side surface 12 of the first lens can be aspherical, and the image side surface 11 of the first lens can be aspherical, so that the first lens 1 can further correct high-order aberrations and improve the image quality of the eyepiece. In some embodiments, the object side surface 12 of the first lens and the image side surface 11 of the first lens can both be even aspherical surfaces, so that the aberrations are effectively corrected by the first lens 1, and the display requirements can be met with the least number of lenses.

[0059] The object side surface 22 of the second lens can be spherical, and the image side surface 21 of the second lens can be spherical, which is convenient for processing and can reduce the cost. Alternatively, the object side surface 22 of the second lens can be aspherical, and the image side surface 21 of the second lens can be aspherical, so that the second lens 2 can further correct high-order aberrations and improve the image quality of the eyepiece. In some embodiments, the object side surface 22 of the second lens and the image side surface 21 of the second lens can both be even aspherical surfaces, so that the aberrations are effectively corrected by the second lens 2, and the display requirements can be met with the least number of lenses.

[0060] The formula of the even aspherical surface can be expressed as:

[0061] ;

[0062] wherein z represents the relative distance of a point on the aspherical surface with a vertical distance x from the optical axis to the tangent plane at the vertex of the aspherical surface, x represents the vertical distance of a point on the aspherical surface to the optical axis, k represents the conic coefficient, R represents the curvature radius, A4 to A 14 represent the 4th to 14th order aspherical coefficients, respectively. In the design, the conic coefficient |k| is ensured to be less than or equal to 100. The lens has a thermal effect, i.e., the property of thermal expansion and contraction. The thermal expansion coefficient of the lens is positive, i.e., the lens expands with the increase of temperature and shrinks with the decrease of temperature. This causes the focal length of the lens to change with the change of temperature, i.e., the focal length of the lens increases at low temperature and decreases at high temperature. In view of this, the thermal effect is considered when designing the surface shape of the first lens 1 and the second lens 2, so as to compensate for the influence of the surface shape of the first lens 1 and the second lens 2 with the change of temperature.

[0063] In some embodiments, the object side surface and the image side surface of the first lens 1 are both aspherical surfaces and satisfy the following conditional expressions:

[0064] R 110 =R 11 / (1+(T1-T0)*tce1);

[0065] A 110i =A 11i / (1+(T1-T0)*tce1);

[0066] R120 =R 12 / (1+(T1-T0)*tce1);

[0067] A 120i =A 12i / (1+(T1-T0)*tce1);

[0068] wherein, R 110 represents a design curvature radius of the image side surface of the first lens, R 11 represents a curvature radius of the image side surface of the first lens at a working temperature, A 110i represents an i-th order design aspheric coefficient of the image side surface of the first lens, A 11i represents an i-th order aspheric coefficient of the image side surface of the first lens at the working temperature; R 120 represents a design curvature radius of the object side surface of the first lens, R 12 represents a curvature radius of the object side surface of the first lens at the working temperature, A 120i represents an i-th order design aspheric coefficient of the object side surface of the first lens, A 12i represents an i-th order aspheric coefficient of the object side surface of the first lens at the working temperature; T1 represents the working temperature, T0 represents an original temperature, and tce1 represents a thermal expansion coefficient of the first lens.

[0069] The design curvature radius of the image side / object side surface of the first lens refers to the design value of the curvature radius of the image side / object side surface of the first lens, which corresponds to the curvature radius of the image side / object side surface of the first lens at an original temperature. The i-th order design aspheric coefficient of the image side / object side surface of the first lens refers to the design value of the i-th order aspheric coefficient of the image side / object side surface of the first lens, which corresponds to the i-th order aspheric coefficient of the image side / object side surface of the first lens at the original temperature. When the first lens is at a working temperature, due to thermal effects, the curvature radius of the image side / object side surface of the first lens becomes R 11 / R 12 , and the i-th order aspheric coefficient of the image side / object side surface of the first lens becomes A 11i / A 12i . In the embodiment, the temperature change of the use scenario is considered when the object side surface and the image side surface of the first lens are designed as aspheres, so as to ensure the imaging effect of the objective lens during use. When the design is ensured, the face shape change of the first lens satisfies the increase of the focal length at high temperature and the decrease of the focal length at low temperature, so as to complete the thermal compensation of the system. Exemplarily, the first lens is a plastic lens, and the lens barrel material is also plastic, so that the thermal expansion and contraction of the lens barrel and the lens will not be significantly different.

[0070] In some embodiments, the object side surface and the image side surface of the second lens 2 are aspheres and satisfy the following conditional expressions:

[0071] R 210 =R 21 / (1 + (T1 - T0) * tce2);

[0072] A 210i =A 21i / (1 + (T1 - T0) * tce2);

[0073] R 220 =R 22 / (1 + (T1 - T0) * tce2);

[0074] A 220i =A 22i / (1 + (T1 - T0) * tce2);

[0075] wherein R 210 represents a design radius of curvature of an image side surface of the second lens, R 21 represents a radius of curvature of the image side surface of the second lens at an operating temperature, A 210i represents an i-th order design aspheric coefficient of the image side surface of the second lens, A 21i represents an i-th order aspheric coefficient of the image side surface of the second lens at the operating temperature; R 220 represents a design radius of curvature of an object side surface of the second lens, R 22 represents a radius of curvature of the object side surface of the second lens at the operating temperature, A 220i represents an i-th order design aspheric coefficient of the object side surface of the second lens, A 22i represents an i-th order aspheric coefficient of the object side surface of the second lens at the operating temperature; T1 represents the operating temperature, T0 represents an original temperature, and tce2 represents a thermal expansion coefficient of the second lens.

[0076] The design radius of curvature of the image side / object side surface of the second lens refers to a design value of the radius of curvature of the image side / object side surface of the second lens, which corresponds to the radius of curvature of the image side / object side surface of the second lens at an original temperature. The i-th order design aspheric coefficient of the image side / object side surface of the second lens refers to a design value of the i-th order aspheric coefficient of the image side / object side surface of the second lens, which corresponds to the i-th order aspheric coefficient of the image side / object side surface of the second lens at the original temperature. When the second lens is at an operating temperature, due to thermal effects, the radius of curvature of the image side / object side surface of the second lens becomes R 21 / R 22 , and the i-th order aspheric coefficient of the image side / object side surface of the second lens becomes A 21i / A 22iIn this embodiment, the temperature variation of the use scene is considered when the aspheric surface design is performed on the object side surface and the image side surface of the second lens, so as to ensure the imaging effect of the ocular lens in use. In the design, the surface shape variation of the second lens is ensured to meet the high temperature focal length increase and the low temperature focal length decrease, so as to complete the system thermal compensation. Exemplarily, the second lens is a plastic lens, and the lens barrel material is also plastic, so that the thermal expansion and contraction of the lens barrel and the lens will not be obviously different.

[0077] In some embodiments, the density of the first lens 1 is 1 / 5-1 / 2 of the density of a glass lens, and the density of the second lens 2 is 1 / 5-1 / 2 of the density of a glass lens. In the ocular lens, the density of the first lens 1 is less than the density of a glass lens, and the density of the second lens 2 is less than the density of a glass lens, so that the first lens 1 and the second lens 2 are light in weight, and the weight of the ocular lens can be reduced. Exemplarily, the first lens 1 is a plastic lens, and the second lens 2 is a plastic lens, so that the weight of the optical machine can be controlled to be less than 2g.

[0078] In some embodiments, the ocular lens further comprises a reflecting element 3 arranged between the image source 4 and the second lens 2, for reflecting the light of the image source 4 to the second lens 2. The reflecting element 3 changes the propagation direction of the light from the image source 4, so that the position arrangement of the first lens 1, the second lens 2 and the image source 4 can be more flexibly adapted to different requirements. The reflecting element 3 can be, but is not limited to, a prism or a mirror, and the prism includes but is not limited to a triangular prism, a quadrangular prism, a pentagonal prism or other polygonal prisms.

[0079] In a specific example, the optical data of each lens of the ocular lens is shown in Table 1.

[0080] Table 1

[0081]

[0082] In the above structure, the aspheric conic coefficient value and the aspheric coefficient of each order of the first lens 1 are shown in Table 2.

[0083] Table 2

[0084]

[0085] The aspheric conic coefficient value and the aspheric coefficient of each order of the second lens 2 are shown in Table 3.

[0086] Table 3

[0087]

[0088] The optical performance parameters of the ocular lens with the above structure are shown in Table 4.

[0089] Table 4

[0090]

[0091] wherein, EFFL refers to effective focal length, EPD refers to entrance pupil distance, FOV refers to field of view, and TTL refers to total track length. The total length of the eyepiece TTL refers to the distance along the optical axis from the image side of the first lens 1 to the image source 4. According to the formula tan (FOV / 2) = (image height / 2) / EFFL, in this embodiment, 0.25 ≤ (image height / 2) / EFFL ≤ 0.3 should be met. In this embodiment, the eyepiece can effectively reduce the weight of the eyepiece under the condition of ensuring the image quality when reaching a field of view of 30 degrees.

[0092] Figure 3 The MTF (Modulation Transfer Function) diagram of the eyepiece provided for the first embodiment, wherein the OTF modulus refers to the modulus of the optical transfer function, characterizes the resolution of the eyepiece, and the higher the value, the better the resolving power of the eyepiece and the stronger the resolution capability. The test wavelength is 0.528 μm to 0.656 μm. It can be seen from Figure 3 that the imaging MTF of the eyepiece in the full field of view range at the center of the picture is ≥0.3@30 lp / mm, which can meet the requirements of human eye resolution. The resolution capability of the human eye is about 0.2@30 lp / mm, that is, the OTF modulus is below 0.2 at 30 lp / mm, which will be recognized as unclear by the human eye.

[0093] Figure 4 The spot diagram of the eyepiece provided for the first embodiment, wherein the RMS radius corresponding to each diagram is 2.225 μm, 4.395 μm, 9.858 μm, 4.554 μm, 8.747 μm, 4.995 μm, 5.015 μm, 9.398 μm, 10.234 μm, 10.233 μm, 10.382 μm and 18.409 μm, respectively. The GEO radius corresponding to each diagram is 4.404 μm, 14.370 μm, 56.683 μm, 12.041 μm, 25.975 μm, 12.551 μm, 11.627 μm, 21.262 μm, 22.920 μm, 22.921 μm, 114.034 μm and 114.516 μm, respectively. It can be seen from Figure 4It can be seen that the root mean square (RMS) of 80% of the field of view of the eyepiece is less than 10 microns, the pixel size used by the system is 6.3 microns, indicating that the system has a small diffraction spot size, almost within 2.5 pixel size, and has good imaging quality.

[0094] Figure 5 The field curvature graph and the distortion graph of the full field of view of the eyepiece provided for the first embodiment are shown in the figure, wherein the left graph is the field curvature graph, the maximum field of view is 7.535 degrees, the sagittal field curvature is 0.0395 mm, and the meridional field curvature is 0.2932 mm. The right graph is the distortion graph, the maximum field of view is 7.535 degrees, and the maximum distortion is 0.8910%. The vertical axis of the field curvature graph and the distortion graph represents the short-side field of view angle, and the unit is degree. From the figure, it can be seen that the distortion curve of the eyepiece is almost monotonous, and there is no obvious mutation, so that the image will not be obviously deformed due to different field angles, the maximum optical distortion is less than 1%, and the shape of the distortion curve is controlled to prevent the occurrence of mustache distortion phenomenon. Figure 5 It can be seen that the distortion curve of the eyepiece is almost monotonous, and there is no obvious mutation, so that the image will not be obviously deformed due to different field angles, the maximum optical distortion is less than 1%, and the shape of the distortion curve is controlled to prevent the occurrence of mustache distortion phenomenon.

[0095] Figure 6 The axial chromatic aberration curve graph of the eyepiece provided for the first embodiment is shown in the figure, the maximum field of view is 7.535 degrees, and the wavelength is 0.528 microns. Figure 6 It can be seen that the axial chromatic aberration of the eyepiece is less than 14 microns, which is less than 2.5 pixel sizes, and no obvious color edge phenomenon will occur.

[0096] Figure 7-1 The MTF graph of the eyepiece provided for the first embodiment at 0℃ is shown in the figure. Figure 7-2 The MTF graph of the eyepiece provided for the first embodiment at 20℃ is shown in the figure. Figure 7-3 The MTF graph of the eyepiece provided for the first embodiment at 70℃ is shown in the figure. It can be seen that the eyepiece imaging is stable at different environmental temperatures. Since the eyepiece system is a consumer electronic product, temperature changes need to be considered for rich use scenarios, so the eyepiece scheme needs to be designed without heat. The thermal expansion coefficient of the lens material needs to be considered for the optical system without heat. Since the thermal expansion coefficient of plastic is generally 10-50 times that of glass material, the influence of temperature on the surface shape is very obvious, so the requirement for the lens material of plastic for non-thermalization is more stringent. In this embodiment, the designed eyepiece system perfectly balances the display performance and the balance of non-thermalization.

[0097] The embodiment also provides an optical machine, comprising: an image source 4 for emitting light; and the eyepiece according to any one of the preceding embodiments, for projecting the light of the image source 4. The optical machine of the embodiment has a light weight.

[0098] In the embodiment, the image source 4 is not limited, and can be, but is not limited to, a liquid crystal display (LCD), an organic light-emitting diode (OLED), a liquid crystal on silicon (LCoS), a digital micromirror device (DMD), or a micro light-emitting diode (Micro-LED).

[0099] The embodiment also provides a near-eye display device, comprising the optical engine and a waveguide arranged on the light exit side of the optical engine and used for transmitting light from the optical engine. The near-eye display device is light in weight.

[0100] The near-eye display device, the optical engine, and the eyepiece thereof are described in detail above. The principles and implementation manners of the present application are described by using specific examples in the present document, and the above description of the embodiments is only used to help understand the method and the core idea of the present application. It should be noted that, for those skilled in the art, the present application can be improved and modified without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the present application.

Claims

1. An eyepiece for projecting light from an image source, characterized in that, The device includes a first lens and a second lens arranged sequentially. Along the optical axis of the eyepiece, the second lens is closer to the image source than the first lens. Each lens includes an object-side surface closer to the image source and an image-side surface farther from the image source. The object-side surface of the first lens is concave and the image-side surface is convex, as are the object-side surface and the image-side surface of the second lens.

2. The eyepiece according to claim 1, characterized in that, The following conditions must be met: -1.3 <f1 / f<-1.0; Where f1 represents the focal length of the first lens, and f represents the focal length of the eyepiece.

3. The eyepiece according to claim 1, characterized in that, The following conditions must be met: 0.5 <f2 / f<0.7; Where f2 represents the focal length of the second lens, and f represents the focal length of the eyepiece.

4. The eyepiece according to claim 1, characterized in that, The following conditions must be met: 0.25 ≤ (image height / 2) / EFFL ≤ 0.3; Wherein, EFFL represents the effective focal length of the eyepiece.

5. The eyepiece according to claim 1, characterized in that, The object-side and image-side surfaces of the first lens are both aspherical and satisfy the following condition: R 110 =R 11 / (1+(T1-T0)*tce1); A 110i =A 11i / (1+(T1-T0)*tce1); R 120 =R 12 / (1+(T1-T0)*tce1); A 120i =A 12i / (1+(T1-T0)*tce1); Among them, R 110 R represents the design radius of curvature of the image-side surface of the first lens. 11 A represents the radius of curvature of the image-side surface of the first lens at the operating temperature. 110i A represents the i-th order design aspherical coefficient of the image-side surface of the first lens. 11i This represents the i-th order aspherical coefficient of the image-side surface of the first lens at the operating temperature. R 120 R represents the design radius of curvature of the object-side surface of the first lens. 12 A represents the radius of curvature of the object-side surface of the first lens at the operating temperature. 120i A represents the i-th order design aspherical coefficient of the object-side surface of the first lens. 12i This represents the i-th order aspherical coefficient of the object side surface of the first lens at the operating temperature. T1 represents the operating temperature, T0 represents the original temperature, and tce1 represents the thermal expansion coefficient of the first lens.

6. The eyepiece according to claim 1, characterized in that, The object-side and image-side surfaces of the second lens are both aspherical and satisfy the following condition: R 210 =R 21 / (1+(T1-T0)*tce2); A 210i =A 21i / (1+(T1-T0)*tce2); R 220 =R 22 / (1+(T1-T0)*tce2); A 220i =A 22i / (1+(T1-T0)*tce2); Among them, R 210 R represents the design radius of curvature of the image-side surface of the second lens. 21 A represents the radius of curvature of the image-side surface of the second lens at the operating temperature. 210i A represents the i-th order design aspherical coefficient of the image-side surface of the second lens. 21i This represents the i-th order aspherical coefficient of the image-side surface of the second lens at the operating temperature. R 220 R represents the design radius of curvature of the object-side surface of the second lens. 22 A represents the radius of curvature of the object-side surface of the second lens at the operating temperature. 220i A represents the i-th order design aspherical coefficient of the object-side surface of the second lens. 22i This represents the i-th order aspherical coefficient of the object side surface of the second lens at the operating temperature. T1 represents the operating temperature, T0 represents the original temperature, and tce2 represents the thermal expansion coefficient of the second lens.

7. The eyepiece according to claim 1, characterized in that, The density of the first lens is 1 / 5 to 1 / 2 of the density of the glass lens, and the density of the second lens is 1 / 5 to 1 / 2 of the density of the glass lens.

8. The eyepiece according to any one of claims 1 to 7, characterized in that, Also includes: A reflective element is disposed between the image source and the second lens to reflect light from the image source to the second lens.

9. An optical engine, characterized in that, include: Image source, used to emit light; The eyepiece according to any one of claims 1 to 8 is used to project light from the image source.

10. A near-eye display device, characterized in that, include: The optical engine as described in claim 9; A waveguide, disposed on the light-emitting side of the optical engine, is used to transmit light from the optical engine.

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