Optical lens and head-mounted display device

Abstract

The invention discloses an optical lens which is small in size and has good optical quality and thermal stability. The optical lens is used for receiving an image light beam from an imaging element, and sequentially comprises a first lens, a second lens, a third lens and a fourth lens with diopters along an optical axis from a light inlet side to a light outlet side, each of the first to fourth lenses comprises a light incident surface which faces the light incident side and allows the image light beam to pass through and a light emergent surface which faces the light emergent side and allows the image light beam to pass through. The light incident surface of the first lens is a concave surface. The second lens has negative diopter, and the light-emitting surface of the second lens is a convex surface. The third lens has positive diopter, and the light incident surface of the third lens is a convex surface. The fourth lens has positive diopter, and the light incident surface of the fourth lens is a concave surface. The optical lens receives an image light beam from the light incident side, the image light beam forms a diaphragm on the light emergent side, and the image light beam has the smallest light beam sectional area at the position of the diaphragm.

Description

Technical Field

[0001] The present invention relates to an optical module and an electronic device, and in particular to an optical lens and a head-mounted display device. Background Art

[0002] With the emergence of multimedia imaging applications such as stereoscopic display and virtual reality, the demand for high resolution of display devices is gradually increasing in order to provide stunning visual effects.

[0003] Waveguide displays, which utilize a waveguide, can be categorized into self-luminous, transmissive, and reflective panel architectures, depending on the type of image source. The image beam generated by the image source (panel) passes through an optical lens to form a virtual image, which is then displayed at a predetermined position in front of the user's eyes. When optical lenses are used in waveguide displays, design considerations such as size, weight, resolution, and thermal drift are crucial.

[0004] The "Background" section is intended only to facilitate understanding of the present invention. Therefore, the information disclosed in this section may contain information that is not already known to those skilled in the art. The information disclosed in this section does not imply that the information or the problems to be solved by one or more embodiments of the present invention were known or understood by those skilled in the art prior to the filing of this application. Summary of the Invention

[0005] The present invention provides an optical lens and a head-mounted display device, which can reduce the volume and have good optical quality and thermal stability.

[0006] The objects and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

[0007] The present invention provides an optical lens that receives an image beam from an imaging element. The optical lens includes a first lens, a second lens, a third lens, and a fourth lens with diopters in sequence along the optical axis from the light incident side to the light exit side, and the first lens to the fourth lens each include a light incident surface facing the light incident side and allowing the image beam to pass through, and a light exit surface facing the light exit side and allowing the image beam to pass through. The light incident surface of the first lens is a concave surface. The second lens has a negative refractive power, and the light exit surface of the second lens is a convex surface. The third lens has a positive refractive power, and the light incident surface of the third lens is a convex surface. The fourth lens has a positive refractive power, and the light incident surface of the fourth lens is a concave surface. The optical lens receives the image beam from the light incident side, and the image beam forms a light bar on the light exit side, and the image beam has the smallest beam cross-sectional area at the position of the light bar.

[0008] The present invention further provides a head-mounted display device comprising an imaging element, an optical lens, and a waveguide element. The imaging element is used to provide an image beam. The optical lens is disposed on the transmission path of the image beam. The optical lens comprises, in order from the light incident side to the light exit side along the optical axis, a first lens, a second lens, a third lens, and a fourth lens having refractive powers. The first lens to the fourth lens each comprise a light incident surface facing the light incident side and allowing the image beam to pass through, and a light exit surface facing the light exit side and allowing the image beam to pass through. The light incident surface of the first lens is concave. The second lens has negative refractive power, and the light exit surface of the second lens is convex. The third lens has positive refractive power, and the light incident surface of the third lens is convex. The fourth lens has positive refractive power, and the light incident surface of the fourth lens is concave. The optical lens receives the image beam from the light incident side, and the image beam forms a light barrier on the light exit side. The image beam has a minimum beam cross-sectional area at the position of the light barrier. The waveguide element is disposed on the light exit side of the optical lens and comprises an optical coupling inlet and an optical coupling outlet. The image light beam from the imaging element passes through the optical lens, enters the waveguide element through the light coupling inlet, and leaves the waveguide element through the light coupling outlet.

[0009] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. 1 is a schematic diagram of a head-mounted display device according to an embodiment of the present invention.

[0011] Figure 2 FIG. 1 is a schematic diagram of an imaging module according to a first embodiment of the present invention.

[0012] Figure 3 for Figure 2 Astigmatism and distortion diagram of the optical lens in .

[0013] Figure 4 for Figure 2 The third-order aberration distribution diagram of the optical lens in .

[0014] 5A to 5D for Figure 2 Modulation Transfer Function (MTF) curves of the optical lens at different temperatures.

[0015] Figure 6 for Figure 2 Relative Illumination distribution diagram of the optical lens in.

[0016] Figure 7 for Figure 2 Schematic diagram of the screen distortion (TV Distortion) of the optical lens.

[0017] Figure 8 FIG. 4 is a schematic diagram of an imaging module according to a second embodiment of the present invention.

[0018] Figure 9 for Figure 8 Astigmatism, field curvature and distortion diagram of the optical lens in .

[0019] 10A to 10D for Figure 8 Modulation transfer function curves of the optical lens at different temperatures.

[0020] Figure 11 for Figure 8 Relative illumination distribution diagram of the optical lens in .

[0021] Figure 12 for Figure 8 Schematic diagram of the screen deformation of the optical lens.

[0022] Figure 13 FIG. 4 is a schematic diagram of an imaging module according to a third embodiment of the present invention.

[0023] Figure 14 for Figure 13 Astigmatism, field curvature and distortion diagram of the optical lens in .

[0024] 15A to 15D for Figure 13 Modulation transfer function curves of the optical lens at different temperatures.

[0025] Figure 16 for Figure 13 Relative illumination distribution diagram of the optical lens in .

[0026] Figure 17 for Figure 13 Schematic diagram of the screen deformation of the optical lens.

[0027] Figure 18 FIG. 4 is a schematic diagram of an imaging module according to a fourth embodiment of the present invention.

[0028] Figure 19 for Figure 18 Astigmatism, field curvature and distortion diagram of the optical lens in .

[0029] 20A to 20D for Figure 18 Modulation transfer function curves of the optical lens at different temperatures.

[0030] Figure 21 for Figure 18 Relative illumination distribution diagram of the optical lens in .

[0031] Figure 22 for Figure 18 Schematic diagram of the screen deformation of the optical lens. DETAILED DESCRIPTION

[0032] The aforementioned technical contents, features, and functions of the present invention will be more clearly understood in the following detailed description of a preferred embodiment with reference to the accompanying drawings. Directional terms such as up, down, left, right, front, and back mentioned in the following embodiments are merely references to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes only and are not intended to limit the present invention.

[0033] Figure 1 This is a schematic diagram of a head mounted display device according to an embodiment of the present invention. Figure 1 . This embodiment provides a head-mounted display device 100, including an optical lens 110, a waveguide element 130, and an imaging element 150. In this embodiment, the head-mounted display device 100 is, for example, a head-mounted display. The imaging element 150 is disposed on the light incident side IS of the optical lens 110 to provide an image beam IM. The optical lens 110 is configured on the transmission path of the image beam IM to receive the image beam IM from the imaging element 150 (or the light incident side IS). The optical lens 110 is a combination of multiple optical lenses with different optical conditions, which will be described in detail in the subsequent paragraphs. In this embodiment, the imaging element 150 is a self-luminous imaging panel, such as a light emitting diode display panel (LED display), an organic light emitting diode display panel (OLED display), or a micro light emitting diode display panel (Micro LED display), but the present invention is not limited thereto. In other words, due to the configuration of the self-luminous imaging element 150 in this embodiment, the head-mounted display device 100 does not need to use a light combining prism (i.e., it does not have a light combining prism). In this way, the size of the head-mounted display device 100 can be reduced. It is worth mentioning that in this embodiment, the imaging element 150 is an imaging panel that provides a monochromatic light source, and the wavelength of the image beam IM is a single wavelength. However, in different embodiments, the imaging element 150 can be an imaging panel that provides a multi-color light source, and the wavelength of the image beam IM can be multiple wavelengths, and the present invention is not limited to this. For example, in this embodiment, the imaging element 150 uses a 0.13-inch micro-LED panel with a diagonal length of 3.2 mm, which is the size of the image circle of the optical lens 110. In this embodiment, the field of view of the optical lens 110 is designed to be 26.5 degrees and the image height is 1.6 mm. According to the relationship between focal length and image height: image height = focal length × tan (half angle of field of view), it is calculated that the focal length of the optical lens 110 should be designed to be close to 6.79 mm.

[0034] The waveguide element 130 is disposed on the light-exiting side ES of the optical lens 110. The waveguide element 130 has opposing upper and lower surfaces (not numbered) and includes an optical coupling inlet ET and an optical coupling outlet OT. The optical coupling inlet ET and the optical coupling outlet OT are, for example, the surface areas of the waveguide element 130 where the image beam IM from the optical lens 110 enters and exits the waveguide element 130, respectively. In this embodiment, both the optical coupling inlet ET and the optical coupling outlet OT are located on the upper surface of the waveguide element 130. After passing through the optical lens 110, the image beam IM from the imaging element 150 enters the waveguide element 130 via the optical coupling inlet ET. The image beam IM propagates within the waveguide element 130 and finally exits the waveguide element 130 via the optical coupling outlet OT, projecting onto a target F, such as the eye of a user of the head-mounted display device 100. The image beam IM forms a light stop ST on the light-exiting side ES of the optical lens 110, and the image beam IM has a minimum beam cross-sectional area at the location of the light stop ST. For example, in this embodiment, the diameter of this minimum beam cross-sectional area is 5.18 mm, which is close to the size of the average human pupil (approximately 3-6 mm). Therefore, after passing through the optical lens 110, the image beam IM is converged to the position of the light stop ST and then diverges after passing through the light stop ST. Specifically, in this embodiment, the light stop ST is formed at or near the light coupling inlet ET of the waveguide element 130. Located on a reference plane formed by the X-axis and the Y-axis, the shape of the light stop ST is, for example, substantially circular, and its diameter in the X-axis direction is substantially the same as that in the Y-axis direction.

[0035] Specifically, in this embodiment, the display device 100 further includes a cover glass 140, an anti-reflection element 160, and a reflective element 170. The optical lens 110, cover glass 140, and imaging element 150 are collectively referred to as the imaging module 105. The cover glass 140 is disposed between the imaging element 150 and the optical lens 110 to protect the imaging element 150 from dust. The image beam IM provided by the imaging element 150 enters the optical lens 110 through the cover glass 140. Meanwhile, an anti-reflection element 160 is disposed at the light coupling inlet ET of the waveguide element 130. The anti-reflection element 160 may be, for example, an anti-reflection layer coated on the upper surface of the waveguide element 130 corresponding to the light coupling inlet ET, or an anti-reflection structure formed by surface treatment on the upper surface of the waveguide element 130 corresponding to the light coupling inlet ET. The anti-reflection element 160 facilitates the image beam IM's entry into the waveguide element 130 and reduces the proportion of light reflected by the surface of the waveguide element 130. A reflective element 170 is provided on the lower surface of the waveguide element 130 opposite the optical coupling outlet OT. The reflective element 170 may be, for example, a reflective film layer coated on the lower surface of the waveguide element 130 opposite the optical coupling outlet OT, or the reflective element 170 may be a reflective structure formed by surface treatment on the lower surface of the waveguide element 130. The reflective element 170 can reflect the image beam IM propagating within the waveguide element 130 and direct the image beam IM toward the optical coupling outlet OT, thereby facilitating the image beam IM within the waveguide element 130 to exit the waveguide element 130 more easily.

[0036] Figure 2 This is a schematic diagram of an imaging module according to a first embodiment of the present invention. Figure 1 and Figure 2 . Figure 2 、 Figure 8 and Figure 13 The imaging module 105 shown is applicable to at least Figure 1 The display device 100 shown in FIG. Figure 2 The imaging module 105 shown is used as an example. In the imaging module 105 of the first embodiment, the optical lens 110 includes, in order from the light incident side IS to the light exit side ES along the optical axis OA, a first lens 111, a second lens 113, a third lens 115, and a fourth lens 117, each having a refractive power. The first lens 111 to the fourth lens 117 each include a light incident surface 9, 7, 5, and 3 facing the light incident side IS through which the image beam IM passes, and a light exit surface 8, 6, 4, and 2 facing the light exit side ES through which the image beam IM passes. Furthermore, the cover glass 140 in the imaging module 105 has a light incident surface 11 and a light exit surface 10, and the imaging element 150 has an imaging surface 12 for emitting the image beam.

[0037] The first lens 111 has positive refractive power. The first lens 111 is made of glass. The light incident surface 9 of the first lens 111 is concave, facing the imaging element 150, and the light exit surface 8 of the first lens 111 is convex, facing the light barrier ST. In this embodiment, the first lens 111 is an aspheric lens, i.e., both the light incident surface 9 and the light exit surface 8 of the first lens 111 are aspheric surfaces, but the present invention is not limited to this.

[0038] The second lens 113 has a negative refractive power. The second lens 113 is made of glass. The light incident surface 7 of the second lens 113 is a concave surface facing the imaging element 150. The light exit surface 6 of the second lens 113 is a convex surface facing the light barrier ST. In other words, the second lens 113 is a convex-concave lens. In this embodiment, the second lens 113 is an aspheric lens, that is, both the light incident surface 7 and the light exit surface 6 of the second lens 113 are aspheric surfaces, but the present invention is not limited to this.

[0039] The third lens 115 has positive refractive power. The third lens 115 is made of glass. The light incident surface 5 of the third lens 115 is convex toward the imaging element 150. The light exit surface 4 of the third lens 115 is convex toward the light barrier ST. In other words, the third lens 115 is a biconvex lens. In this embodiment, the third lens 115 is an aspherical lens, i.e., both the light incident surface 5 and the light exit surface 4 of the third lens 115 are aspherical surfaces, but the present invention is not limited to this.

[0040] The fourth lens 117 has positive refractive power. The fourth lens 117 is made of glass. The light incident surface 3 of the fourth lens 117 is concave, facing the imaging element 150. The light exit surface 2 of the fourth lens 117 is convex, facing the light barrier ST. In other words, the fourth lens 117 is a meniscus lens. In this embodiment, the fourth lens 117 is an aspherical lens, meaning that both the light incident surface 3 and the light exit surface 2 of the fourth lens 117 are aspherical surfaces. However, the present invention is not limited to this embodiment.

[0041] In other words, in this embodiment, the first lens 111 to the fourth lens 117 are all made of glass, and the first lens 111 to the fourth lens 117 are all aspherical lenses. The optical lens 110 only has the above four lenses with refractive power.

[0042] Other detailed optical data of the first embodiment are shown in Table 1 below, where the effective focal length of the optical lens 110 of the first embodiment is 6.70 mm, the field of view half-angle is 13.25 degrees, and the image height is 1.6 mm. It should be noted that the radius of curvature of the light incident surface 9 shown in Table 1 refers to the radius of curvature of the light incident surface 9 of the first lens 111 on the optical axis OA, the radius of curvature of the light emitting surface 8 refers to the radius of curvature of the light emitting surface 8 of the first lens 111 on the optical axis OA, and so on. The spacing of the light incident surface 9 (0.70 mm as shown in Table 1) refers to the distance between the light incident surface 9 and the next surface (the light emitting surface 10 of the protective cover 140 in this example) on the optical axis OA, that is, the distance between the first lens 111 and the protective cover 140 on the optical axis OA is 0.70 mm. The spacing of the light emitting surface 8 (0.97 mm as shown in Table 1) refers to the distance between the light emitting surface 8 and the light incident surface 9 of the first lens 111 on the optical axis OA, that is, the thickness of the first lens 111 on the optical axis OA is 0.97 mm, and so on.

[0043] Table 1:

[0044]

[0045]

[0046] It is also worth noting that in the optical lens 110 of the first embodiment, the aperture value (f / #) of the optical lens 110 is 1.294, the effective focal length of the optical lens 110 is 6.70 mm, the focal length of the third lens element 115 is 4.44 mm, the Abbe number of the third lens element 115 is 70.42, and the focal length of the fourth lens element 117 is 18.32 mm. In other words, the optical lens 110 of the first embodiment satisfies the following equation:

[0047] Optical lens 110 meets 0.3 <f L3 / f<3;

[0048] Optical lens 110 meets V L3 >30;

[0049] Optical lens 110 satisfies |f L4 / f|>1; and

[0050] The optical lens 110 satisfies an aperture value of f / #<2.

[0051] in,

[0052] f L3 is the focal length of the third lens 115;

[0053] f is the effective focal length of the optical lens 110;

[0054] V L3is the Abbe number of the third lens 115; and

[0055] f L4 is the focal length of the fourth lens 117.

[0056] In addition, at least one of the lenses with positive refractive power in the optical lens 110 satisfies the conditional expression:

[0057] dn / dt<0.

[0058] Here, dn / dt is the change in the refractive index of the lens per unit temperature.

[0059] In this embodiment, the lenses having positive refractive power in the optical lens system 110 are the first lens system 111, the third lens system 115, and the fourth lens system 117. The third lens system 115 is made of a glass material having a negative dn / dt value, while the first lens system 111, the second lens system 113, and the fourth lens system are made of a glass material having a positive dn / dt value. This allows the optical lens system 110 to take into account thermal drift and control it within an acceptable range.

[0060] In this embodiment, the eight light-entering surfaces 9, 7, 5, 3 and the light-emitting surfaces 8, 6, 4, 2, a total of eight surfaces, are aspherical surfaces. These aspherical surfaces are defined according to the following formula:

[0061]

[0062] Y is the distance between the point on the aspheric curve and the optical axis;

[0063] Z is the depth of the aspheric surface, that is, the vertical distance between the point on the aspheric surface that is Y away from the optical axis and the tangent plane that is tangent to the vertex on the optical axis of the aspheric surface;

[0064] R is the radius of curvature of the lens surface;

[0065] K is the cone coefficient;

[0066] a2i is the 2i-th order aspheric coefficient.

[0067] The various aspheric coefficients of the aspheric surfaces in formula (1) for this embodiment are shown in Table 2 below. Column number 9 in Table 2 represents the aspheric coefficient of the light-entering surface 9 of the first lens 111, and the same applies to the other columns. In this embodiment, the second-order aspheric coefficient a2 of each aspheric surface is zero and is therefore not listed in the table.

[0068] Table 2:

[0069] surface K <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> <![CDATA[a 10 ]]> <![CDATA[a 12 ]]> <![CDATA[a 14 ]]> 2 0.00E+00 -9.82E-04 2.01E-04 -9.88E-05 1.66E-05 -1.16E-06 8.17E-11 3 0.00E+00 1.22E-03 -3.69E-04 -2.69E-05 3.12E-05 -5.51E-06 2.54E-07 4 0.00E+00 2.52E-03 -1.77E-03 4.35E-04 -6.37E-05 2.50E-06 5.93E-08 5 0.00E+00 3.01E-02 -7.39E-03 8.74E-04 -2.28E-05 -5.37E-06 4.56E-07 6 0.00E+00 -2.72E-02 2.11E-02 -9.26E-03 2.51E-03 -3.96E-04 2.87E-05 7 0.00E+00 -8.18E-02 4.36E-02 -1.67E-02 3.49E-03 -7.44E-16 -5.54E-18 8 0.00E+00 -2.48E-02 -1.78E-02 2.43E-02 -1.65E-02 5.76E-03 -7.75E-04 9 0.00E+00 -3.66E-02 -1.74E-03 1.71E-03 -1.86E-03 8.00E-04 -1.14E-04

[0070] Figure 3 for Figure 2Please refer to the diagram of astigmatism and distortion of optical lenses in the . Figure 3 . Figure 3 The field curvature aberration in the sagittal direction (marked X), the field curvature aberration in the tangential direction (marked Y), and the distortion aberration of the optical lens 110 of the first embodiment are described. Figure 3 It can be seen that the field curvature aberration of the optical lens 110 of this embodiment falls within ±0.008 mm, demonstrating that the optical lens 110 of the first embodiment can effectively eliminate aberrations. Furthermore, the distortion diagram shows that the distortion aberration is maintained within a range of ±2%, indicating that the distortion aberration of the first embodiment meets the imaging quality requirements of the optical lens 110 and can provide good imaging quality.

[0071] Figure 4 for Figure 2 The third-order aberration distribution diagram of the optical lens in . Please refer to Figure 4 .in, Figure 4 The aberration coefficients of various aberrations (including spherical aberration, coma, astigmatism, field curvature, distortion, chromatic aberration, Petzval field curvature, etc.) generated when the image beam IM passes through the light entrance surfaces 9, 7, 5, 3 and the light exit surfaces 8, 6, 4, 2 are shown. Figure 4 It can be seen that the combined aberration between the light exit surface 6 of the second lens 113 and the light entrance surface 5 of the third lens 115 and the aberration of the light entrance surface 7 of the second lens 113 can offset each other, thereby providing good image quality.

[0072] 5A to 5D for Figure 2 The Modulation Transfer Function (MTF) curves of the optical lens at different temperatures are shown in the figure. 5A to 5D .in, Figure 5A shows the green band modulation transfer function curve of each lens in the optical lens 110 at room temperature; Figures 5B to 5D The modulation transfer function curves of the optical lens 110 are shown respectively when the ambient temperature is -10 degrees Celsius, 25 degrees Celsius and 50 degrees Celsius. When the ambient temperature of the first embodiment is -10 degrees Celsius, 25 degrees Celsius and 50 degrees Celsius respectively, the temperature values (°C) of the first lens 111, the second lens 113, the third lens 115 and the fourth lens 117 of the optical lens 110 are shown in Table 3 below. 5A to 5DIt can be seen that when the optical lens 110 of the first embodiment is in an ambient temperature range of -10°C to 50°C and is in thermal equilibrium, without refocusing, the thermal drift of the back focus of the optical lens relative to the center of the projected image is less than 0.01 mm. Therefore, good image quality can be provided.

[0073] Table 3:

[0074] Ambient temperature Fourth lens 117 The third lens 115 Second lens 113 First lens 111 -10℃ 4℃ 7℃ 11℃ 14℃ 25℃ 39℃ 42℃ 46℃ 49℃ 50℃ 64℃ 67℃ 71℃ 74℃

[0075] Figure 6 for Figure 2 Relative Illumination distribution diagram of the optical lens in. Figure 7 for Figure 2 Please refer to the diagram of TV distortion of the optical lens in the figure. Figure 6 and Figure 7 In this embodiment, Figure 6 It can be seen that under different chief ray image height simulations, the relative illumination of the optical lens 110 can be greater than 60%, and Figure 7 It can be seen that the screen deformation is less than 0.4% at a projection distance of 20 meters, thus providing good image quality.

[0076] As a result, the imaging module 105 of the first embodiment is designed to utilize a smaller 0.13-inch monochrome micro-LED panel as the imaging element 150, eliminating the need for an additional three-color light-combining prism, thereby reducing the overall size of the imaging module 105. Furthermore, the projected image of the optical lens 110 of the first embodiment has a high resolution, reaching 125 lp / mm. Furthermore, the optical lens 110 of the first embodiment comprises only four lenses with refractive power, thereby reducing the back focal length and the overall size of the optical lens 110. Furthermore, the positive and negative refractive powers of the optical lens 110 of the first embodiment, combined with the selection of positive and negative dn / dt, take into account thermal drift under specific lens temperature differentials, keeping it within an acceptable range. Furthermore, the first embodiment, through its ultra-large aperture (f / # < 2), allows the optical lens 110 to maintain sufficient brightness when outputting images using only the monochrome imaging element 150.

[0077] In order to fully illustrate the various embodiments of the present invention, other embodiments of the present invention will be described below. It must be noted that the following embodiments use the component numbers and some of the content of the previous embodiments, wherein the same reference numerals are used to represent the same or similar components, and the description of the same technical content is omitted. For the description of the omitted parts, please refer to the previous embodiments, and the following embodiments will not be repeated.

[0078] Figure 8 This is a schematic diagram of an imaging module according to a second embodiment of the present invention. Imaging module 105A of this second embodiment is generally similar to imaging module 105 of the first embodiment, with the following differences: The optical data, aspheric coefficients of optical lens 110, and the parameters of lenses 111, 113, 115, and 117 vary somewhat. Furthermore, in this embodiment, first lens 111 has negative refractive power. Other detailed optical data for the second embodiment are shown in Table 4 below.

[0079] Table 4:

[0080]

[0081]

[0082] It is also worth noting that in the optical lens 110 of the second embodiment, the aperture value f / # of the optical lens 110 is 1.296, the effective focal length of the optical lens 110 is 6.71 mm, the focal length of the third lens 115 is 3.77 mm, the Abbe number of the third lens 115 is 70.42, and the focal length of the fourth lens 117 is -305.96 mm. In this embodiment, the third lens 115 with positive refractive power is selected to use a glass material with a negative dn / dt value, while the first lens 111, the second lens 113 and the fourth lens are selected to use a glass material with a positive dn / dt value. In other words, the optical lens 110 of the second embodiment also meets the aforementioned Figure 1 The optical lens 110 is a linear array.

[0083] The various aspheric coefficients of the aspheric surface in formula (1) of this embodiment are shown in Table 5. In this embodiment, the second-order aspheric coefficient a2 of each aspheric surface is zero and is therefore not listed in the table.

[0084] Table 5:

[0085] surface K <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> <![CDATA[a 10 ]]> <![CDATA[a 12 ]]> <![CDATA[a 14 ]]> 2 0.00E+00 -1.11E-03 3.00E-05 -1.37E-05 -3.38E-06 7.45E-07 -7.13E-08 3 0.00E+00 -2.00E-03 4.25E-04 -4.91E-05 -7.50E-06 6.14E-07 -1.40E-08 4 0.00E+00 -2.52E-03 1.12E-04 2.73E-05 -1.81E-05 -1.03E-06 2.28E-07 5 0.00E+00 3.24E-02 -6.94E-03 5.97E-04 4.40E-05 -1.32E-05 9.03E-07 6 0.00E+00 -3.16E-02 2.48E-02 -1.04E-02 2.59E-03 -3.69E-04 2.48E-05 7 0.00E+00 -8.13E-02 5.14E-02 -1.95E-02 4.97E-03 -3.96E-16 -2.15E-18 8 0.00E+00 -3.27E-02 -1.61E-02 2.50E-02 -1.80E-02 6.64E-03 -9.69E-04 9 0.00E+00 -4.31E-02 -4.58E-04 1.34E-03 -1.69E-03 7.76E-04 -1.22E-04

[0086] Figure 9 for Figure 8 Please refer to the astigmatism field curvature and distortion diagram of the optical lens in Figure 9 . Figure 9 The field curvature aberration in the sagittal direction (marked by X), the field curvature aberration in the tangential direction (marked by Y), and the distortion aberration of the optical lens 110 of the second embodiment are described. Figure 9It can be seen that the field curvature aberration of the optical lens 110 of this embodiment falls within ±0.010 mm, indicating that the optical lens 110 of the second embodiment can effectively eliminate aberrations. The distortion diagram shows that the distortion aberration is maintained within the range of ±2%, indicating that the distortion aberration of the second embodiment meets the imaging quality requirements of the optical lens 110 and can provide good imaging quality.

[0087] 10A to 10D for Figure 8 The modulation transfer function curve of the optical lens at different temperatures is shown in Figure 2. 10A to 10D .in, Figure 10A shows the green light band modulation transfer function curve of each lens in the optical lens 110 at room temperature; FIG. 10B to FIG. 10D The modulation transfer function curves of the optical lens 110 are shown in Figure 6 when the ambient temperature is -10 degrees Celsius, 25 degrees Celsius, and 50 degrees Celsius. When the ambient temperature of the second embodiment is -10 degrees Celsius, 25 degrees Celsius, and 50 degrees Celsius, the temperature values (°C) of the first lens 111, the second lens 113, the third lens 115, and the fourth lens 117 of the optical lens 110 are shown in Table 6 below. 10A to 10D It can be seen that when the optical lens 110 of the second embodiment is in an ambient temperature range of -10°C to 50°C and is in thermal equilibrium, without refocusing, the thermal drift of the back focus of the optical lens relative to the center of the projected image is less than 0.01 mm. Therefore, good image quality can be provided.

[0088] Table 6:

[0089] Ambient temperature Fourth lens 117 The third lens 115 Second lens 113 First lens 111 -10℃ 4℃ 7℃ 11℃ 14℃ 25℃ 39℃ 42℃ 46℃ 49℃ 50℃ 64℃ 67℃ 71℃ 74℃

[0090] Figure 11 for Figure 8 Relative illumination distribution diagram of the optical lens in . Figure 12 for Figure 8 Schematic diagram of screen deformation of optical lens in . Please refer to Figure 11 and Figure 12 In this embodiment, Figure 11 It can be seen that under different chief ray image height simulations, the relative illumination of the optical lens 110 can be greater than 60%, and Figure 12 It can be seen that the screen deformation is less than 0.4% at a projection distance of 20 meters, thus providing good image quality.

[0091] Figure 13This is a schematic diagram of an imaging module according to a third embodiment of the present invention. Imaging module 105B of this third embodiment is generally similar to imaging module 105 of the first embodiment, with the following differences: The optical data, aspheric coefficients of optical lens 110, and the parameters of lenses 111, 113, 115, and 117 vary somewhat. Furthermore, in this embodiment, second lens 113 is a spherical lens. Other detailed optical data for the third embodiment are shown in Table 7 below.

[0092] Table 7:

[0093]

[0094]

[0095] It is also worth noting that in the optical lens 110 of the third embodiment, the aperture value f / # of the optical lens 110 is 1.294, the effective focal length of the optical lens 110 is 6.78 mm, the focal length of the third lens 115 is 5.34 mm, the Abbe number of the third lens 115 is 63.76, and the effective focal length of the fourth lens 117 is 14.51 mm. In this embodiment, the third lens 115 with positive refractive power is selected to use a glass material with a negative dn / dt value, while the first lens 111, the second lens 113 and the fourth lens are selected to use a glass material with a positive dn / dt value. In other words, the optical lens 110 of the third embodiment also meets the aforementioned Figure 1 The optical lens 110 is a linear array.

[0096] The various aspheric coefficients of the aspheric surface in formula (1) of this embodiment are shown in Table 8. In this embodiment, the second-order aspheric coefficient a2 of each aspheric surface is zero and is therefore not listed in the table.

[0097] Table 8:

[0098] surface K <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> <![CDATA[a 10 ]]> <![CDATA[a 12 ]]> <![CDATA[a 14 ]]> 2 0.00E+00 6.19E-04 -1.54E-04 6.53E-05 -1.71E-05 1.70E-06 -7.31E-08 3 0.00E+00 5.94E-04 5.39E-04 -7.84E-05 -1.73E-05 4.39E-06 -2.90E-07 4 0.00E+00 -3.85E-03 8.81E-04 -2.64E-04 1.73E-05 1.95E-06 -1.77E-07 5 0.00E+00 -1.84E-03 3.13E-04 -1.53E-04 5.43E-05 -7.53E-06 5.03E-07 8 0.00E+00 -8.53E-03 -1.24E-02 1.45E-02 -1.21E-02 4.84E-03 -8.28E-04 9 0.00E+00 -1.55E-02 -2.35E-03 -2.76E-03 9.11E-04 -1.23E-04 2.52E-06

[0099] Figure 14 for Figure 13 Please refer to the astigmatism field curvature and distortion diagram of the optical lens in Figure 14 . Figure 14 The field curvature aberration in the sagittal direction (marked by X), the field curvature aberration in the tangential direction (marked by Y), and the distortion aberration of the optical lens 110 of the third embodiment are described. Figure 14 It can be seen that the field curvature aberration of the optical lens 110 of this embodiment falls within ±0.020 mm, indicating that the optical lens 110 of the third embodiment can effectively eliminate aberrations. The distortion diagram shows that the distortion aberration is maintained within the range of ±2%, indicating that the distortion aberration of the third embodiment meets the imaging quality requirements of the optical lens 110 and can provide good imaging quality.

[0100] 15A to 15D for Figure 13 The modulation transfer function curve of the optical lens at different temperatures is shown in Figure 2. 15A to 15D .in, Figure 15A shows the green light band modulation transfer function curve of each lens in the optical lens 110 at room temperature; Figures 15B to 15D The modulation transfer function curves of the optical lens 110 are shown in Figure 9 when the ambient temperature is -10 degrees Celsius, 25 degrees Celsius, and 50 degrees Celsius. When the ambient temperature of the third embodiment is -10 degrees Celsius, 25 degrees Celsius, and 50 degrees Celsius, the temperature values (°C) of the first lens 111, the second lens 113, the third lens 115, and the fourth lens 117 of the optical lens 110 are shown in Table 9 below. 15A to 15D It can be seen that when the optical lens 110 of the third embodiment is in an ambient temperature range of -10°C to 50°C and is in thermal equilibrium, without refocusing, the thermal drift of the back focus of the optical lens relative to the center of the projected image is less than 0.01 mm. Therefore, good image quality can be provided.

[0101] Table 9:

[0102] Ambient temperature Fourth lens 117 The third lens 115 Second lens 113 First lens 111 -10℃ 4℃ 7℃ 11℃ 14℃ 25℃ 39℃ 42℃ 46℃ 49℃ 50℃ 64℃ 67℃ 71℃ 74℃

[0103] Figure 16 for Figure 13 Relative illumination distribution diagram of the optical lens in . Figure 17 for Figure 13 Schematic diagram of screen deformation of optical lens in . Please refer to Figure 16 and Figure 17 In this embodiment, Figure 16 It can be seen that under different chief ray image height simulations, the relative illumination of the optical lens 110 can be greater than 70%, and Figure 17 It can be seen that the screen deformation is less than 1.3% at a projection distance of 20 meters, thus providing good image quality.

[0104] Figure 18 This is a schematic diagram of an imaging module according to a fourth embodiment of the present invention. Figure 18 The imaging module 105C of this fourth embodiment is substantially similar to the imaging module 105 of the first embodiment, with the following differences: the optical data, aspheric coefficients, and parameters of the optical lens 110, lenses 111, 113, 115, and 117, vary somewhat. Furthermore, in this embodiment, the optical lens 110 further includes a fifth lens 119 disposed between the first lens 111 and the fourth lens 117. Specifically, the fifth lens 119 is disposed between the first lens 111 and the second lens 113, but the present invention is not limited thereto.

[0105] The fifth lens 119 has positive refractive power. The fifth lens 119 is made of plastic. The light incident surface 14 of the fifth lens 119 is concave, facing the imaging element 150. The light exit surface 13 of the fifth lens 119 is convex, facing the light barrier ST. In other words, the fifth lens 119 is a meniscus lens. In this embodiment, the third lens 115 of the fifth lens 119 is a spherical lens, i.e., both the light incident surface 14 and the light exit surface 13 of the fifth lens 119 are spherical surfaces, but the present invention is not limited to this.

[0106] In addition, in this embodiment, the first lens 111 has a negative refractive power. The first lens 111 is made of plastic. The second lens 113 is also made of plastic.

[0107] The third lens 115 is made of glass. The fourth lens 117 is made of plastic. Other detailed optical data of the fourth embodiment are shown in Table 10 below.

[0108] Table 10:

[0109]

[0110] It is worth noting that in the optical lens 110 of the fourth embodiment, the effective focal length of the optical lens 110 is 6.71 mm, the focal length of the third lens 115 is 5.5 mm, the Abbe number of the third lens 115 is 63.90, and the focal length of the fourth lens 117 is 10.96 mm. In other words, the optical lens 110 of the fourth embodiment also meets the aforementioned Figure 1 The optical lens 110 is a linear array.

[0111] The various aspheric coefficients of the aspheric surface in formula (1) of this embodiment are shown in Table 11. In this embodiment, the second-order aspheric coefficient a2 of each aspheric surface is zero and is therefore not listed in the table.

[0112] Table 11:

[0113] surface K <![CDATA[a4]]> <![CDATA[a6]]> <![CDATA[a8]]> <![CDATA[a 10 ]]> <![CDATA[a 12 ]]> <![CDATA[a 14 ]]> 2 0.00E+00 -1.26E-04 1.92E-04 -6.08E-05 1.33E-05 -2.53E-07 -9.25E-08 3 0.00E+00 5.39E-04 2.85E-03 -1.80E-03 7.30E-04 -1.34E-04 8.27E-06 4 0.00E+00 3.31E-04 7.59E-04 -4.33E-04 1.95E-04 -2.05E-05 -2.35E-06 5 0.00E+00 1.33E-03 1.73E-05 3.13E-04 -6.98E-05 -3.99E-05 6.21E-06 6 0.00E+00 -4.75E-02 1.64E-02 -5.19E-03 1.36E-03 -3.10E-04 3.68E-05 7 0.00E+00 -7.77E-02 1.99E-02 -1.02E-02 1.05E-03 7.55E-04 -4.54E-04 8 0.00E+00 -4.94E-02 -2.95E-02 2.23E-02 -1.53E-02 5.04E-03 -7.04E-04 9 0.00E+00 -4.01E-02 -2.33E-02 9.97E-03 -2.64E-03 3.34E-04 -1.65E-05

[0114] Figure 19 for Figure 18 Please refer to the astigmatism field curvature and distortion diagram of the optical lens in Figure 19 . Figure 19 The field curvature aberration in the sagittal direction (marked by X), the field curvature aberration in the tangential direction (marked by Y), and the distortion aberration of the optical lens 110 of the fourth embodiment are described. Figure 19It can be seen that the field curvature aberration of the optical lens 110 of this embodiment falls within ±0.010 mm, indicating that the optical lens 110 of the fourth embodiment can effectively eliminate aberrations. The distortion aberration diagram shows that the distortion aberration is maintained within the range of ±2%, indicating that the distortion aberration of the fourth embodiment meets the imaging quality requirements of the optical lens 110 and can provide good imaging quality.

[0115] 20A to 20D for Figure 18 The modulation transfer function curve of the optical lens at different temperatures is shown in Figure 2. 20A to 20D .in, Figure 20A shows the green light band modulation transfer function curve of each lens in the optical lens 110 at room temperature; FIG. 20B to FIG. 20D The modulation transfer function curves of the optical lens 110 are shown in Figure 12 when the ambient temperature is -10 degrees Celsius, 25 degrees Celsius, and 50 degrees Celsius. When the ambient temperature of the fourth embodiment is -10 degrees Celsius, 25 degrees Celsius, and 50 degrees Celsius, the temperature values (°C) of the first lens 111, the second lens 113, the third lens 115, the fourth lens 117, and the fifth lens 119 of the optical lens 110 are shown in Table 12 below. 20A to 20D It can be seen that when the optical lens 110 of the fourth embodiment is used in an ambient temperature range of -10°C to 50°C and in thermal equilibrium, without re-adjusting the focal length, the thermal drift of the optical lens' back focus relative to the center of the projected image is less than 0.01 mm. Therefore, good image quality can be provided.

[0116] Table 12:

[0117]

[0118] Figure 21 for Figure 18 Relative illumination distribution diagram of the optical lens in . Figure 22 for Figure 18 Schematic diagram of screen deformation of optical lens in . Please refer to Figure 21 and Figure 22 In this embodiment, Figure 21 It can be seen that under different chief ray image height simulations, the relative illumination of the optical lens 110 can be greater than 60%, and Figure 22 It can be seen that the screen deformation is less than 0.4% at a projection distance of 20 meters, thus providing good image quality.

[0119] In summary, in the optical lens and head-mounted display device of the present invention, the imaging module design can be used in conjunction with a smaller monochrome micro-light-emitting diode panel as an imaging element, so there is no need for an additional three-color light-combining prism, which can reduce the size of the overall imaging module. In addition, the projected image of the optical lens has a high resolution of up to 125lp / mm. In addition, the positive and negative refractive powers of the optical lens are combined with the selection of positive and negative dn / dt, which takes into account the thermal drift phenomenon within an acceptable range under specific lens temperature difference conditions. In addition, the optical lens, through the design of an ultra-large aperture, can ensure that the optical lens still has sufficient brightness when outputting images using only a monochrome imaging element.

[0120] However, what is described above is only a preferred embodiment of the present invention, and it should not be used to limit the scope of implementation of the present invention. That is, all simple equivalent changes and modifications made in accordance with the claims and the content of the invention are still within the scope of the patent of the present invention. In addition, any embodiment or claim of the present invention does not need to achieve all the purposes, advantages or features disclosed by the present invention. In addition, the abstract and title (invention name) are only used to assist in the retrieval of patent documents, and are not used to limit the scope of rights of the present invention. In addition, the terms "first", "second", etc. mentioned in this specification or claims are only used to name the name of the element or to distinguish different embodiments or scopes, and are not used to limit the upper or lower limit on the number of elements.

Claims

1. An optical lens for receiving an image beam from an imaging element, characterized in that: The optical lens includes, in order from the light incident side to the light exit side along the optical axis, a first lens, a second lens, a third lens, and a fourth lens having refractive powers, and each of the first lens to the fourth lens includes a light incident surface facing the light incident side and allowing the image beam to pass therethrough, and a light exit surface facing the light exit side and allowing the image beam to pass therethrough, wherein: The light incident surface of the first lens is a concave surface; The second lens has negative refractive power, and the light-emitting surface of the second lens is a convex surface; The third lens has positive refractive power, and the light incident surface of the third lens is a convex surface; The fourth lens has positive refractive power, and the light incident surface of the fourth lens is a concave surface; and The optical lens receives the image beam from the light incident side. The image beam forms a light barrier on the light exit side, and the image beam has a minimum beam cross-sectional area at the position of the light barrier.

2. The optical lens according to claim 1, wherein: The light-emitting surface of the first lens is a convex surface.

3. The optical lens according to claim 1, wherein: The light incident surface of the second lens is a concave surface.

4. The optical lens according to claim 1, wherein: The light-emitting surface of the third lens is a convex surface.

5. The optical lens according to claim 1, wherein: The light-emitting surface of the fourth lens is a convex surface.

6. The optical lens according to claim 1, wherein: The first lens to the fourth lens are made of glass.

7. The optical lens according to claim 1, wherein: The first lens, the third lens, and the fourth lens are aspherical lenses.

8. The optical lens according to claim 1, wherein: There are only four lenses with refractive power in the optical lens.

9. The optical lens according to claim 1, wherein: The optical lens further includes a fifth lens disposed between the first lens and the fourth lens, wherein the fifth lens has positive refractive power.

10. The optical lens according to claim 9, wherein: The fifth lens is a spherical lens.

11. The optical lens according to claim 1, wherein: The optical lens satisfies the conditional formula: 0.3 <f L3 / f<3, where f L3 is the focal length of the third lens, and f is the effective focal length of the optical lens.

12. The optical lens according to claim 1, wherein: The optical lens satisfies the conditional formula: V L3 >30, where V L3 is the Abbe number of the third lens.

13. The optical lens according to claim 1, wherein: The optical lens satisfies the conditional formula: |f L4 / f|>1, where f L4 is the focal length of the fourth lens, and f is the effective focal length of the optical lens.

14. The optical lens according to claim 1, wherein: The aperture value of the optical lens is less than 2.

15. The optical lens according to claim 1, wherein: At least one of the lenses with positive refractive power in the optical lens satisfies the conditional formula: dn / dt<0, where dn / dt is a change in the refractive index of the lens per unit temperature.

16. The optical lens according to claim 1, wherein: The composite aberration between the light exit surface of the second lens and the light incident surface of the third lens and the aberration of the light incident surface of the second lens cancel each other out.

17. A head-mounted display device, characterized in that: The head-mounted display device includes an imaging element, an optical lens, and a waveguide element, wherein: The imaging element is used to provide an image beam; The optical lens is disposed on a transmission path of the image beam. The optical lens includes, in order from a light incident side to a light exit side along an optical axis, a first lens, a second lens, a third lens, and a fourth lens having refractive powers. The first lens to the fourth lens each include a light incident surface facing the light incident side and allowing the image beam to pass therethrough, and a light exit surface facing the light exit side and allowing the image beam to pass therethrough, wherein: The light incident surface of the first lens is a concave surface; The second lens has negative refractive power, and the light-emitting surface of the second lens is a convex surface; The third lens has positive refractive power, and the light incident surface of the third lens is a convex surface; The fourth lens has positive refractive power, and the light incident surface of the fourth lens is a concave surface; and The optical lens receives the image beam from the light incident side, the image beam forms a light barrier on the light exit side, and the image beam has a minimum beam cross-sectional area at the position of the light barrier; and The waveguide element is arranged on the light-emitting side of the optical lens and has a light coupling inlet and a light coupling outlet. The image light beam from the imaging element passes through the optical lens, enters the waveguide element through the light coupling inlet, and leaves the waveguide element through the light coupling outlet.

18. The head-mounted display device according to claim 17, wherein: The imaging element is a self-luminous imaging panel.

19. The head-mounted display device according to claim 18, wherein: The head-mounted display device does not include a light-combining prism.

20. The head-mounted display device according to claim 18, wherein: The imaging element is an imaging panel that provides a monochromatic light source, and the wavelength of the image light beam is a single wavelength.

Images