Optical engine projection lens and AR device

Abstract

The application discloses a light engine projection lens and AR equipment, the projection lens is suitable for diffractive optical waveguide, and comprises a diaphragm, a first lens group, a second lens group and an imaging module which are sequentially arranged along an optical axis from an object side to an image side; the light passing size of the diaphragm is matched with the entrance pupil size of the diffractive optical waveguide, the first lens group and the second lens group each comprise a plurality of lenses with different optical powers, and the lenses in the first lens group and the second lens group are all spherical lenses. The diaphragm light passing size is matched with the entrance pupil size of the diffractive optical waveguide, so that the projection lens can match the diffractive optical waveguide, in addition, all the lenses in the projection lens are spherical lenses, high resolution and small distortion can be realized, and the production cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of AR display technology, in particular to a light engine projection lens and AR device. BACKGROUND

[0002] Currently, with the increasing demand of consumers for car safety and driving experience, navigation head-up display (Head Up Display, HUD for short) is being used in more and more cars. HUD can project driving information directly into the driver's line of sight (such as inside the windshield or on the screen), allowing the driver to focus on the outside during driving. This can improve the driving habits of the driver and reduce driving accidents caused by looking down.

[0003] At the same time, with the increasing demand for HUD viewing angle, the volume of HUD is increasing, and traditional HUD is difficult to meet the needs of compact vehicles. HUD using diffraction waveguide technology can greatly reduce the volume of the entire module, which is bound to be the key direction of future HUD development, especially in AR-HUD. The projection lens used in traditional HUD cannot be directly used in HUD matching diffraction waveguide, so how to overcome this defect is a problem that needs to be solved by those skilled in the art. SUMMARY

[0004] The embodiments of the present application provide a light engine projection lens and AR device, aiming to provide a projection lens matched with a diffraction light waveguide HUD.

[0005] The embodiments of the present application provide a light engine projection lens suitable for a diffraction light waveguide, comprising a stop, a first lens group, a second lens group and an imaging module arranged in order from the object side to the image side along the optical axis.

[0006] The light passing size of the stop matches the entrance pupil size of the diffraction light waveguide, the first lens group and the second lens group each include a plurality of lenses with different focal lengths, and the lenses in the first lens group and the second lens group are spherical lenses.

[0007] Further, the first lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in order from the object side to the image side along the optical axis,

[0008] The first lens has positive focal length and is convex near the side close to the stop; the second lens has negative focal length and is convex near the side close to the stop; the third lens has positive focal length and is convex near the side close to the stop; and the fourth lens has negative focal length and is concave near the side close to the stop.

[0009] Further, the second lens group comprises, in order from the object side to the image side along the optical axis, a fifth lens, a sixth lens, a seventh lens, and an eighth lens,

[0010] The fifth lens has positive focal power and is convex on the side close to the diaphragm; the sixth lens has positive focal power and is convex on the side close to the diaphragm; the seventh lens has negative focal power and is convex on the side close to the diaphragm; and the eighth lens has positive focal power and is convex on the side close to the diaphragm.

[0011] Further, the relationship between the total length of the projection lens and the effective focal length of the system is: 1.5 < L / EFL < 2.5; wherein L represents the total length of the system, and EFL represents the effective focal length of the system.

[0012] Further, the relationship between the effective focal length of the system and the focal length of the first lens is: 1 < f1 / EFL < 1.5; wherein EFL represents the effective focal length of the system, and f1 represents the focal length of the first lens.

[0013] Further, the relationship between the effective focal length of the system and the focal length of the eighth lens is: 0.6 < f8 / EFL < 1.5; wherein EFL represents the effective focal length of the system, and f8 represents the focal length of the eighth lens.

[0014] Further, the relationship between the effective focal length of the system and the back focal length of the system is: 0.4 < BFL / EFL < 0.8; wherein EFL represents the effective focal length of the system, and BFL represents the back focal length of the system.

[0015] Further, the second lens and the third lens are cemented together, and the seventh lens and the eighth lens are cemented together.

[0016] Further, the imaging module comprises, in order from the object side to the image side along the optical axis, a prism unit and an imaging unit; the prism unit comprises at least one prism; and the imaging unit is any one of a DLP module, an LCOS module, a MicroLED module, and an LBS module.

[0017] The embodiment of the present application also provides an AR device adopting the optical engine projection lens according to any one of the above.

[0018] The embodiment of the present application provides a light engine projection lens and an AR device, the projection lens is suitable for a diffractive optical waveguide, and comprises a diaphragm, a first lens group, a second lens group and an imaging module which are sequentially arranged along an optical axis from an object side to an image side; the diaphragm has a light passing size matched with an entrance pupil size of the diffractive optical waveguide, the first lens group and the second lens group each comprise a plurality of lenses with different focal lengths, and the lenses in the first lens group and the second lens group are all spherical lenses. The embodiment of the present application matches the light passing size of the diaphragm with the entrance pupil size of the diffractive optical waveguide, so that the projection lens can match the diffractive optical waveguide, in addition, all the lenses in the projection lens are spherical lenses, high resolution and small distortion can be realized, and the production cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1 A structural schematic diagram of a light engine projection lens provided by the embodiment of the present application is provided.

[0021] Figure 2 A first field curvature schematic diagram and a first distortion schematic diagram of a light engine projection lens provided by the embodiment of the present application are provided.

[0022] Figure 3 A first spherical aberration curve schematic diagram of a light engine projection lens provided by the embodiment of the present application is provided.

[0023] Figure 4 A first chromatic aberration curve schematic diagram of a light engine projection lens provided by the embodiment of the present application is provided.

[0024] Figure 5 A second field curvature schematic diagram and a second distortion schematic diagram of a light engine projection lens provided by the embodiment of the present application are provided.

[0025] Figure 6 A second spherical aberration curve schematic diagram of a light engine projection lens provided by the embodiment of the present application is provided.

[0026] Figure 7 A second chromatic aberration curve schematic diagram of a light engine projection lens provided by the embodiment of the present application is provided.

[0027] Figure 8 A third field curvature schematic diagram and a third distortion schematic diagram of a light engine projection lens provided by the embodiment of the present application are provided.

[0028] Figure 9 A third spherical aberration curve schematic diagram of a light engine projection lens provided by an embodiment of the present application is shown in the figure;

[0029] Figure 10 A third chromatic aberration curve schematic diagram of a light engine projection lens provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0031] It should be understood that, when used in the specification and the appended claims, the terms "comprise" and "include" indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0032] It should also be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0033] It should be further understood that the term "and / or" used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0034] Please see Figure 1 The embodiment of the present application provides a light engine projection lens suitable for a diffractive optical waveguide, which comprises, in sequence from an object side to an image side along an optical axis, a diaphragm L0, a first lens group, a second lens group and an imaging module.

[0035] The diaphragm L0 has a light passing size matched with an entrance pupil size of the diffractive optical waveguide, the first lens group and the second lens group each comprise a plurality of lenses with different optical powers, and the lenses in the first lens group and the second lens group are all spherical lenses.

[0036] In the embodiment, the projection lens comprises a diaphragm L0, lens groups (i.e. the first lens group and the second lens group) and an imaging module, and is matched with the diffraction optical waveguide by matching the diaphragm aperture with the entrance pupil size of the diffraction optical waveguide, and in addition, all the lenses in the projection lens are spherical lenses, which can realize high resolution and small distortion, and also has the characteristics of low production cost.

[0037] In the embodiment, different focal length lenses are matched and combined with the diaphragm L0 aperture, so as to realize the projection lens matched with the large size diffraction waveguide HUD, and in addition, by optimizing the focal length distribution, the aberrations such as spherical aberration, lateral chromatic aberration and distortion can be optimized to the minimum, and the problem of balancing large entrance pupil and large aberration can be solved, and in addition, since the all-spherical lens design scheme is adopted, the advantages of high resolution, simplified process and low cost are also achieved.

[0038] In an embodiment, in combination with Figure 1 As shown in the figure, the first lens group comprises a first lens L1, a second lens L2, a third lens L3 and a fourth lens L4 arranged in sequence from the object side to the image side along the optical axis,

[0039] The first lens L1 has positive focal length, and the side S1 close to the diaphragm L0 is a convex surface (the side S2 away from the diaphragm L0 is a convex surface); the second lens L2 has negative focal length, and the side S3 close to the diaphragm L0 is a convex surface; the third lens L3 has positive focal length, and the side S4 close to the diaphragm L0 is a convex surface (the side S5 away from the diaphragm L0 is a convex surface); the fourth lens L4 has negative focal length, and the side S6 close to the diaphragm L0 is a concave surface (the side S7 away from the diaphragm L0 is a concave surface).

[0040] Further, the second lens group comprises a fifth lens L5, a sixth lens L6, a seventh lens L7 and an eighth lens L8 arranged in sequence from the object side to the image side along the optical axis;

[0041] The fifth lens L5 has positive focal length, and the side S8 close to the diaphragm L0 is a convex surface (the side S9 away from the diaphragm L0 is a convex surface); the sixth lens L6 has positive focal length, and the side S10 close to the diaphragm L0 is a convex surface (the side S11 away from the diaphragm L0 is a convex surface); the seventh lens L7 has negative focal length, and the side S12 close to the diaphragm L0 is a convex surface (the side S13 away from the diaphragm L0 is a convex surface); the eighth lens L8 has positive focal length, and the side S13 close to the diaphragm L0 is a convex surface, and the side S14 towards the imaging side is a concave surface.

[0042] In the embodiment, the first lens group and the second lens group together include eight lenses arranged along the optical axis from the object side to the image side in order: a first lens L1 having positive refractive power, which is convex on the stop side; a second lens L2 having negative refractive power, which is convex on the stop side; a third lens L3 having positive refractive power, which is concave on the imaging side; a fourth lens L4 having negative refractive power, which is concave on the stop side; a fifth lens L5 having positive refractive power, which is convex on the stop side; a sixth lens L6 having positive refractive power, which is convex on the stop side; a seventh lens L7 having negative refractive power, which is convex on the stop side; and an eighth lens L8 having positive refractive power, which is concave on the imaging side.

[0043] More preferably, the second lens L2 and the third lens L3 are cemented together, and the seventh lens L7 and the eighth lens L8 are cemented together. In this way, chromatic aberration can be corrected, and image quality can be improved.

[0044] In an embodiment, the relationship between the total length of the projection lens and the effective focal length of the system is: 1.5 < L / EFL < 2.5; where L represents the total length of the system, and EFL represents the effective focal length of the system.

[0045] The focal length relationship between the effective focal length of the system and the back focal length of the system is: 0.4 < BFL / EFL < 0.8; where EFL represents the effective focal length of the system, and BFL represents the back focal length of the system.

[0046] Where EFL (Effective Focal Length) is the distance from the center of the lens to the focal point, and the back focal length (BFD) is also known as the back focal length (BFL), which is the distance from the vertex of the last optical surface of the system to the rear focal point.

[0047] The focal length relationship between the effective focal length of the system and the focal length of the first lens L1 is: 1 < f1 / EFL < 1.5; where EFL represents the effective focal length of the system, and f1 represents the focal length of the first lens L1.

[0048] The focal length relationship between the effective focal length of the system and the focal length of the eighth lens L8 is: 0.6 < f8 / EFL < 1.5; where EFL represents the effective focal length of the system, and f8 represents the focal length of the eighth lens L8.

[0049] In an embodiment, the imaging module includes a prism unit L9 and an imaging unit L10 arranged along the optical axis from the object side to the image side in order; the prism unit L9 includes at least one prism; and the imaging unit L10 is any one of a DLP module, an LCOS module, a MicroLED module, and an LBS module.

[0050] In one embodiment, the projection lens is optimized for blue light (wavelength 460 nm), green light (wavelength 525 nm) and red light (wavelength 620 nm) respectively, as shown in Table 1.

[0051]

[0052] Table 1

[0053] According to Table 1, the focal length EFL is 47.2 mm, the total length L is 92.9 mm, f1 = 59.3 mm, f8 = 46.4 mm, BFL = 25.5 mm, the aperture number F / # is 2.6, and the field angle is 17.2°.

[0054] The field curvature and distortion are shown in Figure 2 , wherein Figure 2 (a) is a field curvature graph, the horizontal axis represents the field curvature value, and the vertical axis represents the normalized pupil radius, S is the meridional field curvature value, and T is the sagittal field curvature value; Figure 2 (b) is a distortion graph, which shows the distortion values of light rays of different wavelengths at different image heights on the imaging surface, the horizontal axis is the distortion value, and the vertical axis represents the half field height; the field curvature is -0.01 mm to 0.05 mm, and the overall distortion is controlled within 2%.

[0055] The spherical aberration curve is shown in Figure 3 , which shows the chromatic aberration of each wavelength at different heights on the imaging surface relative to the central wavelength, the horizontal axis represents the axial aberration value, and the vertical axis represents the normalized pupil radius. It can be seen that the deviation of the axial chromatic aberration is -0.025 mm to 0.05 mm.

[0056] The lateral chromatic aberration curve is shown in Figure 4 , which shows the aberration of each wavelength on the optical axis at the imaging surface, the horizontal axis represents the lateral aberration value, and the vertical axis represents the normalized pupil radius. The maximum chromatic aberration is 4 um.

[0057] From the above, it can be seen that the field curvature distortion, on-axis spherical aberration and lateral chromatic aberration of the image emitted by the projection lens provided in the embodiment are well corrected.

[0058] In another embodiment, the projection lens is optimized for blue light (wavelength 460 nm), green light (wavelength 525 nm) and red light (wavelength 620 nm) respectively, as shown in Table 2.

[0059]

[0060] Table 2

[0061] In combination with Table 2, the effective focal length EFL is 49mm, the total optical length L = 95.5mm, f1 = 56.1mm, f8 = 50.1mm, BFL = 25.3mm, the aperture number F / # is 2.7, and the field angle is 16.6°.

[0062] The field curvature and distortion are shown in Figure 5 , wherein, Figure 5 (a) is a field curvature graph, the horizontal coordinate represents the field curvature value, the vertical coordinate represents the normalized pupil radius, S is the meridional field curvature value, and T is the sagittal field curvature value; Figure 5 (b) is a distortion graph, representing the distortion value of light rays of different wavelengths at different image heights on the imaging surface, the horizontal axis is the distortion value, and the vertical axis represents the half field height; the field curvature is -0.005mm-0.07mm, and the overall distortion is controlled within 2%.

[0063] The spherical aberration curve is shown in Figure 6 , which represents the chromatic aberration of each wavelength at different heights on the imaging surface relative to the central wavelength, the horizontal axis represents the axial aberration value, and the vertical axis represents the normalized pupil radius. It can be seen that the deviation of the axial chromatic aberration is -0.02mm-0.05mm.

[0064] The lateral chromatic aberration curve is shown in Figure 7 , which represents the aberration of each wavelength on the optical axis at the imaging surface, the horizontal axis represents the lateral aberration value, and the vertical axis represents the normalized pupil radius. The maximum chromatic aberration is 4um.

[0065] From the above, it can be seen that the image emitted by the projection lens provided in the embodiment is well corrected in terms of field curvature distortion, on-axis spherical aberration, and lateral chromatic aberration.

[0066] In another specific embodiment, as shown in Table 3, the projection lens is optimized for blue light (wavelength 460nm), green light (wavelength 525nm), and red light (wavelength 620nm) respectively. Among them, the effective focal length EFL is 45mm, the total optical length L = 91.5mm, f1 = 54.7mm, f8 = 43.3mm, BFL = 25.2mm, the aperture number F / # is 2.5, and the field angle is 16°.

[0067]

[0068] Table 3

[0069] The field curvature and distortion are shown in Figure 8 , wherein, Figure 8 (a) is a field curvature graph, the horizontal coordinate represents the field curvature value, the vertical coordinate represents the normalized pupil radius, S is the meridional field curvature value, and T is the sagittal field curvature value; Figure 8(b) is a distortion map showing the distortion values of light rays of different wavelengths at different image heights on the imaging plane, the horizontal axis is the distortion value, and the vertical axis represents the half field height; the field curvature is 0mm-0.05mm, and the overall distortion is controlled within 2%.

[0070] The spherical aberration curve is shown in Figure 9 , which shows the chromatic aberration of each wavelength at different heights on the imaging plane relative to the central wavelength, the horizontal axis represents the axial aberration value, and the vertical axis represents the normalized pupil radius. It can be seen that the deviation of the axial chromatic aberration is-0.018mm-0.046mm.

[0071] The lateral chromatic aberration curve is shown in Figure 10 , which shows the aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents the lateral aberration value, and the vertical axis represents the normalized pupil radius. The maximum chromatic aberration is 4.2um.

[0072] As can be seen from the above, the image emitted by the projection lens provided by the embodiment has good field curvature distortion, on-axis spherical aberration and lateral chromatic aberration.

[0073] The embodiment of the application also provides an AR device using the light engine projection lens according to any one of the above.

[0074] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the related parts are referred to the method part. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the application, the application can be improved and modified, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0075] It should be further pointed out that in the specification, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitation, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or equipment including the element.

Claims

1. A light engine projection lens suitable for use with a diffractive optical waveguide, characterized in that, The optical engine projection lens comprises, in sequence from the object side to the image side along the optical axis, an aperture stop, a first lens group, a second lens group, and an imaging module; The aperture stop has a light passing size matched with an entrance pupil size of the diffractive optical waveguide, the first lens group and the second lens group each comprise a plurality of lenses with different focal lengths, and the lenses in the first lens group and the second lens group are all spherical lenses; The first lens group comprises, in sequence from the object side to the image side along the optical axis, a first lens, a second lens, a third lens, and a fourth lens; The first lens has a positive focal length, and a convex surface close to the side of the aperture stop; the second lens has a negative focal length, and a convex surface close to the side of the aperture stop; the third lens has a positive focal length, and a convex surface close to the side of the aperture stop; and the fourth lens has a negative focal length, and a concave surface close to the side of the aperture stop; The second lens group comprises, in sequence from the object side to the image side along the optical axis, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; The fifth lens has a positive focal length, and a convex surface close to the side of the aperture stop; the sixth lens has a positive focal length, and a convex surface close to the side of the aperture stop; the seventh lens has a negative focal length, and a convex surface close to the side of the aperture stop; the eighth lens has a positive focal length, and a convex surface close to the side of the aperture stop; and the optical engine projection lens has a total of 8 lenses with focal lengths. The system effective focal length of the optical engine projection lens and the focal length of the first lens satisfy the relationship: 1 < f1 / EFL < 1.5; wherein EFL represents the system effective focal length, and f1 represents the focal length of the first lens. The system effective focal length and the focal length of the eighth lens satisfy the relationship: 0.6 < f8 / EFL < 1.5; wherein EFL represents the system effective focal length, and f8 represents the focal length of the eighth lens.

2. The light engine projection lens of claim 1, wherein, The system total length and the system effective focal length of the optical engine projection lens satisfy the relationship: 1.5 < L / EFL < 2.5; wherein L represents the system total length, and EFL represents the system effective focal length.

3. The light engine projection lens of claim 1, wherein, The system effective focal length and the system back focal length satisfy the relationship: 0.4 < BFL / EFL < 0.8; wherein EFL represents the system effective focal length, and BFL represents the system back focal length.

4. The light engine projection lens of claim 1, wherein, The second lens and the third lens are cemented together, and the seventh lens and the eighth lens are cemented together.

5. The light engine projection lens of claim 1, wherein, The imaging module comprises, in sequence from the object side to the image side along the optical axis, a prism unit and an imaging unit; the prism unit comprises at least one prism; and the imaging unit is any one of a DLP module, an LCOS module, a MicroLED module, and an LBS module.

6. An AR device, comprising: The optical engine projection lens is used.

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