Dual-channel display optical system and AR device

Abstract

The utility model discloses a dual-channel display optical system and AR equipment. The dual-channel display optical system comprises a projection module, a light-emitting element, a first lens module and a second lens module, the projection module comprises a free-form surface prism, a compensation prism and a display; the compensation prism is arranged on one side of the free-form surface prism, the first lens module is arranged at one end of the free-form surface prism, and the displayer, the light-emitting element and the second lens module are all arranged at the other end of the free-form surface prism. Compared with the prior art, the projection path of the single prism is realized, the imaging chromatic aberration is corrected, the imaging quality is improved, the complexity of a light path is effectively reduced, the size and the weight of the AR equipment are effectively reduced, and the use experience of the AR equipment is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to projection display technical field, especially a kind of optical system and AR equipment of double-channel display. BACKGROUND

[0002] With the rapid development of optical technology, the requirement of user to AR equipment in function, volume and weight is also higher and higher, and the reason affecting the use experience of AR equipment mainly involves optical system in AR equipment.The optical system of existing AR equipment usually adopts b i rdbath, optical waveguide or free surface etc.

[0003] In view of this, it is necessary to provide a kind of optical system and AR equipment of double-channel display to solve the above problems. SUMMARY

[0004] In view of the deficiencies of prior art, the utility model provides a kind of optical system and AR equipment of double-channel display, which can effectively solve the problems of relatively high optical path complexity of AR equipment, high light loss rate, relatively high volume and weight of AR equipment, and relatively large assembly difficulty.

[0005] To achieve the above purpose, the first aspect of the utility model provides a kind of optical system of double-channel display, which includes projection module, light emitting element, first lens module and second lens module;Projection module includes free surface prism, compensation prism and display;Compensation prism is arranged on one side of free surface prism, first lens module is arranged on one end of free surface prism, display, light emitting element and second lens module are all arranged on the other end of free surface prism.

[0006] In a preferred embodiment, the free surface prism includes first curve, second curve and third curve;First curve is away from compensation prism, second curve is close to compensation prism, half-transmitting and half-reflecting film is attached on second curve, and third curve faces display and light emitting element.

[0007] In a preferred embodiment, the first curve is attached with diffraction element.

[0008] In a preferred embodiment, the angular resolution of display is θ, the angular resolution of human eye is δ, and it satisfies: δ < θ < 2 δ.

[0009] In a preferred embodiment, the horizontal field of view of display is w, and the vertical field of view of display is v, and it satisfies: 20.19 ° < w < 40.38 °, 15.21 ° < v < 30.42 °.

[0010] In one preferred embodiment, the first lens module comprises, in sequence, a first lens, a first diaphragm, a second lens, a third lens, a protective sheet, and a first image plane.

[0011] In one preferred embodiment, the first lens, the second lens, and the third lens are all plastic aspherical lenses.

[0012] In one preferred embodiment, the second lens module comprises, in sequence, a fourth lens, a fifth lens, a sixth lens, a second diaphragm, a doublet lens, and a second image plane.

[0013] In one preferred embodiment, the fourth lens and the fifth lens are both negative-power lenses, and the sixth lens and the doublet lens are both positive-power lenses.

[0014] The second aspect of the utility model provides a kind of AR equipment, it includes the optical system of double-channel display in any one of preceding.

[0015] The utility model has the advantages that: the projection module composed of single freeform prism and compensating prism, additionally provided first lens module and second lens module to assist projection module, the projection path of single prism can be realized, light loss rate is reduced and chromatic aberration is corrected, the optical path complexity of optical system can be effectively reduced, the volume and weight of optical path system are reduced, the volume and weight of AR equipment are further reduced, and the use experience of AR equipment is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The structure diagram of the optical system of double-channel display provided by the embodiment of the utility model is shown in the figure;

[0017] Figure 2 The structure diagram of the projection module provided by the embodiment of the utility model is shown in the figure;

[0018] Figure 3 The MTF curve diagram of the projection module provided by the embodiment of the utility model is shown in the figure;

[0019] Figure 4 The distortion curve comparison diagram of the projection module provided by the embodiment of the utility model is shown in the figure;

[0020] Figure 5 The sagittal chromatic aberration comparison diagram of the freeform prism provided by the embodiment of the utility model is shown in the figure;

[0021] Figure 6 The chromatic focal shift curve comparison diagram of the freeform prism provided by the embodiment of the utility model is shown in the figure;

[0022] Figure 7 The structure diagram of the first lens module provided by the embodiment of the utility model is shown in the figure;

[0023] Figure 8 A point spread diagram of the first lens module provided by the embodiment of the present application;

[0024] Figure 9 An MTF curve diagram of the first lens module provided by the embodiment of the present application;

[0025] Figure 10 A structure schematic diagram of the second lens module provided by the embodiment of the present application;

[0026] Figure 11 A point spread diagram of the second lens module provided by the embodiment of the present application;

[0027] Figure 12 An MTF curve diagram of the second lens module provided by the embodiment of the present application. DETAILED DESCRIPTION

[0028] In the present application, the terms "arranged", "provided with", and "connected" should be understood in a broad sense. For example, it can be fixed connection, detachable connection, or integral structure; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] The terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0030] In addition, in addition to being used to represent the orientation or positional relationship, the above-mentioned part of the terms can also be used to represent other meanings, for example, the term "upper" can also be used to represent a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0031] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0032] Please refer to Figure 1 and Figure 2In the embodiment, the optical system of the dual-channel display includes a projection module 1, a light-emitting element 2, a first lens module 3, and a second lens module 4. The projection module 1 includes a free-form surface prism 11, a compensation prism 12, and a display 13.

[0033] The free-form surface prism 11 is configured to project light emitted by the display 13 onto the pupil of a user, and the compensation prism 12 is configured to compensate for distortion of the light. The first lens module 3 is configured to implement an iris tracking function, the second lens module 4 is configured to capture a real scene, and the light-emitting element 2 is configured to emit infrared light to assist in implementing the iris tracking function. Specifically, the compensation prism 12 is disposed on one side of the free-form surface prism 11, the first lens module 3 is disposed on one end of the free-form surface prism 11, and the display 13, the light-emitting element 2, and the second lens module 4 are all disposed on the other end of the free-form surface prism 11.

[0034] Specifically, in a preferred embodiment, some parameters of some components of the optical system of the dual-channel display are as follows: based on the condition of a user's eyelashes and eyelids and the condition of a myopic user, and in combination with the fact that the free-form surface prism 11 has an inclined surface, the effective exit pupil distance is the distance between the inclined surface and the human eye, and the effective exit pupil distance needs to be at least 20 mm, and preferably, the effective exit pupil distance is 23 mm. To avoid loss of field of view and fatigue of the user during use of the AR device, the exit pupil diameter of the optical system is set to 8 mm. The resolution of the display 13 is 1200x900, the pixel size is 15 um, the display range of the display 13 is 18.75 mmx13.5 mm, and the aspect ratio is 4:3.

[0035] Based on the structure of the free-form surface prism 11, the mirror-eye distance of the display 13 is set to 30 mm, the distance from the lower edge of the display 13 to the center of the pupil is set to 9.54 mm, and the distance from the corner of the eye to the center of the pupil is set to 15 mm, so as to determine that the working distance of the first lens module 3 is 31.48 mm and the half field of view angle is 25.48°.

[0036] Since the reflectivity of the iris is high and the absorbance of the pupil is high under the irradiation of a near-infrared light source, the boundary between the iris and the pupil is obvious, and thus the recognition accuracy of the center of the pupil is significantly improved. The light-emitting element 2 is designed by using an infrared light source with a main wavelength of 850 nm, and the spectral range is 832 nm to 872 nm. Since the maximum field of view angle of a single human eye is about 150°, the field of view angle of the second lens module 4 can be defined as 150°, and the working wavelength is visible light.

[0037] The working principles of the optical system of the dual-channel display are as follows: after the user wears the AR device, the line-of-sight of the user is locked, the light emitting element 2 emits infrared rays, the infrared rays are projected into the pupil of the user through the free-form surface prism 11 to produce a dark pupil effect on the user's eyes, the first lens module 3 is started and the image of the human eye is acquired, and the image is processed to extract parameter information such as the center point of the pupil, the center of the iris and the left and right eye corner points of the human eye. Based on the left and right eye corner points, the center point of the pupil and the optical axis, two three-dimensional vectors are formed, and the line-of-sight calibration is repeatedly performed multiple times to obtain multiple three-dimensional vectors. In the calibration process, the mapping relationship between the 3D structure model of the human eye and the real scene information is established, and finally the line-of-sight mapping function can be obtained. In the subsequent use process, when the eyeball or the head rotates, the line-of-sight direction of the eye can be calculated through image processing combined with the mapping relationship, and the line-of-sight tracking function is realized.

[0038] The second lens module 4 acquires the external environment image information and transmits the information to the background information processing system in real time. The information processing system detects and segments the obtained environment image, and then generates corresponding target identity information. According to the information obtained by the first lens module 3, the line-of-sight focus point of the user is determined, the target object at the line-of-sight focus point is located, the target object is matched with the obtained target identity information, the virtual and real images are superimposed and input to the display 13 of the projection module 1, and the image source on the display 13 is projected into the pupil of the user through a single free-form surface prism 11. The user can see that the virtual feature information is superimposed on the real scene, so that the function of augmented reality is realized.

[0039] After the display 13 projects the light rays of the image source into the free-form surface prism 11, part of the light rays enter the compensation prism 12 from the free-form surface prism 11 to compensate for the distortion of the projected light rays, so as to adjust the overall distortion value of the light rays and optimize the imaging quality.

[0040] It is understood that the projection module 1 composed of a single free-form surface prism 11 and a compensation prism 12 is added with the first lens module 3 and the second lens module 4 to assist the projection module 1, the projection path of the single prism can be realized, the light loss rate is reduced and the chromatic aberration is corrected, the optical system can be effectively reduced in complexity, the volume and weight of the optical system are reduced, the volume and weight of the AR device are reduced, and the use experience of the AR device is improved.

[0041] Further, refer to Figure 2In one embodiment, the free-form surface prism 11 comprises a first curved surface 111, a second curved surface 112 and a third curved surface 113; the first curved surface 111 is far away from the compensation prism 12, the second curved surface 112 is close to the compensation prism 12, and a semi-transparent and semi-reflective film is attached to the second curved surface 112, and the third curved surface 113 faces the display 13 and the light emitting element 2.

[0042] Specifically, the first curved surface 111, the second curved surface 112 and the third curved surface 113 surround each other to form the free-form surface prism 11, which is a wedge-shaped prism. The light emitted by the display 13 enters the free-form surface prism 11 after refraction by the third curved surface 113, and the refracted light is reflected on the first curved surface 111 and then totally reflected from the first curved surface 111 to the second curved surface 112. Since the semi-transparent and semi-reflective film is attached to the second curved surface 112, the light is both reflected and transmitted on the second curved surface 112. The light reflected on the second curved surface 112 exits the free-form surface prism 11 through the first curved surface 111 and is projected into the user's pupil; the light transmitted on the second curved surface 112 enters the compensation prism 12 and compensates for the perspective distortion caused by the semi-transparent and semi-reflective film, thereby optimizing the overall distortion of the projected light.

[0043] Please refer to Figure 3 , Figure 3 (a) is the MTF curve of the projection channel composed of the free-form surface prism 11, and Figure 3 From the information in (a), the MTF value is better than 0.28 when the spatial frequency is 30 lp / mm under the full range of field of view light. The figure is the MTF curve of the transmission channel composed of the compensation prism 12, and from the information in the figure, the MTF value is better than 0.16 when the spatial frequency is 30 lp / mm under the full range of field of view light.

[0044] Further, please refer to Figure 4 , Figure 4 (a) is the distortion curve of the projection module 1 without adding the compensation prism 12, Figure 4 (b) is the distortion curve of the projection module 1 after adding the compensation prism 12. From the information in Figure 4 (a), the maximum distortion value under the full field of view is 2.79% when the compensation prism 12 is not added, and from the information in (b), the maximum distortion value under the full field of view is 0.29% after the compensation prism 12 is added, that is, the distortion of the projection module 1 is improved after the compensation prism 12 is added.

[0045] In a preferred embodiment, a diffraction element is attached to the first curved surface 111.

[0046] The diffractive element is used to correct the chromatic aberration of the light. The diffractive element can be a diffractive element with binary surface phase representation or a diffractive element with aspheric surface, which can be selected according to the actual design requirements. When the diffractive element is a diffractive element with aspheric surface, a microstructure needs to be etched on the base surface of the first curved surface 111.

[0047] Preferably, for the convenience of light tracing, the diffractive element is a diffractive element with binary surface phase representation. Specifically, the binary surface is a four-term polynomial binary surface, and the related coefficients are A1 = 1.16, A2 = -3.457E-002, A3 = -9.18E-004, A4 = -1.70E-005, and the diffraction order M is 1.

[0048] Specifically, please refer to Figure 5 , Figure 5 The vertical chromatic aberration comparison chart of the free-form surface prism 11 attached with the diffractive element and the free-form surface prism 11 without the diffractive element is shown in FIG. 6. Figure 5 It can be seen that, in the edge field of view, the vertical chromatic aberration value of the free-form surface prism 11 attached with the diffractive element is 3.04 um, which is relatively small, and the improvement is 92.3% compared with the free-form surface prism 11 without the diffractive element. In the central field of view, the vertical chromatic aberration value of the free-form surface prism 11 attached with the diffractive element is -13.98 um, which is increased by 1.55 um compared with the free-form surface prism 11 without the diffractive element.

[0049] Further, please refer to Figure 6 , Figure 6 The chromatic focal shift curve comparison chart of the free-form surface prism 11 attached with the diffractive element and the free-form surface prism 11 without the diffractive element is shown in FIG. 7. Figure 6 It can be seen that, after the diffractive element is attached, the maximum focal shift of the free-form surface prism 11 changes from 116.417 um to 74.491 um, and the improvement is 36.01%.

[0050] It can be understood that, without increasing the number of prisms, the diffractive element attached on the first curved surface 111 can effectively correct the chromatic aberration of the light, reduce the system chromatic aberration of the optical system, and further improve the imaging quality.

[0051] Further, in an embodiment, the angular resolution of the display 13 is θ, the angular resolution of the human eye is δ, and δ < θ < 2δ is satisfied. The horizontal field of view angle of the display 13 is w, and the vertical field of view angle of the display 13 is v, and 20.19° < w < 40.38° and 15.21° < v < 30.42° are satisfied.

[0052] Specifically, to make full use of the resolution of the display 13, the aspect ratio of the field of view should be consistent with the aspect ratio of the image source, and the field of view and the resolution of the display 13 should satisfy:

[0053]

[0054] In general, the angular resolution of the human eye is usually 0.017°, so the horizontal field of view of the display 13 is w, and the vertical field of view of the display 13 is v, and it satisfies: 20.19° < w < 40.38°, 15.21° < v < 30.42°, preferably, w = 31.6°, v = 24.2°.

[0055] It can be understood that by setting the angular resolution, the horizontal field of view and the vertical field of view of the display 13, the imaging picture is clear, the positioning is accurate, the stereoscopic feeling of the image is enhanced, the projection distortion can be effectively controlled within 5%, the perspective distortion can be effectively controlled within 3%, and the comfort of the user wearing is ensured.

[0056] Further, please refer to Figure 7 In the embodiment, the first lens module 3 includes a first lens 31, a first diaphragm 32, a second lens 33, a third lens 34, a protective sheet 35 and a first image surface 36 arranged in sequence, and the first lens 31, the second lens 33 and the third lens 34 are all plastic aspherical lenses.

[0057] Specifically, in a preferred embodiment, the curvature of the surface of the first lens 31 away from the first diaphragm 32 is 8.74E-001 mm, and the thickness is 5.00E-001 mm, the curvature of the surface of the first lens 31 close to the first diaphragm 32 is 3.55E+000 mm, and the thickness is 3.57E-001 mm. The curvature of the surface of the second lens 33 close to the first diaphragm 32 is -2.31E+000 mm, and the thickness is 2.29E-001 mm, the curvature of the surface of the second lens 33 away from the first diaphragm 32 is -5.46E+000 mm, and the thickness is 5.00E-002 mm. The curvature of the surface of the third lens 34 close to the first diaphragm 32 is -6.24E+000 mm, and the thickness is 4.10E-001 mm, the curvature of the surface of the third lens 34 away from the first diaphragm 32 is 4.02E+000 mm, and the thickness is 5.15E-002 mm.

[0058] Further, please refer to Figure 8 , Figure 8 The (a) to (c) in the table correspond to the point column distribution of the first lens module 3 at the working distance of 29.82 mm, 31.48 mm and 33.14 mm, respectively. From the table, it can be seen that the point column distribution of the first lens module 3 is good at the working distance of 29.82 mm, 31.48 mm and 33.14 mm. Figure 8From the information in the figure, it can be seen that, under the three working distances, the maximum root mean square radius of the full field of view is 1.779 um, all within two pixel sizes (2.2 um), indicating that the first lens module 3 is clear and the imaging quality is relatively good.

[0059] Please refer to Figure 9 , Figure 9 (a) to (c) in the figure correspond to the MTF curves of the first lens module 3 under working distances of 29.82 mm, 31.48 mm and 33.14 mm, respectively. It is easy to understand that the closer the MTF value is to 1, the better the performance of the lens. From the information in the figure, it can be seen that under different field heights in the low frequency region, the MTF values along the tangential and sagittal directions tend to 1, indicating that the imaging quality is relatively good; as the spatial frequency increases, the MTF values along the tangential and sagittal directions under different field heights decrease slowly, and at 1 / 2 Nyquist frequency 220 l p / mm, the MTF values of the full field of view are all greater than 0.23, indicating that the imaging quality meets the requirements.

[0060] It can be understood that by arranging the first lens 31, the second lens 33 and the third lens 34, the volume of the first lens module 3 can be effectively reduced while meeting the imaging requirements, thereby reducing the occupied space of the first lens module 3 in the AR device, and further reducing the volume and weight of the AR device, thereby improving the user's experience.

[0061] Further, please refer to Figure 10 In one embodiment, the second lens module 4 includes a fourth lens 41, a fifth lens 42, a sixth lens 43, a second diaphragm 46, a double-cemented lens 44 and a second image surface 45 arranged in sequence, the fourth lens 41 and the fifth lens 42 are both negative focal length lenses, and the sixth lens 43 and the double-cemented lens 44 are both positive focal length lenses.

[0062] Specifically, the fourth lens 41 is a negative focal length lens, the surface of which is curved outward, greatly reducing the deflection angle of light entering the second lens module 4 under a large field of view, which can effectively prevent the problem of large-angle light overflow. The fifth lens 42 is also a negative focal length lens, which can further include large field of view light. The sixth lens 43 is a positive focal length lens, which can correct the included light. The double-cemented lens 44 is also a positive focal length lens, which can further correct aberration imaging. At the same time, the double-cemented lens 44 can realize mutual compensation of chromatic dispersion, thereby playing a role in achromatization.

[0063] Further, please refer to Figure 11 , Figure 11 Figure 2 shows the point spread function distribution of the second lens module 4 under working distances of 250 mm to 50,000 mm. Figure 11It can be known from the information in the table that the maximum root mean square radius of the full field of view is 1.891um under the working distance of 250mm to 50000mm, and is within the size of two pixels (2.2um), that is, the second lens module 4 is clear, and the imaging quality is relatively good.

[0064] Please refer to Figure 12 , Figure 12 Corresponding to the MTF curve of the second lens module 4 when the working distance is 250mm, 500mm, 1500mm and 50000mm, respectively. Figure 12 It can be known from the information in the table that the MTF value of the full field of view is greater than 0.1 at the Nyquist frequency 240l p / mm in the full working distance range, and the MTF value near the central field of view is greater than 0.25, that is, the second lens module 4 has relatively good imaging quality in the full field of view, and can meet the requirements.

[0065] It can be understood that by arranging the fourth lens 41, the fifth lens 42, the sixth lens 43 and the double-cemented lens 44, the volume of the second lens module 4 can be effectively reduced while meeting the imaging requirements, thereby reducing the occupied space of the second lens module 4 in the AR device, and further reducing the volume and weight of the AR device, thereby improving the user experience.

[0066] In summary, the projection module 1 composed of a single free-form prism 11 and a compensation prism 12 is added to the first lens module 3 and the second lens module 4, and the projection path of the single prism is realized, the light loss rate is reduced, and the chromatic aberration is corrected, the optical system light path complexity can be effectively reduced, and the volume and weight of the optical system can be reduced, thereby reducing the volume and weight of the AR device, and further improving the user experience of the AR device.

[0067] The second aspect of the utility model provides a kind of AR equipment, it includes the optical system of double-channel display described above, can effectively reduce light loss rate and correct chromatic aberration, can effectively reduce the optical system light path complexity, while reducing the volume and weight of the optical path system, thereby reducing the volume and weight of the AR device, and further improving the user experience of the AR equipment.

[0068] The above is only the specific embodiment of the present application, it should be pointed out that, for ordinary skilled person in the art, without departing from the principle of the present application, a number of improvements and refinements can be made, these improvements and refinements should be regarded as the protection scope of the present application.

Claims

1. An optical system for a dual channel display, characterized by, The projection module, the light emitting element, the first lens module and the second lens module; the projection module comprises a free-form surface prism, a compensation prism and a display; the compensation prism is arranged on one side of the free-form surface prism, the first lens module is arranged on one end of the free-form surface prism, and the display, the light emitting element and the second lens module are arranged on the other end of the free-form surface prism.

2. The optical system of a dual channel display according to claim 1, wherein, The free-form surface prism comprises a first curved surface, a second curved surface and a third curved surface; the first curved surface is away from the compensation prism, the second curved surface is close to the compensation prism, a semi-transparent and semi-reflective film is attached to the second curved surface, and the third curved surface faces the display and the light emitting element.

3. The optical system of a dual channel display according to claim 2, wherein, The first curved surface is attached with a diffraction element.

4. The optical system of the dual channel display according to claim 1, wherein, The angular resolution of the display is θ, the angular resolution of the human eye is δ, and δ < θ < 2δ is satisfied.

5. The optical system of the dual channel display according to claim 1, wherein, The horizontal field of view angle of the display is w, the vertical field of view angle of the display is v, and 20.19° < w < 40.38° and 15.21° < v < 30.42° are satisfied.

6. The optical system of the dual channel display according to claim 1, wherein, The first lens module comprises a first lens, a first diaphragm, a second lens, a third lens, a protective sheet and a first image plane which are sequentially arranged.

7. The optical system of a dual channel display according to claim 6, wherein, The first lens, the second lens and the third lens are all plastic aspherical lenses.

8. The optical system of the dual channel display according to claim 1, wherein, The second lens module comprises a fourth lens, a fifth lens, a sixth lens, a second diaphragm, a double-cemented lens and a second image plane which are sequentially arranged.

9. The optical system of a dual channel display according to claim 8, wherein, The fourth lens and the fifth lens are both negative focal length lenses, and the sixth lens and the double-cemented lens are both positive focal length lenses.

10. An AR device, comprising: An optical system comprising the dual-channel display of any one of the preceding claims 1 to 9.

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