Optical projection system and electronic equipment

Abstract

The embodiment of the present application discloses an optical projection system and an electronic device; wherein, the optical projection system includes a light source module, a light guide device and an imaging module; the light source module is used to generate projection light; the light guide device includes a waveguide substrate, and a coupling-in region and a coupling-out region arranged on the waveguide substrate; wherein, the coupling-in region is located on the optical transmission path of the light source module; the projection light enters the waveguide substrate through the coupling-in region and propagates to the coupling-out region through total reflection, and then exits from the coupling-out region at the same angle as the incident angle; the imaging module is located on the light output transmission path of the coupling-out region, and the light emitted through the coupling-out region can directly enter the imaging module for projection imaging. The solution provided by the embodiment of the present application is to set a light guide device between the illumination light path and the imaging light path, which helps to reduce the volume of the entire system while ensuring optical performance.

Description

Technical Field

[0001] The present application belongs to the field of optical projection technology, and specifically relates to an optical projection system and an electronic device. Background Art

[0002] In recent years, smart wearable devices, as a major category of electronic devices, have received more and more attention and favor from consumers. At present, smart wearable devices include augmented reality devices (AR, Augmented Reality), virtual reality devices (VR, VirtuaH ReaHity), mediated reality devices (MR, Mediated Reality) and XR devices. Among them, taking AR devices as an example, a common form of AR devices is AR glasses, which are head-mounted devices. At present, the shortcomings of AR glasses are mainly concentrated in their large thickness and generally heavy weight. This is contrary to the first performance requirement of AR devices, which is wearable comfort, including miniaturization and thinness. In order to enhance the user experience, the miniaturization and thinness design of AR has become an important development direction of AR glasses. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for an optical projection system and an electronic device, which at least solves the problem of large volume of existing optical projection systems.

[0004] According to a first aspect of the present application, an optical projection system is provided, comprising:

[0005] A light source module, the light source module is used to generate projection light;

[0006] A light guide device comprising a waveguide substrate, and an incoupling region and an outcoupling region disposed on the waveguide substrate; wherein the incoupling region is located on the optical transmission path of the light source module; the projection light enters the waveguide substrate through the incoupling region and is totally reflected and propagates to the outcoupling region, and then emerges from the outcoupling region at the same angle as the incident angle;

[0007] The imaging module is located on the light transmission path of the outcoupling area, and the light emitted through the outcoupling area can directly enter the imaging module for projection imaging.

[0008] Optionally, the light source module includes a plurality of light-emitting chips and is capable of emitting light of different wavelength bands;

[0009] The waveguide substrate is a multi-layer stacked structure, and each layer corresponds to light of a wavelength band.

[0010] Optionally, the imaging module includes a polarization element, an imaging lens, and an LCOS chip sequentially arranged along the same optical axis; wherein the polarization element and the outcoupling region are adjacently arranged;

[0011] The area of ​​the outcoupling region is half the area of ​​the polarization element.

[0012] Optionally, the waveguide substrate includes a red substrate, a green substrate, and a blue substrate that are stacked; wherein the green substrate is located between the red substrate and the blue substrate, so that the light guide device can diffract light of three different wavelength bands;

[0013] The thickness of the waveguide substrate is 0.5 mm to 0.8 mm, and the refractive index of the waveguide substrate is 1.6 to 1.8.

[0014] Optionally, the red light substrate is located on a side close to the light source module, and the blue light substrate is located on a side away from the light source module.

[0015] Optionally, the light source module includes a light source, a collimating device and a light combining device;

[0016] The light source includes a red light chip, a green light chip, and a blue light chip, and the red light chip, the green light chip, and the blue light chip are respectively arranged at a target angle and enclosed around the periphery of the collimating device and the light combining device;

[0017] The collimating devices are provided in three pieces and are respectively arranged on the optical transmission paths of the red light chip, the green light chip and the blue light chip;

[0018] The light combining device is used to combine the collimated light rays into a beam of light. The light combining device includes a first filter and a second filter. The first filter is configured to transmit blue light and reflect red light, and the second filter is configured to transmit red light and blue light and reflect green light.

[0019] Optionally, the first filter is tilted at an angle of 32° to 34° relative to the optical axis of the blue light chip; and the second filter is tilted at an angle of 38° to 40° relative to the optical axis of the blue light chip.

[0020] Optionally, each of the collimating devices (106) includes a collimating lens group or a single metasurface lens, and the collimating device is used to collimate the projection light emitted by the corresponding light-emitting chip into parallel light and then emit it to the light combining device;

[0021] Wherein, the collimating lens group includes a first collimating lens and a second collimating lens arranged along the same optical axis and spaced apart. Optionally, the imaging lens includes a first imaging lens group or a second imaging lens group;

[0022] The FOV of the first imaging lens group is 55° to 65°;

[0023] The FOV of the second imaging lens group is 25° to 35°.

[0024] Optionally, the first imaging lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence along the same optical axis; wherein the first lens is located on a side close to the outcoupling area, and the seventh lens is located on a side away from the outcoupling area;

[0025] The optical power of the first lens, the second lens, the fourth lens, the fifth lens, and the seventh lens is positive, and the optical power of the third lens and the sixth lens is negative.

[0026] Optionally, the effective focal length of the first imaging lens group is 6.5 mm to 7.3 mm, and the F number of the first imaging lens group is 2.1 to 2.5.

[0027] Optionally, when the imaging lens includes the first imaging lens group, the diameter of the corresponding LCOS chip is 6.8 mm to 7.4 mm.

[0028] Optionally, the second imaging lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged in sequence along the same optical axis; wherein the first lens is located on a side close to the outcoupling area, and the seventh lens is located on a side away from the outcoupling area;

[0029] The optical power of the first lens, the second lens, the fifth lens, and the sixth lens is positive, and the optical power of the third lens, the fourth lens, and the seventh lens is negative.

[0030] Optionally, the effective focal length of the second imaging lens group is 5.5 mm to 6.5 mm, and the F number of the second imaging lens group is 1.4 to 1.6.

[0031] Optionally, when the imaging lens includes the second imaging lens group, the corresponding LCOS chip has a diameter of 5.5 mm to 6.5 mm.

[0032] Optionally, the light source module and the imaging module are located on the same side of the light guide device; wherein the imaging module includes a polarization element, an imaging lens and an LCOS chip arranged in sequence along the same optical axis;

[0033] The projection light emitted by the light source module enters the interior of the waveguide substrate through the coupling-in area, and then exits from the coupling-out area. The exiting light passes through the polarizing element, and the polarizing element can transmit the P light while reflecting the S light. After the P light is emitted through the imaging lens, it reaches the LCOS chip. The LCOS chip modulates the light, converts the invalid light into S light, and retains the P light with image information. The P light with image information will pass through the imaging lens again and then through the polarizing element before being emitted.

[0034] According to a second aspect of the present application, an electronic device is also provided. The electronic device includes:

[0035] a housing; and

[0036] The optical projection system as described in the first aspect.

[0037] The beneficial effects of this application are:

[0038] The optical projection system proposed in the embodiment of the present application is a compact LCOS projection optical architecture. By introducing a light-guiding device between the illumination optical path and the imaging optical path, the illumination and imaging can share the same optical path. While ensuring optical performance, the number of optical devices used in the entire optical architecture is reduced, which helps to reduce the volume of the entire optical projection system, thereby realizing the miniaturization and lightweight design of electronic devices such as smart wearable devices. Moreover, the design of the entire optical path architecture is relatively simple and the production cost is low.

[0039] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0041] Figure 1 A schematic structural diagram of an optical projection system provided in an embodiment of the present application;

[0042] Figure 2 A schematic structural diagram of a light source module of an optical projection system provided in an embodiment of the present application;

[0043] Figure 3 A side view of a light guide component of an optical projection system provided in an embodiment of the present application;

[0044] Figure 4 One of the structural diagrams of the light guide device of the optical projection system provided in an embodiment of the present application;

[0045] Figure 5 A second structural diagram of a light guide component of an optical projection system provided in an embodiment of the present application;

[0046] Figure 6 A structural diagram of a first imaging lens assembly of an optical projection system provided in an embodiment of the present application;

[0047] Figure 7 A structural diagram of a second imaging lens assembly of an optical projection system provided in an embodiment of the present application;

[0048] Figure 8 A light path diagram provided in an embodiment of the present application;

[0049] Figure 9 Another optical path diagram provided in an embodiment of the present application;

[0050] Figure 10 One of the distortion diagrams of the optical projection system provided in an embodiment of the present application;

[0051] Figure 11 One of the through-focus MTF diagrams of the optical projection system provided in an embodiment of the present application;

[0052] Figure 12 One of the vertical axis chromatic aberration diagrams of the optical projection system provided in an embodiment of the present application;

[0053] Figure 13 One of the MTF graphs of the optical projection system provided in an embodiment of the present application;

[0054] Figure 14 The second distortion diagram of the optical projection system provided in an embodiment of the present application;

[0055] Figure 15 The second through-focus MTF diagram of the optical projection system provided in an embodiment of the present application;

[0056] Figure 16 The second vertical axis chromatic aberration diagram of the optical projection system provided in an embodiment of the present application;

[0057] Figure 17 The second MTF diagram of the optical projection system provided in an embodiment of the present application;

[0058] Description of reference numerals:

[0059] 1. Light source module; 101. Red light chip; 102. Green light chip; 103. Blue light chip; 104. First filter; 105. Second filter; 106. Collimator; 2. Light guide device; 201. Waveguide substrate; 202. Incoupling region; 203. Outcoupling region; 3. Polarization element; 4. Imaging lens; 401. First lens; 402. Second lens; 403. Third lens; 404. Fourth lens; 405. Fifth lens; 406. Sixth lens; 407. Seventh lens; 5. LCOS chip. DETAILED DESCRIPTION

[0060] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0061] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0062] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0063] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0064] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0065] The following is combined with Figures 1 to 17 , the optical projection system and electronic device provided in the embodiments of the present application are described in detail.

[0066] The optical projection system provided in the embodiments of the present application can be applied to, for example, AR devices.

[0067] The optical projection system provided in the embodiment of the present application is shown in FIG. Figure 1 The optical projection system includes: a light source module 1, a light guide device 2 and an imaging module. The entire optical path structure is simple.

[0068] The light source module 1 can be used to generate projection light. Figure 3The light guide device 2 includes a waveguide substrate 201, and an incoupling region 202 and an outcoupling region 203 disposed on the waveguide substrate 201. The incoupling region 202 is located on the optical transmission path of the light source module 1. The projection light enters the waveguide substrate 201 through the incoupling region 202 and is totally reflected and propagates to the outcoupling region 203, where it is then emitted from the outcoupling region 203 at the same angle as the incident angle. The imaging module is located on the light output transmission path of the outcoupling region 203, and the light emitted through the outcoupling region 203 can directly enter the imaging module for projection imaging.

[0069] The optical projection system provided by the above embodiments achieves miniaturization and lightweight design while maintaining its optical performance. It is well-suited for use in electronic devices such as AR headsets, enhancing user comfort and immersive experience.

[0070] Specifically, the optical projection system provided in the above-described embodiment of the present application introduces at least one light guide device 2 between the light source module 1 and the imaging module. The light guide device 2 is, for example, a diffraction light waveguide, so that illumination and imaging can share a common optical path. Because the light guide device 2 is relatively thin and lightweight, and after the light guide device 2 is introduced, optical devices such as relay lenses can be omitted (the optical device required in traditional projection optical systems is a lens-type steering system, which is larger and heavier than the light guide device 2), which helps to reduce the volume of the optical projection system.

[0071] The main function of introducing the light guide device 2 between the light source module 1 and the imaging module is to guide the projection light emitted by the light source module 1 into the interior of the waveguide substrate 201. Through total internal reflection within the waveguide substrate 201, the projection light will then exit the outcoupling region 203 at the same angle as when it entered, enter the imaging module, and ultimately form an image in the human eye. The light guide device 2 can be used to converge the projection light into the imaging module, which helps improve the lighting effect.

[0072] For example, the projection light is coupled into the interior of the waveguide substrate 201 through the coupling-in region 202 at a first angle, is totally reflected within the waveguide substrate 201, and propagates to the coupling-out region 203, and then is emitted through the coupling-out region 203 at the first angle (the angle at which it was incident on the coupling-in region 202). It should be noted that this is the performance of the diffraction waveguide itself.

[0073] The optical projection system provided in the embodiments of the present application is a novel optical architecture. The light guide device 2 is introduced between the light source module 1 and the imaging module, eliminating the bulky relay portion that would otherwise be independently provided, significantly reducing the size of the optical projection system. In particular, the light guide device 2 is a lighting waveguide that enables the transmission of projection light. This advantageously does not alter the angle between the outgoing and incident light, resulting in high optical efficiency and a thin, compact design, thus occupying very little space.

[0074] According to the optical projection system provided in the above-mentioned embodiment of the present application, the light source module 1 is capable of emitting projection light, which enters the waveguide substrate 201 through the coupling-in region 202, undergoes total reflection inside the waveguide substrate 201, and then is emitted from the coupling-out region 203 to the imaging module, and the imaging module finally performs projection imaging.

[0075] The optical projection system proposed in the embodiment of the present application is a compact LCOS projection optical architecture. By introducing a light guide device 2 between the light source module 1 and the imaging module, the illumination and imaging can share the same optical path. While ensuring optical performance, the number of optical devices used in the entire optical architecture is reduced, which is conducive to reducing the volume of the entire optical projection system, and thus can realize the miniaturization and lightweight design of electronic devices such as smart wearable devices; moreover, the design of the entire optical path architecture is relatively simple and the production cost is low.

[0076] It should be emphasized that the optical projection system provided in the embodiments of the present application includes a light guide device 2 located between the light source module 1 and the imaging module. It is used to converge the projection light emitted by the light source module 1 into the imaging module. The light emitted by the light source module 1 is projection light and does not carry image information. The light guide device 2 acts as a relay, redirecting the projection light to the imaging module. Because the light guide device 2 enables light to be emitted at the same angle as the incident angle, the lighting effect can be improved.

[0077] In some examples of this application, see Figure 2 The light source module 1 includes a plurality of light emitting chips and can emit light of different wavelength bands. The waveguide substrate 201 is a multi-layer stacked structure, and each layer corresponds to a light of a different wavelength band.

[0078] The light source module 1 includes, for example, a light source. The light source includes, for example, a plurality of light-emitting chips in the above example. Specifically, each light-emitting chip is, for example, an LED.

[0079] Different light emitting chips can emit light of different wavelengths, for example. On this basis, the light source module 1 can emit light of different wavelengths.

[0080] It should be noted that the light source of the light source module 1 is responsible for emitting divergent light, and the light needs to be collimated into parallel light through, for example, a collimating device 106, and then the light of different bands is combined into a beam of light through the light combining device and then incident on the light guide device 2.

[0081] In the above example, the light guide device 2 includes a waveguide substrate 201, and the waveguide substrate 201 can be designed as a multi-layer stacked structure to correspond to the light of different wavelengths emitted by the light source module 1, so as to facilitate high-efficiency transmission of light of different wavelengths.

[0082] For example, the light source module 1 can emit red light, green light and blue light (i.e., RGB three-color light). At this time, the structure of the waveguide substrate 201 of the light guide device 2 can be designed as a three-layer stacked structure, i.e., including a red light substrate, a green light substrate and a blue light substrate, so as to diffract and transmit the RGB three-color light respectively.

[0083] In addition, it should be noted that in order to achieve a lightweight and miniaturized design of the entire optical projection system, the thickness of the light guide device 2 should not be too large. For example, the thickness of the waveguide substrate 201 of the light guide device 2 can be designed to be 0.5 mm to 0.8 mm.

[0084] Of course, as the number of stacked layers of the waveguide substrate 201 increases, for example, when the number of stacked layers is greater than three, the thickness of the waveguide substrate 201 will increase. In the embodiment of the present application, the thickness of each layer can be flexibly adjusted according to the number of stacked layers to ensure reasonable control of the thickness of the waveguide substrate 201.

[0085] According to the above example of the present application, the thickness range of the waveguide substrate 201 includes but is not limited to the above 0.5 mm to 0.8 mm.

[0086] The red light R, the green light G, and the blue light B are all visible light, and each has a different wavelength. For example, the wavelength of the red light R is 590 nm to 640 nm, the wavelength of the green light G is 510 nm to 560 nm, and the wavelength of the blue light B is 440 nm to 490 nm.

[0087] The optical projection system provided by the above embodiment of the present application includes a light source module 1. The light source module 1 is a lighting light path design and belongs to the lighting light path part of the optical projection system.

[0088] The light source module 1 is, for example, a multi-color light source. The light source module 1 is capable of emitting projection light for projection, and the projection light may include light of multiple different wavelengths, such as green light, red light, and blue light. Of course, the light source module 1 in the embodiments of the present application includes, but is not limited to, emitting light of these three colors and may also emit light of other colors, as long as it can emit visible light.

[0089] In some examples of this application, see Figure 1 The imaging module includes a polarizing element 3, an imaging lens 4, and an LCOS chip 5, which are sequentially arranged along the same optical axis. The polarizing element 3 is adjacent to the outcoupling region 203. The area of ​​the outcoupling region 203 is half the area of ​​the polarizing element 3.

[0090] The imaging module provided according to the above example of the present application includes three main parts, namely the above-mentioned polarization element 3, the imaging lens 4 and the LCOS chip 5.

[0091] The polarizing element 3 is located on the light incident path of the imaging lens 4.

[0092] The polarizing element 3 is, for example, a polarizer. The polarizer is located near the outcoupling region 203 of the light guide 2. At this point, the polarizer covers the entrance pupil of the imaging lens 4. The area and shape of the polarizer can be used as a reference when designing the size of the outcoupling region 203. Specifically, the outcoupling region 203 occupies half of the polarizer, so that projection light can enter through half of the polarizer, while a portion of the light can exit through the other half of the polarizer.

[0093] For example, when the entrance pupil area of ​​the imaging lens 4 is a rectangle with a size of 4 mm*4 mm, the outcoupling area 203 on the light guide device 2 is a rectangle with a size of 4 mm*2 mm. Figure 4 The outcoupling region 203 occupies half of the entrance pupil region, that is, half of the polarization element 3 .

[0094] For another example, when the entrance pupil area of ​​the imaging lens 4 is a circle with a diameter of 4 mm, the outcoupling area 203 on the light guide device 2 is a semicircle with a diameter of 4 mm. Figure 5 The outcoupling region 203 occupies half of the entrance pupil region, that is, half of the polarization element 3 .

[0095] The LCOS chip 5 has dense pixels, and the pixels can be selectively controlled, for example, to convert the polarization states of S light and P light.

[0096] The imaging lens 4 is used to image the image information generated by the LCOS chip 5 into the human eye.

[0097] In one example, the waveguide substrate 201 includes a stacked red light substrate, a green light substrate, and a blue light substrate; wherein the green light substrate is located between the red light substrate and the blue light substrate, so that the light guide device can diffract light of three different wavelength bands; the thickness of the waveguide substrate 201 is 0.5 mm to 0.8 mm, and the refractive index of the waveguide substrate 201 is 1.6 to 1.8.

[0098] It should be noted that the light guide device 2 can reduce production costs within the above-mentioned refractive index range, and can receive light within a range of plus or minus 25° within the above-mentioned refractive index range, which can fully meet basic optical requirements.

[0099] Optionally, the waveguide substrate 201 may be made of glass, which can improve the temperature resistance of the entire light guide device 2.

[0100] Optionally, the red light substrate is located on a side close to the light source module 1 , and the blue light substrate is located on a side away from the light source module 1 .

[0101] At this time, the green substrate is sandwiched between the red substrate and the blue substrate.

[0102] In some examples of this application, see Figure 2 , the light source module 1 includes a light source, a collimating device 106 and a light combining device. The light source includes a red light chip 101, a green light chip 102 and a blue light chip 103, and the red light chip 101, the green light chip 102 and the blue light chip 103 are respectively arranged at target angles and enclosed in the periphery of the collimating device 106 and the light combining device. The collimating devices 106 are set in three, and are respectively arranged on the optical transmission paths of the red light chip 101, the green light chip 102 and the blue light chip 103. The light combining device is used to combine the collimated parallel light rays into a beam of light, and the light combining device includes a first filter 104 and a second filter 105, the first filter 104 is configured to transmit blue light and reflect red light, and the second filter 105 is configured to transmit red light and blue light and reflect green light.

[0103] That is to say, the light source module 1 provided in the embodiment of the present application can combine RGB three-color light into one beam of light based on three independent RGB lamp beads and two filters.

[0104] Specifically, the optical combining device includes a first filter 104 and a second filter 105; wherein, the first filter 104 can transmit blue light (440nm~490nm) and reflect red light (590nm~640nm); the second filter 105 can transmit red and blue light (440nm~490nm, 590nm~640nm) and reflect green light (510nm~560nm).

[0105] See also Figure 2 The arrangement of the light sources in the light source module 1 provided in the embodiment of the present application is relatively compact, which helps to reduce the overall volume. In the light source module 1, the two filters included in the light combining device are tilted and arranged within the space surrounded by the three collimating devices 106.

[0106] Optionally, the first filter 104 is tilted at an angle of 32° to 34° relative to the optical axis of the blue light chip 103 ; and the second filter 105 is tilted at an angle of 38° to 40° relative to the optical axis of the blue light chip 103 .

[0107] The tilt angles of the first filter 104 and the second filter 105 during installation can be within the ranges shown in the above examples. Within these ranges, and based on the optical architecture of the light source module 1, the entire light source module 1 can be miniaturized. In other words, the light source module 1 can be optimized in size.

[0108] Optionally, each of the collimating devices 106 includes a collimating lens group or a single metasurface lens, and the collimating device 106 is used to collimate the projection light emitted by the corresponding light-emitting chip into parallel light and then emit it to the light-combining device; wherein the collimating lens group includes a first collimating lens and a second collimating lens arranged along the same optical axis and at intervals.

[0109] See also Figure 2 When the collimating device 106 is configured as a collimating lens assembly, it includes two collimating lenses spaced apart along the same optical axis, namely the first and second collimating lenses in the above example. Taking the red light chip as an example, the red light emitted by the red light chip 101 can sequentially pass through the first and second collimating lenses to form 0° parallel light output, thereby achieving a collimated effect on the red light. It should be noted that the collimation principles of the green and blue light are the same as those of the red light described above and will not be repeated here.

[0110] The collimator lens assembly is designed to include two collimating lenses. This design allows each collimating lens to have a smaller curvature, which results in a smaller thickness. Compared to a single collimating lens, the combined design of two collimating lenses is actually thinner than a single collimating lens design, which helps reduce the thickness of the entire light source module and also reduces the difficulty of manufacturing the collimating lenses.

[0111] Table 1 shows the optical design parameters of a collimating lens assembly, which are as follows:

[0112] Table 1

[0113]

[0114] In addition, it should be noted that the collimator lens group is introduced into the light source module provided in the embodiments of the present application. The function of the collimator lens group is to converge the divergent projection light emitted by the light source into a relatively parallel beam of light. According to the Rahe invariant theorem, the spot size formed by the light after passing through the collimator lens group, the angle of the light, the luminous area of ​​the light source, and the luminous angle of the light source are related as follows:

[0115] S (spot size) * tan (light angle) = S (light source luminous area) * tan (light source luminous angle). For example, the selected LED light source luminous area is 1mm 2 , the luminous angle is ±60°, when the required collimated spot angle is 30°, the required collimated spot size can be calculated to be 3mm 2 .

[0116] See also Figure 8 and Figure 9 The two optical path diagrams shown are the same LED light source on the left side of the optical path and the collimated light spot on the right side of the optical path. When the light angle is small, the light spot size is large, see Figure 8 When the light angle is larger, the spot size is smaller, see Figure 9 shown.

[0117] The collimated light passes through the light guide 2 and enters the imaging lens 4. Since the light guide 2 itself does not change the angle of the light, the angle of the collimated light is the light angle of the imaging lens 4. According to the formula: tan (light guide angle) * imaging lens focal length * illumination spot size at the LCOS chip = tan (imaging lens FOV) * imaging lens focal length * LCOS chip active area size.

[0118] The size of the illumination spot at the LCOS chip 5 is generally required to be slightly larger than the active area of ​​the LCOS chip 5 to prevent dark bands from forming on the screen. Therefore, the angle of the collimated light spot is equal to (FOV+2)° required by the optical projection system.

[0119] In the embodiment of the present application, for the light guide device 2, the coupling area of ​​the coupling region 202 thereon and the angle of the light coupled into the coupling region 202 satisfy the following relationship, as shown in Table 2 below:

[0120] Table 2

[0121] Light angle (°) <![CDATA[Coupled-in area (mm 2 )]]> 10 6.2 15 6 20 5.8 25 5.6 30 5.3 35 5.1 40 4.8

[0122] Of course, the collimating device 106 can also directly use a metasurface lens to achieve the light collimation effect. Only one metasurface lens can replace the collimating lens assembly composed of two collimating lenses mentioned above, and its thickness is on the micron level. The advantage of metasurface lenses is that they have a good light uniformity effect and occupy a small space.

[0123] According to the optical projection module provided in the embodiment of the present application, see Figure 1 and Figure 2 , and its working principle is as follows:

[0124] The light source (RGB three-color light source) emits a projection light with a certain divergence angle (for example, a divergence angle of plus or minus 75°), which becomes a projection light with a smaller divergence angle after passing through the collimating device 106, and enters the coupling-in area 202 on the waveguide substrate 201. After being totally reflected inside the waveguide substrate 201, it is emitted from the coupling-out area 203. Next, the light emitted from the coupling-out area 203 will pass through the polarizing element 3. The function of the polarizing element 3 is, for example, to transmit P light and absorb S light. After passing through the imaging lens 4, the P light reaches the surface of the LCOS chip 5, and is modulated by the LCOS chip 5 to convert invalid light into S light, while retaining valid image information (for example, P light). Therefore, the P light with image information will pass through the imaging lens 4 again, pass through the polarizing element 3, and finally be emitted.

[0125] According to the optical projection system provided in the above embodiment of the present application, the imaging module 4 can be designed as a large FOV imaging lens or a medium FOV imaging lens. Both imaging lenses can achieve clear imaging while ensuring that the parallel light entering from the entrance pupil can form a rectangular light spot on the LCOS chip 5, ensuring brightness uniformity on the LCOS chip 5.

[0126] In some examples of the present application, the imaging lens 4 includes a first imaging lens group or a second imaging lens group; wherein the FOV of the first imaging lens group is 55° to 65°; and the FOV of the second imaging lens group is 25° to 35°.

[0127] Specifically, the FOV of the first imaging lens group is 55° to 65°, which corresponds to an imaging lens with a large FOV, while the FOV of the second imaging lens group is 25° to 35°, which corresponds to an imaging lens with a medium FOV.

[0128] In one example, the optical projection system includes an imaging lens 4, see Figure 6 As shown, the imaging lens 4 adopts the above-mentioned first imaging lens group. The imaging lens 4 includes a first lens 401, a second lens 402, a third lens 403, a fourth lens 404, a fifth lens 405, a sixth lens 406, and a seventh lens 407 arranged in sequence along the same optical axis; wherein the first lens 401 is located on a side close to the outcoupling region 203, and the seventh lens 407 is located on a side away from the outcoupling region 203; the optical power of the first lens 401, the second lens 402, the fourth lens 404, the fifth lens 405, and the seventh lens 407 is positive, and the optical power of the third lens 403 and the sixth lens 406 is negative.

[0129] Specifically, Tables 3 and 4 list the optical parameters of the seven lenses included in the first imaging lens group.

[0130] Table 3

[0131]

[0132]

[0133] The fourth lens 404 and the fifth lens 405 can be glued together to improve imaging quality.

[0134] Table 4

[0135]

[0136] The effective focal length of the first imaging lens group is 6.5 mm to 7.3 mm, and the F number of the first imaging lens group is 2.1 to 2.5.

[0137] In the above example, setting the F number to 2.1 to 2.5 can provide users with a good sense of immersion and visual comfort while reducing the difficulty of lens processing.

[0138] Wherein, when the imaging lens 4 includes the first imaging lens group, the diameter of the corresponding LCOS chip 5 is 6.8 mm to 7.4 mm.

[0139] In the above example, the diameter of the LCOS chip 5 is set to 6.8 mm to 7.4 mm, and the image plane size is relatively large, which can improve the resolution, make the projected image more delicate, and be more comfortable to watch.

[0140] According to the above example of the present application, the imaging lens 4 is an imaging lens with a large FOV.

[0141] See also Figure 10 , Figure 10 The distortion diagram shows the difference in image plane position of clear images with different fields of view under a large field of view. Figure 10 It can be seen that as the field of view angle increases, the distortion increases. When the FOV is about 30°, the distortion is about 10%. However, overall, under each field of view, the distortion of the projection light after passing through the imaging lens 4 can fully meet the requirements of the human eye.

[0142] See also Figure 11 and Figure 13 , Figure 11 Shown is the through-focus MTF diagram, Figure 13 The MTF curve is a modulation transfer function graph. Combined, they show that within a wide field of view, clear projected images can be seen at both the edges and the center. This means that the clarity of the entire image is relatively consistent across the wider field of view. The entire image seen by the user is clear and complete, providing an excellent visual experience.

[0143] Figure 12 The vertical axis chromatic aberration is also called magnification chromatic aberration. Figure 12 It can be seen that the vertical axis chromatic aberration is relatively small, basically between the two black dotted lines, and the quality of the projected image is good.

[0144] In one example, the optical projection system includes an imaging lens 4, see Figure 7 As shown, the imaging lens 4 adopts the above-mentioned second imaging lens group. The imaging lens 4 includes a first lens 401, a second lens 402, a third lens 403, a fourth lens 404, a fifth lens 405, a sixth lens 406, and a seventh lens 407 arranged in sequence along the same optical axis; wherein the first lens 401 is located on a side close to the outcoupling region 203, and the seventh lens 407 is located on a side away from the outcoupling region 203; the optical power of the first lens 401, the second lens 402, the fifth lens 405, and the sixth lens 406 is positive, and the optical power of the third lens 403, the fourth lens 404, and the seventh lens 407 is negative.

[0145] Specifically, Tables 5 and 6 list the optical parameters of the seven lenses included in the second imaging lens group.

[0146] Table 5

[0147]

[0148]

[0149] Table 6

[0150] Lens number Optical power range First lens 8～9 Second lens 6～7 The third lens -4～-3.5 Fourth lens -4.5～-4 Fifth lens 3.5～4 Sixth lens 6～6.5 Seventh lens -10.5～-9.5

[0151] The effective focal length of the second imaging lens group is 5.5 mm to 6.5 mm, and the F number of the second imaging lens group is 1.4 to 1.6.

[0152] In the above example, setting the F-number to 1.4 to 1.6 can give users excellent immersion and visual comfort.

[0153] Wherein, in the case of the second imaging lens group of the imaging lens 4, the corresponding LCOS chip 5 has a diameter of 5.5 mm to 6.5 mm.

[0154] In the above example, the diameter of the LCOS chip 5 is set to 5.5 mm to 6.5 mm, and the image plane size is also larger, which can improve the resolution, make the projected image more delicate, and be more comfortable to watch.

[0155] According to the above example of the present application, the imaging lens 4 is an imaging lens with a medium FOV.

[0156] See also Figure 14 , Figure 14 The distortion diagram shows the difference in image plane position of clear images with different fields of view under a large field of view. Figure 14 It can be seen that as the field of view angle increases, the distortion will increase, but overall, under each field of view, the distortion of the projection light after passing through the imaging lens 4 can fully meet the requirements of the human eye.

[0157] See also Figure 15 and Figure 17 , Figure 15 Shown is the through-focus MTF diagram, Figure 17 The MTF curve is a modulation transfer function graph. Combined, they show that within a wide field of view, clear projected images can be seen at both the edges and the center. This means that the clarity of the entire image is relatively consistent across the wider field of view. The entire image seen by the user is clear and complete, providing an excellent visual experience.

[0158] Figure 16 The vertical axis chromatic aberration is also called magnification chromatic aberration. Figure 16 It can be seen that the vertical axis chromatic aberration is relatively small, basically between the two black dotted lines, and the quality of the projected image is good.

[0159] In some examples of this application, see Figure 1The light source module 1 and the imaging module are located on the same side of the light guide device 2; wherein the imaging module includes a polarization element 3, an imaging lens 4 and an LCOS chip 5 arranged in sequence along the same optical axis; the projection light emitted by the light source module 1 enters the interior of the waveguide substrate 201 through the coupling-in region 202, and then exits from the coupling-out region 203. The exiting light passes through the polarization element 3, and the polarization element 3 can transmit P light while reflecting S light. After the P light is emitted through the imaging lens 4, it reaches the LCOS chip 5. The LCOS chip 5 modulates the light, converts the invalid light into S light, and retains the P light with image information. The P light with image information will pass through the imaging lens 4 again and then pass through the polarization element 3 before exiting.

[0160] See also Figure 1 According to the optical projection system provided in the embodiment of the present application, its optical structure is as follows: an incoupling region 202 and an outcoupling region 203 are provided on the waveguide substrate 201, and the incoupling region 202 and the outcoupling region 203 are both located on the same side of the waveguide substrate 201. The imaging module and the light source module 1 can be arranged on the same side of the light guide device 2, that is, the imaging module and the light source module 1 are located on the same side, thereby achieving a compact and lightweight design of the optical projection system.

[0161] After being emitted from the outcoupling region 203 of the light guide device 2 , the projection light can be turned back in the imaging module, thereby extending the light propagation path and improving the imaging quality.

[0162] In another aspect, an embodiment of the present application further provides an electronic device, which includes a housing and the optical projection system described above.

[0163] The above-mentioned electronic device is, for example, a wearable device, and the wearable device is, for example, AR smart glasses or an AR smart helmet.

[0164] The specific implementation of the projection display system and wearable device electronic equipment in the embodiments of the present application can refer to the embodiments of the optical projection system described above, and therefore at least have all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0165] Although some specific embodiments of the present application have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. An optical projection system, characterized in that: include: A light source module (1), the light source module (1) being used to generate projection light; A light guide device (2), comprising a waveguide substrate (201), and an incoupling region (202) and an outcoupling region (203) arranged on the waveguide substrate (201); wherein the incoupling region (202) is located on the light transmission path of the light source module (1); the projection light is incident on the waveguide substrate (201) through the incoupling region (202) and propagates to the outcoupling region (203) by total reflection, and then emerges from the outcoupling region (203) at the same angle as the incident angle; An imaging module, the imaging module being located on the light transmission path of the outcoupling region (203), and the light emitted through the outcoupling region (203) can directly enter the imaging module for projection imaging; The light source module (1) and the imaging module are located on the same side of the light guide device (2); The imaging module comprises a polarization element (3), an imaging lens (4) and an LCOS chip (5) which are sequentially arranged along the same optical axis; The projection light emitted by the light source module (1) enters the interior of the waveguide substrate (201) through the coupling-in region (202) and then exits from the coupling-out region (203). The exiting light passes through the polarizing element (3). The polarizing element (3) is capable of transmitting P light while reflecting S light. The P light exits through the imaging lens (4) and reaches the LCOS chip (5). The LCOS chip (5) modulates the light and converts the invalid light into S light while retaining the P light with image information. The P light with image information is again emitted through the imaging lens (4) and then through the polarizing element (3).

2. The optical projection system according to claim 1, wherein: The light source module (1) comprises a plurality of light-emitting chips and is capable of emitting light of different wavelength bands; The waveguide substrate (201) is a multi-layer stacked structure, and each layer corresponds to light of a wavelength band.

3. The optical projection system according to claim 1, wherein: The imaging module comprises a polarization element (3), an imaging lens (4), and an LCOS chip (5) arranged in sequence along the same optical axis; wherein the polarization element (3) and the outcoupling region (203) are arranged adjacent to each other; The area of ​​the outcoupling region (203) is half the area of ​​the polarization element (3).

4. The optical projection system according to claim 1, wherein: The waveguide substrate (201) comprises a red light substrate, a green light substrate and a blue light substrate which are stacked; wherein the green light substrate is located between the red light substrate and the blue light substrate, so that the light guide device can diffract light of three different wavelength bands; The thickness of the waveguide substrate (201) is 0.5 mm to 0.8 mm, and the refractive index of the waveguide substrate (201) is 1.6 to 1.

8.

5. The optical projection system according to claim 4, characterized in that: The red light substrate is located on a side close to the light source module (1), and the blue light substrate is located on a side away from the light source module (1).

6. The optical projection system according to any one of claims 1 to 5, characterized in that: The light source module (1) comprises a light source, a collimating device (106) and a light combining device; The light source comprises a red light chip (101), a green light chip (102), and a blue light chip (103), and the red light chip (101), the green light chip (102), and the blue light chip (103) are respectively arranged at target angles and enclosed on the periphery of the collimating device (106) and the light combining device; The collimating devices (106) are provided in three numbers and are respectively arranged on the optical transmission paths of the red light chip (101), the green light chip (102), and the blue light chip (103); The light combining device is used to combine the collimated parallel light rays into a beam of light. The light combining device comprises a first filter (104) and a second filter (105). The first filter (104) is configured to transmit blue light and reflect red light, and the second filter (105) is configured to transmit red light and blue light and reflect green light.

7. The optical projection system according to claim 6, wherein: The first filter (104) has an inclination angle of 32° to 34° relative to the optical axis of the blue light chip (103); The second filter (105) has an inclination angle of 38° to 40° relative to the optical axis of the blue light chip (103).

8. The optical projection system according to claim 6, wherein: Each of the collimating devices (106) comprises a collimating lens group or a single metasurface lens, and the collimating device (106) is used to collimate the projection light emitted by the corresponding light-emitting chip into parallel light and then emit it to the light combining device; The collimating lens assembly includes a first collimating lens and a second collimating lens which are arranged along the same optical axis and at intervals.

9. The optical projection system according to any one of claims 1 to 5, characterized in that: The imaging lens (4) comprises a first imaging lens group or a second imaging lens group; The FOV of the first imaging lens group is 55° to 65°; The FOV of the second imaging lens group is 25° to 35°.

10. The optical projection system according to claim 9, wherein: The first imaging lens group comprises a first lens (401), a second lens (402), a third lens (403), a fourth lens (404), a fifth lens (405), a sixth lens (406), and a seventh lens (407) arranged in sequence along the same optical axis; wherein the first lens (401) is located on a side close to the outcoupling region (203), and the seventh lens (407) is located on a side away from the outcoupling region (203); The optical focal powers of the first lens (401), the second lens (402), the fourth lens (404), the fifth lens (405) and the seventh lens (407) are positive, and the optical focal powers of the third lens (403) and the sixth lens (406) are negative.

11. The optical projection system according to claim 10, wherein: The effective focal length of the first imaging lens group is 6.5 mm to 7.3 mm, and the F number of the first imaging lens group is 2.1 to 2.

5.

12. The optical projection system according to claim 10, wherein: When the imaging lens (4) includes the first imaging lens group, the diameter of the corresponding LCOS chip (5) is 6.8 mm to 7.4 mm.

13. The optical projection system according to claim 9, wherein: The second imaging lens group comprises a first lens (401), a second lens (402), a third lens (403), a fourth lens (404), a fifth lens (405), a sixth lens (406), and a seventh lens (407) arranged in sequence along the same optical axis; wherein the first lens (401) is located on a side close to the outcoupling region (203), and the seventh lens (407) is located on a side away from the outcoupling region (203); The optical focal powers of the first lens (401), the second lens (402), the fifth lens (405) and the sixth lens (406) are positive, and the optical focal powers of the third lens (403), the fourth lens (404) and the seventh lens (407) are negative.

14. The optical projection system according to claim 13, wherein: The effective focal length of the second imaging lens group is 5.5 mm to 6.5 mm, and the F number of the second imaging lens group is 1.4 to 1.

6.

15. The optical projection system according to claim 14, wherein: When the imaging lens (4) includes the second imaging lens group, the corresponding LCOS chip (5) has a diameter of 5.5 mm to 6.5 mm.

16. An electronic device, characterized in that: include: case; as well as The optical projection system according to any one of claims 1 to 15.

Images