A desktop projection system and electronic device

Abstract

This application provides a desktop projection system and an electronic device. The desktop projection system includes an image source and a micro projection optical engine. The image source has a light-emitting surface for emitting image light. The micro projection optical engine includes a projection lens and an exit pupil stop arranged along the optical axis, with the projection lens located between the image source and the exit pupil stop, for projecting the image light onto a projection surface to form a projected image. The light-emitting surface of the image source is tilted at a first angle α relative to a plane perpendicular to the optical axis, and the optical axis of the micro projection optical engine is tilted at a second angle b relative to the projection surface. The first angle α and the second angle b are configured to jointly compensate for the optical path difference between the upper and lower fields of view caused by the tilt of the optical axis, so as to achieve near-distance projection imaging.

Description

Technical Field

[0001] This application relates to the field of micro-projection optical engine technology, and more specifically, to a desktop projection system and an electronic device. Background Technology

[0002] With the rapid development of electronic device technology, the functions of portable devices such as mobile phones and smartwatches are becoming increasingly rich, and users' demand for scenario-based applications of these devices is constantly increasing. Integrating micro-projection functionality into electronic devices, enabling them to project information onto a desktop when the device is stationary, brings greater convenience to information prompts and interactive operations, and has become a focus of industry attention.

[0003] Most existing projection optical engines are based on DLP (Digital Light Processing) or LCoS (Liquid Crystal on Silicon) technology, which are relatively large and difficult to integrate into portable electronic devices such as mobile phones. MicroLED technology, due to its self-emissive characteristics, does not require an additional light source. Theoretically, projection functionality can be achieved simply by adding a magnifying imaging lens to the display chip, making miniaturized projection optical engines possible.

[0004] However, existing MicroLED projection optical engines are mainly used in the field of augmented reality (AR) displays. To match the waveguide coupling characteristics, their optical engine design typically projects the image to infinity, forming a virtual image in the human eye. Desktop projection applications require the optical engine to achieve close-range real image projection, and the projection direction is tilted downwards. This poses a significant challenge to the optical engine's imaging: on the one hand, the short projection distance and tilted imaging surface result in a large optical path difference between the upper and lower fields of view, making aberration correction difficult; on the other hand, to ensure the portability of electronic devices, the size of the optical engine must be strictly controlled.

[0005] Therefore, how to provide a miniaturized micro-projection system that can be integrated into electronic devices and achieve clear imaging on a desktop has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this application is to provide a new technology solution for a desktop projection system and electronic device, in order to solve the problem that existing micro-projection devices are difficult to balance miniaturization and clear imaging, and cannot be effectively integrated into portable electronic devices to realize desktop projection functions.

[0007] In a first aspect, this application provides a desktop projection system, the desktop projection system comprising: An image source having a luminescent surface for emitting image light; and, A miniature projection optical engine includes a projection lens and an exit pupil stop arranged along the optical axis, wherein the projection lens is located between the image source and the exit pupil stop, and is used to project the image light onto a projection surface to form a projected image; Wherein, the light-emitting surface of the image source is tilted at a first angle α relative to the plane perpendicular to the optical axis, and the optical axis of the micro-projection optical engine is tilted at a second angle β relative to the projection surface; the first angle α and the second angle β are configured to jointly compensate for the optical path difference between the upper and lower fields of view caused by the tilt of the optical axis, so as to achieve near-distance projection imaging.

[0008] Optionally, the first angle a and the second angle b satisfy the following relationship: -0.49<a / 2α-[f / (r·cotα)] / [sinb / (H / L)]<0.9; Where r is half the diagonal image height of the effective display area of ​​the emitting surface of the image source, α is half the field of view of the micro-projection optical engine, f is the focal length of the micro-projection optical engine, H is the vertical distance from the center of the exit pupil aperture to the projection surface, and L is the distance from the center of the projected image to the center of the exit pupil aperture.

[0009] Optionally, the vertical distance H from the center of the exit pupil aperture to the projection surface satisfies: 9mm < H < 17mm.

[0010] Optionally, the distance L from the center of the projected image to the center of the exit pupil aperture satisfies: 57mm < L < 63mm.

[0011] Optionally, the focal lengths of each lens in the projection lens satisfy the following relationship: 0.24<1 / f-(1 / f1+1 / f2+……+1 / f n <0.36; Where f is the focal length of the projection lens, f n Let be the focal length of the nth lens, and n be the number of lenses in the projection lens.

[0012] Optionally, the projection lens includes four or five lenses with optical power.

[0013] Optionally, each lens in the projection lens is an aspherical lens.

[0014] Optionally, the projection lens has zero offset, an aperture number F of 1.86 ≤ F ≤ 2.5, and a focal length f of 3.7 mm < f < 4.6 mm.

[0015] Optionally, the first angle a satisfies the relationship: 12° < a < 27°, and the second angle b satisfies the relationship: 9° < b < 16°.

[0016] Optionally, the image source is a MicroLED display screen.

[0017] Secondly, this application provides an electronic device, the electronic device comprising: The device itself; and, A desktop projection system is built into the housing of the device body, and the desktop projection system is the desktop projection system described in the first aspect.

[0018] One technical advantage of this application is: The desktop projection system provided in this application adopts a dual-tilt collaborative design, with the image source's emitting surface tilted at a first angle 'a' and the micro-projection optical engine tilted at a second angle 'b'. The first angle 'a' and the second angle 'b' jointly compensate for the optical path difference between the upper and lower fields of view caused by the optical axis tilt, effectively correcting aberrations in near-distance tilted projection without introducing freeform surfaces or increasing the number of lenses. Simultaneously, the overall tilt of the micro-projection optical engine achieves a zero-offset design, avoiding increased size. Therefore, this application achieves miniaturization of the optical engine while ensuring image clarity, enabling the desktop projection system to be easily integrated into portable electronic devices such as mobile phones and smartwatches, meeting the application requirements of near-distance desktop projection.

[0019] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0021] Figure 1 This is one of the schematic diagrams illustrating the usage state of the electronic device provided in the embodiments of this application; Figure 2 This is the second schematic diagram of the usage state of the electronic device provided in the embodiments of this application; Figure 3 A schematic diagram of a desktop projection system integrated into an electronic device, as provided in an embodiment of this application; Figure 4 This is one of the structural schematic diagrams of the desktop projection system provided in the embodiments of this application; Figure 5 for Figure 4 One of the schematic diagrams showing the projection state of a desktop projection system; Figure 6 for Figure 4 The second schematic diagram of the projection state of the desktop projection system is shown. Figure 7 According to Figure 6 The resulting projection distortion map; Figure 8 for Figure 4 The MTF diagram of the desktop projection system is shown. Figure 9 This is the second schematic diagram of the desktop projection system provided in the embodiments of this application; Figure 10 for Figure 9 One of the schematic diagrams showing the projection state of a desktop projection system; Figure 11 for Figure 9 The second schematic diagram of the projection state of the desktop projection system is shown. Figure 12 According to Figure 11 The resulting projection distortion map; Figure 13 for Figure 9 The MTF diagram of the desktop projection system is shown. Figure 14 This is the third schematic diagram of the desktop projection system provided in the embodiments of this application; Figure 15 for Figure 14 One of the schematic diagrams showing the projection state of a desktop projection system; Figure 16 for Figure 14 The second schematic diagram of the projection state of the desktop projection system is shown. Figure 17 According to Figure 16 The resulting projection distortion map; Figure 18 for Figure 14 The MTF diagram of the desktop projection system is shown.

[0022] Explanation of reference numerals in the attached figures: 1. Image source; 2. Miniature projection optical engine; 21. Projection lens; 211. First lens; 212. Second lens; 213. Third lens; 214. Fourth lens; 215. Fifth lens; 22. Exit pupil aperture; 3. Projection surface; 4. Device body; 01. Image light; 02. Projected image. Detailed Implementation

[0023] 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 arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0024] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0025] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0026] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0028] The desktop projection system and electronic device provided in the embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0029] According to one aspect of the embodiments of this application, a desktop projection system is provided, see [link to relevant documentation]. Figure 3 The desktop projection system includes an image source 1 and a miniature projection optical engine 2. The image source 1 has a light-emitting surface for emitting image light O1. The miniature projection optical engine 2 includes a projection lens 21 and an exit pupil stop 22 arranged along the optical axis, with the projection lens 21 located between the image source 1 and the exit pupil stop 22, for projecting the image light O1 onto a projection surface 3 to form a projected image O2. The light-emitting surface of the image source 1 is tilted at a first angle α relative to a plane perpendicular to the optical axis, and the optical axis of the miniature projection optical engine 2 is tilted at a second angle b relative to the projection surface. The first angle α and the second angle b are configured to jointly compensate for the optical path difference between the upper and lower fields of view caused by the tilt of the optical axis, thereby achieving near-distance projection imaging.

[0030] The desktop projection system provided in this application can be applied to various electronic devices, such as mobile phones, smartwatches, tablets, augmented reality devices, or virtual reality devices. (See also...) Figure 1 and Figure 2 This system enables the projection of information onto a horizontal support surface, such as a desktop, when the electronic device is placed still, providing greater convenience for information prompts and interactive operations. The desktop projection system of this application will be described in detail below with reference to the accompanying drawings.

[0031] See Figure 3 The desktop projection system includes an image source 1 and a miniature projection optical engine 2.

[0032] The image source 1 has a light-emitting surface that emits image light 01 carrying image information. To meet the requirements of miniaturization and integration, in the embodiments of this application, the image source 1 may, for example, be a MicroLED display screen. MicroLED displays have self-emissive characteristics, eliminating the need for additional lighting sources, thereby significantly simplifying the optomechanical structure, facilitating the miniaturization design of desktop projection systems, and making them easier to integrate into various portable electronic devices.

[0033] The micro projection optical engine 2 includes a projection lens 21 and an exit pupil stop 22, which are arranged sequentially along the same optical axis. Specifically, along the direction of light propagation, the projection lens 21 is located between the image source 1 and the exit pupil stop 22.

[0034] The projection lens 21 is used to receive the image light 01 emitted by the image source 1 and project it onto a projection surface 3, thereby forming an enlarged projected image 02 on the projection surface 3. In embodiments of this application, the projection surface 3 may be, for example, a desktop, see [link to relevant documentation]. Figure 1 This is to meet the needs of desktop projection applications when electronic devices are idle.

[0035] To achieve good image quality, the projection lens 21 is designed to consist of multiple lenses, for example, see [link to relevant documentation]. Figure 4 , Figure 9 and Figure 14 By rationally designing the optical power distribution of each lens and optimizing the lens surface using aspherical surfaces, various aberrations such as spherical aberration, coma, and astigmatism can be effectively corrected, thereby achieving high-quality magnified imaging of the image light 01. The introduction of aspherical lenses can reduce the number of lenses used while ensuring image quality, which is beneficial for achieving miniaturized design of the projection lens 21.

[0036] The exit pupil stop 22 is disposed on the exit side of the projection lens 21 to limit the aperture of the imaging beam and control the range of light angles participating in the imaging.

[0037] By rationally configuring the position and size of the exit pupil 22, key imaging performance aspects of the desktop projection system, such as depth of field, resolution, and image illumination uniformity, can be adjusted. For example, appropriately reducing the aperture of the exit pupil 22 can increase the depth of field but may reduce the resolution; while increasing the aperture of the exit pupil 22 is beneficial for improving the resolution but may affect edge illumination. Therefore, the exit pupil 22 needs to be optimized according to the specific projection distance and imaging requirements to balance various imaging indicators, thereby improving the overall imaging quality of the micro-projection optical engine 2.

[0038] In the embodiments of this application, the exit pupil aperture 22 and the projection lens 21 are arranged along the same optical axis, and cooperate with the tilt design of the image source 1 to jointly achieve clear imaging of close-range tilted projection.

[0039] See Figure 3The key design feature of this application embodiment lies in its dual-tilt design. Specifically, the emitting surface of the image source 1 is tilted at a first angle α relative to the plane perpendicular to the optical axis, while the overall optical axis of the micro-projection optical engine 2 is tilted at a second angle b relative to the projection surface 3. Through the coordinated operation of the first angle α and the second angle b, the optical path difference between the upper and lower fields of view caused by the tilted projection of the optical axis is compensated, thereby achieving clear imaging of close-range projection.

[0040] In desktop projection applications, the optical engine needs to project downwards onto the desktop at an angle. This results in unequal optical path lengths for light rays emitted from different positions on the image source's luminous surface, reaching corresponding points on the projection surface (e.g., the desktop). The optical path difference is particularly significant between the upper and lower fields of view. If not corrected promptly, this can lead to noticeable aberrations and severely affect the clarity of the projected image.

[0041] This application embodiment achieves effective correction of aberrations caused by tilted projection by using dual tilt adjustment—that is, tilting the light-emitting surface of the image source 1 at a first angle a, and tilting the overall optical axis of the micro-projection optical engine 2 at a second angle b—to make the optical path lengths of the upper and lower fields of view more consistent, thereby achieving effective correction of aberrations caused by tilted projection without introducing complex freeform surfaces.

[0042] Furthermore, by tilting the overall optical axis of the micro-projection optical engine 2, the field of view of the emitted light is made exactly equal to the designed field of view of the projection lens 21, achieving a zero-offset design. This design avoids the problem of traditional projection optical engines having to increase in size due to offset, and is conducive to the overall miniaturization of the optical engine.

[0043] In summary, the desktop projection system of this application embodiment, through its dual-tilt design, ensures both the image clarity of near-distance tilt projection and a compact optical engine size without increasing the number of lenses or introducing complex optical surfaces. This allows for easy integration into various portable electronic devices such as mobile phones and smartwatches, meeting the practical application needs of desktop projection.

[0044] See some examples in this application. Figure 3 The first angle α and the second angle b satisfy the following relationship: -0.49 < a / 2α - [f / (r·cotα)] / [sinb / (H / L)] < 0.9; where r is half the image height of the effective display area diagonally of the luminous surface of the image source 1, α is half the field of view of the micro-projection optical engine 2, f is the focal length of the micro-projection optical engine 2, H is the vertical distance from the center of the exit pupil diaphragm 22 to the projection surface 3, and L is the distance from the center of the projected image 02 to the center of the exit pupil diaphragm 22.

[0045] The equation in this example quantifies the matching relationship between various optical parameters in the dual-tilt design. In the equation, a / 2α reflects the relative relationship between the tilt angle of image source 1 and the field of view; f / (r·cotα) is related to the imaging characteristics of projection lens 21; and sinb / (H / L) reflects the geometric relationship between the overall tilt angle of the micro-projection optical engine 2 and the projection distance L and the height H of the optical engine from the tabletop. Through the combined calculation of these three parts, the compensation effect of dual tilt on optical path difference can be accurately described.

[0046] When the calculated value of the above relationship falls within the range of -0.48 to 0.9, it indicates that the matching of the first angle a and the second angle b is in the optimal range. Within this range, the image source tilt and the overall optical engine tilt can work together to effectively compensate for the optical path difference between the upper and lower fields of view caused by the optical axis tilt, so that the projected image can still maintain clear imaging quality under near-distance tilted projection conditions.

[0047] When the calculated value of the relation is close to 0.9, it corresponds to a configuration where the image source 1 has a larger tilt angle and the micro-projection engine 2 has a smaller overall tilt angle; when the calculated value is close to -0.49, it corresponds to a configuration where the image source 1 has a smaller tilt angle and the micro-projection engine 2 has a larger overall tilt angle; when the calculated value is in the middle, it is a configuration where the two are relatively balanced. Regardless of the configuration, as long as the calculated value falls within the range of -0.49 to 0.9, a good aberration correction effect can be achieved.

[0048] By introducing this relationship in the example, this application provides a quantitative design basis for dual-tilt designs. Technicians can rationally configure the values ​​of the first angle 'a' and the second angle 'b' based on specific application requirements such as the projection distance L, the height H of the optical engine from the tabletop, and the field of view, ensuring ideal imaging performance in different application scenarios.

[0049] Where r is half the image height of the diagonal of the effective display area of ​​the emitting surface of the image source 1. Specifically, the emitting surface of the image source 1 is usually rectangular, and its effective display area has mutually perpendicular side lengths, so r is half the length of the diagonal of this rectangular area. This parameter reflects the size characteristics of the emitting surface of the image source.

[0050] See some examples in this application. Figure 3 The vertical distance H from the center of the exit pupil aperture 22 to the projection surface 3 satisfies: 9mm < H < 17mm.

[0051] See Figure 3The vertical distance H from the center of the exit pupil 22 to the projection surface 3 satisfies: 9mm < H < 17mm. This vertical distance H is the height of the micro-projection optical engine 2 in its working state, specifically indicating the vertical distance from the center of the exit pupil 22 along a direction perpendicular to the projection surface 3 to the projection surface 3. In desktop projection applications, the projection surface 3 is the desktop, therefore H corresponds to the height of the exit pupil center of the integrated micro-projection optical engine 2 from the desktop when the electronic device is placed flat on the desktop.

[0052] Limiting H to the range of 9mm to 17mm serves two purposes. First, this height range matches the thickness of portable electronic devices such as mobile phones and smartwatches, ensuring that the micro-projection optical engine 2 is completely integrated into the casing of the electronic device without causing it to protrude or increase in thickness, thus meeting the requirements of product appearance design and portability. Second, this height range ensures an appropriate spatial relationship between the projected image and the electronic device, preventing the projected image from being too small or obstructed by the device due to excessive distance, and also preventing it from exceeding the desktop range due to excessive distance, providing flexibility for subsequent scenario-based applications and information interaction design.

[0053] See some examples in this application. Figure 3 The distance L from the center of the projected image 02 to the center of the exit pupil aperture 22 satisfies: 57mm < L < 63mm.

[0054] See Figure 3 The distance L from the center of the projected image 02 to the center of the exit pupil stop 22 satisfies: 57mm < L < 63mm. This distance L is the projection distance, specifically the straight-line distance from the center of the exit pupil stop 22 along the optical path to the center of the projected image 02. In desktop projection applications, L corresponds to the actual distance from the exit pupil position of the micro-projection optical engine 2 to the center of the projected image.

[0055] The L-shape is designed within the range of 57mm to 63mm to maintain a suitable distance between the projected image and the electronic device. Within this distance range, the projected image can be clearly projected onto the table near the electronic device, ensuring both an appropriate screen size and placing the image content within the user's natural line of sight for easy viewing and interaction.

[0056] Furthermore, this distance range matches the aforementioned H range (9mm < H < 17mm), jointly defining the spatial size requirements suitable for desktop projection scenarios of portable electronic devices. Under the synergistic constraint of these two sets of parameters, the micro-projection optical engine 2 can achieve good imaging effects within a compact installation space, meeting practical application needs.

[0057] In some examples of this application, the focal lengths of the lenses in the projection lens 21 satisfy the following relationship: 0.24 < 1 / f - (1 / f1 + 1 / f2 + ... + 1 / f n ) < 0.36; where f is the focal length of the projection lens 21, f n Let n be the focal length of the nth lens, and n be the number of lenses in the projection lens 21.

[0058] The relationship in this example reflects the matching relationship between the overall optical power of the projection lens 21 and the sum of the optical powers of each lens. Here, 1 / f represents the total optical power of the entire projection lens 21, and (1 / f1 + 1 / f2 + ... + 1 / f...) n The sum of the optical power of each lens is represented by ), and the difference between the two reflects the compensation amount of the optical power distribution inside the projection lens 21.

[0059] Limiting this difference to between 0.24 and 0.36 allows for optimized lens configuration while maintaining image quality. If the difference is too small, it indicates that the optical power distribution of each lens is too concentrated, which may lead to insufficient aberration correction capability. If the difference is too large, it may be necessary to increase the number of lenses or use complex surface shapes to compensate, which is not conducive to the miniaturization of projection lenses.

[0060] By introducing this relationship, this application provides a quantitative design basis for the optical power allocation of the projection lens 21. Under the guidance of this relationship, four or five lenses can be used to achieve the required projection imaging function, which not only ensures good aberration correction effect, but also controls the number of lenses, which is conducive to the overall miniaturization of the micro projection optical engine 2.

[0061] For example, when using a 4-lens configuration, the calculated value can reach approximately 0.35; when using a 5-lens configuration, the calculated value can reach approximately 0.25. Regardless of the number of lenses used, as long as the calculated value falls within the range of 0.24 to 0.36, good image quality can be achieved, meeting the application requirements of near-field desktop projection.

[0062] See some examples in this application. Figure 4 , Figure 9 and Figure 14 The projection lens 21 includes 4 or 5 lenses with optical power.

[0063] By employing a configuration of 4 or 5 lenses, this application is able to achieve a simple structure and compact size of the projection lens 21 while ensuring image quality.

[0064] In optical design, the number of lenses directly affects the length, weight, and manufacturing cost of a projection lens. Too many lenses increase the overall size of the optical engine, making it difficult to integrate into portable electronic devices; while too few lenses make it difficult to correct various aberrations and fail to meet the requirements for clear imaging.

[0065] This application, through the aforementioned dual-tilt design, enables excellent aberration correction using only 4 or 5 lenses. This design advantage stems from the synergistic effect of the tilt of the image source 1 and the overall tilt of the micro-projection optical engine 2, effectively compensating for the optical path difference caused by near-distance tilted projection and reducing the aberration correction burden on the projection lens 21 itself. Therefore, without employing an excessive number of lenses or complex freeform surfaces, a simple structure and compact size of the projection lens 21 can be achieved while maintaining image clarity. This facilitates the overall miniaturization of the micro-projection optical engine 2 and its integration into various portable electronic devices.

[0066] In some examples of this application, each lens in the projection lens 21 is an aspherical lens.

[0067] Compared to traditional spherical lenses, aspherical lenses have stronger aberration correction capabilities, achieving equal or even better image quality with fewer lenses. This application, based on the use of 4 or 5 lenses, designs each lens as an aspherical surface, fully leveraging the advantages of aspherical surfaces in aberration correction. This example can effectively correct various aberrations such as spherical aberration, coma, and astigmatism, enabling the projection lens 21 to maintain good imaging performance with a limited number of lenses.

[0068] Furthermore, the use of aspherical lenses helps to shorten the overall length of the projection lens 21, further reducing the size of the micro-projection optical engine. This is of great significance for desktop projection systems that need to be integrated into portable electronic devices such as mobile phones and smartwatches. This application achieves miniaturization of the optical engine while ensuring image quality through the combination of aspherical lenses and a dual-tilt design.

[0069] In some examples of this application, the offset of the projection lens 21 is zero, the aperture number F is 1.86≤F≤2.5, and the focal length f satisfies 3.7mm<f<4.6mm.

[0070] Zero offset, or zero offset design, means that by tilting the overall optical axis of the micro-projection optical engine 2, the field of view of the emitted light is exactly equal to the designed field of view of the projection lens 21, eliminating the need to adjust the optical path through offset as in traditional projection optical engines. This design avoids the problem of increased optical engine size caused by offset, and is beneficial for miniaturizing the optical engine.

[0071] The f-number (F) represents the light-gathering capability of a projection lens. The smaller the F-number, the larger the aperture and the more light enters. In this example, the f-number (F) is designed between 1.86 and 2.5, which ensures both image brightness and depth of field and resolution requirements, allowing the projected image to maintain a clear imaging effect under different lighting conditions.

[0072] Focal length f is one of the fundamental parameters of a projection lens, determining the magnification and projection distance. In this example, f is limited to the range of 3.7mm to 4.6mm, which matches the aforementioned ranges of H and L, enabling a suitable projection screen size to be achieved within a compact installation space, thus meeting the application requirements of desktop projection.

[0073] See some examples in this application. Figure 3 The first angle a satisfies the relationship: 12° < a < 27°, and the second angle b satisfies the relationship: 9° < b < 16°.

[0074] The first angle 'a' is the tilt angle of the light-emitting surface of the image source 1 relative to a plane perpendicular to the optical axis, and the second angle 'b' is the tilt angle of the overall optical axis of the micro-projection optical engine 2 relative to the projection surface 3. The values ​​of these two angles need to be designed and matched according to parameters such as the projection distance L and the height H of the optical engine from the tabletop.

[0075] In this example, limiting the first angle 'a' to the range of 12° to 27° and the second angle 'b' to the range of 9° to 16° are optimized ranges derived from extensive optical simulations and experimental verification. Within this angle range, the tilt of the image source 1 and the overall tilt of the micro-projection optical engine 2 can form an effective synergy, jointly compensating for the optical path difference between the upper and lower fields of view caused by the tilt of the optical axis, thus achieving optimal aberration correction.

[0076] In some examples of this application, the image source 1 is a MicroLED display screen.

[0077] MicroLED displays are a self-emissive display technology where each pixel is composed of light-emitting diodes at the micrometer scale, offering advantages such as self-illumination, high brightness, high contrast, and fast response.

[0078] Using a MicroLED display as image source 1: First, the self-emissive nature of MicroLED eliminates the need for additional lighting sources, significantly simplifying the optical engine structure and facilitating the overall miniaturization of the micro-projection optical engine 2; second, MicroLED has high luminous efficiency and brightness, ensuring screen brightness under close-range imaging conditions in desktop projection; third, MicroLED has small pixel size and high integration, enabling high resolution within a limited chip area, meeting the clarity requirements of projected images.

[0079] This application, by combining a MicroLED display with a dual-tilt design, fully leverages the advantages of MicroLED in miniaturization and luminous performance, providing a feasible technical path for the realization of desktop projection systems.

[0080] The desktop projection system of this application will be described in detail below through Examples 1 to 3.

[0081] Example 1 See Figure 4 This embodiment 1 provides a desktop projection system. The desktop projection system includes an image source 1 and a miniature projection optical engine 2.

[0082] See Figure 5 and Figure 6 The image source 1 has a light-emitting surface for emitting image light O1. In this embodiment 1, the image source 1 uses a 0.05-inch MicroLED display screen with a resolution of 256×86 and a pixel size of 5μm.

[0083] The miniature projection optical engine 2 includes a projection lens 21 and an exit pupil stop 22 arranged along the optical axis. The projection lens 21 is located between the image source 1 and the exit pupil stop 22, and is used to project the image light 01 onto a projection surface 3 to form a projected image 02. In this embodiment 1, the projection surface 3 is a desktop. The diameter D of the exit pupil stop 22 is 2.7 mm, and a front-mounted aperture design is adopted.

[0084] In this design, the light-emitting surface of the image source 1 is tilted at a first angle α relative to the plane perpendicular to the optical axis, and the first angle α is 26.6°; the overall optical axis of the micro-projection optical engine 2 is tilted at a second angle b relative to the projection surface 3, and the second angle b is 10°. Through the coordinated operation of the first angle α and the second angle b, the optical path difference between the upper and lower fields of view caused by the tilted projection of the optical axis is compensated, thereby achieving clear imaging of near-distance desktop projection.

[0085] In this embodiment 1, the vertical distance H from the center of the exit pupil 22 of the micro-projection optical engine 2 to the projection surface 3 is 10mm, meaning the height of the optical engine above the table is 10mm; the distance L from the center of the projected image 02 to the center of the exit pupil 22 is 57.6mm, meaning the projection distance is 57.6mm. With this parameter configuration, the field of view (FOV) of the emitted light from the micro-projection optical engine 2 is 15°, enabling the formation of a tilted projection image on the table.

[0086] Please refer to Tables 1 and 2 below for the optical parameters of this embodiment 1.

[0087] Table 1 Optical parameters of the desktop projection system

[0088] It should be noted that, see Figure 4 In this embodiment 1, the projection lens 21 is equipped with four lenses: a first lens 211, a second lens 212, a third lens 213, and a fourth lens 214. These four lenses are arranged sequentially along the optical axis from one side of the exit pupil stop 22 to the side of the image source 1, that is, in the opposite direction of light propagation, they are the first lens 211, the second lens 212, the third lens 213, and the fourth lens 214. The focal lengths corresponding to each lens are f1, f2, f3, and f4, as shown in Table 1.

[0089] Table 2 Projection Lens Parameters (Focal length f is 4.5mm, F-number is 1.86)

[0090] After testing, see Figure 7 In this embodiment 1, the top side of the projected image is approximately 11.4 mm long, the bottom side is approximately 19.7 mm long, and the height is approximately 5.34 mm. The image exhibits some geometric distortion, but this can be corrected using an anti-distortion compensation algorithm, ultimately resulting in a rectangular image with dimensions of 11.4 mm × 5.34 mm.

[0091] See Figure 8 In this embodiment, the image modulation transfer function (MTF) is greater than 0.5@100lp / mm, and the imaging quality is good at the Nyquist frequency, which meets the application requirements of desktop projection.

[0092] Example 2 See Figure 9 This embodiment 2 provides another desktop projection system. The desktop projection system includes an image source 1 and a miniature projection optical engine 2.

[0093] See Figure 10 and Figure 11 The image source 1 has a light-emitting surface for emitting image light O1. In this embodiment 2, the image source 1 uses a MicroLED display screen with a resolution of 480×260 and a pixel size of 4μm.

[0094] The miniature projection optical engine 2 includes a projection lens 21 and an exit pupil aperture 22 arranged along the optical axis. The projection lens 21 is located between the image source 1 and the exit pupil aperture 22, and is used to project the image light 01 onto a projection surface 3 to form a projected image 02. In this embodiment 2, the projection surface 3 is a desktop. The diameter D of the exit pupil aperture 22 is 1.7 mm, and a front aperture design is adopted.

[0095] In this design, the light-emitting surface of the image source 1 is tilted at a first angle α, which is 13°, relative to a plane perpendicular to the optical axis; the overall optical axis of the micro-projection optical engine 2 is tilted at a second angle b, which is 15.1°, relative to the projection surface 3. Through the coordinated operation of the first angle α and the second angle b, the optical path difference between the upper and lower fields of view caused by the tilted projection of the optical axis is compensated, thereby achieving clear imaging for near-distance desktop projection.

[0096] In this embodiment 2, the vertical distance H from the center of the exit pupil 22 of the micro-projection optical engine 2 to the projection surface 3 is 16mm, that is, the height of the optical engine above the table is 16mm; the distance L from the center of the projected image 02 to the center of the exit pupil 22 is 62.6mm, that is, the projection distance is 62.6mm. Under this parameter configuration, the field of view (FOV) of the emitted light from the micro-projection optical engine 2 is 30°, which can form a tilted projection image on the table.

[0097] The optical parameters of this embodiment 2 are shown in Tables 3 and 4 below.

[0098] Table 3 Optical parameters of the desktop projection system

[0099] It should be noted that, see Figure 9 In this embodiment 2, the projection lens 21 is equipped with five lenses: a first lens 211, a second lens 212, a third lens 213, a fourth lens 214, and a fifth lens 215. These five lenses are arranged sequentially along the optical axis from one side of the exit pupil stop 22 to the side of the image source 1, that is, in the opposite direction of light propagation, they are the first lens 211, the second lens 212, the third lens 213, the fourth lens 214, and the fifth lens 215. The focal lengths corresponding to each lens are f1, f2, f3, f4, and f5, as shown in Table 2.

[0100] Table 4 Projection Lens Parameters (Focal length f is 3.8mm, F-number is 2.5)

[0101] After testing, see Figure 12 In this embodiment 2, the top side of the projected image is approximately 19.6 mm long, the bottom side is approximately 58.2 mm long, and the height is approximately 21.1 mm. The image exhibits some geometric distortion, but this can be corrected using an anti-distortion compensation algorithm, ultimately resulting in a rectangular image with dimensions of 19.6 mm × 21.1 mm.

[0102] See Figure 13 In this embodiment 2, the image modulation transfer function (MTF) is greater than 0.55@120lp / mm, and the imaging quality is good at the Nyquist frequency, which meets the application requirements of desktop projection.

[0103] Example 3 See Figure 14 This embodiment provides yet another desktop projection system. The desktop projection system includes an image source 1 and a miniature projection optical engine 2.

[0104] Referring to Figures 15 and 16, the image source 1 has a light-emitting surface for emitting image light O1. In this embodiment 3, the image source 1 uses a 0.05-inch MicroLED display screen with a resolution of 256×86 and a pixel size of 5μm.

[0105] The miniature projection optical engine 2 includes a projection lens 21 and an exit pupil stop 22 arranged along the optical axis. The projection lens 21 is located between the image source 1 and the exit pupil stop 22, and is used to project the image light 01 onto a projection surface 3 to form a projected image 02. In this embodiment 3, the projection surface 3 is a desktop. The diameter of the exit pupil stop 22 is 2.8 mm, and a front-mounted aperture design is adopted.

[0106] In this design, the light-emitting surface of the image source 1 is tilted at a first angle α relative to the plane perpendicular to the optical axis, and the first angle α is 16.7°; the overall optical axis of the micro-projection optical engine 2 is tilted at a second angle b relative to the projection surface 3, and the second angle b is 15°. Through the coordinated operation of the first angle α and the second angle b, the optical path difference between the upper and lower fields of view caused by the tilted projection of the optical axis is compensated, thereby achieving clear imaging of near-distance desktop projection.

[0107] In this embodiment 3, the vertical distance H from the center of the exit pupil 22 of the micro-projection optical engine 2 to the projection surface 3 is 15mm, that is, the height of the optical engine above the table is 15mm; the distance L from the center of the projected image 02 to the center of the exit pupil 22 is 58mm, that is, the projection distance is 58mm. Under this parameter configuration, the field of view (FOV) of the emitted light of the micro-projection optical engine 2 is 15.3°, which can form a tilted projection image on the table.

[0108] The optical parameters of this embodiment 3 are shown in Tables 5 and 6 below.

[0109] Table 5 Optical parameters of the desktop projection system

[0110] It should be noted that, see Figure 14In this embodiment 3, the projection lens 21 is equipped with four lenses: a first lens 211, a second lens 212, a third lens 213, and a fourth lens 214. These lenses are arranged sequentially along the optical axis from one side of the exit pupil stop 22 to the side of the image source 1, that is, in the opposite direction of light propagation, they are the first lens 211, the second lens 212, the third lens 213, and the fourth lens 214. The focal lengths corresponding to each lens are f1, f2, f3, and f4, as shown in Table 3.

[0111] Table 6 Projection Lens Parameters (Focal length f is 4.5mm, F-number is 1.86)

[0112] After testing, see Figure 17 In this embodiment 3, the top side of the projected image is approximately 12.4mm, the bottom side is approximately 17.9mm, and the height is approximately 5.1mm. The image exhibits some geometric distortion, but this can be corrected using an anti-distortion compensation algorithm, ultimately resulting in a rectangular image with dimensions of 12.9mm × 5.1mm.

[0113] See Figure 18 In this embodiment, the image modulation transfer function (MTF) is greater than 0.35 @ 100lp / mm, resulting in good image quality at the Nyquist frequency, which meets the application requirements of desktop projection.

[0114] According to another embodiment of this application, an electronic device is provided, see [link to relevant documentation]. Figure 3 The electronic device includes: a device body 4 and a desktop projection system, wherein the desktop projection system is built into the housing of the device body 4, and the desktop projection system is the desktop projection system described above.

[0115] The desktop projection system described is the same as that described in any of the foregoing embodiments. Its specific structure and working principle have been described in detail above and will not be repeated here. This desktop projection system includes an image source 1 and a miniature projection optical engine 2, and achieves close-range desktop projection imaging through a dual-tilt design.

[0116] When the electronic device is placed on a horizontal support surface (e.g., a desktop), the desktop projection system is configured to project onto that horizontal support surface. Users can view the projected image on a desktop near the electronic device without holding the device, thus enabling functions such as information prompts and interactive operations.

[0117] In embodiments of this application, the electronic device can be any one of a mobile phone, smartwatch, tablet computer, augmented reality device, or virtual reality device. By integrating a miniaturized desktop projection system into these portable devices, the application scenarios of the device can be expanded and the user experience improved without significantly increasing the device size.

[0118] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0119] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A desktop projection system, characterized in that, include: The image source (1) has a light-emitting surface for emitting image light (01). as well as, The micro projection optical engine (2) includes a projection lens (21) and an exit pupil stop (22) arranged along the optical axis. The projection lens (21) is located between the image source (1) and the exit pupil stop (22) and is used to project the image light (01) onto a projection surface (3) to form a projected image (02). Wherein, the light-emitting surface of the image source (1) is tilted at a first angle a relative to the plane perpendicular to the optical axis, and the optical axis of the micro projection optical engine (2) is tilted at a second angle b relative to the projection surface (3); the first angle a and the second angle b are configured to jointly compensate for the optical path difference between the upper and lower fields of view caused by the tilt of the optical axis, so as to realize close-range projection imaging.

2. The desktop projection system according to claim 1, characterized in that, The first angle a and the second angle b satisfy the following relationship: -0.49<a / 2α-[f / (r·cotα)] / [sinb / (H / L)]<0.9; Where r is half the diagonal image height of the effective display area of ​​the luminous surface of the image source (1), α is half the field of view of the micro-projection optical engine (2), f is the focal length of the micro-projection optical engine (2), H is the vertical distance from the center of the exit pupil stop (22) to the projection surface (3), and L is the distance from the center of the projected image (02) to the center of the exit pupil stop (22).

3. The desktop projection system according to claim 2, characterized in that, The vertical distance H from the center of the exit pupil aperture (22) to the projection surface (3) satisfies: 9mm < H < 17mm.

4. The desktop projection system according to claim 2, characterized in that, The distance L from the center of the projected image (02) to the center of the exit pupil aperture (22) satisfies: 57mm < L < 63mm.

5. The desktop projection system according to claim 1 or 2, characterized in that, The focal lengths of each lens in the projection lens (21) satisfy the following relationship: 0.24<1 / f-(1 / f1+1 / f2+……+1 / f n )<0.36; Where f is the focal length of the projection lens (21), f n Let n be the focal length of the nth lens, and n be the number of lenses in the projection lens (21).

6. The desktop projection system according to claim 5, characterized in that, The projection lens (21) includes 4 or 5 lenses with optical power.

7. The desktop projection system according to claim 6, characterized in that, All lenses in the projection lens (21) are aspherical lenses.

8. The desktop projection system according to claim 1, characterized in that, The offset of the projection lens (21) is zero, the aperture number F is 1.86≤F≤2.5, and the focal length f satisfies 3.7mm<f<4.6mm.

9. The desktop projection system according to claim 1, characterized in that, The first angle a satisfies the relationship: 12° < a < 27°, and the second angle b satisfies the relationship: 9° < b < 16°.

10. The desktop projection system according to claim 1, characterized in that, The image source (1) is a MicroLED display screen.

11. An electronic device, characterized in that, include: The device body (4); and, A desktop projection system is built into the housing of the device body (4), and the desktop projection system is the desktop projection system according to any one of claims 1 to 10.

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