Sham lens, projection device and projection system for projection

Abstract

The application belongs to the technical field of projection lenses, and provides a Sharm lens for projection, a projection device and a projection system. The Sharm lens for projection comprises a rear group and a front group arranged in sequence from an object side to an image side along an optical path direction, and the rear group and the front group are separately and spacedly arranged; the rear group comprises a lens module with a positive optical power-negative optical power-positive optical power structure, and in the lens module with the positive optical power-negative optical power-positive optical power structure, a first positive optical power lens group, a first negative optical power lens group and a second positive optical power lens group are arranged in sequence from the object side to the image side along the optical path direction; and the front group comprises a negative optical power lens and a positive optical power lens arranged in sequence from the object side to the image side along the optical path direction. The Sharm lens for projection has the advantages of small F#, good imaging quality and the like through cooperation of the multiple lenses in the rear group and the front group.

Description

Technical Field

[0001] This application belongs to the field of projection lens technology, and particularly relates to a SAM lens, projection device and projection system that can be used for projection. Background Technology

[0002] Defect detection on circuit boards is a crucial step in the electronics manufacturing industry, ensuring the quality, reliability, and safety of electronic devices. Currently, projection systems are commonly used for circuit board defect detection. These systems typically include a projection device and a camera. The projection optical engine in the projection device projects straight structured light stripes onto the surface of the circuit board. These straight structured light stripes deform on the curved surface of the circuit board. The camera can then capture the deformed pattern based on the degree of deformation of the straight structured light stripes at different angles. Combined with algorithms, this allows for accurate calculation and reconstruction of the three-dimensional (3D) information of the circuit board under test.

[0003] During the testing process, since the projection lens in the projection engine coincides with the camera's field of view, when the camera is placed perpendicular to the projection screen, the projection lens needs to be tilted relative to the camera to minimize interference and meet the accuracy requirements of triangulation. However, for conventional projection systems, a tilted projection lens will inevitably cause the imaging surface to tilt. Consequently, the position of the projection surface may become defocused, leading to out-of-focus and blurry images, resulting in a significant deterioration in image quality.

[0004] A Schahm lens is a type of lens that utilizes Schahm's law for imaging. When used as a projection lens, a Schahm lens can achieve clear imaging across the entire field of view of the tilted target, i.e., obtain clear image quality, by using a tilted digital micromirror device (DMD) as the display chip, according to Schahm's law. However, after tilting the DMD, the numerical aperture of the illumination structure in the projection optical engine may not match the light-receiving numerical aperture of the projection lens. This can cause a significant decrease in projection brightness, resulting in poor image quality. Utility Model Content

[0005] In view of this, embodiments of this application provide a SAM lens, a projection device, and a projection system that can be used for projection. The SAM lens that can be used for projection can improve the problem of poor image quality caused by the mismatch between the numerical aperture of the existing lighting structure and the light-receiving numerical aperture of the projection lens, which leads to a decrease in projection brightness.

[0006] A first aspect of this application provides a SAM lens for projection, comprising: a rear group and a front group, wherein the rear group and the front group are arranged sequentially from the object side to the image side along the optical path direction, and the rear group and the front group are separate and spaced apart.

[0007] The rear group includes a lens module with a power structure of positive power-negative power-positive power. In the positive power-negative power-positive power lens module, a first positive power lens group, a first negative power lens group, and a second positive power lens group are arranged sequentially from the object side to the image side along the optical path direction. The first positive power lens group includes at least one positive power lens, the first negative power lens group includes at least one negative power lens, and the second positive power lens group includes at least one positive power lens.

[0008] The front group includes a negative power lens and a third positive power lens arranged sequentially from the object side to the image side along the optical path direction.

[0009] In some embodiments, the rear group includes a first spherical positive power lens, a second spherical positive power lens, a third spherical negative power lens, a fourth spherical negative power lens, a fifth spherical negative power lens, a sixth spherical positive power lens, an aperture stop, and a seventh spherical positive power lens arranged sequentially from the object side to the image side along the optical path direction.

[0010] And / or,

[0011] The front group includes an eighth spherical negative power lens and a ninth spherical positive power lens arranged sequentially from the object side to the image side along the optical path direction.

[0012] In some embodiments, the fifth spherical negative power lens and the sixth spherical positive power lens are combined to form a cemented lens.

[0013] In some embodiments, the eighth spherical negative power lens and the ninth spherical positive power lens form the front group in a close contact manner with their edges in contact.

[0014] In some embodiments, the positive power lens in the rear group is made of crown glass, the Abbe number of the crown glass is greater than or equal to 50, and / or the refractive index of the crown glass is 1.5 to 1.6.

[0015] The negative power lens in the rear group is made of flint glass, the Abbe number of which is less than or equal to 50, and / or the refractive index of which is 1.6 to 1.9.

[0016] In some embodiments, the focal length of the Sham lens that can be used for projection is 25mm to 30mm;

[0017] And / or, the focal length of the rear group is 25.47mm to 31.13mm;

[0018] And / or, the focal length of the front group is 34.76mm to 42.49mm;

[0019] And / or, the focal length of the first spherical positive power lens is 19.43 mm to 23.74 mm;

[0020] And / or, the focal length of the second spherical positive power lens is 22.44 mm to 27.43 mm;

[0021] And / or, the focal length of the third spherical negative power lens is -72.94 to -59.68 mm;

[0022] And / or, the focal length of the fourth spherical negative power lens is -14.76 to -12.08 mm;

[0023] And / or, the focal length of the cemented lens formed by combining the fifth spherical negative power lens and the sixth spherical positive power lens is 106.08 mm to 129.66 mm;

[0024] And / or, the focal length of the seventh spherical positive power lens is 28.28 mm to 34.57 mm;

[0025] And / or, the focal length of the eighth spherical negative power lens is -23.99 to -19.63 mm;

[0026] And / or, the focal length of the ninth spherical positive power lens is 24.05 mm to 29.40 mm.

[0027] In some embodiments, the Sham lens that can be used for projection is designed to operate in the visible light band of 420nm to 680nm.

[0028] And / or, the aperture number of the Sham lens that can be used for projection is 2.4 to 2.6;

[0029] And / or, the working distance of the SAM lens that can be used for projection is 150mm to 250mm;

[0030] And / or, the tilt angle of the projection surface of the Sham lens that can be used for projection is 20° to 30°.

[0031] A second aspect of this application provides a projection device including the aforementioned Sham lens for projection.

[0032] In some embodiments, the projection device further includes: a display chip, a display chip protective glass, and an equivalent prism, wherein the display chip, the display chip protective glass, the equivalent prism, and the SAM lens that can be used for projection are arranged sequentially from the object side to the image side along the optical path direction;

[0033] The display chip and the protective glass for the display chip are placed at an angle relative to the optical axis of the Sham lens that can be used for projection.

[0034] A third aspect of this application provides a projection system including the projection device described above.

[0035] Compared with the prior art, this application has the following technical effects:

[0036] This application provides a Sham lens for projection, a projection device, and a projection system. The Sham lens includes a rear group and a front group arranged sequentially along the optical path. The rear group forms a basically symmetrical structure with a "positive-negative-positive" optical power layout. The symmetry of the optical power structure can be used to reduce transverse aberration, and the lens splitting can smooth the light transition and reduce higher-order aberrations. Meanwhile, the front group consists of a pair of closely spaced positive and negative optical power lenses, which can achieve distortion correction. Therefore, the Sham lens for projection in this embodiment has a small aperture number, high brightness, and excellent image quality. The superior performance of the Sham lens can improve the performance of the projection device, thereby enabling the projection system to achieve clear imaging. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a Sham lens that can be used for projection, provided in an embodiment of this application;

[0039] Figure 2 This is a schematic diagram of the front group in a Sham lens that can be used for projection, provided in an embodiment of this application;

[0040] Figure 3 This is a schematic diagram of the rear element in a Sham lens that can be used for projection, provided in an embodiment of this application;

[0041] Figure 4 This is a schematic diagram of the light path of a Sham lens that can be used for projection, provided in an embodiment of this application;

[0042] Figure 5 This is a schematic diagram of an actual scene where light passes through a Sham lens provided in an embodiment of this application, which can be used for projection;

[0043] Figure 6 This is an MTF curve of a Sham lens image on a screen, which can be used for projection, provided in an embodiment of this application.

[0044] Figure label:

[0045] 100 - Schahm lens, 110 - Rear group of Schahm lens, 111 - First spherical positive power lens, 112 - Second spherical positive power lens, 113 - Third spherical negative power lens, 114 - Fourth spherical negative power lens, 115 - Fifth spherical negative power lens, 116 - Sixth spherical positive power lens, 117 - Aperture, 118 - Seventh spherical positive power lens, 120 - Front group of Schahm lens, 121 - Eighth spherical negative power lens, 122 - Ninth spherical positive power lens, 101 - Display chip, 102 - Display chip protective glass, 103 - Equivalent prism, 1 - Screen. Detailed Implementation

[0046] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0047] The term "comprising" and any variations thereof in the specification, claims, and accompanying drawings are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus.

[0048] Furthermore, the terms "first," "second," "third," "fourth," "fifth," "sixth," "seventh," "eighth," and "ninth" are used to distinguish different objects, rather than to describe a specific order.

[0049] The term "at least one" means "one or more".

[0050] In addition, the term "electrical connection" can refer to a direct electrical connection between two components, or an electrical connection between two components via one or more other components; "electrical connection" can refer to an electrical connection via a wire, or an electrical connection via a radio signal.

[0051] Example 1

[0052] This application provides a Sham lens that can be used for projection. (See reference...) Figures 1 to 5 As shown, the Sham lens 100 for projection in this embodiment may include a rear group 110 and a front group 120. The rear group 110 and the front group 120 are arranged sequentially from the object side to the image side along the optical path direction. The rear group 110 and the front group 120 are separate and spaced apart.

[0053] Please refer to this again. Figures 1 to 5 As shown, the rear group 110 of the Sham lens 100 that can be used for projection may include a lens module with a "positive-negative-positive" optical power structure. The "positive-negative-positive" optical power lens module may include a first positive optical power lens group, a first negative optical power lens group, and a second positive optical power lens group arranged sequentially from the object side to the image side along the optical path direction. The first positive optical power lens group may include at least one positive optical power lens, specifically at least one spherical positive optical power lens. The first negative optical power lens group may include at least one negative optical power lens, specifically at least one spherical negative optical power lens. The second positive optical power lens group may include at least one positive optical power lens, specifically at least one spherical positive optical power lens. The number and arrangement of lenses in each group can be determined according to actual needs.

[0054] Please refer to this again. Figures 1 to 5 As shown, the front group 120 of the Sham lens 100 used for projection may include negative power lenses and positive power lenses arranged sequentially from the object side to the image side along the optical path. When there are multiple negative power lenses and multiple positive power lenses, for example, three negative power lenses and three positive power lenses, they can be arranged sequentially from the object side to the image side along the optical path: negative power lens, positive power lens, negative power lens, positive power lens, negative power lens, and positive power lens. Specifically, the negative power lens can be a spherical negative power lens, and the positive power lens can be a spherical positive power lens. The number of lenses can be determined according to actual needs.

[0055] It should be noted that the direction of the optical path is... Figures 1 to 5 The OX direction in the diagram is the direction from O to X.

[0056] In practical applications, the rear group 110 and the front group 120, which are arranged sequentially from the object side to the image side along the optical path, can be separated by an air gap, that is, the rear group 110 and the front group 120 do not contact each other.

[0057] As an example, see reference Figure 2 As shown, the rear group 110 may include a first positive power lens, a second positive power lens, a third negative power lens, a fourth negative power lens, a fifth negative power lens, a sixth positive power lens, and a seventh positive power lens arranged sequentially from the object side to the image side along the optical path direction. The first and second positive power lenses constitute the "positive" group in the "positive-negative-positive" lens module; the third, fourth, and fifth negative power lenses constitute the "negative" group in the "positive-negative-positive" lens module; and the sixth and seventh positive power lenses constitute the "positive" group in the "positive-negative-positive" lens module.

[0058] In the Sham lens 100 used for projection, the rear group 110 first uses two positive power lenses (a first positive power lens and a second positive power lens) in succession to distribute the optical power, making the light transition smooth and reducing higher-order aberrations. Then, three negative power lenses (a third negative power lens, a fourth negative power lens, and a fifth negative power lens) are used in succession to distribute the light deflection angle of the light after passing through the two positive power lenses, reducing or even avoiding large light angles and reducing aberrations. Finally, two positive power lenses (a sixth positive power lens and a seventh positive power lens) are used again. In this way, the two positive power lenses can smoothly converge the divergent light rays after passing through the three negative power lenses, reducing or even avoiding the generation of higher-order aberrations.

[0059] It should be noted that in the three "positive-negative-positive" optical power lenses in the rear group 110, each optical power lens group can be split into lenses with smaller optical power. Specifically, the first positive optical power lens group can be split into two positive optical power lenses, the first negative optical power lens group can be split into three negative optical power lenses, and the second positive optical power lens group can be split into two positive optical power lenses. Thus, each lens after splitting only needs to handle a portion of the optical power, making refraction more "smooth," thereby reducing aperture aberrations, primarily spherical aberration, coma, and astigmatism. Here, aperture aberration refers to aberrations related to the incident aperture of light (i.e., the distance from the optical axis or the angle of incidence).

[0060] Overall, the rear element 110 of the Sham lens 100, which can be used for projection, can form a basic symmetrical optical power distribution similar to the Cook three-element "positive-negative-positive" distribution. This allows for effective reduction of transverse aberrations through the symmetrical distribution on the "positive-negative-positive" optical power architecture. Furthermore, the undulating shape of the beam within the "positive-negative-positive" optical power architecture is beneficial for field curvature correction.

[0061] As an example, see reference Figure 3 As shown, the negative power lens group in the front group 120 can contain one negative power lens, and the positive power lens group can contain one positive power lens. Specifically, the front group 120 may include an eighth negative power lens and a ninth positive power lens arranged sequentially from the object side to the image side along the optical path. Thus, the eighth negative power lens and the ninth positive power lens together form a pair of aberration correction units, thereby achieving overall aberration balance through the cancellation of positive and negative aberrations, especially in the correction of distortion, achieving high brightness and good image quality.

[0062] This application provides a Sham lens for projection, comprising a rear group and a front group arranged sequentially along the optical path. The rear group forms a basically symmetrical structure with a "positive-negative-positive" optical power group layout. This symmetry of the optical power structure can reduce transverse aberration, and the lens splitting allows for smooth light transition, reducing higher-order aberrations. Simultaneously, the front group consists of a pair of closely spaced positive and negative optical power lens groups, which can achieve distortion correction. Therefore, the Sham lens for projection in this embodiment has a small aperture number (F-number, F#), high brightness, and excellent image quality, exhibiting superior performance.

[0063] In some embodiments, reference Figure 2 As shown, the rear group 110 of the Sham lens 100 for projection provided in this application embodiment may include: a first spherical positive power lens 111, a second spherical positive power lens 112, a third spherical negative power lens 113, a fourth spherical negative power lens 114, a fifth spherical negative power lens 115, a sixth spherical positive power lens 116, and a seventh spherical positive power lens 118 arranged sequentially from the object side to the image side along the optical path direction. Among them, the first spherical positive power lens 111 and the second spherical positive power lens 112 constitute the "positive" group in the "positive-negative-positive" lens module; the third spherical negative power lens 113, the fourth spherical negative power lens 114 and the fifth spherical negative power lens 115 constitute the "negative" group in the "positive-negative-positive" lens module; and the sixth spherical positive power lens 116 and the seventh spherical positive power lens 118 constitute the "positive" group in the "positive-negative-positive" lens module.

[0064] refer to Figure 3As shown, the front group 120 of the Sham lens 100 for projection provided in this application embodiment may include: an eighth spherical negative power lens 121 and a ninth spherical positive power lens 122 arranged sequentially from the object side to the image side along the optical path direction. Thus, the eighth spherical negative power lens 121 and the ninth spherical positive power lens 122 together form a pair of aberration correction units, thereby achieving overall aberration balance through the cancellation of positive and negative aberrations, especially for distortion correction, achieving high brightness and good image quality.

[0065] A spherical lens refers to a lens whose surface shape is spherical, and its surface curvature determines the refraction path of light. Spherical lenses control the convergence or divergence of light rays through their radius of curvature and optical power (positive or negative). For example, a spherical lens with positive optical power can be used to converge light rays and compensate for the diverging effect of a spherical lens with negative optical power, while a spherical lens with negative optical power can be used to diverge light rays, adjust the optical path length, and correct aberrations.

[0066] Please refer to this again. Figure 2 As shown, in the Sham lens 100 for projection provided in this application embodiment, the rear group 110 may further include: an aperture stop 117, a sixth spherical positive power lens 116 and a seventh spherical positive power lens 118 respectively disposed on the left and right sides of the aperture stop 117, so that the relative aperture can be increased by its positive power, the light receiving angle can be increased, and the brightness can be further improved.

[0067] The following provides identification of the optical elements or specific locations of the SAM lens 100 that can be used for projection, including surface, type, radius of curvature, thickness, and glass type, thus providing a specific SAM lens 100 that can be used for projection. The display chip (e.g., DMD) of this SAM lens 100 that can be used for projection is 0.47 inches, and the throw ratio (TR) is approximately 2.5.

[0068] The actual settings of the Sham lens 100 that can be used for projection are shown in Table 1 below.

[0069] It should be noted that the object plane in Table 1 refers to the plane on which the object being photographed or projected is located, i.e., the target plane (external scene) in the actual scene, such as the surface of a circuit board.

[0070] A tilted surface refers to a tilted refractive surface in a Sham lens 100 that can be used for projection, or an artificially tilted object and / or image plane. Tilted surfaces are often used to adjust the depth-of-field plane to match the object or image plane.

[0071] Both the lens and the aperture are spherical, and their surface curvature determines the path of light refraction.

[0072] Thickness refers to the thickness of a single optical element or the thickness of the air, measured in mm.

[0073] The blank space in the glass model number represents air.

[0074] S2-S16 and S18-S23 represent the specific optical surface numbers in the SAM lens 100 that can be used for projection, and are numbered according to the optical path direction (from O to X). Among them, each optical surface facing O is the left surface, and each optical surface facing X is the right surface.

[0075] The image plane refers to the plane on which light rays are focused and formed after passing through a lens and an aperture.

[0076] Table 1

[0077]

[0078]

[0079] Figure 4 This is a schematic diagram of the light path of a Sham lens 100 that can be used for projection and has the settings in Table 1.

[0080] Figure 5 This is a schematic diagram of an actual scene with a Sham lens 100 that can be used for projection, as set in Table 1.

[0081] It should be noted that, Figure 4 and Figure 5 The different colors in the image represent different beams of light in the field of view.

[0082] This application provides a Sham lens for projection. The rear group of the Sham lens, along the optical path, sequentially comprises a first spherical positive power lens, a second spherical positive power lens, a third spherical negative power lens, a fourth spherical negative power lens, a fifth spherical negative power lens, a sixth spherical positive power lens, an aperture stop, and a seventh spherical positive power lens. The front group of the Sham lens, along the optical path, sequentially comprises an eighth spherical negative power lens and a ninth spherical positive power lens. The rear group consists of two positive power lenses, three negative power lenses, and two positive power lenses arranged consecutively. The symmetrical optical power distribution of the rear group ("positive-negative-positive") is beneficial for correcting transverse aberrations. The lens splitting method allows the light deflection angle to be distributed more evenly on each lens surface, resulting in a smooth transition of light, reduced higher-order aberrations, and improved image quality. Meanwhile, since the eighth spherical negative optical power lens and the ninth spherical positive optical power lens in the front group form a pair of aberration correction units, and higher-order aberrations can be generated using the narrow air gap between them, the distortion and asymmetric aberrations can be effectively corrected. This enables the SAM lens used for projection to achieve the goals of small F#, high brightness, and good image quality.

[0083] In some embodiments, reference Figure 3 As shown, in the Sham lens 100 for projection provided in this application embodiment, an eighth spherical negative power lens 121 and a ninth spherical positive power lens 122 arranged sequentially from the object side to the image side along the optical path direction in the front group 120 are arranged in a close contact form with their edges in contact.

[0084] This application provides a Sham lens that can be used for projection. In this Sham lens, an eighth spherical negative power lens and a ninth spherical positive power lens are closely connected at the edges to form a front group, which can form a pair of aberration correction units. The narrow air gap between the two lenses generates higher-order aberrations, effectively correcting distortion and asymmetric aberrations, so that the Sham lens has the effects of small F#, high brightness and good imaging.

[0085] In some embodiments, reference Figures 1 to 5 As shown, in the Sham lens 100 for projection provided in this application embodiment, the fifth spherical negative power lens 115 and the sixth spherical positive power lens 116 are cemented together at the junction.

[0086] On the one hand, the optical power of the cemented lens is relatively weak and cannot withstand large light refraction, so it can only be placed in the region where the beam transitions smoothly, and the vicinity of aperture stop 117 is more suitable. On the other hand, the vicinity of aperture stop 117 is the position where the overlap of all beams in the field of view is the highest, so the correction of chromatic aberration can cover the entire field of view more evenly, thus making the correction of chromatic aberration more effective. Therefore, in this embodiment, the fifth spherical negative power lens 115 and the sixth spherical positive power lens 116 are cemented at the junction.

[0087] The aforementioned fifth spherical negative power lens 115 and sixth spherical positive power lens 116 can be cemented together using an adhesive (i.e., the two are in contact). The cementation of the fifth spherical negative power lens 115 and the sixth spherical positive power lens 116 is an optical cementation, which can eliminate reflection loss at the lens interface, simplify the optical path structure, and assist in correcting aberrations, such as chromatic aberration.

[0088] In practical applications, adhesives can be selected from epoxy resin, acrylic resin (UV curing adhesive), silicone resin, etc.

[0089] Specifically, the selection of adhesive materials and processes needs to meet performance requirements such as optical properties, temperature resistance, humidity resistance, low shrinkage, and long-term stability. For example, the refractive index of the adhesive should be as close as possible to the materials of the two lenses being bonded to reduce interface reflection and the risk of stray light and light transmission loss; and / or, the adhesive should have high transparency, for example, a light transmittance greater than or equal to 99%, and be free of bubbles, impurities, and color shift to reduce the risk of light absorption or scattering. Of course, other properties are also possible, which will not be discussed in detail here.

[0090] In the Sham lens for projection provided in this application embodiment, a cemented lens is formed by combining a fifth spherical negative power lens and a sixth spherical positive power lens, that is, the fifth spherical negative power lens and the sixth spherical positive power lens are in contact. In this way, chromatic aberration can be corrected by cementing lenses with different refractive indices, thereby further improving the image quality.

[0091] In some embodiments, reference Figures 1 to 5 As shown, in the Sham lens 100 for projection provided in this application embodiment, the positive power lenses (first spherical positive power lens 111, second spherical positive power lens 112, sixth spherical positive power lens 116, and seventh spherical positive power lens 118) in the rear group 110 can be made of crown glass, wherein the Abbe number Vd1 of the crown glass is greater than or equal to 50.

[0092] The negative power lenses (third spherical negative power lens 113, fourth spherical negative power lens 114, and fifth spherical negative power lens 115) in the rear group 110 can be made of flint glass, wherein the Abbe number Vd2 of the flint glass is less than or equal to 50.

[0093] In practical applications, the refractive index n1 of crown glass can be 1.5 to 1.6, which makes the positive power lens less able to deflect light, reducing the separation of red, green and blue light when they converge and avoiding "color trailing".

[0094] The refractive index n2 of flint glass can be 1.6 to 1.9, which makes the negative power lens have strong deflection ability and can "reverse cancel" the residual dispersion of the positive lens. That is, by designing the ratio of the optical power of the positive and negative lenses, light of different wavelengths can be focused on the same image plane (achromatic).

[0095] Considering that the Schahm lens used for projection in this embodiment needs to be used in the visible light band, effective chromatic aberration correction is required to obtain good image quality. Therefore, in the Schahm lens for projection provided in this application embodiment, chromatic aberration is corrected in a distributed manner throughout the lens. The materials of the positive power lens and the negative power lens are designed to be different at different positions. In this way, even without using cemented lenses, different areas can have a certain chromatic aberration compensation capability while adjusting the optical path (to meet the tilt imaging requirements of Schahm's law), thus achieving a good balance in aberration correction.

[0096] In some embodiments, reference Figures 1 to 5 As shown, in the SAM lens 100 for projection provided in this application embodiment, the focal length of the SAM lens 100 for projection is 25mm to 30mm.

[0097] Based on the above, in this embodiment, the focal length of the rear group 110 of the SAM lens 100 that can be used for projection is 25.47mm to 31.13mm; and / or, the focal length of the front group 120 of the SAM lens 100 that can be used for projection is 34.76mm to 42.49mm; and / or, the focal length of the first spherical positive power lens 111 is 19.43mm to 23.74mm; and / or, the focal length of the second spherical positive power lens 112 is 22.44mm to 27.43mm; and / or, the focal length of the third spherical negative power lens 113 is -72.94mm to -59.68mm; and / or Alternatively, the focal length of the fourth spherical negative power lens 114 is -14.76 to -12.08 mm; and / or, the focal length of the cemented lens formed by combining the fifth spherical negative power lens 115 and the sixth spherical positive power lens 116 is 106.08 mm to 129.66 mm; and / or, the focal length of the seventh spherical positive power lens 118 is 28.28 mm to 34.57 mm; and / or, the focal length of the eighth spherical negative power lens 121 is -23.99 to -19.63 mm; and / or, the focal length of the ninth spherical positive power lens 122 is 24.05 mm to 29.40 mm.

[0098] Specifically, the focal length of the SAM lens 100 that can be used for projection can be 25mm, 26mm, 27mm, 28mm, 29mm or 30mm, etc.

[0099] The focal length of the rear 110 element can be 25.47mm, 26mm, 27mm, 28mm, 29mm, 30mm, or 31.13mm, etc.

[0100] The focal length of the front 120 group can be 34.76mm, 35mm, 36mm, 37mm, 38mm, 39mm, 40mm, 41mm or 42.49mm, etc.

[0101] The focal length of the first spherical positive power lens 111 can be 19.43mm, 20mm, 21mm, 22mm, 23mm or 23.74mm, etc.

[0102] The focal length of the second spherical positive power lens 112 can be 22.44mm, 23mm, 24mm, 25mm, 26mm or 27.43mm, etc.

[0103] The focal length of the third spherical negative power lens 113 can be -72.94mm, -70mm, -67mm, -64mm, -60mm or -59.68mm, etc.

[0104] The focal length of the fourth spherical negative power lens 114 can be -14.76mm, -14mm, -13.5mm, -13mm, -12.5mm or -12.08mm, etc.

[0105] The focal length of the cemented lens formed by combining the fifth spherical negative power lens 115 and the sixth spherical positive power lens 116 can be 106.08mm, 110mm, 115mm, 120mm, 125mm or 129.66mm, etc.

[0106] The focal length of the seventh spherical positive power lens 118 can be 28.28mm, 29mm, 30mm, 31mm, 32mm, 33mm or 34.57mm, etc.

[0107] The focal length of the eighth spherical negative power lens 121 can be -23.99mm, -23mm, -22mm, -21mm, -20mm or -19.63mm, etc.

[0108] The focal length of the ninth spherical positive power lens 122 can be 24.05mm, 25mm, 26mm, 27mm, 28mm or 29.40mm, etc.

[0109] The Sham lens for projection provided in this application embodiment achieves effects such as small F#, high brightness, and good imaging by setting the focal lengths of the Sham lens itself and the rear group, front group, first spherical positive power lens, second spherical positive power lens, third spherical negative power lens, fourth spherical negative power lens, fifth spherical negative power lens, and sixth spherical positive power lens combined with the cemented lens, seventh spherical positive power lens, eighth spherical negative power lens, and ninth spherical positive power lens in the Sham lens.

[0110] In some embodiments, reference Figures 1 to 5As shown, in the SAM lens 100 for projection provided in this application embodiment, the SAM lens 100 is used to operate in the visible light band of 420nm to 680nm; and / or, the F# of the SAM lens 100 for projection is 2.4 to 2.6; and / or, the working distance of the SAM lens 100 for projection is 150mm to 250mm; and / or, the tilt angle of the projection surface of the SAM lens 100 for projection is 20° to 30°.

[0111] It should be noted that the working distance mentioned above refers to the distance between the lens vertex at the outermost end of the lens and the projection imaging surface.

[0112] Specifically, the F# of the SAM lens 100 that can be used for projection can be 2.4, 2.5, or 2.6, etc.; the working distance of the SAM lens 100 that can be used for projection can be 150mm, 180mm, 200mm, 220mm, or 250mm, etc.; and the tilt angle of the projection surface of the SAM lens 100 that can be used for projection can be 20°, 22°, 24°, 26°, 28°, or 30°, etc.

[0113] The SAM lens for projection provided in this application embodiment achieves effects such as small F#, high brightness, and good imaging by setting the working band, working distance, F#, and tilt angle of the projection surface of the SAM lens.

[0114] Figure 6 The diagram shows the Modulation Transfer Function (MTF) at the screen. It should be noted that the MTF is an important indicator for evaluating the ability of an optical system to transmit signals of different spatial frequencies. It represents the overall resolving power of the optical system and reflects its ability to reproduce object details; the closer the value is to 1, the better the transmission effect.

[0115] The aforementioned "screen" refers to the receiving / display interface corresponding to the image plane of the SAM lens used for projection, that is, the physical carrier on which the target plane (image plane) of the lens is located. Specifically, in the case of using a SAM lens for projection, the screen here is the projection screen on which the image is projected. Screen 1 in the embodiments of this application is as follows... Figure 5 As shown.

[0116] Figure 6The horizontal axis represents spatial frequency in cycles per millimeter (mm), and the vertical axis represents the optical transfer function (OTF) modulus (i.e., the MTF value). The OTF modulus is used to evaluate the imaging quality of the SAM lens 100 suitable for projection, and its value ranges from 0 to 1. A higher and straighter MTF curve indicates better imaging quality of the SAM lens 100 suitable for projection, stronger ability to reproduce realistic images, better overlap of curves across different fields of view, and better consistency of image quality. Figure 6 In the mean square, the MTF observation line pair is 12.2 lp / mm.

[0117] from Figure 6 It can be clearly seen that in the visible light band (typically in the range of 380nm to 760nm), with a spatial frequency of 12.2 lp / mm, the MTF across the entire field of view is above 0.45, which meets the requirements of practical applications. At this projection distance, 93 lp / mm at the display chip is equivalent to 12.2 lp / mm at the projection surface.

[0118] Example 2

[0119] This application provides a projection device, which may include at least one Sham lens as described in Embodiment 1, arranged sequentially from the object side to the image side along the optical path direction and suitable for projection.

[0120] In practical applications, the projection device in this embodiment can specifically be a projection lens device for machine vision.

[0121] Furthermore, the projection device in this embodiment may also include: a display chip, a display chip protective glass, and an equivalent prism, wherein the display chip and the display chip protective glass are placed at an angle relative to the optical axis; the display chip, the display chip protective glass, the equivalent prism, and the Sham lens that can be used for projection are arranged sequentially from the object side to the image side along the optical path direction.

[0122] It should be noted that the aforementioned optical axis refers to the main optical axis of the entire projection device, specifically the optical axis along which the optical paths of the Sham lenses used for projection are collinear.

[0123] In practical applications, the display chip can be a DMD, etc., depending on the actual needs.

[0124] In the projection device provided in this application embodiment, the rear group of the Sham lens, which can be used for projection, forms a basically symmetrical structure with a "positive-negative-positive" optical power layout. At the same time, the front group consists of a pair of closely spaced positive and negative optical power lenses. In this way, the rear group of the Sham lens can reduce transverse aberration by utilizing the symmetry of the optical power structure, and the lens splitting makes the light transition smooth and reduces higher-order aberrations. Meanwhile, the front group obtains distortion correction through the combination of positive and negative optical power lenses, so that the Sham lens has a small F# and excellent imaging quality, thereby realizing clear imaging of the projection device.

[0125] Example 3

[0126] This application provides a projection system, which may include the projection device and camera described in Embodiment 2. The camera can be any of a monocular camera, a binocular camera, or a 3D camera.

[0127] In practical applications, the projection system in this embodiment can specifically be a projection lens system for machine vision.

[0128] In the projection system provided in this application embodiment, clear imaging can be achieved through the cooperation of the projection device and the camera, and the projection system has good performance.

[0129] This section only introduces the content related to the invention point; other information can be obtained by referring to relevant technologies, and will not be explained in detail here.

[0130] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A Sham lens for projection, characterized in that, include: The rear group and the front group are arranged sequentially from the object side to the image side along the optical path direction. The rear group and the front group are separate and spaced apart. The rear group includes a lens module with a power structure of positive power-negative power-positive power. In the positive power-negative power-positive power lens module, a first positive power lens group, a first negative power lens group, and a second positive power lens group are arranged sequentially from the object side to the image side along the optical path direction. The first positive power lens group includes at least one positive power lens, the first negative power lens group includes at least one negative power lens, and the second positive power lens group includes at least one positive power lens. The front group includes a negative power lens and a positive power lens arranged sequentially from the object side to the image side along the optical path direction.

2. The Sham lens for projection according to claim 1, characterized in that, The rear group includes a first spherical positive power lens, a second spherical positive power lens, a third spherical negative power lens, a fourth spherical negative power lens, a fifth spherical negative power lens, a sixth spherical positive power lens, an aperture stop, and a seventh spherical positive power lens, arranged sequentially from the object side to the image side along the optical path direction. And / or, The front group includes an eighth spherical negative power lens and a ninth spherical positive power lens arranged sequentially from the object side to the image side along the optical path direction.

3. The Sham lens for projection according to claim 2, characterized in that, The fifth spherical negative power lens and the sixth spherical positive power lens are combined to form a cemented lens.

4. The Sham lens for projection according to claim 3, characterized in that, The eighth spherical negative power lens and the ninth spherical positive power lens are in close contact at the edges to form the front group.

5. A Sham lens for projection according to any one of claims 1 to 4, characterized in that, The positive power lens in the rear group is made of crown glass, the Abbe number of the crown glass is greater than or equal to 50, and / or the refractive index of the crown glass is 1.5 to 1.

6. The negative power lens in the rear group is made of flint glass, the Abbe number of which is less than or equal to 50, and / or the refractive index of which is 1.6 to 1.

9.

6. A Sham lens for projection according to any one of claims 1 to 4, characterized in that, The focal length of the Sham lens that can be used for projection is 25mm to 30mm; And / or, the focal length of the rear group is 25.47mm to 31.13mm; And / or, the focal length of the front group is 34.76mm to 42.49mm; And / or, the focal length of the first spherical positive power lens is 19.43 mm to 23.74 mm; And / or, the focal length of the second spherical positive power lens is 22.44 mm to 27.43 mm; And / or, the focal length of the third spherical negative power lens is -72.94 to -59.68 mm; And / or, the focal length of the fourth spherical negative power lens is -14.76 to -12.08 mm; And / or, the focal length of the cemented lens formed by combining the fifth spherical negative power lens and the sixth spherical positive power lens is 106.08 mm to 129.66 mm; And / or, the focal length of the seventh spherical positive power lens is 28.28 mm to 34.57 mm; And / or, the focal length of the eighth spherical negative power lens is -23.99mm to -19.63mm; And / or, the focal length of the ninth spherical positive power lens is 24.05 mm to 29.40 mm.

7. A Sham lens for projection according to any one of claims 1 to 4, characterized in that, The Sham lens, which can be used for projection, is designed to operate in the visible light band of 420nm to 680nm. And / or, the aperture number of the Sham lens that can be used for projection is 2.4 to 2.6; And / or, the working distance of the SAM lens that can be used for projection is 150mm to 250mm; And / or, the tilt angle of the projection surface of the Sham lens that can be used for projection is 20° to 30°.

8. A projection device, characterized in that, Includes a Sham lens that can be used for projection as described in any one of claims 1 to 7.

9. The projection device according to claim 8, characterized in that, The projection device further includes: a display chip, a display chip protective glass, and an equivalent prism. The display chip, the display chip protective glass, the equivalent prism, and the Sham lens that can be used for projection are arranged sequentially from the object side to the image side along the optical path direction. The display chip and the protective glass for the display chip are placed at an angle relative to the optical axis of the Sham lens that can be used for projection.

10. A projection system, characterized in that, Includes the projection device as described in claim 8 or 9.

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