Projection lens and projection equipment

Abstract

The embodiment of the invention provides a projection lens and projection equipment. Wherein the projection lens sequentially comprises a first lens group, a diaphragm and a second lens group from an imaging side to an image source side along an optical axis; the first lens group is composed of a first lens, a second lens and a third lens, the first lens is a plastic aspherical lens, and the second lens and the third lens are glass spherical lenses; the second lens group is composed of a fourth lens, a fifth lens and a sixth lens, the fourth lens and the fifth lens are glass spherical lenses, and the sixth lens is a glass aspheric lens; the diaphragm is positioned between the third lens and the fourth lens; the projection lens satisfies the following conditions: 2 < T / D < 3.5; wherein T is the total optical length of the projection lens, and D is the maximum effective clear aperture in the first lens group.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of projection display technology, and more specifically, to a projection lens and a projection device. Background Art

[0002] With the rapid development of the projector market, laser projectors have gradually gained favor among consumers due to their advantages such as bright colors, high color gamut, and compact size. However, laser projectors also have some technical difficulties, the most prominent of which is the color difference problem. Although the three-color laser light source brings rich color performance, it also brings large color difference, which has a negative impact on the user experience of laser projectors. As the core component of laser projectors, the projection lens is currently difficult to design, and the design indicators will directly determine the subjective performance of the laser projector's picture, such as clarity, contrast, and picture uniformity. Summary of the invention

[0003] The purpose of this application is to provide a new technical solution for a projection lens and a projection device.

[0004] In a first aspect, the present application provides a projection lens. The projection lens includes a first lens group, an aperture, and a second lens group in sequence from the imaging side to the image source side along the optical axis;

[0005] The first lens group is composed of a first lens, a second lens and a third lens, the first lens is a plastic aspherical lens, and the second lens and the third lens are glass spherical lenses;

[0006] The second lens group is composed of a fourth lens, a fifth lens and a sixth lens, the fourth lens and the fifth lens are glass spherical lenses, and the sixth lens is a glass aspherical lens;

[0007] The aperture is located between the third lens and the fourth lens;

[0008] The projection lens satisfies: 2<T / D<3.5; wherein T is the total optical length of the projection lens, and D is the largest effective light aperture in the first lens group.

[0009] Optionally, the effective aperture of the first lens is D, and the projection lens satisfies: 2<T / D<3.5.

[0010] Optionally, the optical power of the first lens is negative, the optical power of the second lens is negative, and the optical power of the third lens is positive;

[0011] The optical power of the fourth lens is positive, the optical power of the fifth lens is negative, and the optical power of the sixth lens is positive.

[0012] Optionally, the first lens is a convex-concave lens, the second lens is a biconcave lens, and the third lens is a biconvex lens;

[0013] The fourth lens and the fifth lens are meniscus lenses, and the sixth lens is a biconvex lens.

[0014] Optionally, the first lens group and / or the second lens group can be moved along the optical axis.

[0015] Optionally, the second lens and the third lens are bonded together to form a first double bonded lens group;

[0016] The fourth lens and the fifth lens are bonded together to form a second double bonded lens group.

[0017] Optionally, the refractive index of the second lens is Nd 2 , the refractive index of the third lens is Nd 3 , and Nd 2 <Nd 3 ;

[0018] The Abbe number of the second lens is Vd 2 , the Abbe number of the third lens is Vd 3 , and Vd 2 >Vd 3 .

[0019] Optionally, the refractive index of the fourth lens is Nd 4 , the refractive index of the fifth lens is Nd 5 , and Nd 4 <Nd 5 ;

[0020] The Abbe number of the fourth lens is Vd 4 , the Abbe number of the fifth lens is Vd 5 , and Vd 4 >Vd 5 .

[0021] Optionally, the first lens has a negative optical power and has at least one aspherical surface;

[0022] The sixth lens has positive refractive power and has at least one aspherical surface.

[0023] Optionally, the effective focal length of the first lens group is F1, the total effective focal length of the projection lens is F, and 1.5≤|F1 / F|≤1.85;

[0024] The effective focal length of the second lens group is F2, the total effective focal length of the projection lens is F, and 1.5≤|F2 / F|≤1.85.

[0025] Optionally, the projection lens further includes: a light source, a color combining prism and a galvanometer;

[0026] Wherein, the galvanometer and the sixth lens are arranged adjacent to each other, and the color combining prism is located between the light source and the galvanometer.

[0027] In a second aspect, the present application provides a projection device. The projection device comprises:

[0028] casing; and

[0029] The projection lens as described in the first aspect.

[0030] The beneficial effects of this application are:

[0031] The embodiment of the present application provides a projection lens capable of eliminating chromatic aberration, which can be applied to a projection device, especially a laser projection device. The projection lens includes a first lens group, an aperture and a second lens group in sequence from the imaging side to the image source side along the optical axis; wherein the first lens group is composed of a plastic aspherical lens (i.e., the first lens) and two glass spherical lenses (i.e., the second lens and the third lens); the second lens group is composed of a glass spherical lens (i.e., the fourth lens) and two glass aspherical lenses (i.e., the fifth lens and the sixth lens); the present application also constrains the total optical length of the projection lens to be equal to the maximum length of the lens in the first lens group. Large effective aperture; through the selected lens combination, the projection lens of the present application can achieve better aberration correction and improve imaging quality; the use of aspherical lenses is particularly helpful in reducing optical problems such as spherical aberration and distortion, thereby providing clearer images; the projection lens satisfies the ratio of 2<T / D<3.5, which means that while maintaining a large effective aperture D, the total optical length T of the projection lens is effectively controlled. This compact design makes the projection lens easier to integrate into various projection devices, and also helps to reduce the overall size and weight of the projection device.

[0032] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0034] Figure 1 A schematic diagram of the structure of a projection lens provided in an embodiment of the present application;

[0035] Figure 2 An optical path diagram of a projection lens provided in an embodiment of the present application;

[0036] Figure 3A dot array diagram of a projection lens provided in an embodiment of the present application;

[0037] Figure 4 A spatial frequency modulation transfer function diagram of a projection lens provided by an embodiment of the present application;

[0038] Figure 5 A defocus curve diagram of the projection lens provided in an embodiment of the present application;

[0039] Figure 6 A diagram showing the relationship between the modulation transfer function and the field of view of the projection lens provided in an embodiment of the present application;

[0040] Figure 7 Field curvature and distortion diagram of the projection lens provided in the embodiment of the present application;

[0041] Figure 8 A vertical axis chromatic aberration diagram of the projection lens provided in an embodiment of the present application;

[0042] Fig. 9 A relative illumination diagram of a projection lens provided in an embodiment of the present application;

[0043] Fig.10 This is a light aberration diagram of the projection lens provided in an embodiment of the present application.

[0044] Description of reference numerals:

[0045] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Aperture; 8. Galvanometer; 9. Color combining prism; 10. Light source; 11. Protective glass. DETAILED DESCRIPTION

[0046] 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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0047] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0048] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0049] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0050] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0051] The projection lens and the projection device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0052] According to an embodiment of the present application, a projection lens is provided. Figure 1 and Figure 2 The projection lens includes a first lens group, an aperture 7 and a second lens group in sequence from the imaging side to the image source side along the optical axis; wherein the first lens group is composed of a first lens 1, a second lens 2 and a third lens 3, the first lens 1 is a plastic aspherical lens, the second lens 2 and the third lens 3 are glass spherical lenses; the second lens group is composed of a fourth lens 4, a fifth lens 5 and a sixth lens 6, the fourth lens 4 is a glass spherical lens, and the sixth lens 6 is a glass aspherical lens; the aperture 7 is located between the third lens 3 and the fourth lens 4; the projection lens satisfies: 2<T / D<3.5; wherein T is the total optical length of the projection lens, and D is the largest effective aperture in the first lens group.

[0053] The projection lens provided in the embodiment of the present application may be a laser projection lens, which effectively overcomes the problem of large chromatic aberration in existing laser projection lenses.

[0054] It should be noted that the projection lens provided in the embodiments of the present application includes but is not limited to a laser projection lens, and may also be a projection lens of other light sources.

[0055] The projection lens provided in the embodiment of the present application is shown in FIG. Figure 1 The projection lens has two lens groups (i.e., a first lens group and a second lens group) arranged along the optical axis from the imaging side to the image source side, and the two lens groups are separated by an aperture 7.

[0056] Specifically, the first lens group is composed of three lenses, namely: a first lens 1 (plastic aspherical lens), a second lens 2 (glass spherical lens) and a third lens 3 (glass spherical lens). The first lens group is located at the front end of the entire projection lens. This lens combination design can provide a good initial aberration correction basis for the laser projection lens of the present application.

[0057] The second lens group is also composed of three lenses, namely: the fourth lens 4 (glass spherical lens), the fifth lens 5 (glass spherical lens) and the sixth lens 6 (glass aspherical lens). This group of lenses further refines the aberration correction, especially the chromatic aberration correction, so as to achieve high imaging quality.

[0058] The projection lens of the embodiment of the present application further includes a stop 7. Figure 1 The aperture 7 is located between the third lens 3 and the fourth lens 4, and plays a key role in controlling the light flux and optimizing the image quality.

[0059] The first lens 1 to the sixth lens 6 in the present application are described in detail below.

[0060] The first lens 1 is a plastic aspherical lens. The selection of plastic material takes into account lightweight and cost-effectiveness. The aspherical surface design enables it to more accurately control the direction of light, which helps to reduce aberrations, especially spherical aberration. The first lens 1 can effectively correct initial chromatic aberration.

[0061] The second lens 2 is a glass spherical lens, and the second lens 2 is disposed adjacent to the first lens 1. The second lens 2 cooperates with the first lens 1 to further correct aberrations. In addition, the use of glass material improves the light transmittance and thermal stability of the lens.

[0062] The third lens 3 is a glass spherical lens. As the lens closest to the aperture 7 in the first lens group, the third lens 3 can continue to optimize aberration correction, especially field curvature and distortion. In addition, similar to the second lens 2, the third lens 3 also corrects chromatic aberration by selecting a specific glass material, and works in conjunction with the first lens 1 and the second lens 2.

[0063] The fourth lens 4 is a glass spherical lens. As the first lens of the second lens group, it is also closest to the aperture 7. The fourth lens and subsequent lenses jointly undertake the task of further correcting aberrations. The fourth lens 4 corrects chromatic aberrations by selecting glass materials, and works in conjunction with other lenses in the entire lens group to achieve overall chromatic aberration correction.

[0064] The fifth lens 5 is a glass spherical lens, which cooperates with the fourth lens 4 to further optimize aberration correction, especially chromatic aberration and high-order aberration. The addition of the fifth lens 5 makes the entire second lens group more capable of correcting aberrations.

[0065] The sixth lens 6 is a glass aspherical lens. The aspherical design enables it to more accurately control the direction of light and reduce aberration and chromatic aberration. As a key chromatic aberration correction element, the sixth lens 6 effectively suppresses chromatic aberration to an extremely low level through the aspherical design and the selection of glass materials, ensuring high definition and color accuracy of imaging quality.

[0066] The projection lens provided in the embodiment of the present application satisfies the condition: 2<T / D<3.5; wherein T is the total optical length of the projection lens, and D is the largest effective light aperture in the first lens group.

[0067] T is the total optical length of the projection lens of the present application, which refers to the straight-line distance from the first optical surface to the last optical surface of the projection lens, and reflects the overall size and length of the entire projection lens.

[0068] For each lens, its effective aperture refers to the maximum diameter that allows light to pass through. This diameter determines the amount of light that the lens can collect, which in turn affects the image quality and brightness of the entire projection lens.

[0069] In the projection lens of the present application, the maximum effective aperture D in the first lens group refers to the maximum effective aperture in the first lens group, because the diameters of different lenses may be different. This maximum effective aperture determines the upper limit of the luminous flux of the first lens group and even the entire lens, and is one of the important factors affecting the performance of the entire projection lens. When designing the projection lens, the present application needs to ensure that the aperture is large enough to collect enough light, while also considering factors such as the overall size and weight of the projection lens.

[0070] The first lens group, as the first lens group close to the imaging side, plays a vital role in the aberration correction of the projection lens. The projection lens satisfies the ratio of 2<T / D<3.5, which means that while maintaining a large effective aperture D, the total optical length T of the entire projection lens is effectively controlled. This compact design makes the lens easier to integrate into various projection devices, and also helps to reduce the overall size and weight of the device.

[0071] The projection lens of the present application, the first lens 1 to the sixth lens 6, through careful design and material selection, together constitute a highly efficient, compact projection lens with excellent chromatic aberration correction.

[0072] The projection lens provided in the embodiment of the present application has a significant chromatic aberration correction capability. Specifically, by using a plastic aspheric lens (first lens 1) and a glass aspheric lens (sixth lens 6), combined with careful lens material selection (such as a resin material with strong light resistance and a glass with a low refractive index), the projection lens effectively suppresses the chromatic aberration problem commonly seen in laser projectors.

[0073] The embodiment of the present application provides a projection lens capable of achromatic aberration, which can be applied to projection equipment, especially laser projection equipment. The projection lens includes a carefully designed first lens group, an aperture and a second lens group in sequence from the imaging side to the image source side along the optical axis; wherein the first lens group is composed of a plastic aspherical lens (i.e., the first lens 1) and two glass spherical lenses (i.e., the second lens 2 and the third lens 3); the second lens group is composed of a glass spherical lens (i.e., the fourth lens 4) and two glass aspherical lenses (i.e., the fifth lens 5 and the sixth lens 6); and the present application also constrains the total optical length of the projection lens and the largest effective aperture in the first lens group. The present application uses a selected lens combination, and the projection lens can achieve better aberration correction and improve imaging quality. The use of aspherical lenses is particularly helpful in reducing optical problems such as spherical aberration and distortion, thereby providing clearer and more accurate images. The projection lens satisfies the ratio of 2<T / D<3.5, which means that while maintaining a large effective aperture D, the total optical length T of the projection lens is effectively controlled. This compact design makes the projection lens easier to integrate into various projection devices, and also helps to reduce the overall size and weight of the projection equipment.

[0074] In addition, some lenses in the projection lens are made of glass, which has good thermal and chemical stability and can maintain stable performance over a wide temperature range.

[0075] In some examples of the present application, the effective clear aperture of the first lens 1 is D, and the projection lens satisfies: 2<T / D<3.5.

[0076] See also Figure 1 , the first lens 1 is the lens with the largest aperture in the entire projection lens, that is, the lens with the largest aperture in the first lens group. The first lens 1 satisfies: 2<T / D<3.5, indicating that the projection lens has achieved a relatively compact design while maintaining a large aperture. This design not only ensures that enough light enters the projection lens, improves the brightness and clarity of the image, but also avoids the problem of bulky and inconvenient to carry caused by the projection lens being too long.

[0077] The first lens 1 is the front-end element of the projection lens, and its effective aperture D directly determines the amount of light that the projection lens can collect. A larger D value means that more light can enter the projection lens, which is crucial for improving the brightness and contrast of the projected image. At the same time, the compact T / D ratio ensures the efficient transmission and focusing of light inside the projection lens, reducing the loss and scattering of light. In addition, in this example of the present application, a reasonable T / D ratio can effectively correct aberrations, thereby improving the clarity and accuracy of the image.

[0078] In some examples of the present application, the optical focal power of the first lens 1 is negative, the optical focal power of the second lens 2 is negative, the optical focal power of the third lens 3 is positive, the optical focal power of the fourth lens 4 is positive, the optical focal power of the fifth lens 5 is negative, and the optical focal power of the sixth lens 6 is positive.

[0079] The projection lens provided in the embodiment of the present application has six lenses with optical focal lengths configured as negative, negative, positive, positive, negative, and positive from the imaging side to the image source side. This is a carefully designed optical system layout designed to achieve efficient optical performance, especially for the correction of chromatic aberration and aberration.

[0080] By specially configuring the optical focal length and selecting the lens material (glass or plastic), the projection lens of the present application can effectively correct chromatic aberration, especially suppress vertical axis chromatic aberration, and ensure high color accuracy of imaging.

[0081] That is to say, in the present application, the optical focal length configuration (negative, negative, positive, positive, negative, positive) of the first lens 1 to the sixth lens 6 is an efficient and compact optical system design, which can achieve excellent chromatic aberration and aberration correction effects, ensuring the high imaging quality of the laser projector.

[0082] In some examples of this application, see Figure 1 The first lens 1 is a convex-concave lens, the second lens 2 is a biconcave lens, and the third lens 3 is a biconvex lens; the fourth lens 4 and the fifth lens 5 are concave-convex lenses, and the sixth lens 6 is a biconvex lens.

[0083] In this example of the present application, the surface configurations of the first lens 1 to the sixth lens 6 are convex-concave, bi-concave, bi-convex, concave-convex, concave-convex, and bi-convex, respectively. This is an important part of the optical design of the projection lens of the present application and has a direct impact on the optical performance of the entire projection lens.

[0084] See also Figure 1 , the following description is made taking the first lens 1 in the first lens group as an example.

[0085] The surface of the first lens 1 away from the aperture 7 is the front surface, and the surface of the first lens 1 close to the aperture 7 is the rear surface. In conjunction with this example of the present application, the front surface of the first lens 1 is a convex surface, and the rear surface of the first lens 1 is a concave surface. Based on this, the front and rear surfaces of the second lens 2 are both concave surfaces. The front and rear surfaces of the third lens 3 are both convex surfaces.

[0086] Please continue to see Figure 1 , the fourth lens 4 in the second lens group is taken as an example for explanation.

[0087] The surface of the fourth lens 4 close to the aperture 7 is the front surface, and the surface away from the aperture 7 is the rear surface. In combination with this example of the present application, the front surface of the fourth lens 4 is concave, and the rear surface is convex. Based on this, the front surface of the fifth lens 5 is concave, and the rear surface is convex. The front and rear surfaces of the sixth lens 6 are both convex.

[0088] The first lens 1 of the present application is a convexo-concave lens. The convexo-concave lens has a surface shape with one side convex and the other side concave. This design can correct aberrations, including chromatic aberration, to a certain extent. The convexo-concave lens can refract light of different wavelengths to different degrees through its special optical surface shape, thereby reducing chromatic aberration to a certain extent.

[0089] The second lens 2 of the present application is a biconcave lens. The biconcave lens has a surface shape with both sides concave. In the lens combination proposed in the present application, the second lens 2 is designed as a biconcave lens, which can be used in conjunction with other lenses to change the propagation path and convergence mode of light, thereby affecting the performance of chromatic aberration. In other words, the biconcave lens introduced in the present application helps to balance the chromatic aberration of the entire projection lens.

[0090] The third lens 3 of the present application is a biconvex lens. The biconvex lens has a surface shape with convex surfaces on both sides, and is a converging lens. In the lens combination (a combination of six lenses) provided in the present application, the biconvex lens can be used in conjunction with other lenses to achieve overall chromatic aberration correction.

[0091] The fourth lens 4 and the fifth lens 5 of the present application are both concave-convex lenses. The surface shape of these two lenses is similar to that of the first lens 1, with one side convex and one side concave, and they also have a certain aberration correction capability. In the lens combination provided by the present application (i.e., the combination formed by six lenses), the coordinated use of multiple concave-convex lenses can significantly improve the effect of chromatic aberration suppression.

[0092] The sixth lens 6 of the present application is a biconvex lens. Like the third lens 3, the biconvex lens has a shape with convex sides and is a converging lens. Similarly, in the lens combination (a combination of six lenses) provided in the present application, the last biconvex lens can work together with other lenses to achieve overall chromatic aberration correction.

[0093] In this example of the present application, multiple types of lenses are used, including convex-concave lenses, bi-concave lenses, bi-convex lenses, and concave-convex lenses. This diverse design can provide more freedom to correct chromatic aberration and other aberrations.

[0094] Through precise design and calculation, the six lenses in this application can cooperate with each other to achieve effective suppression of chromatic aberration. For example, the convex-concave lens and the concave-convex lens can be used to initially correct chromatic aberration, while the biconcave lens may help balance the chromatic aberration of the entire lens combination. Finally, the biconvex lens can work together with other lenses to achieve overall chromatic aberration correction.

[0095] In summary, the lens combination in this example of the present application has certain advantages in terms of chromatic aberration suppression. Through precise design and calculation, these lenses can cooperate with each other to achieve effective correction of chromatic aberration, thereby improving the imaging quality of the projection lens.

[0096] In some examples of the present application, the first mirror group and / or the second mirror group is movable along the optical axis.

[0097] That is to say, in the projection lens provided in the embodiment of the present application, the first lens group and the second lens group are designed to be movable. Specifically, at least one of the first lens group and the second lens group can move along the optical axis.

[0098] When one of the first lens group and the second lens group moves relative to the other along the optical axis, the distance between the two lens groups can be changed.

[0099] When the first lens group and the second lens group move simultaneously, the distance between the two lens groups and the rear color combining prism can be changed.

[0100] By moving the first lens group and / or the second lens group along the optical axis, the focal length of the projection lens can be changed, thereby realizing a zoom function. In other words, by changing the relative position between the two lens groups, the focal length of the projection lens can be adjusted, thereby changing the size of the projected image. This design allows the projection lens to focus within a certain focal length range to adapt to different projection distances and screen sizes.

[0101] Changes in focal length will directly affect the size of the projected image.

[0102] For example, as the focal length increases, the projected image shrinks.

[0103] For another example, the focal length becomes shorter and the projected image becomes larger.

[0104] In the present application, the movement of the mirror group can be manually controlled or electrically controlled.

[0105] By designing that the lens group moves along the optical axis, the projection lens can be more flexibly adapted to different application scenarios and requirements. For example, in situations where the projection size and focal length need to be adjusted, this design can greatly improve the practicality of the projection lens.

[0106] In an example of the present application, when the first lens group and the second lens group move together, the movement range is -0.011 mm to 0.013 mm, and the corresponding projection size change is 40 inches to 100 inches. It should be noted that the first lens group and the second lens group can move together in a direction close to the color combining prism 9, or can move in a direction away from the color combining prism 9.

[0107] In some examples of this application, see Figure 1 In the first lens group, the second lens 2 and the third lens 3 are glued together to form a first double-glue lens group; in the second lens group, the fourth lens 4 and the fifth lens 5 are glued together to form a second double-glue lens group.

[0108] In the projection lens provided in the present application, a first double-cemented lens group and a second double-cemented lens group are respectively arranged on both sides of the aperture 7, and this design can optimize vertical axis chromatic aberration. In other words, both sides of the aperture 7 are cemented lens groups.

[0109] The double-cemented lens group design helps achieve more consistent color performance across the entire projected image. The double-cemented lens group design also helps reduce aberrations and improves the imaging quality of the projection lens.

[0110] The design of the double-cemented lens group can also optimize the space utilization inside the projection lens. By gluing the two lenses tightly together, the space inside the projection lens can be used more effectively, making the projection lens more compact and miniaturized. In addition, the design of the double-cemented lens group can simplify the assembly process of the projection lens.

[0111] The design of the double-cemented lens group can improve the stability of the entire projection lens. Because the lenses are tightly combined, they are not easily affected and disturbed by the external environment. This helps to ensure that the lens maintains stable imaging quality and performance under different working conditions.

[0112] In this example of the present application, the first double cemented lens group and the second double cemented lens group are respectively located on both sides of the aperture 7, which helps to correct chromatic aberration more evenly in the entire field of view.

[0113] In some examples of the present application, the refractive index of the second lens 2 is Nd 2 The refractive index of the third lens 3 is Nd 3 , and Nd 2 <Nd 3 ; The Abbe number of the second lens 2 is Vd 2 , the Abbe number of the third lens 3 is Vd 3 , and Vd 2 >Vd 3 .

[0114] In some examples of the present application, the refractive index of the fourth lens 4 is Nd 4 The refractive index of the fifth lens 5 is Nd 5 , and Nd 4 <Nd 5 The Abbe number of the fourth lens 4 is Vd 4 , the Abbe number of the fifth lens 5 is Vd 5 , and Vd 4 >Vd 5 .

[0115] The projection lens provided in the embodiment of the present application has a double-cemented lens group on each side of the aperture 7, namely the first double-cemented lens group and the second double-cemented lens group in the above example. The design of this double-cemented lens group is very effective in chromatic aberration correction. By selecting suitable lens materials, especially a lens combination with a high Abbe number (low dispersion) and a low refractive index (high dispersion), vertical axis chromatic aberration can be significantly reduced.

[0116] In the example of the present application, the first double-cemented lens group and the second double-cemented lens group are respectively composed of lenses with different refractive indices and Abbe numbers, which can accurately correct the chromatic aberration caused by light of different wavelengths and improve the color reproduction and clarity of the projected image.

[0117] Specifically, the first double-cemented lens group is composed of the second lens 2 and the third lens 3 cemented together. The refractive index relationship involved in the first double-cemented lens group is: the refractive index Nd of the second lens 2 is 2 is smaller than the refractive index Nd of the third lens 3 3 , the Abbe number relationship is: the Abbe number Vd of the second lens 2 2 Greater than the Abbe number Vd of the third lens 3 3 This combination of refractive index and Abbe number helps correct chromatic aberration. Since the third lens 3 has a higher refractive index, it can bend light over a shorter path, while the second lens 2 has a lower refractive index and a higher Abbe number (i.e., lower dispersion), which can compensate for the dispersion introduced by the third lens 3 to a certain extent. This combination helps reduce chromatic aberration caused by the different speeds of light of different wavelengths passing through the lens, thereby improving the color reproduction and clarity of the projected image.

[0118] The present application can also optimize other aberrations such as spherical aberration and coma by carefully designing the refractive index and Abbe number of the second lens 2 and the third lens 3, thereby improving the imaging quality of the projection picture.

[0119] Specifically, the second double-cemented lens group is composed of the fourth lens 4 and the fifth lens 5 cemented together. The refractive index relationship involved is: the refractive index Nd of the fourth lens 4 is 4 is smaller than the refractive index Nd of the fifth lens 5 5 ; The Abbe number relationship is: the Abbe number Vd of the fourth lens 4 4 Greater than the Abbe number Vd of the fifth lens 5 5 .

[0120] Similar to the combination of the second lens 2 and the third lens 3, the combination of the fourth lens 4 and the fifth lens 5 is also intended to correct chromatic aberration. The fifth lens has a higher refractive index for efficiently bending light, while the fourth lens has a lower refractive index and a higher Abbe number for compensating for dispersion. This combination helps achieve more comprehensive chromatic aberration correction in the entire projection lens.

[0121] In addition, by optimizing the refractive index and Abbe number of the second lens 2 to the fifth lens 5, other optical properties of the projection lens, such as contrast, resolution, and distortion control, can also be improved. The improvement of these properties works together to make the projected image clearer, more delicate, and more realistic.

[0122] In the present application, by selecting lens materials with different refractive indices and Abbe numbers for bonding, the image quality degradation caused by monochromatic aberration and chromatic aberration can be effectively compensated.

[0123] In some examples of the present application, the first lens 1 has at least one aspherical surface; the sixth lens 6 has at least one aspherical surface.

[0124] Since the first lens 1 and the sixth lens 6 are respectively located at two ends of the entire lens combination, their aspherical surfaces can effectively compensate for the chromatic aberration caused by the lens material, thereby improving the color reproduction capability of the projection lens.

[0125] The design of the aspherical surface enables the projection lens of the present application to better correct various aberrations, including spherical aberration, coma, astigmatism, etc., thereby improving the clarity and contrast of the image.

[0126] By designing the optical power and aspherical surface of the first lens 1 and the sixth lens 6, the imaging performance of the entire projection lens can be optimized to achieve a high-definition, high-contrast projection image.

[0127] In addition, the use of aspherical lenses can reduce the number of lenses required, thereby simplifying the projection lens structure, which helps to reduce the size of the lens and reduce manufacturing costs.

[0128] In this example of the present application, the aspheric surface design of the first lens 1 and the sixth lens 6 and their optical power configuration are one of the key factors to achieve high imaging quality. By designing these parameters, the projection lens can effectively correct chromatic aberration and aberration, and improve the clarity and contrast of the image. At the same time, this design also helps to reduce the volume of the projection lens and reduce the manufacturing cost.

[0129] In this application, the aspheric surfaces are all even-order aspheric surfaces, and the surface height is given by the following formula:

[0130]

[0131] z is the surface height, c is the inverse of the radius of curvature, k is the cone coefficient, a 1 ~a 8 is the even aspheric coefficient.

[0132] In some examples of the present application, the effective focal length of the first lens group is F1, and the total effective focal length of the projection lens is F, 1.5≤|F1 / F|≤1.85; the effective focal length of the second lens group is F2, and the total effective focal length of the projection lens is F, 1.5≤|F2 / F|≤1.85.

[0133] In this example of the present application, the ratio between the effective focal length of each of the first lens group (composed of a plastic aspherical lens and two glass spherical lenses) and the second lens group (composed of two glass spherical lenses and one glass aspherical lens) and the total effective focal length of the entire projection lens is mentioned. Specifically, both ratios are limited to a range of 1.5 to 1.85, and this design can bring the following technical effects.

[0134] The ratio of the effective focal length (F1, F2) of each of the first lens group and the second lens group to the total effective focal length F of the entire projection lens is set within a range of 1.5 to 1.85. This range is neither too loose nor too strict, ensuring a reasonable match between the focal length of each lens group and the total focal length F of the entire lens. In this way, it can be ensured that light can be well focused and aberration corrected when passing through each lens group. This helps to reduce various aberrations such as chromatic aberration, spherical aberration, and coma, thereby improving the clarity, contrast, and color reproduction of the projected image.

[0135] Specifically, when |F1 / F| or |F2 / F| is greater than the upper limit of 1.85, it means that the first lens group or the second lens group is larger than the total focal length F of the overall projection lens. Since a lens group with a longer focal length may require a larger lens size and a more complex structure to maintain the required imaging performance, this will increase the overall volume and weight of the designed lens. Therefore, it is necessary to balance the relationship between imaging performance and volume control during design. In addition, a lens group with a longer focal length has higher requirements on the processing accuracy and assembly of the lens, which may increase the manufacturing difficulty and cost.

[0136] When |F1 / F| or |F2 / F| is less than the lower limit of 1.5, it means that the focal length of the first lens group or the second lens group is shorter than that of the entire lens, which will reduce the control ability of the lens group on light, thereby affecting the imaging quality of the lens.

[0137] In some examples of this application, see Figure 1 and Figure 2 The projection lens further includes: a light source 10, a color combining prism 9 and a galvanometer 8; wherein the galvanometer 8 is disposed adjacent to the sixth lens 6, and the color combining prism 9 is located between the light source 10 and the galvanometer 8.

[0138] The light source 10 is the core light-emitting component of the projection lens of the present application, which is responsible for providing projection light. In this example of the present application, the light source 10 is placed after the color combining prism 9 as the starting point of the entire projection light path.

[0139] In the present application, the light source 10 is, for example, a three-color laser light source.

[0140] A protective glass 11 is disposed on the light emitting surface of the light source 10 , for example.

[0141] The color combining prism 9 plays a vital role in the projection lens of the present application. It is responsible for combining the light beams from different light sources (usually red, green and blue) into a composite light beam. In this way, the projection lens can achieve full-color projection. In this example of the present application, the color combining prism 9 is located between the light source 10 and the galvanometer 8, ensuring that the three primary colors of light can be accurately combined and directed to the subsequent optical system.

[0142] The galvanometer 8 plays a vital role in the projection lens of the present application. The galvanometer 8 is arranged after the light source 10 and the color combining prism 9, and before the sixth lens 6. It can not only accurately control the projection position of the laser light, but also is one of the key technologies for realizing high-definition, color, and dynamic image projection.

[0143] The projection lens provided in the embodiment of the present application is shown in FIG. Figure 2The projection light emitted by the light source 10, such as laser light, is finally converged onto a plane to form an image.

[0144] The projection lens provided in the embodiment of the present application has strong applicability. The design indicators of the projection lens are: F / # is 2.2, projection ratio is 1.2, Offset = 100%, the total optical length of the projection lens is 36.9mm, telecentricity is <1°, vertical axis chromatic aberration is <0.15Pixel, full field MTF>0.75, focal length = 6.2, root mean square radius RMS radius <0.34Pixel, relative illumination>85%.

[0145] The design indicators of the projection lens of the present application indicate that it is applicable to a variety of projection devices and can meet the needs of different users.

[0146] It should be noted that the projection lens provided in the present application can further adjust the projection size by changing the relative positions of the first lens group and the second lens group, thereby increasing the flexibility and applicability of the projection device using the projection lens.

[0147] In summary, the projection lens of the embodiment of the present application achieves effective suppression of chromatic aberration, compact size, and significant improvement in imaging quality through ingenious optical design and lens material selection.

[0148] According to another embodiment of the present application, a projection device is provided, characterized in that it includes: a housing and the projection lens as described above.

[0149] The projection device provided in the embodiment of the present application is, for example, a laser projector. The laser projector has the advantages of bright colors, high color gamut, compact size, etc., and also effectively overcomes the problem of large color difference in the prior art.

[0150] It should be noted that the projection equipment of the present application includes but is not limited to a laser projector.

[0151] The projection lens of the present application is described in detail below through Example 1.

[0152] Example 1

[0153] See also Figure 1 The projection lens provided in this embodiment 1 includes, along the optical axis from the imaging side to the image source side, a first lens group, an aperture 7, a second lens group, a galvanometer 8, a color combining prism 9 and a light source 10;

[0154] The first lens group is composed of a first lens 1, a second lens 2 and a third lens 3, wherein the first lens 1 is a plastic aspherical lens with a negative optical power; the second lens 2 and the third lens 3 are glass spherical lenses, the optical power of the second lens 2 is negative, and the optical power of the third lens 3 is positive;

[0155] The second lens group is composed of a fourth lens 4, a fifth lens 5 and a sixth lens 6. The fourth lens 4 and the fifth lens 5 are glass spherical lenses, and the sixth lens 6 is a glass aspherical lens. The fourth lens 4 has a positive focal power, the fifth lens 5 has a negative focal power, and the sixth lens 6 has a positive focal power.

[0156] The aperture 7 is located between the third lens 3 and the fourth lens 4;

[0157] The first lens 1 is a convex-concave lens, the second lens 2 is a biconcave lens, the third lens 3 is a biconvex lens, the fourth lens 4 and the fifth lens 5 are concave-convex lenses, and the sixth lens 6 is a biconvex lens;

[0158] The first lens group and / or the second lens group are capable of moving along the optical axis;

[0159] The second lens 2 and the third lens 3 are glued together to form a first double glued lens group, and the fourth lens 4 and the fifth lens 5 are glued together to form a second double glued lens group;

[0160] The refractive index of the second lens 2 is Nd 2 The refractive index of the third lens 3 is Nd 3 , and Nd 2 <Nd 3 ; The Abbe number of the second lens 2 is Vd 2 , the Abbe number of the third lens 3 is Vd 3 , and Vd 2 >Vd 3 ;

[0161] The refractive index of the fourth lens 4 is Nd 4 The refractive index of the fifth lens 5 is Nd 5 , and Nd 4 <Nd 5 The Abbe number of the fourth lens 4 is Vd 4 , the Abbe number of the fifth lens 5 is Vd 5 , and Vd 4 >Vd 5 ;

[0162] The first lens 1 has a negative optical power and has at least one aspherical surface; the sixth lens 6 has a positive optical power and has at least one aspherical surface;

[0163] The effective focal length of the first lens group is F1, and the total effective focal length of the projection lens is F, 1.5≤|F1 / F|≤1.85; the effective focal length of the second lens group is F2, and the total effective focal length of the projection lens is F, 1.5≤|F2 / F|≤1.85;

[0164] The projection lens satisfies: 2<T / D<3.5; wherein T is the total optical length of the projection lens, and D is the effective aperture of the first lens 1;

[0165] The light source 10 is a laser light source.

[0166] Table 1 and Table 2 show various parameters of projection lens lenses, as follows.

[0167] Table 1: Lens parameter table

[0168]

[0169] Table 2 Aspheric coefficient table

[0170] Surface serial number 1 2 10 11 Cone coefficient (K) -3.423 -1.517 -1.244 -10.347 Second-order aspheric coefficients 0.00 0.00 0.00 0.00 Fourth-order aspheric coefficients 2.00E-05 7.74E-04 4.22E-05 -5.08E-04 Sixth-order aspheric coefficients -9.12E-07 7.13E-06 -2.00E-05 -1.38E-06 Eighth-order aspheric coefficients 7.25E-09 -5.77E-09 -5.60E-08 5.55E-07 Tenth-order aspheric coefficients 5.81E-11 -5.74E-09 1.11E-10 1.89E-10

[0171] It should be noted that the surface numbers in Table 1 and Table 2 are 1-18, that is, a total of 18 surfaces, see Figure 1 The optical architecture of the projection lens shown has 18 surfaces from left to right.

[0172] The projection lens of the present application not only exhibits excellent performance in suppressing chromatic aberration, but also achieves significant reduction in volume. That is, it can meet the dual needs of miniaturization and high-definition imaging of laser projectors, such as Figures 3 to 10 Detailed display.

[0173] Figure 3 The point diagram shows that the root mean square radius (RMS) of the projection lens of Example 1 is ≤1.831 μm over the entire field of view, which is equivalent to 0.34 pixel width, demonstrating its excellent optical precision.

[0174] Figure 4 The spatial frequency modulation transfer function diagram, Figure 5 The defocus curve and Figure 6 The modulation transfer function and field of view relationship diagram confirm that the projection lens of Example 1, at a spatial frequency of 93lp / mm, still maintains a high level of modulation transfer function of more than 75%, and has a wide focal depth range of more than ±0.015mm, and the MTF value of the full field of view is also stably higher than 0.75. These indicators together ensure the delicate presentation of image details and the sense of depth.

[0175] from Figure 7From the field curvature and distortion diagram, it can be seen that the field curvature of the projection lens of the present embodiment 1 is ≤0.016 mm, and the distortion rate is ≤1.3%.

[0176] from Figure 8 It can be seen from the vertical axis chromatic aberration diagram that the red-blue (RB) chromatic aberration is less than 0.8μm (i.e. 0.148 pixels), the red-green (RG) chromatic aberration is less than 0.43μm (0.07 pixels), and the blue-green (BG) chromatic aberration is less than 0.32μm (0.059 pixels), and the chromatic aberration is extremely effectively suppressed.

[0177] from Fig. 9 The relative illumination diagram shows that the illumination uniformity of the entire screen exceeds 85%, and the edge light is fully retained, avoiding brightness loss and ensuring the overall brightness and balance of the picture.

[0178] Fig.10 It is a ray aberration diagram, which expresses the function diagram of ray line aberration changing with pupil coordinates, also called ray fan diagram. Fig.10 It can be seen that there are 10 groups, corresponding to 10 fields of view, and each group includes 2 pictures, which are the changes of meridian aberration and sagittal aberration with pupil. These pictures intuitively show the excellent compensation ability of the design for various aberrations. Fig.10 What can be confirmed is that most aberrations have been effectively corrected, further improving the image clarity and visual effects.

[0179] The above embodiments focus on 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. Considering the simplicity of the text, they will not be repeated here.

[0180] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A projection lens, characterized in that: The lens system includes a first lens group, an aperture (7) and a second lens group in sequence from the imaging side to the image source side along the optical axis; The first lens group is composed of a first lens (1), a second lens (2) and a third lens (3), the first lens (1) is a plastic aspherical lens, and the second lens (2) and the third lens (3) are glass spherical lenses; The second lens group is composed of a fourth lens (4), a fifth lens (5) and a sixth lens (6); the fourth lens (4) and the fifth lens (5) are glass spherical lenses, and the sixth lens (6) is a glass aspherical lens; The aperture (7) is located between the third lens (3) and the fourth lens (4); The projection lens satisfies: 2<T / D<3.5; wherein T is the total optical length of the projection lens, and D is the largest effective light aperture in the first lens group.

2. The projection lens according to claim 1, characterized in that: The effective aperture of the first lens (1) is D, and the projection lens satisfies: 2<T / D<3.

5.

3. The projection lens according to claim 1, characterized in that: The optical focal power of the first lens (1) is negative, the optical focal power of the second lens (2) is negative, the optical focal power of the third lens (3) is positive, the optical focal power of the fourth lens (4) is positive, the optical focal power of the fifth lens (5) is negative, and the optical focal power of the sixth lens (6) is positive.

4. The projection lens according to claim 3, characterized in that: The first lens (1) is a convex-concave lens, the second lens (2) is a biconcave lens, the third lens (3) is a biconvex lens, the fourth lens (4) and the fifth lens (5) are concave-convex lenses, and the sixth lens (6) is a biconvex lens.

5. The projection lens according to claim 1, wherein: The first lens group and / or the second lens group can be moved along the optical axis.

6. The projection lens according to claim 1, wherein: The second lens (2) and the third lens (3) are bonded together to form a first double bonded lens group; The fourth lens (4) and the fifth lens (5) are bonded together to form a second double bonded lens group.

7. The projection lens according to claim 6, characterized in that: The refractive index of the second lens (2) is Nd2, the refractive index of the third lens (3) is Nd3, and Nd2<Nd3; The Abbe number of the second lens (2) is Vd2, the Abbe number of the third lens (3) is Vd3, and Vd2>Vd3.

8. The projection lens according to claim 7, characterized in that: The refractive index of the fourth lens (4) is Nd4, the refractive index of the fifth lens (5) is Nd5, and Nd4<Nd5; The Abbe number of the fourth lens (4) is Vd4, the Abbe number of the fifth lens (5) is Vd5, and Vd4>Vd5.

9. The projection lens according to claim 3, characterized in that: The first lens (1) has at least one aspherical surface; The sixth lens (6) has at least one aspherical surface.

10. The projection lens according to claim 1, wherein: The effective focal length of the first lens group is F1, the total effective focal length of the projection lens is F, 1.5≤|F1 / F|≤1.85; The effective focal length of the second lens group is F2, the total effective focal length of the projection lens is F, and 1.5≤|F2 / F|≤1.

85.

11. The projection lens according to any one of claims 1 to 10, characterized in that: The projection lens further comprises: a light source (10), a color combining prism (9) and a galvanometer (8); The galvanometer (8) and the sixth lens (6) are arranged adjacent to each other, and the color combining prism (9) is located between the light source (10) and the galvanometer (8).

12. A projection device, characterized in that: include: shell; and The projection lens according to any one of claims 1 to 11.

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