Prime lens and projection device

Abstract

The utility model discloses a prime lens and a projection device, and relates to the technical field of optical lenses, the prime lens is provided with an object side and an image side which are oppositely arranged along the optical axis direction, and the prime lens comprises a first lens to a fifth lens which are sequentially arranged from the object side to the image side; the first lens, the second lens and the fifth lens are plastic aspheric lenses; the third lens and the fourth lens are glass spherical lenses; the focal length of the first lens is f1, and 280mm < = f1 < = 300mm; the focal length of the second lens is f2, and f2 is more than or equal to-810mm and less than or equal to-800mm; the focal length of the third lens is f3, and f3 is larger than or equal to-110 mm and smaller than or equal to-100 mm. The focal length of the fourth lens is f4, and f4 is more than or equal to 60mm and less than or equal to 70mm; the focal length of the fifth lens is f5, and f5 is more than or equal to-660mm and less than or equal to-630mm; the focal length f of the prime lens is larger than or equal to 130 mm and smaller than or equal to 150 mm, the aperture value F of the prime lens is larger than or equal to 2.0 and smaller than or equal to 2.6, and the resolution ratio of the prime lens is higher than 1080 P. According to the utility model, high resolution is realized through arrangement and combination of a plurality of lenses, selection of shapes and materials of the lenses and setting of focal lengths.

Description

Technical Field

[0001] The utility model relates to the technical field of optical lenses, in particular to a fixed-focus lens and a projection device. Background Art

[0002] With the development of projection technology in recent years, projectors have been widely used in home, education, office and other fields. The common projections on the market are all achieved by direct projection.

[0003] Currently, fixed-focus lenses generally have disadvantages such as large size, high cost and low resolution. Utility Model Content

[0004] The main purpose of the utility model is to provide a fixed-focus lens and a projection device, and in particular to a fixed-focus lens, which aims to solve the problems of high cost and low resolution of existing fixed-focus lenses.

[0005] To achieve the above-mentioned object, the utility model provides a fixed-focus lens, which has an object side and an image side arranged opposite to each other along the optical axis direction, and comprises a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence from the object side to the image side;

[0006] Among them, the first lens, the second lens, and the fifth lens are set as plastic aspherical lenses; the third lens and the fourth lens are set as glass spherical lenses; the focal length of the first lens is f1, 280mm≤f1≤300mm; the focal length of the second lens is f2, -810mm≤f2≤-800mm; the focal length of the third lens is f3, -110mm≤f3≤-100mm; the focal length of the fourth lens is f4, 60mm≤f4≤70mm; the focal length of the fifth lens is f5, -660mm≤f5≤-630mm; so that the focal length f of the fixed-focus lens is 130mm≤f≤150mm, the aperture value F of the fixed-focus lens is 2.0≤F≤2.6, and the resolution of the fixed-focus lens is higher than 1080P.

[0007] In one implementation, the first lens and the fourth lens have positive refractive power, and the second lens, the third lens, and the fifth lens have negative refractive power.

[0008] In one embodiment, the first lens is a meniscus lens, the object side surface of the first lens is set to be convex, and the image side surface is set to be concave;

[0009] The second lens is a meniscus lens, the object side surface of the second lens is set to be a concave surface, and the image side surface is set to be a convex surface;

[0010] The third lens is a biconcave lens, the object side surface of the third lens is set as a concave surface, and the image side surface is set as a concave surface;

[0011] The fourth lens is a biconvex lens, the object side surface of the fourth lens is set to be a convex surface, and the image side surface is set to be a convex surface;

[0012] The fifth lens is a meniscus lens, the object side surface of the fifth lens is set to be convex, and the image side surface is set to be concave.

[0013] In one implementation, the third lens and the fourth lens are cemented together.

[0014] In one embodiment, the refractive index of the first lens is N1, 1.40≤N1≤1.60;

[0015] The refractive index of the second lens is N2, 1.50≤N2≤1.70;

[0016] The refractive index of the third lens is N3, 1.65≤N3≤1.80;

[0017] The refractive index of the fourth lens is N4, 1.70≤N4≤1.90;

[0018] The refractive index of the fifth lens is N5, 1.50≤N5≤1.70.

[0019] In one embodiment, the Abbe number of the first lens is V1, 50≤V1≤70;

[0020] The Abbe number of the second lens is V2, 20≤V2≤40;

[0021] The Abbe number of the third lens is V3, 30≤V3≤55;

[0022] The Abbe number of the fourth lens is V4, 25≤V4≤50;

[0023] The Abbe number of the fifth lens is V5, 20≤V5≤40.

[0024] In one implementation, the total length of the fixed-focus lens is TTL, TTL≤76.85 mm; the effective focal length of the fixed-focus lens is EFL, and the fixed-focus lens satisfies: TTL / EFL≤2.

[0025] In one embodiment, the fixed-focus lens further includes:

[0026] an aperture, disposed between the second lens and the third lens;

[0027] A lens, disposed on the image side of the fifth lens;

[0028] The light emitting surface is arranged on the image side of the mirror.

[0029] In one embodiment, the diameter D1 of the first lens satisfies: D1≤33 mm; and / or,

[0030] The diameter of the light emitting surface is D2, and D2≤148mm.

[0031] The utility model also provides a projection device, the projection device includes a fixed-focus lens, the fixed-focus lens has an object side and an image side that are arranged opposite to each other along the optical axis direction, and the fixed-focus lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are arranged in sequence from the object side to the image side;

[0032] Among them, the first lens, the second lens, and the fifth lens are set as plastic aspherical lenses; the third lens and the fourth lens are set as glass spherical lenses; the focal length of the first lens is f1, 280mm≤f1≤300mm; the focal length of the second lens is f2, -810mm≤f2≤-800mm; the focal length of the third lens is f3, -110mm≤f3≤-100mm; the focal length of the fourth lens is f4, 60mm≤f4≤70mm; the focal length of the fifth lens is f5, -660mm≤f5≤-630mm; so that the focal length f of the fixed-focus lens is 130mm≤f≤150mm, the aperture value F of the fixed-focus lens is 2.0≤F≤2.6, and the resolution of the fixed-focus lens is higher than 1080P.

[0033] The technical solution of the utility model realizes high resolution by adopting an arrangement and combination of multiple lenses, selecting the lens shape, material and setting the focal length. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0035] Figure 1 A schematic structural diagram of an embodiment of a fixed-focus lens provided by the utility model;

[0036] Figure 2 A schematic diagram of a vertical axis chromatic aberration curve of a fixed-focus lens provided by the utility model;

[0037] Figure 3 A schematic diagram of the SPOT points of the fixed-focus lens provided by the utility model;

[0038] Figure 4 This is a schematic diagram of the MTF of the fixed-focus lens provided by the utility model.

[0039] Description of Figure Numbers:

[0040] 100. Fixed-focus lens; 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Aperture; 7. Mirror; 8. Luminous surface.

[0041] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0043] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0044] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0045] Currently, fixed-focus lenses generally have disadvantages such as large size, high cost, and low resolution.

[0046] The utility model provides a fixed-focus lens.

[0047] See also Figure 1 In one embodiment of the utility model, the fixed-focus lens 100 has an object side and an image side that are arranged opposite to each other along the optical axis direction, and the fixed-focus lens 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5 that are arranged in sequence from the object side to the image side;

[0048] Among them, the first lens 1, the second lens 2, and the fifth lens 5 are set as plastic aspherical lenses; the third lens 3 and the fourth lens 4 are set as glass spherical lenses; the focal length of the first lens 1 is f1, 280mm≤f1≤300mm; the focal length of the second lens 2 is f2, -810mm≤f2≤-800mm; the focal length of the third lens 3 is f3, -110mm≤f3≤-100mm; the focal length of the fourth lens 4 is f4, 60mm≤f4≤70mm; the focal length of the fifth lens 5 is f5, -660mm≤f5≤-630mm; so that the focal length f of the fixed-focus lens 100 is 130mm≤f≤150mm, the aperture value F of the fixed-focus lens 100 is 2.0≤F≤2.6, and the resolution of the fixed-focus lens 100 is higher than 1080P.

[0049] The technical solution of the utility model adopts five fixed-focus lenses 100, wherein the first lens 1, the second lens 2, and the fifth lens 5 are set as plastic lenses, and the third lens 3 and the fourth lens 4 are set as glass lenses. Under mass processing conditions, the production cost of the fixed-focus lens 100 can be reduced by setting plastic lenses. The fixed-focus lens 100 adopts a mixed arrangement of glass and plastic lenses, mainly to achieve lightweight, cost control and adaptability to different use environments while ensuring imaging quality. Glass lenses can effectively correct aberrations and provide clear imaging effects. Plastic lenses are relatively light and low in cost, but are not as good as glass in terms of dispersion control. By combining the two, the lightness and cost advantages of plastic lenses can be utilized while maintaining good imaging quality. Moreover, plastic lenses are lighter than glass lenses, and lightweight lenses are easier to carry and operate, especially in outdoor shooting or occasions where fast movement is required. In order to prevent the plastic lens from being out of focus at high temperatures, it is possible to consider using new polymer materials, such as cycloolefin copolymer (COC), which has high heat resistance and a glass transition temperature of 140 to 170°C, and is suitable for optical applications that require high temperature resistance. In addition, the first lens 1, the second lens 2, and the fifth lens 5 are set as plastic aspheric lenses; aspheric lenses can effectively correct spherical aberration and other aberrations in the optical system and improve the imaging quality. In the glass-plastic hybrid fixed-focus lens 100, the combination of glass lens and plastic lens can achieve high resolution, while taking into account the lens's day and night confocality, 0°C to 50°C non-out of focus and other performance, expanding the application range of the lens. So that the resolution of the fixed-focus lens 100 is higher than 1080P. In addition, in order to make the focal length f of the fixed-focus lens 100 satisfy: 130mm≤f≤150mm, the aperture value F of the fixed-focus lens 100 satisfies: 2.0≤F≤2.6. Therefore, the focal length of each lens is designed as follows: the focal length of the first lens 1 is f1, 280mm≤f1≤300mm; the focal length of the second lens 2 is f2, -810mm≤f2≤-800mm; the focal length of the third lens 3 is f3, -110mm≤f3≤-100mm; the focal length of the fourth lens 4 is f4, 60mm≤f4≤70mm; the focal length of the fifth lens 5 is f5, -660mm≤f5≤-630mm. Through the combination of different lenses and the reasonable distribution of optical focal length, the fixed-focus lens 100 has good performances such as small size, high resolution, and very good athermal difference.

[0050] In order to achieve better imaging effects, the fixed-focus lens 100 can achieve a balance between the convergence and divergence of light in the optical system by combining a positive lens and a negative lens, thereby reducing aberrations and improving imaging quality. Among them, the first lens 1 and the fourth lens 4 have positive optical power, and the second lens 2, the third lens 3, and the fifth lens 5 have negative optical power. The optical power of the lens is also related to the refractive index and curvature radius of the lens. By adjusting these parameters, the optical performance of the lens can be further optimized.

[0051] In order to enlarge the focal length of the fixed-focus lens 100 and change the size and shape of the image, the third lens 3 is set as a double concave lens, the object side surface of the third lens 3 is set as a concave surface, and the image side surface is set as a concave surface; the fourth lens 4 is set as a double convex lens, the object side surface of the fourth lens 4 is set as a convex surface, and the image side surface is set as a convex surface.

[0052] In a specific embodiment, the parameters of the fixed-focus lens 100 are as follows:

[0053] Table 1:

[0054]

[0055] Specifically, the surface shape of each aspheric lens can be defined by but not limited to the following aspheric formula:

[0056]

[0057] Among them, z represents the axial sagittal height of the aspheric surface in the Z direction; y represents the height of the aspheric surface; c represents the curvature of the fitted sphere, which is the inverse of the radius of curvature; k represents the cone coefficient; the 4th order term, 6th order term, 8th order term, 10th order term, 12th order term, 14th order term, and 16th order term represent the high-order aspheric coefficients respectively. The high-order coefficients of each aspheric mirror surface can be seen from the following table:

[0058] Table 2:

[0059]

[0060]

[0061] In order to effectively reduce spherical aberration and improve the performance of the optical system, the three lenses are set as meniscus lenses. The first lens 1 is a meniscus lens, the object side surface of the first lens 1 is set as a convex surface, and the image side surface is set as a concave surface; the second lens 2 is a meniscus lens, the object side surface of the second lens 2 is set as a concave surface, and the image side surface is set as a convex surface; the fifth lens 5 is a meniscus lens, the object side surface of the fifth lens 5 is set as a convex surface, and the image side surface is set as a concave surface. The meniscus lens has a convex surface and a concave surface, which can be a positive lens or a negative lens, which is used to shorten the focal length or increase the focal length, and at the same time increase the numerical aperture of the system or reduce the numerical aperture of the system.

[0062] In order to reduce the spherical aberration and chromatic aberration of the fixed focus lens 100, the third lens 3 and the fourth lens 4 are glued together. Spherical aberration is a phenomenon in which light is focused at different positions due to the curved surface shape of the lens. In a double glued lens, by selecting glass materials with different refractive indices, the focusing ability of the two surfaces of the lens on light can be complementary, thereby reducing spherical aberration. For example, one side of a lens can be a convex lens and the other side can be a concave lens, and the combination of the two can offset each other's spherical aberration to a certain extent. Chromatic aberration is a focus shift caused by the different propagation speeds of light of different wavelengths passing through the lens. In a double glued lens, chromatic aberration can be reduced by selecting materials with different dispersion characteristics. For example, low-dispersion materials and high-dispersion materials can be combined together so that light of different wavelengths passing through the lens is focused on both sides of the lens, thereby offsetting chromatic aberration. In addition, compared with a single lens, a glued lens reduces light energy loss, which is reflected in the following aspects: by gluing optical lenses together, the number of interfaces between air and glass can be reduced, thereby significantly reducing light energy loss and increasing imaging brightness. Since gluing can compensate for slight differences in the radius of curvature of the gluing surface, the precision requirements of the gluing surface can be appropriately reduced, which helps to improve the overall performance of the optical system. The design and manufacture of the fixed-focus lens 100 need to consider the influence of light refraction. When designing the fixed-focus lens 100, in addition to considering the shape and structure of the lens, it is also necessary to select suitable materials to optimize the refraction effect of light, thereby improving the imaging quality. The refractive index of the first lens 1 is N1, 1.40≤N1≤1.60; the refractive index of the second lens 2 is N2, 1.50≤N2≤1.70; the refractive index of the third lens 3 is N3, 1.65≤N3≤1.80; the refractive index of the fourth lens 4 is N4, 1.70≤N4≤1.90; the refractive index of the fifth lens 5 is N5, 1.50≤N5≤1.70.

[0063] For a single lens: the Abbe number of the first lens 1 is V1, 50≤V1≤70; the Abbe number of the second lens 2 is V2, 20≤V2≤40; the Abbe number of the third lens 3 is V3, 30≤V3≤55; the Abbe number of the fourth lens 4 is V4, 25≤V4≤50; the Abbe number of the fifth lens 5 is V5, 20≤V5≤40.

[0064] In order to ensure that the overall size of the fixed-focus lens 100 is small, the total length of the fixed-focus lens 100 is TTL, TTL≤76.85mm; the effective focal length of the fixed-focus lens 100 is EFL, and the fixed-focus lens 100 satisfies: TTL / EFL≤2. The ratio of TTL divided by EFL is of great significance in optical design. This ratio can reflect the design characteristics of the lens, such as the compactness and optical performance of the lens. In some cases, the smaller the ratio of TTL to EFL, the more compact the design of the lens, which may have better optical performance and a smaller volume. In addition, the ratio of TTL to EFL is also related to the field of view (FOV) of the lens. Generally, the smaller the TTL, the smaller the focal length, and therefore the larger the relative FOV. This means that while maintaining the same field of view, a lens with a smaller TTL can be designed to be more compact.

[0065] The fixed-focus lens 100 also includes: an aperture 6, a Fresnel lens 7 and a light-emitting surface 8. The aperture 6 is arranged between the second lens 2 and the third lens 3. In the fixed-focus lens 100, the role of the aperture 6 is particularly prominent because they usually have a larger aperture and can provide more light under low-light conditions, thereby ensuring the brightness and clarity of the image. The Fresnel lens 7 is arranged on the image side of the fifth lens 5. The application of the Fresnel lens 7 in the fixed-focus lens 100 is mainly to reduce the size and weight of the lens while maintaining or improving the optical performance of the lens. This lens uses the diffraction phenomenon of light to reduce aberrations. When used in combination with ordinary glass lenses, it can provide good aberration compensation performance. Compared with many traditional camera lenses that use the photorefractive phenomenon, the Fresnel lens can reduce the number of lenses, thereby making the lens more compact and lightweight. The light-emitting surface 8 is arranged on the image side of the Fresnel lens 7.

[0066] In order to ensure the diameter of the lens, the diameter D1 of the first lens 1 satisfies: D1≤33mm; and / or the diameter of the light emitting surface 8 is D2, D2≤148mm.

[0067] The utility model also provides a projection device, which includes a fixed-focus lens 100. The specific structure of the fixed-focus lens 100 refers to the above-mentioned embodiment. Since the present projection device adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here. Among them, the fixed-focus lens 100 has an object side and an image side that are relatively arranged along the optical axis direction. The fixed-focus lens 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5 arranged in sequence from the object side to the image side;

[0068] Among them, the first lens 1, the second lens 2, and the fifth lens 5 are set as plastic aspherical lenses; the third lens 3 and the fourth lens 4 are set as glass spherical lenses; the focal length of the first lens 1 is f1, 280mm≤f1≤300mm; the focal length of the second lens 2 is f2, -810mm≤f2≤-800mm; the focal length of the third lens 3 is f3, -110mm≤f3≤-100mm; the focal length of the fourth lens 4 is f4, 60mm≤f4≤70mm; the focal length of the fifth lens 5 is f5, -660mm≤f5≤-630mm; so that the focal length f of the fixed-focus lens 100 is 130mm≤f≤150mm, the aperture value F of the fixed-focus lens 100 is 2.0≤F≤2.6, and the resolution of the fixed-focus lens 100 is higher than 1080P.

[0069] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A fixed-focus lens, characterized in that: The fixed-focus lens has an object side and an image side that are arranged opposite to each other along the optical axis direction, and the fixed-focus lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens that are arranged in sequence from the object side to the image side; Among them, the first lens, the second lens, and the fifth lens are set as plastic aspherical lenses; the third lens and the fourth lens are set as glass spherical lenses; the focal length of the first lens is f1, 280mm≤f1≤300mm; the focal length of the second lens is f2, -810mm≤f2≤-800mm; the focal length of the third lens is f3, -110mm≤f3≤-100mm; the focal length of the fourth lens is f4, 60mm≤f4≤70mm; the focal length of the fifth lens is f5, -660mm≤f5≤-630mm; so that the focal length f of the fixed-focus lens is 130mm≤f≤150mm, the aperture value F of the fixed-focus lens is 2.0≤F≤2.6, and the resolution of the fixed-focus lens is higher than 1080P.

2. The fixed-focus lens according to claim 1, wherein: The first lens and the fourth lens have positive refractive power, and the second lens, the third lens and the fifth lens have negative refractive power.

3. The fixed-focus lens according to claim 2, wherein: The first lens is a meniscus lens, the object side surface of the first lens is set to be a convex surface, and the image side surface is set to be a concave surface; The second lens is a meniscus lens, the object side surface of the second lens is set to be a concave surface, and the image side surface is set to be a convex surface; The third lens is a biconcave lens, the object side surface of the third lens is set as a concave surface, and the image side surface is set as a concave surface; The fourth lens is a biconvex lens, the object side surface of the fourth lens is set to be a convex surface, and the image side surface is set to be a convex surface; The fifth lens is a meniscus lens, the object side surface of the fifth lens is set to be convex, and the image side surface is set to be concave.

4. The fixed-focus lens according to claim 1, wherein: The third lens and the fourth lens are cemented together.

5. The fixed-focus lens according to claim 1, wherein: The refractive index of the first lens is N1, 1.40≤N1≤1.60; The refractive index of the second lens is N2, 1.50≤N2≤1.70; The refractive index of the third lens is N3, 1.65≤N3≤1.80; The refractive index of the fourth lens is N4, 1.70≤N4≤1.90; The refractive index of the fifth lens is N5, and 1.50≤N5≤1.

70.

6. The fixed-focus lens according to claim 1, wherein: The Abbe number of the first lens is V1, 50≤V1≤70; The Abbe number of the second lens is V2, 20≤V2≤40; The Abbe number of the third lens is V3, 30≤V3≤55; The Abbe number of the fourth lens is V4, 25≤V4≤50; The Abbe number of the fifth lens is V5, 20≤V5≤40.

7. The fixed-focus lens according to claim 1, wherein: The total length of the fixed-focus lens is TTL, TTL≤76.85 mm; the effective focal length of the fixed-focus lens is EFL, and the fixed-focus lens satisfies: TTL / EFL≤2.

8. The fixed-focus lens according to claim 1, wherein: The fixed-focus lens further comprises: an aperture, disposed between the second lens and the third lens; A lens, disposed on the image side of the fifth lens; The light emitting surface is arranged on the image side of the mirror.

9. The fixed-focus lens according to claim 8, wherein: The diameter D1 of the first lens satisfies: D1≤33 mm; and / or, The diameter of the light emitting surface is D2, and D2≤148mm.

10. A projection device, characterized in that: Comprising the fixed-focus lens as described in any one of claims 1 to 9.

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