Projection system

Abstract

The utility model belongs to the technical field of projection, and discloses a projection system, which comprises an external lens and a projection lens. The external lens comprises a first lens L1 with negative focal power and a second lens L2 with positive focal power, wherein the first lens L1 and the second lens L2 are arranged from a light emitting side to a light incident side, and the first lens L1 and the second lens L2 are coaxial. At least one of the first lens L1 and the second lens L2 is an aspheric lens; the total focal length Fs of the external lens satisfies the following condition:-2200mm < = Fs < = 0mm. According to the utility model, through reasonable configuration of the external lens, the problem of large overall structure size is solved.

Description

Technical Field

[0001] This utility model belongs to the field of projection technology, and in particular relates to a projection system. Background Technology

[0002] With the continuous development of the optical projection field and the advancement of technology, various projection lenses are gradually entering people's lives. Currently, projection lenses are usually fixed-focus lenses. Common fixed-focus lenses cannot achieve zoom functionality to achieve larger magnification ratios, requiring external lenses to achieve different magnification ratios. However, current external lenses use more elements and have a larger overall size, making it difficult to achieve good projection effects when used in conjunction with projection lenses.

[0003] In other words, existing external lenses suffer from large size issues. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model discloses a projection system that solves the problem of large overall structural size by rationally configuring external lenses.

[0005] The specific technical solution of this utility model is as follows:

[0006] A projection system includes an external lens and a projection lens;

[0007] The external lens includes a first lens L1 with negative optical power and a second lens L2 with positive optical power arranged from the light-emitting side to the light-incoming side, wherein the first lens L1 and the second lens L2 are coaxial.

[0008] Of the first lens L1 and the second lens L2, at least one is an aspherical lens;

[0009] The total focal length Fs of the external lens satisfies: -2200mm≤Fs≤0mm.

[0010] Preferably, the refractive index of the aspherical lens is greater than or equal to 1.48 and less than or equal to 1.8.

[0011] Preferably, the focal length F1 of the first lens L1 and the total focal length Fs of the external lens satisfy the following condition: 25≤Fs / F1≤150;

[0012] The focal length F2 of the second lens L2 and the total focal length Fs of the external lens satisfy the following condition: -80≤Fs / F2≤-15.

[0013] Preferably, the external lens and the projection lens satisfy one or more of the following:

[0014] The projection ratio TR1 of the external lens and the projection ratio TR of the projection lens satisfy the following condition: 1.0 ≤ TR / TR1 ≤ 4.0;

[0015] The aperture ΦL1 of the first lens L1 and the aperture ΦG1 of the first lens of the projection lens satisfy the following condition: 1.0 ≤ ΦL1 / ΦG1 ≤ 3.5;

[0016] The aperture ΦL1 of the first lens L1 and the F-number F# of the projection lens satisfy the following relationship: 10≤ΦL1 / F#≤50;

[0017] The total focal length Fs of the external lens and the total focal length F0 of the projection lens satisfy the following condition: -350≤Fs / F0≤-90.

[0018] Preferably, the optical total length TTL1 of the external lens and the optical total length TTL of the projection lens satisfy the following condition: 0.7≤TTL1 / TTL≤1.

[0019] Preferably, the total optical length TTL1 of the external lens and the total focal length F0 of the projection lens satisfy the following condition: 3≤TTL1 / F0≤8.

[0020] Preferably, the first lens L1 is a biconcave lens and the second lens L2 is a biconvex lens.

[0021] Preferably, the projection lens includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a galvanometer G6, a prism G7, a protective glass G8, and a digital microchip arranged from the light-emitting side to the light-incident side.

[0022] The first lens G1 is a convex-concave lens, the second lens G2 is a biconvex lens, the third lens G3 is a concave-convex lens, the fourth lens G4 is a concave-convex lens, and the fifth lens G5 is a biconvex lens.

[0023] The third lens G3 and the fourth lens G4 constitute a doublet lens.

[0024] Preferably, the first lens G1 is an aspherical lens with negative optical power, the second lens G2 is a spherical or aspherical lens with positive optical power, the third lens G3 has negative optical power and the fourth lens G4 has positive optical power, or the third lens G3 has positive optical power and the fourth lens G4 has negative optical power, and the fifth lens G5 is an aspherical lens with positive optical power.

[0025] Compared with the prior art, the present invention can magnify the angle of light by setting the first lens L1, thereby magnifying the projected image and helping to correct distortion. The second lens L2 can converge the light emitted from the projection lens and also plays the role of correcting chromatic aberration and controlling the beam aperture. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an embodiment of the present utility model.

[0027] In the diagram: 100 - External lens; 200 - Projection lens; G1 - First lens; G2 - Second lens; 10 - Aperture; G3 - Third lens; G4 - Fourth lens; G5 - Fifth lens; G6 - Galvanometer; G7 - Prism; G8 - Protective glass; 20 - Digital microchip; 30 - Projection screen; L1 - First lens; L2 - Second lens; L3 - Third lens; L4 - Fourth lens; L5 - Fifth lens. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to specific embodiments.

[0029] like Figure 1 As shown, a projection system includes an external lens 100 and a projection lens 200; the external lens 100 includes a first lens L1 with negative optical power and a second lens L2 with positive optical power arranged from the light-emitting side to the light-incident side, the first lens L1 and the second lens L2 being coaxial; at least one of the first lens L1 and the second lens L2 is an aspherical lens; the total focal length Fs of the external lens 100 satisfies: -2200mm≤Fs≤0mm.

[0030] In this embodiment, the external lens 100 features a certain aberration correction capability, light weight, low cost, miniaturization, and high imaging quality. It can be used in conjunction with the projection lens 200. The external lens 100 is positioned on the light-emitting side of the projection lens 200, thereby changing the projection ratio of the projection lens 200 and achieving a zoom effect, which can shorten the focal length. The projection lens 200, in conjunction with the external lens 100, can support a projection ratio reduction of 1 to 5 times. That is, at the same distance, the original image size can be enlarged by 1 to 5 times while maintaining a certain projection quality. For example, a projection image of 40 to 250 inches can be achieved at a distance of 1.6m.

[0031] Specifically, in this embodiment, the first lens L1 is configured with negative optical power, which magnifies the angle of light, thereby enlarging the projected image and correcting distortion. The second lens L2 is configured with positive optical power, which converges the light emitted from the projection lens 200, corrects chromatic aberration, and controls the beam aperture, facilitating a smaller aperture. The combination of the second lens L2 and the first lens L1 helps to cancel out chromatic aberration. In this embodiment, when the first lens L1 is an aspherical lens, it helps correct distortion, reduces weight, and improves manufacturing stability, further enhancing the overall performance of the external lens 100. When the second lens L2 is an aspherical lens, it helps reduce weight and the aperture of the middle portion of the external lens 100, while also improving manufacturing stability and resulting in smoother light convergence, effectively improving performance stability. When both the first lens L1 and the second lens L2 are aspherical, weight and volume are significantly reduced while maintaining high performance. This effectively reduces the overall size of the external lens 100, achieves a higher magnification, and lowers the projection ratio. By properly configuring the first lens L1 and the second lens L2, an even smaller projection ratio is obtained.

[0032] In this embodiment, the refractive index of the aspherical lens is greater than or equal to 1.48 and less than or equal to 1.8. Both the first lens L1 and the second lens L2 in this embodiment are aspherical lenses to improve distortion and astigmatism. In particular, when the second lens L2 is an aspherical lens, it is beneficial to improve edge resolution and enhance overall performance.

[0033] In this embodiment, the focal length F1 of the first lens L1 and the total focal length Fs of the external lens 100 satisfy the following relationship: 25 ≤ Fs / F1 ≤ 150; the focal length F2 of the second lens L2 and the total focal length Fs of the external lens 100 satisfy the following relationship: -80 ≤ Fs / F2 ≤ -15. This arrangement facilitates a reasonable allocation of the focal lengths of the first lens L1 and the second lens L2, ensuring the rationality of the focal lengths of the first lens L1 and the second lens L2, which helps to eliminate chromatic aberration and ensure imaging performance. In different technical solutions of this embodiment, Fs / F1 = 25, 30, 34, 40, 150, and Fs / F2 = -80, -29, -25, -20, -15.

[0034] In this embodiment, the external lens 100 and the projection lens 200 satisfy one or more of the following:

[0035] The projection ratio TR1 of the external lens 100 and the projection ratio TR of the projection lens 200 satisfy the following condition: 1.0 ≤ TR / TR1 ≤ 4.0;

[0036] The aperture ΦL1 of the first lens L1 and the aperture ΦG1 of the first lens of the projection lens 200 satisfy the following condition: 1.0≤ΦL1 / ΦG1≤3.5;

[0037] The aperture ΦL1 of the first lens L1 and the F-number F# of the projection lens 200 satisfy the following relationship: 10≤ΦL1 / F#≤50;

[0038] The total focal length Fs of the external lens 100 and the total focal length F0 of the projection lens 200 satisfy the following condition: -350≤Fs / F0≤-90.

[0039] Regarding TR / TR1, the throw ratio is defined as the ratio of the projection distance to the width of the projected image. This balances the throw ratio and the length of the external lens 100, ensuring that the external lens 100 has a small throw ratio, enabling the conversion from telephoto to medium telephoto, short telephoto, or ultra-short telephoto. In different technical solutions of this embodiment, TR / TR1 = 1.0, 1.7, 3.2, and 4.0.

[0040] Regarding ΦL1 / ΦG1, this setting helps ensure that the size of the external lens 100 matches the size of the projection lens 200, which helps to compress the aperture of the external lens 100, ensuring a small aperture, while also balancing the throw ratio and the length of the external lens 100. In this embodiment, the first lens of the projection lens 200 refers to the lens in the projection lens 200 that is closest to the external lens 100. In different technical solutions of this embodiment, ΦL1 / ΦG1 = 1.0, 1.5, 2.0, 2.6, 3.5.

[0041] Regarding ΦL1 / F#, this avoids the external lens 100 having an excessively large aperture when F# is small, thereby increasing lens manufacturability or reducing processing difficulty, while also balancing the projection ratio and the length of the external lens 100. In the different technical solutions of this embodiment, ΦL1 / F# = 10, 15, 20, 23, 26, 50.

[0042] Regarding Fs / F0, this setting helps ensure that the external lens 100 can reduce the focal length of the projection lens 200, thereby achieving a zoom effect. It can convert a telephoto lens into a medium-long telephoto or a short telephoto lens, and also balances the projection ratio and the length of the external lens 100. In different technical solutions of this embodiment, Fs / F0 = -350, -160, -130, -100, and -90.

[0043] In this embodiment, the total optical length TTL1 of the external lens 100 and the total optical length TTL of the projection lens 200 satisfy the following condition: 0.7 ≤ TTL1 / TTL ≤ 1. This setting is beneficial for compressing the total optical length of the external lens 100, which in turn helps to reduce the overall size of the external lens 100, thus achieving miniaturization. It also balances the relationship between the projection ratio and the length of the external lens 100. In different technical solutions of this embodiment, TTL1 / TTL = 0.7, 0.8, 0.9, and 1.

[0044] In this embodiment, the total optical length TTL1 of the external lens 100 and the total focal length F0 of the projection lens 200 satisfy the following condition: 3 ≤ TTL1 / F0 ≤ 8. This setting helps to ensure the miniaturization and compact structure of the external lens 100. With a fixed focal length of the projection lens 200, the length of the external lens 100 or the number of lenses in the external lens 100 can be increased to achieve a smaller projection ratio. The relationship between the projection ratio and the length of the external lens 100 can be balanced by one or more of the above constraints. Using this external lens 100 can effectively improve the projection ratio of the projection lens 200, achieve short-throw projection, improve chromatic aberration, and suppress distortion to a certain extent. The entire external lens 100 has advantages such as miniaturization, small aperture, light weight, and low cost, while ensuring certain imaging performance. In different technical solutions of this embodiment, TTL1 / F0 = 3, 5, 7, and 8.

[0045] In this embodiment, the first lens L1 is a biconcave lens and the second lens L2 is a biconvex lens. The projection lens 200 includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a galvanometer G6, a prism G7, a protective glass G8, and a digital microchip 20 arranged from the light-emitting side to the light-receiving side; the first lens G1 is a convex-concave lens, the second lens G2 is a biconvex lens, the third lens G3 is a concave-convex lens, the fourth lens G4 is a concave-convex lens, and the fifth lens G5 is a biconvex lens; the third lens G3 and the fourth lens G4 constitute a cemented doublet lens. Further, the first lens G1 is an aspherical lens with negative optical power, the second lens G2 is a spherical or aspherical lens with positive optical power, the third lens G3 has negative optical power and the fourth lens G4 has positive optical power, or the third lens G3 has positive optical power and the fourth lens G4 has negative optical power, and the fifth lens G5 is an aspherical lens with positive optical power.

[0046] Table 1 below shows the basic structural parameters of the projection lens 200 in this embodiment.

[0047] Table 1

[0048]

[0049] The surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formulas:

[0050]

[0051] In the formula, z is the surface sagitta; c is the curvature; r is the radial coordinate; k is the quadratic coefficient; and α is a coefficient. The values ​​of α in the formulas corresponding to the aspherical surfaces in Table 1 are shown in Table 2 below:

[0052] Table 2

[0053]

[0054]

[0055] Specifically, in this embodiment, such as Figure 1 As shown, the external lens 100 of the projection module consists of two lenses. The first lens L1 has negative optical power, and the second lens L2 has positive optical power. The first lens L1 and the second lens L2 are sequentially arranged along a direction away from the projection screen 30, and the first lens L1 and the second lens L2 are coaxially arranged, and both the first lens L1 and the second lens L2 are coaxially arranged with the projection lens 200. It should be noted that in some other technical solutions of this embodiment, the external lens 100 and the projection lens 200 may be non-coaxial.

[0056] In this embodiment, the first lens L1 serves to diverge light and correct distortion, while the second lens L2 serves to collect light and control the beam aperture. The first lens L1 is a biconcave lens, and the second lens L2 is a biconvex lens. By appropriately setting the lens surface shapes, it can correct chromatic aberration. When the external lens 100 and the projection lens 200 are coaxial, the optical axis can be ensured to always be at the center of the lens, guaranteeing good resolution at the center of the image. In this embodiment, the first lens L1 and the second lens L2 can be optionally set to aspherical lenses. By using aspherical lenses, the local light correction capability can be enhanced, resulting in better resolution. When both the first lens L1 and the second lens L2 are aspherical lenses, costs, weight, and volume can be reduced, while overall resolution can be improved.

[0057] In this embodiment, the total focal length Fs of the external lens 100 satisfies: -2200mm≤Fs≤0mm. As a preferred technical solution, -2193mm≤Fs≤-600mm. This setting helps to ensure that the total focal length of the external lens 100 is negative, thereby ensuring the effect of the external lens 100 in reducing the projection ratio of the projection lens 200.

[0058] Table 3 below shows the basic structural parameters of the external lens 100 in this embodiment.

[0059] Table 3

[0060] surface Radius of curvature (mm) Thickness (mm) The light-emitting side of the first lens L1 -20 5.6 The incident side of the first lens L1 33.5 11.35 The light-emitting side of the second lens L2 32 9.9 The incident side of the second lens L2 -58 14

[0061] The above are merely preferred embodiments of this utility model. It should be noted that the above preferred embodiments should not be considered as limitations on this utility model, and the scope of protection of this utility model should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A projection system, characterized in that, Including external lenses and projection lenses; The external lens includes a first lens L1 with negative optical power and a second lens L2 with positive optical power arranged from the light-emitting side to the light-incoming side, wherein the first lens L1 and the second lens L2 are coaxial. Of the first lens L1 and the second lens L2, at least one is an aspherical lens; The total focal length Fs of the external lens satisfies: -2200mm≤Fs≤0mm.

2. The projection system as described in claim 1, characterized in that, The refractive index of the aspherical lens is greater than or equal to 1.48 and less than or equal to 1.

8.

3. A projection system as described in claim 1, characterized in that, The focal length F1 of the first lens L1 and the total focal length Fs of the external lens 100 satisfy the following condition: 25≤Fs / F1≤150; The focal length F2 of the second lens L2 and the total focal length Fs of the external lens 100 satisfy the following condition: -80≤Fs / F2≤-15.

4. A projection system as described in claim 1, characterized in that, The external lens and the projection lens satisfy one or more of the following: The projection ratio TR1 of the external lens and the projection ratio TR of the projection lens satisfy the following condition: 1.0 ≤ TR / TR1 ≤ 4.0; The aperture ΦL1 of the first lens L1 and the aperture ΦG1 of the first lens of the projection lens satisfy the following condition: 1.0 ≤ ΦL1 / ΦG1 ≤ 3.5; The aperture ΦL1 of the first lens L1 and the F-number F# of the projection lens satisfy the following relationship: 10≤ΦL1 / F#≤50; The total focal length Fs of the external lens and the total focal length F0 of the projection lens satisfy the following condition: -350≤Fs / F0≤-90.

5. A projection system as described in claim 1, characterized in that, The optical total length TTL1 of the external lens and the optical total length TTL of the projection lens satisfy the following condition: 0.7≤TTL1 / TTL≤1.

6. A projection system as described in claim 1, characterized in that, The total optical length TTL1 of the external lens and the total focal length F0 of the projection lens satisfy the following condition: 3≤TTL1 / F0≤8.

7. A projection system as described in claim 1, characterized in that, The first lens L1 is a biconcave lens, and the second lens L2 is a biconvex lens.

8. A projection system as described in claim 1, characterized in that, The projection lens includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a fifth lens G5, a galvanometer G6, a prism G7, a protective glass G8, and a digital microchip arranged from the light-emitting side to the light-incoming side. The first lens G1 is a convex-concave lens, the second lens G2 is a biconvex lens, the third lens G3 is a concave-convex lens, the fourth lens G4 is a concave-convex lens, and the fifth lens G5 is a biconvex lens. The third lens G3 and the fourth lens G4 constitute a doublet lens.

9. A projection system as described in claim 8, characterized in that, The first lens G1 is an aspherical lens with negative optical power, the second lens G2 is a spherical or aspherical lens with positive optical power, the third lens G3 has negative optical power and the fourth lens G4 has positive optical power, or the third lens G3 has positive optical power and the fourth lens G4 has negative optical power, and the fifth lens G5 is an aspherical lens with positive optical power.

Images