A projector lens

Abstract

A projector lens relates to the technical field of imaging lenses, comprising a first lens, a second lens, an aperture, and a third lens; the first lens, the second lens, and the third lens are arranged in sequence from the object side to the image side; the aperture is arranged between the first lens and the second lens, or the aperture is arranged between the second lens and the third lens; the first lens and the third lens have positive focal lengths, and the second lens has negative focal lengths; the first lens has a convex light entrance surface and a concave light exit surface; the second lens has a concave light entrance surface and a convex light exit surface; the third lens has a convex light entrance surface and a convex light exit surface. The present invention, by preferably limiting the number of lenses, the concave-convex shapes of each surface, the distance between each lens, the aperture position, the center thickness of each lens, the refractive index, and limiting at least two lenses to be aspherical lenses, can have the advantages of a large field of view, a large image surface, and low distortion, thereby improving imaging clarity and providing space for designing a short throw ratio and performing off-axis.

Description

Technical Field

[0001] The present invention belongs to the technical field of imaging lenses, and in particular relates to a projector lens. Background Art

[0002] With the continuous development of projection technology, electronic devices using this technology have become widely used in people's lives, such as home projectors and car indicator lights. However, current projection lenses mainly use multiple lens groups, and the large number of lens elements used results in large size and high cost. In particular, the all-glass lenses of 1080P single-chip LCD projectors currently on the market have poor image quality and a long focal length. This makes it impossible to achieve off-axis imaging of the LCD while maintaining the required throw ratio, seriously affecting the user experience. Therefore, a new solution is urgently needed to address this problem. Summary of the Invention

[0003] In view of the shortcomings of the current technology, the present invention provides a projector lens, comprising a first lens, a second lens, an aperture and a third lens;

[0004] The first lens, the second lens and the third lens are arranged in sequence from the object side to the image side;

[0005] The aperture is arranged between the first lens and the second lens, or the aperture is arranged between the second lens and the third lens;

[0006] The first lens and the third lens have positive optical power, and the second lens has negative optical power;

[0007] The light incident surface of the first lens is convex, and the light emitting surface is concave;

[0008] The light incident surface of the second lens is concave, and the light emitting surface is convex;

[0009] The light incident surface of the third lens is a convex surface, and the light emitting surface is a convex surface;

[0010] At least two of the first lens, the second lens, and the third lens are aspherical lenses.

[0011] Both surfaces of the aspheric lens are aspheric.

[0012] The projector lens satisfies the following relationship:

[0013] 0.5mm≤f1 / f≤1.5mm;

[0014] -1.2mm≤f2 / f≤-0.2mm;

[0015] 0.2mm≤f3 / f≤1.2mm;

[0016] Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f is the focal length of the projector lens.

[0017] The projector lens satisfies the following relationship:

[0018] -2mm≤f1 / f2≤-1mm;

[0019] -1.5mm≤f2 / f3≤-0.5mm;

[0020] Where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and f is the focal length of the projector lens. Properly allocating the focal lengths of the lenses can help reduce tolerance sensitivity and improve overall performance.

[0021] The projector lens satisfies the following relationship:

[0022] 1.47≤Nd1≤1.75;

[0023] 1.55≤Nd2≤1.68;

[0024] 1.47≤Nd3≤1.75;

[0025] Where Nd1 is the refractive index of the material of the first lens, Nd2 is the refractive index of the material of the second lens, and Nd3 is the refractive index of the material of the third lens. Properly selecting the refractive index of each lens material can better correct field curvature and off-axis aberrations, improving the lens's resolving power and environmental adaptability.

[0026] The projector lens satisfies the following relationship:

[0027] 0.7mm≤T1 / T2≤1.5mm;

[0028] 0.5mm≤T2 / T3≤1.5mm;

[0029] T2≤10mm;

[0030] Wherein, T1 is the center thickness of the first lens, T2 is the center thickness of the second lens, and T3 is the center thickness of the third lens. Reasonable distribution of lens thickness can improve processing yield and shorten the total length of the lens.

[0031] The projector lens satisfies the following relationship:

[0032] 10mm≤D12≤20mm;

[0033] 0.2mm≤D23≤3mm;

[0034] Wherein, D12 is the distance from the light-exiting surface of the first lens to the light-entering surface of the second lens, and D23 is the distance from the light-exiting surface of the second lens to the light-entering surface of the third lens. Setting the distance between each lens in this way helps improve the image quality of the lens and shorten the overall length of the lens.

[0035] The present invention has the beneficial effect of optimizing the number of lenses, the concave-convex shapes of each surface, the distance between each lens, the aperture position, the center thickness of each lens, the refractive index, and the requirement that at least two lenses be aspherical. This projector lens combines the advantages of a wide field of view, a large image area, and low distortion, improving image clarity while also allowing for a short throw ratio and off-axis design. The projector lens disclosed in the present invention meets high requirements for both half-image height and focal length. When used in a 3-inch LCD projector, this lens achieves high standards for parameters such as throw ratio, off-axis, field curvature, and distortion. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a structural schematic diagram of a projector lens embodiment 1 of the present invention.

[0037] Figure 2 This is a field curvature distortion diagram of a projector lens embodiment 1 of the present invention.

[0038] Figure 3 This is the MTF diagram of Example 1 of a projector lens of the present invention.

[0039] Figure 4 This is a structural schematic diagram of a projector lens embodiment 2 of the present invention.

[0040] Figure 5 This is a field curvature distortion diagram of a projector lens embodiment 2 of the present invention.

[0041] Figure 6 This is the MTF diagram of Example 2 of a projector lens of the present invention.

[0042] In the figure: 1-first lens, 2-second lens, 3-aperture, 4-third lens. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below with reference to the accompanying drawings.

[0044] The present invention provides a projector lens, comprising a first lens 1, a second lens 2, an aperture 3 and a third lens 4;

[0045] The first lens 1, the second lens 2 and the third lens 4 are arranged in sequence from the object side to the image side;

[0046] The aperture 3 is disposed between the first lens 1 and the second lens 2, or the aperture 3 is disposed between the second lens 2 and the third lens 4;

[0047] The first lens 1 and the third lens 4 have positive optical power, and the second lens 2 has negative optical power;

[0048] The light incident surface of the first lens 1 is convex, and the light emitting surface is concave;

[0049] The light incident surface of the second lens 2 is concave, and the light emitting surface is convex;

[0050] The light incident surface of the third lens 4 is a convex surface, and the light emitting surface is a convex surface;

[0051] At least two of the first lens 1 , the second lens 2 and the third lens 4 are aspherical lenses.

[0052] Furthermore, both surfaces of the aspheric lens are aspheric.

[0053] In some embodiments, the projector lens satisfies the following relationship:

[0054] 0.5mm≤f1 / f≤1.5mm;

[0055] -1.2mm≤f2 / f≤-0.2mm;

[0056] 0.2mm≤f3 / f≤1.2mm;

[0057] Wherein, f1 is the focal length of the first lens 1 , f2 is the focal length of the second lens 2 , f3 is the focal length of the third lens 4 , and f is the focal length of the projector lens.

[0058] In other embodiments, the projector lens satisfies the following relationship:

[0059] -2mm≤f1 / f2≤-1mm;

[0060] -1.5mm≤f2 / f3≤-0.5mm;

[0061] Wherein, f1 is the focal length of the first lens 1 , f2 is the focal length of the second lens 2 , f3 is the focal length of the third lens 4 , and f is the focal length of the projector lens.

[0062] In some embodiments, the projector lens satisfies the following relationship:

[0063] 1.47≤Nd1≤1.75;

[0064] 1.55≤Nd2≤1.68;

[0065] 1.47≤Nd3≤1.75;

[0066] Wherein, Nd1 is the refractive index of the material of the first lens 1 , Nd2 is the refractive index of the material of the second lens 2 , and Nd3 is the refractive index of the material of the third lens 4 .

[0067] In some embodiments, the projector lens satisfies the following relationship:

[0068] 0.7mm≤T1 / T2≤1.5mm;

[0069] 0.5mm≤T2 / T3≤1.5mm;

[0070] T2≤10mm;

[0071] Wherein, T1 is the center thickness of the first lens 1 , T2 is the center thickness of the second lens 2 , and T3 is the center thickness of the third lens 4 .

[0072] In some embodiments, the projector lens satisfies the following relationship:

[0073] 10mm≤D12≤20mm;

[0074] 0.2mm≤D23≤3mm;

[0075] Wherein, D12 is the distance from the light exit surface of the first lens 1 to the light incident surface of the second lens 2 , and D23 is the distance from the light exit surface of the second lens 2 to the light incident surface of the third lens 4 .

[0076] Example 1

[0077] In this embodiment, if Figure 1-Figure 3 As shown, from left to right along the direction of light propagation are the first lens 1, the second lens 2, the aperture 3, and the third lens 4. The first lens 1 and the third lens 4 have positive focal power, while the second lens 2 has negative focal power. The first lens 1 has a convex light-entry surface and a concave light-exit surface; the second lens 2 has a concave light-entry surface and a convex light-exit surface; and the third lens 4 has a convex light-entry surface and a convex light-exit surface.

[0078] The specific design parameters of the projection lens of this embodiment are shown in Table 1:

[0079]

[0080] Table 1

[0081] The light incident surface and the light exit surface of the second lens 2 and the third lens 4 are both aspherical surfaces, and the surface shapes satisfy the following formula:

[0082]

[0083] In the above formula, z is the aspheric surface height, r is the radius of the aspheric surface, k is the quadratic surface coefficient, c is the curvature, A4, A6, A8, A 10 、A 12 、A 14 、A 16 is the high-order coefficient of the aspheric surface.

[0084] The specific parameters are shown in Table 2:

[0085]

[0086] Table 2

[0087] The relevant parameters of each lens are as follows:

[0088] Projector lens focal length f = 88.4 mm;

[0089] The focal length of the first lens 1 is f1 = 99.4 mm;

[0090] The focal length of the second lens 2 is f2 = -61.3 mm;

[0091] The third lens 4 has a focal length of f3 = 61.08 mm;

[0092] The center thickness of the first lens 1 is T1 = 5.4 mm;

[0093] The center thickness of the second lens 2 is T2 = 4.9 mm;

[0094] The center thickness of the third lens 4 is T3 = 5.1 mm;

[0095] The distance D12 from the light exit surface of the first lens 1 to the light incident surface of the second lens 2 is 15.4 mm.

[0096] The distance D23 from the light exit surface of the second lens 2 to the light entrance surface of the third lens 4 is 0.5 mm.

[0097] The projector lens in this embodiment has a designed half-image height of 43mm and a focal length of 88.4mm. When applied to a 3-inch LCD projector, this parameter maintains a throw ratio of 1.35 with 50% off-axis, an MTF ≥ 0.5 @ 14.5 lp / mm, field curvature ≤ ±1mm, and distortion ≤ 0.3%.

[0098] Example 2

[0099] In this embodiment, if Figure 4-Figure 6As shown, from left to right along the direction of light propagation are the first lens 1, the aperture 3, the second lens 2, and the third lens 4. The first lens 1 and the third lens 4 have positive focal power, while the second lens 2 has negative focal power. The first lens 1 has a convex light-entry surface and a concave light-exit surface; the second lens 2 has a concave light-entry surface and a convex light-exit surface; and the third lens 4 has a convex light-entry surface and a convex light-exit surface.

[0100] The specific design parameters of the projection lens of this embodiment are shown in Table 3:

[0101]

[0102] Table 3

[0103] The light incident surface and light exit surface of the first lens 1, the second lens 2, and the third lens 4 are all aspherical surfaces, and their surface shapes satisfy the following formula:

[0104]

[0105] In the above formula, z is the aspheric surface height, r is the radius of the aspheric surface, k is the quadratic surface coefficient, c is the curvature, A4, A6, A8, A 10 、A 12 、A 14 、A 16 is the high-order coefficient of the aspheric surface.

[0106] The specific parameters are shown in Table 4:

[0107]

[0108] Table 4

[0109] The relevant parameters of each lens are as follows:

[0110] The focal length of the projector lens is f = 87.53 mm;

[0111] The focal length of the first lens 1 is f1 = 88.13 mm;

[0112] The focal length of the second lens 2 is f2 = -50.18 mm;

[0113] The third lens 4 has a focal length of f3 = 54.91 mm;

[0114] The center thickness of the first lens 1 is T1 = 7.1 mm;

[0115] The center thickness of the second lens 2 is T2 = 5.43 mm;

[0116] The center thickness of the third lens 4 is T3 = 6.8 mm;

[0117] The distance D12 from the light exit surface of the first lens 1 to the light incident surface of the second lens 2 is 13.84 mm.

[0118] The distance D23 from the light exit surface of the second lens 2 to the light entrance surface of the third lens 4 is 0.24 mm.

[0119] The projector lens in this embodiment has a designed half-image height of 43mm and a focal length of 87.53mm. When applied to a 3-inch LCD projector, this parameter maintains a throw ratio of 1.35 with 50% off-axis, an MTF ≥ 0.5@14.5lp / mm, field curvature ≤ ±1mm, and distortion ≤ 0.5%.

[0120] Finally, the present invention should explain that: the above embodiments are detailed descriptions of the technical solutions of the present invention and are not limited to the aforementioned embodiments. Those skilled in the art should understand that modifications or replacements of the features and parameters in the aforementioned embodiments do not depart from the spirit and scope of the technical solutions of the aforementioned embodiments.

Claims

1. A projector lens, characterized in that: It includes a first lens (1), a second lens (2), an aperture (3) and a third lens (4); The first lens (1), the second lens (2) and the third lens (4) are arranged in sequence from the object side to the image side; The aperture (3) is arranged between the first lens (1) and the second lens (2), or the aperture (3) is arranged between the second lens (2) and the third lens (4); The first lens (1) and the third lens (4) have positive optical power, and the second lens (2) has negative optical power; The light incident surface of the first lens (1) is a convex surface, and the light emitting surface is a concave surface; The light incident surface of the second lens (2) is a concave surface, and the light emitting surface is a convex surface; The third lens (4) has a convex light incident surface and a convex light exit surface; At least two of the first lens (1), the second lens (2) and the third lens (4) are aspherical lenses; The projector lens satisfies the following relationship: 10mm≤D12≤20mm; 0.2mm≤D23≤3mm; Wherein, D12 is the distance from the light-emitting surface of the first lens (1) to the light-entering surface of the second lens (2), and D23 is the distance from the light-emitting surface of the second lens (2) to the light-entering surface of the third lens (4).

2. The projector lens according to claim 1, wherein: Both surfaces of the aspheric lens are aspheric.

3. The projector lens according to claim 1, wherein: The projector lens satisfies the following relationship: 0.5≤f1 / f≤1.5; -1.2≤f2 / f≤-0.2; 0.2≤f3 / f≤1.2; Wherein, f1 is the focal length of the first lens (1), f2 is the focal length of the second lens (2), f3 is the focal length of the third lens (4), and f is the focal length of the projector lens.

4. The projector lens according to claim 1, wherein: The projector lens satisfies the following relationship: -2≤f1 / f2≤-1; -1.5≤f2 / f3≤-0.5; Wherein, f1 is the focal length of the first lens (1), f2 is the focal length of the second lens (2), f3 is the focal length of the third lens (4), and f is the focal length of the projector lens.

5. The projector lens according to claim 1, wherein: The projector lens satisfies the following relationship: 1.47≤Nd1≤1.75; 1.55≤Nd2≤1.68; 1.47≤Nd3≤1.75; Wherein, Nd1 is the refractive index of the material of the first lens (1), Nd2 is the refractive index of the material of the second lens (2), and Nd3 is the refractive index of the material of the third lens (4).

6. The projector lens according to claim 1, wherein: The projector lens satisfies the following relationship: 0.7≤T1 / T2≤1.5; 0.5≤T2 / T3≤1.5; T2≤10mm; Wherein, T1 is the center thickness of the first lens (1), T2 is the center thickness of the second lens (2), and T3 is the center thickness of the third lens (4).

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