WO2019109596A1 - 投影镜头 - Google Patents

投影镜头 Download PDF

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Publication number
WO2019109596A1
WO2019109596A1 PCT/CN2018/086743 CN2018086743W WO2019109596A1 WO 2019109596 A1 WO2019109596 A1 WO 2019109596A1 CN 2018086743 W CN2018086743 W CN 2018086743W WO 2019109596 A1 WO2019109596 A1 WO 2019109596A1
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Prior art keywords
lens
projection lens
optical axis
projection
image source
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PCT/CN2018/086743
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English (en)
French (fr)
Inventor
黄林
宋立通
Original Assignee
浙江舜宇光学有限公司
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Priority claimed from CN201711260269.3A external-priority patent/CN107783258B/zh
Priority claimed from CN201721662767.6U external-priority patent/CN207473185U/zh
Application filed by 浙江舜宇光学有限公司 filed Critical 浙江舜宇光学有限公司
Priority to US16/226,951 priority Critical patent/US11385441B2/en
Publication of WO2019109596A1 publication Critical patent/WO2019109596A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces

Definitions

  • the present application relates to a projection lens, and more particularly, to a projection lens including four lenses.
  • the three-dimensional depth camera can obtain the three-dimensional position and size information of the object, which is of great significance in the application of AR (Augmented Reality) technology.
  • Coded structured light technology is one of the most important deep recognition branching techniques.
  • the principle of the coded structure light depth recognition technology is: a specially coded image is projected onto the object by the projection lens module; an image receiving module is used to receive the reflected pattern information; and the depth information of the object is obtained through the back end algorithm processing.
  • the projection lens directly affects the recognition range and accuracy of depth recognition.
  • the present invention is directed to a projection lens having a large field of view and miniaturization features to better meet the application requirements of a depth recognition projection lens.
  • the present application provides a projection lens that can be adapted for use in a portable electronic product that can at least solve or partially address at least one of the above disadvantages of the prior art.
  • the present application provides a projection lens that includes, in order from the imaging side to the image source side along the optical axis, a first lens, a second lens, a third lens, and a fourth lens.
  • the first lens may have a positive power
  • the imaging side surface may be a convex surface
  • the second lens has a positive power or a negative power
  • the image source side surface may be a convex surface
  • the third lens may have a positive power
  • the fourth lens has a positive power or a negative power.
  • the maximum incident angle CRA of the chief ray, the optical total length TTL of the projection lens, and the half IH of the diagonal of the image source region can satisfy 0 ⁇ (1+TAN(CRA))*TTL/IH. ⁇ 2.5.
  • the maximum half angle of view HFOV of the projection lens may satisfy 0.9 ⁇ TAN (HFOV) ⁇ 1.2.
  • the light transmittance of the projection lens may be greater than 85% in the light wave band of 800 nm to 1000 nm.
  • the effective focal length f1 of the first lens and the effective focal length f2 of the second lens may satisfy 2.0 ⁇
  • the radius of curvature R4 of the image source side surface of the second lens and the radius of curvature R5 of the image side surface of the third lens may satisfy 0.8 ⁇ R4 / R5 ⁇ 1.2.
  • the distance SAG32 on the optical axis to the apex of the effective half aperture of the image source side surface to the third lens may satisfy 0.3 ⁇ SAG31/SAG32 ⁇ 0.7.
  • the effective half aperture DT11 of the imaging side surface of the first lens and the effective half aperture DT21 of the image source side surface of the first lens may satisfy 0.7 ⁇ DT11 / DT21 ⁇ 1.0.
  • the center thickness CT3 of the third lens on the optical axis and the center thickness CT4 of the fourth lens on the optical axis may satisfy 1.5 ⁇ CT3/CT4 ⁇ 2.5.
  • the separation distance T12 of the first lens and the second lens on the optical axis and the separation distance T23 of the second lens and the third lens on the optical axis may satisfy 0.4 ⁇ T12/T23 ⁇ 0.7.
  • the present application also provides a projection lens that includes, in order from the imaging side to the image source side along the optical axis, a first lens, a second lens, a third lens, and a fourth lens.
  • the first lens may have a positive power
  • the imaging side surface may be a convex surface
  • the second lens has a positive power or a negative power
  • the image source side surface may be a convex surface
  • the third lens may have a positive power
  • the fourth lens has a positive power or a negative power.
  • the effective focal length f1 of the first lens and the effective focal length f2 of the second lens can satisfy 2.0 ⁇
  • the present application also provides a projection lens that includes, in order from the imaging side to the image source side along the optical axis, a first lens, a second lens, a third lens, and a fourth lens.
  • the first lens may have a positive power
  • the imaging side surface may be a convex surface
  • the second lens has a positive power or a negative power
  • the image source side surface may be a convex surface
  • the third lens may have a positive power
  • the fourth lens has a positive power or a negative power.
  • the intersection of the imaging side surface of the third lens and the optical axis to the apex of the effective half-diameter apex of the imaging side surface of the third lens on the optical axis SAG31 and the intersection of the image source side surface of the third lens and the optical axis to the third lens The distance SAG32 of the effective half-caliber apex of the source side surface on the optical axis satisfies 0.3 ⁇ SAG31/SAG32 ⁇ 0.7.
  • a plurality of (for example, four) lenses are used, and the projection lens is miniaturized by appropriately distributing the power, the surface shape, the center thickness of each lens, and the on-axis spacing between the lenses.
  • At least one beneficial effect such as large field of view, high image quality, low sensitivity, and deep recognition requirements.
  • FIG. 1 is a schematic structural view of a projection lens according to Embodiment 1 of the present application.
  • 2A to 2C respectively show an axial chromatic aberration curve, an astigmatism curve, and a distortion curve of the projection lens of Embodiment 1;
  • FIG. 3 is a schematic structural view of a projection lens according to Embodiment 2 of the present application.
  • 4A to 4C respectively show an axial chromatic aberration curve, an astigmatism curve, and a distortion curve of the projection lens of Embodiment 2;
  • FIG. 5 is a schematic structural diagram of a projection lens according to Embodiment 3 of the present application.
  • 6A to 6C respectively show an axial chromatic aberration curve, an astigmatism curve, and a distortion curve of the projection lens of Embodiment 3;
  • FIG. 7 is a schematic structural diagram of a projection lens according to Embodiment 4 of the present application.
  • 8A to 8C respectively show an axial chromatic aberration curve, an astigmatism curve, and a distortion curve of the projection lens of Embodiment 4;
  • FIG. 9 is a schematic structural diagram of a projection lens according to Embodiment 5 of the present application.
  • 10A to 10C respectively show an axial chromatic aberration curve, an astigmatism curve, and a distortion curve of the projection lens of Embodiment 5.
  • first, second, etc. are used to distinguish one feature from another, and do not represent any limitation of the feature.
  • first lens discussed below may also be referred to as a second lens
  • second lens may also be referred to as a first lens, without departing from the teachings of the present application.
  • the thickness, size, and shape of the lens have been somewhat exaggerated for convenience of explanation.
  • the spherical or aspherical shape shown in the drawings is shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the spherical or aspherical shape shown in the drawings.
  • the drawings are only examples and are not to scale.
  • a paraxial region refers to a region near the optical axis. If the surface of the lens is convex and the position of the convex surface is not defined, it indicates that the surface of the lens is convex at least in the paraxial region; if the surface of the lens is concave and the position of the concave surface is not defined, it indicates that the surface of the lens is at least in the paraxial region. Concave.
  • the surface closest to the image source side in each lens is referred to as an image source side surface, and the surface closest to the image side in each lens is referred to as an image side surface.
  • the projection lens according to an exemplary embodiment of the present application may include, for example, four lenses having powers, that is, a first lens, a second lens, a third lens, and a fourth lens.
  • the four lenses are sequentially arranged from the imaging side to the image source side along the optical axis.
  • the first lens may have a positive power
  • the imaging side surface may be a convex surface
  • the second lens has a positive power or a negative power
  • the image source side surface may be a convex surface
  • the third lens may be There is a positive power
  • the fourth lens has a positive power or a negative power.
  • the second lens may have a positive power, and an image forming side surface thereof may be a concave surface.
  • the image source side surface of the fourth lens may be a concave surface.
  • the projection lens of the present application can satisfy the conditional expression 0 ⁇ (1+TAN(CRA))*TTL/IH ⁇ 2.5, where CRA is the maximum incident angle of the main ray, and TTL is the optics of the projection lens.
  • the total length, IH is half the length of the diagonal of the source region.
  • the total optical length of the projection lens refers to the distance from the imaging side surface of the first lens to the image source surface on the optical axis.
  • the total optical length TTL in the present application may refer to the image from the imaging side surface of the first lens to the image. The distance of the source surface on the optical axis.
  • CRA, TTL, and IH can further satisfy 2.0 ⁇ (1 + TAN (CRA)) * TTL / IH ⁇ 2.5, for example, 2.12 ⁇ (1 + TAN (CRA)) * TTL / IH ⁇ 2.31. Satisfying the conditional expression 0 ⁇ (1 + TAN (CRA)) * TTL / IH ⁇ 2.5, a larger field of view angle and a shorter total optical length can be obtained to meet the requirements of large depth recognition range and miniaturization of the projection module.
  • the projection lens of the present application may satisfy the conditional expression 2.0 ⁇
  • the projection lens of the present application may satisfy the conditional expression 0.8 ⁇ R4/R5 ⁇ 1.2, where R4 is the radius of curvature of the image source side surface of the second lens, and R5 is the imaging side surface of the third lens Radius of curvature. More specifically, R4 and R5 may further satisfy 0.83 ⁇ R4 / R5 ⁇ 1.07. Satisfying the conditional formula 0.8 ⁇ R4/R5 ⁇ 1.2, the field curvature aberration of the system can be effectively corrected to ensure the balance of imaging quality between the central region and the edge region.
  • the projection lens of the present application may satisfy the conditional expression 0.3 ⁇ SAG31/SAG32 ⁇ 0.7, wherein SAG31 is the effective half of the intersection of the imaging side surface and the optical axis of the third lens to the imaging side surface of the third lens.
  • the distance of the apex of the aperture on the optical axis, SAG32 is the distance from the intersection of the source side surface of the third lens and the optical axis to the apex of the effective half aperture of the image source side surface of the third lens on the optical axis.
  • SAG31 and SAG32 may further satisfy 0.40 ⁇ SAG31/SAG32 ⁇ 0.60, for example, 0.50 ⁇ SAG31/SAG32 ⁇ 0.53. Satisfying the conditional expression 0.3 ⁇ SAG31/SAG32 ⁇ 0.7, the spherical aberration of the system can be effectively eliminated to obtain a high-definition image.
  • the projection lens of the present application may satisfy the conditional expression 0.7 ⁇ DT11/DT21 ⁇ 1.0, wherein DT11 is the effective half aperture of the imaging side surface of the first lens, and DT21 is the image source side surface of the first lens. Effective half-caliber. More specifically, DT11 and DT21 can further satisfy 0.86 ⁇ DT11 / DT21 ⁇ 0.95. Satisfying the conditional expression 0.7 ⁇ DT11/DT21 ⁇ 1.0 is beneficial to obtain a shorter total lens length to meet the lens miniaturization requirements.
  • the projection lens of the present application may satisfy the conditional expression 1.5 ⁇ CT3/CT4 ⁇ 2.5, where CT3 is the center thickness of the third lens on the optical axis, and CT4 is the center of the fourth lens on the optical axis. thickness. More specifically, CT3 and CT4 can further satisfy 1.64 ⁇ CT3 / CT4 ⁇ 2.43. Satisfying the conditional expression 1.5 ⁇ CT3/CT4 ⁇ 2.5 is advantageous for obtaining a larger angle of view and ensuring higher image quality.
  • the projection lens of the present application may satisfy the conditional expression 0.4 ⁇ T12/T23 ⁇ 0.7, where T12 is the separation distance of the first lens and the second lens on the optical axis, and T23 is the second lens and the The separation distance of the three lenses on the optical axis. More specifically, T12 and T23 can further satisfy 0.56 ⁇ T12 / T23 ⁇ 0.62. Satisfying the conditional formula 0.4 ⁇ T12/T23 ⁇ 0.7, it is beneficial to reduce the tolerance sensitivity of the lens to meet the lens workability requirements.
  • the projection lens of the present application has a light transmittance of greater than 85% in a light wave band of about 800 nm to about 1000 nm. Such an arrangement is advantageous for obtaining a high-brightness projection picture and reducing the aperture requirement for the projection lens.
  • the projection lens of the present application may satisfy the conditional formula 0.9 ⁇ TAN(HFOV) ⁇ 1.2, where HFOV is the maximum half angle of view of the projection lens. More specifically, HFOV can further satisfy 0.95 ⁇ TAN (HFOV) ⁇ 1.04. The conditional formula 0.9 ⁇ TAN(HFOV) ⁇ 1.2 is satisfied, which can meet the requirements of the depth recognition region range and maintain high recognition accuracy.
  • the above projection lens may further include at least one aperture to enhance the imaging quality of the lens.
  • the aperture may be disposed at any position as needed, for example, the aperture may be disposed between the imaging side and the first lens.
  • the above projection lens may further include other well-known optical projection elements such as prisms, field mirrors and the like.
  • the main difference of the projection lens is that the light of the general imaging lens forms an image surface from the object side to the imaging side; while the light of the general projection lens is enlarged from the image side to the imaging side, the image plane is enlarged and projected to the projection surface. .
  • the amount of light entering the projection lens is controlled by the object numerical aperture and the lens aperture.
  • the projection lens according to the above-described embodiment of the present application can employ, for example, four lenses, so that the projection lens has the projection lens by rationally distributing the power of each lens, the face shape, the center thickness of each lens, and the on-axis spacing between the lenses. Miniaturization, large field of view, low sensitivity, high image quality, and at least one beneficial effect to meet deep recognition requirements.
  • At least one of the mirror faces of each lens is an aspherical mirror.
  • the aspherical lens is characterized by a continuous change in curvature from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, the aspherical lens has better curvature radius characteristics, and has the advantages of improving distortion and improving astigmatic aberration. With an aspherical lens, the aberrations that occur during imaging can be eliminated as much as possible, improving image quality.
  • the various results and advantages described in this specification can be obtained without varying the number of lenses that make up the projection lens without departing from the technical solutions claimed herein.
  • the projection lens is not limited to including four lenses.
  • the projection lens can also include other numbers of lenses if desired.
  • FIG. 1 is a block diagram showing the structure of a projection lens according to Embodiment 1 of the present application.
  • a projection lens sequentially includes an aperture STO, a first lens E1, a second lens E2, a third lens E3, and a portion from the imaging side to the image source side along the optical axis.
  • the first lens E1 has a positive power, the imaging side surface S1 is a convex surface, and the image side surface S2 is a concave surface;
  • the second lens E2 has a positive power, the imaging side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
  • the third lens E3 has positive refractive power, the imaging side surface S5 is concave, the image side surface S6 is convex, and the fourth lens E4 has negative refractive power, the imaging side surface S7 is convex, and the image side surface S8 is Concave.
  • S9 may be an image source surface, and light from the source side of the projection lens sequentially passes through the respective surfaces S8 to S1 and is finally imaged on the screen (not shown).
  • the light transmittance of the projection lens is greater than 85%.
  • Table 1 shows the surface type, radius of curvature, thickness, material, and conical coefficient of each lens of the projection lens of Example 1, in which the unit of curvature radius and thickness are both millimeters (mm).
  • each aspherical lens can be defined by using, but not limited to, the following aspherical formula:
  • x is the distance of the aspherical surface at height h from the optical axis, and the distance from the aspherical vertex is high;
  • k is the conic coefficient (given in Table 1);
  • Ai is the correction coefficient of the a-th order of the aspherical surface.
  • Table 2 gives the high order term coefficients A 4 , A 6 , A 8 , A 10 , A 12 , A 14 and A 16 which can be used for the respective aspherical mirror faces S1 - S8 in the embodiment 1.
  • Table 3 gives the total optical length TTL of the projection lens in Embodiment 1 (i.e., the distance from the imaging side surface S1 of the first lens E1 to the image source surface S9 on the optical axis), the maximum half angle of view HFOV, and the total effective The focal length f and the effective focal lengths f1 to f4 of the respective lenses.
  • the projection lens in Embodiment 1 satisfies:
  • R4 / R5 0.98, wherein R4 is the radius of curvature of the image source side surface S4 of the second lens E2, and R5 is the radius of curvature of the image side surface S5 of the third lens E3;
  • SAG31/SAG32 0.50, wherein SAG31 is the distance from the intersection of the imaging side surface S5 of the third lens E3 and the optical axis to the effective half-diameter apex of the imaging side surface S5 of the third lens E3 on the optical axis, and SAG32 is the third lens The distance from the intersection of the image source side surface S6 and the optical axis of E3 to the effective half aperture apex of the image source side surface S6 of the third lens E3 on the optical axis;
  • DT11 / DT21 0.89, wherein DT11 is the effective half diameter of the imaging side surface S1 of the first lens E1, and DT21 is the effective half diameter of the image source side surface S2 of the first lens E1;
  • CT3/CT4 1.94, wherein CT3 is the center thickness of the third lens E3 on the optical axis, and CT4 is the center thickness of the fourth lens E4 on the optical axis;
  • T12/T23 0.56, where T12 is the separation distance of the first lens E1 and the second lens E2 on the optical axis, and T23 is the separation distance of the second lens E2 and the third lens E3 on the optical axis;
  • TAN(HFOV) 1.04, where HFOV is the maximum half angle of view of the projection lens.
  • 2A shows an axial chromatic aberration curve of the projection lens of Embodiment 1, which indicates that light of different wavelengths is deviated from a focus point after the lens.
  • 2B shows an astigmatism curve of the projection lens of Embodiment 1, which shows a meridional field curvature and a sagittal image plane curvature.
  • 2C shows a distortion curve of the projection lens of Embodiment 1, which shows distortion magnitude values in the case of different viewing angles.
  • the projection lens given in Embodiment 1 can achieve good image quality.
  • FIG. 3 is a schematic structural view of a projection lens according to Embodiment 2 of the present application.
  • a projection lens sequentially includes an aperture STO, a first lens E1, a second lens E2, a third lens E3, and a portion from the imaging side to the image source side along the optical axis.
  • the first lens E1 has a positive power, the imaging side surface S1 is a convex surface, and the image side surface S2 is a concave surface;
  • the second lens E2 has a positive power, the imaging side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
  • the third lens E3 has positive refractive power, the imaging side surface S5 is concave, the image side surface S6 is convex, and the fourth lens E4 has negative refractive power, the imaging side surface S7 is convex, and the image side surface S8 is Concave.
  • S9 may be an image source surface, and light from the source side of the projection lens sequentially passes through the respective surfaces S8 to S1 and is finally imaged on the screen (not shown).
  • the light transmittance of the projection lens is greater than 85%.
  • Table 4 shows the surface type, the radius of curvature, the thickness, the material, and the conical coefficient of each lens of the projection lens of Example 2, wherein the unit of the radius of curvature and the thickness are each mm (mm).
  • the image forming side surface and the image source side surface of any one of the first lens E1 to the fourth lens E4 are aspherical.
  • Table 5 shows the high order coefficient which can be used for each aspherical mirror in Embodiment 2, wherein each aspherical surface type can be defined by the formula (1) given in the above Embodiment 1.
  • Table 6 gives the optical total length TTL, the maximum half angle of view HFOV, the total effective focal length f of the projection lens of Embodiment 2, and the effective focal lengths f1 to f4 of the respective lenses.
  • 4A shows an axial chromatic aberration curve of the projection lens of Embodiment 2, which indicates that light of different wavelengths is deviated from a focus point after the lens.
  • 4B shows an astigmatism curve of the projection lens of Embodiment 2, which shows meridional field curvature and sagittal image plane curvature.
  • 4C shows a distortion curve of the projection lens of Embodiment 2, which shows distortion magnitude values in the case of different viewing angles.
  • the projection lens given in Embodiment 2 can achieve good image quality.
  • FIG. 5 is a schematic structural view of a projection lens according to Embodiment 3 of the present application.
  • a projection lens sequentially includes an aperture STO, a first lens E1, a second lens E2, a third lens E3, and a portion from the imaging side to the image source side along the optical axis.
  • the first lens E1 has a positive power, the imaging side surface S1 is a convex surface, and the image side surface S2 is a concave surface;
  • the second lens E2 has a positive power, the imaging side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
  • the third lens E3 has positive refractive power, the imaging side surface S5 is concave, the image side surface S6 is convex, and the fourth lens E4 has negative power, the imaging side surface S7 is concave, and the image side surface S8 is Concave.
  • S9 may be an image source surface, and light from the source side of the projection lens sequentially passes through the respective surfaces S8 to S1 and is finally imaged on the screen (not shown).
  • the light transmittance of the projection lens is greater than 85%.
  • Table 7 shows the surface type, the radius of curvature, the thickness, the material, and the conical coefficient of each lens of the projection lens of Example 3, wherein the units of the radius of curvature and the thickness are each mm (mm).
  • the imaging side surface and the image source side surface of any one of the first lens E1 to the fourth lens E4 are aspherical.
  • Table 5 shows the high order coefficient which can be used for each aspherical mirror in Embodiment 2, wherein each aspherical surface type can be defined by the formula (1) given in the above Embodiment 1.
  • Table 9 gives the optical total length TTL, the maximum half angle of view HFOV, the total effective focal length f of the projection lens of Embodiment 3, and the effective focal lengths f1 to f4 of the respective lenses.
  • Fig. 6A shows an axial chromatic aberration curve of the projection lens of Embodiment 3, which shows that light of different wavelengths is deviated from the focus point after the lens.
  • Fig. 6B shows an astigmatism curve of the projection lens of Embodiment 3, which shows meridional field curvature and sagittal image plane curvature.
  • Fig. 6C shows a distortion curve of the projection lens of Embodiment 3, which shows the distortion magnitude value in the case of different viewing angles. 6A to 6C, the projection lens given in Embodiment 3 can achieve good image quality.
  • FIG. 7 is a block diagram showing the structure of a projection lens according to Embodiment 4 of the present application.
  • a projection lens sequentially includes an aperture STO, a first lens E1, a second lens E2, a third lens E3, and a portion from the imaging side to the image source side along the optical axis.
  • the first lens E1 has a positive power, the imaging side surface S1 is a convex surface, and the image side surface S2 is a concave surface;
  • the second lens E2 has a positive power, the imaging side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
  • the third lens E3 has positive refractive power, the imaging side surface S5 is concave, the image side surface S6 is convex, and the fourth lens E4 has negative refractive power, the imaging side surface S7 is convex, and the image side surface S8 is Concave.
  • S9 may be an image source surface, and light from the source side of the projection lens sequentially passes through the respective surfaces S8 to S1 and is finally imaged on the screen (not shown).
  • the light transmittance of the projection lens is greater than 85%.
  • Table 10 shows the surface type, the radius of curvature, the thickness, the material, and the conical coefficient of each lens of the projection lens of Example 4, wherein the unit of the radius of curvature and the thickness are each mm (mm).
  • the imaging side surface and the image source side surface of any one of the first lens E1 to the fourth lens E4 are aspherical.
  • Table 11 shows the high order coefficient which can be used for each aspherical mirror in Embodiment 4, wherein each aspherical surface type can be defined by the formula (1) given in the above Embodiment 1.
  • Table 12 gives the optical total length TTL, the maximum half angle of view HFOV, the total effective focal length f of the projection lens of Embodiment 4, and the effective focal lengths f1 to f4 of the respective lenses.
  • Fig. 8A shows an axial chromatic aberration curve of the projection lens of Embodiment 4, which shows that light of different wavelengths is deviated from the focus point after the lens.
  • Fig. 8B shows an astigmatism curve of the projection lens of Embodiment 4, which shows meridional field curvature and sagittal image plane curvature.
  • Fig. 8C shows a distortion curve of the projection lens of Embodiment 4, which shows distortion magnitude values in the case of different viewing angles. 8A to 8C, the projection lens given in Embodiment 4 can achieve good image quality.
  • FIG. 9 is a block diagram showing the structure of a projection lens according to Embodiment 5 of the present application.
  • a projection lens sequentially includes an aperture STO, a first lens E1, a second lens E2, a third lens E3, and a portion from the imaging side to the image source side along the optical axis.
  • the first lens E1 has a positive power, the imaging side surface S1 is a convex surface, and the image side surface S2 is a concave surface;
  • the second lens E2 has a positive power, the imaging side surface S3 is a concave surface, and the image side surface S4 is a convex surface;
  • the third lens E3 has a positive refractive power, the imaging side surface S5 is a concave surface, the image side surface S6 is a convex surface, and the fourth lens E4 has a positive refractive power, the imaging side surface S7 is a convex surface, and the image side surface S8 is a concave surface.
  • S9 may be an image source surface, and light from the source side of the projection lens sequentially passes through the respective surfaces S8 to S1 and is finally imaged on the screen (not shown).
  • the light transmittance of the projection lens is greater than 85%.
  • Table 13 shows the surface type, radius of curvature, thickness, material, and conical coefficient of each lens of the projection lens of Example 5, in which the unit of the radius of curvature and the thickness are each mm (mm).
  • the imaging side surface and the image source side surface of any one of the first lens E1 to the fourth lens E4 are aspherical.
  • Table 14 shows the high order coefficient which can be used for each aspherical mirror surface in Embodiment 5, wherein each aspherical surface type can be defined by the formula (1) given in the above Embodiment 1.
  • Table 15 gives the optical total length TTL, the maximum half angle of view HFOV, the total effective focal length f of the projection lens of Embodiment 5, and the effective focal lengths f1 to f4 of the respective lenses.
  • Fig. 10A shows an axial chromatic aberration curve of the projection lens of Embodiment 5, which shows that light of different wavelengths is deviated from the focus point after the lens.
  • Fig. 10B shows an astigmatism curve of the projection lens of Embodiment 5, which shows meridional field curvature and sagittal image plane curvature.
  • Fig. 10C shows a distortion curve of the projection lens of Embodiment 5, which shows distortion magnitude values in the case of different viewing angles. 10A to 10C, the projection lens given in Embodiment 5 can achieve good image quality.
  • Embodiments 1 to 5 respectively satisfy the relationship shown in Table 16.

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Abstract

一种投影镜头，沿光轴由成像侧至像源侧依序包括：第一透镜（E1）、第二透镜（E2）、第三透镜（E3）和第四透镜（E4）。其中，第一透镜具有正光焦度，其成像侧表面为凸面；第二透镜具有正光焦度或负光焦度，其像源侧表面为凸面；第三透镜具有正光焦度；以及第四透镜具有正光焦度或负光焦度。

Description

投影镜头
相关申请的交叉引用
本申请要求于2017年12月4日提交于中国国家知识产权局(SIPO)的、专利申请号为201711260269.3的中国专利申请以及于2017年12月4日提交至SIPO的、专利申请号为201721662767.6的中国专利申请的优先权和权益，以上中国专利申请通过引用整体并入本文。
技术领域
本申请涉及一种投影镜头，更具体地，本申请涉及一种包括四片透镜的投影镜头。
背景技术
近年来，深度识别技术得到了快速发展，三维深度相机可以获得拍摄对象的三维位置及尺寸信息，这在AR(增强现实)技术应用中具有重要意义。
编码结构光技术是最重要的深度识别分支技术之一。编码结构光深度识别技术原理是：由投影镜头模块将经过特殊编码的图像投射到拍摄对象上；利用一个成像接收模块来接收反射回来的图案信息；以及经过后端算法处理得到拍摄对象的深度信息。投影镜头作为编码结构光深度识别技术的核心元件，直接影响了深度识别的识别范围和准确度。
因此，本发明旨在提供一种具有大视场、小型化特征的投影镜头，以较好地满足深度识别投影镜头的应用需求。
发明内容
本申请提供了可适用于便携式电子产品的、可至少解决或部分解决现有技术中的上述至少一个缺点的投影镜头。
一方面，本申请提供了这样一种投影镜头，该镜头沿光轴由成像 侧至像源侧依序包括：第一透镜、第二透镜、第三透镜和第四透镜。其中，第一透镜可具有正光焦度，其成像侧表面可为凸面；第二透镜具有正光焦度或负光焦度，其像源侧表面可为凸面；第三透镜可具有正光焦度；以及第四透镜具有正光焦度或负光焦度。
在一个实施方式中，主光线的最大入射角度CRA、投影镜头的光学总长度TTL与像源区域对角线长的一半IH之间可满足0＜(1+TAN(CRA))*TTL/IH＜2.5。
在一个实施方式中，投影镜头的最大半视场角HFOV可满足0.9＜TAN(HFOV)＜1.2。
在一个实施方式中，在800nm至1000nm的光波波段中，投影镜头的光线透过率可大于85％。
在一个实施方式中，第一透镜的有效焦距f1与第二透镜的有效焦距f2可满足2.0＜|f1/f2|＜2.8。
在一个实施方式中，第二透镜的像源侧表面的曲率半径R4与第三透镜的成像侧表面的曲率半径R5可满足0.8＜R4/R5＜1.2。
在一个实施方式中，第三透镜的成像侧表面和光轴的交点至第三透镜的成像侧表面的有效半口径顶点在光轴上的距离SAG31与第三透镜的像源侧表面和光轴的交点至第三透镜的像源侧表面的有效半口径顶点在光轴上的距离SAG32可满足0.3＜SAG31/SAG32＜0.7。
在一个实施方式中，第一透镜的成像侧表面的有效半口径DT11与第一透镜的像源侧表面的有效半口径DT21可满足0.7＜DT11/DT21＜1.0。
在一个实施方式中，第三透镜于光轴上的中心厚度CT3与第四透镜于光轴上的中心厚度CT4可满足1.5＜CT3/CT4＜2.5。
在一个实施方式中，第一透镜和第二透镜在光轴上的间隔距离T12与第二透镜和第三透镜在光轴上的间隔距离T23可满足0.4＜T12/T23＜0.7。
另一方面，本申请还提供了这样一种投影镜头，该镜头沿光轴由成像侧至像源侧依序包括：第一透镜、第二透镜、第三透镜和第四透镜。其中，第一透镜可具有正光焦度，其成像侧表面可为凸面；第二 透镜具有正光焦度或负光焦度，其像源侧表面可为凸面；第三透镜可具有正光焦度；以及第四透镜具有正光焦度或负光焦度。其中，第一透镜的有效焦距f1与第二透镜的有效焦距f2可满足2.0＜|f1/f2|＜2.8。
又一方面，本申请还提供了这样一种投影镜头，该镜头沿光轴由成像侧至像源侧依序包括：第一透镜、第二透镜、第三透镜和第四透镜。其中，第一透镜可具有正光焦度，其成像侧表面可为凸面；第二透镜具有正光焦度或负光焦度，其像源侧表面可为凸面；第三透镜可具有正光焦度；以及第四透镜具有正光焦度或负光焦度。其中，第三透镜的成像侧表面和光轴的交点至第三透镜的成像侧表面的有效半口径顶点在光轴上的距离SAG31与第三透镜的像源侧表面和光轴的交点至第三透镜的像源侧表面的有效半口径顶点在光轴上的距离SAG32可满足0.3＜SAG31/SAG32＜0.7。
本申请采用了多片(例如，四片)透镜，通过合理分配各透镜的光焦度、面型、各透镜的中心厚度以及各透镜之间的轴上间距等，使得上述投影镜头具有小型化、大视场、高成像品质、低敏感度、可满足深度识别要求等至少一个有益效果。
附图说明
结合附图，通过以下非限制性实施方式的详细描述，本申请的其他特征、目的和优点将变得更加明显。在附图中：
图1示出了根据本申请实施例1的投影镜头的结构示意图；
图2A至图2C分别示出了实施例1的投影镜头的轴上色差曲线、象散曲线以及畸变曲线；
图3示出了根据本申请实施例2的投影镜头的结构示意图；
图4A至图4C分别示出了实施例2的投影镜头的轴上色差曲线、象散曲线以及畸变曲线；
图5示出了根据本申请实施例3的投影镜头的结构示意图；
图6A至图6C分别示出了实施例3的投影镜头的轴上色差曲线、象散曲线以及畸变曲线；
图7示出了根据本申请实施例4的投影镜头的结构示意图；
图8A至图8C分别示出了实施例4的投影镜头的轴上色差曲线、象散曲线以及畸变曲线；
图9示出了根据本申请实施例5的投影镜头的结构示意图；
图10A至图10C分别示出了实施例5的投影镜头的轴上色差曲线、象散曲线以及畸变曲线。
具体实施方式
为了更好地理解本申请，将参考附图对本申请的各个方面做出更详细的说明。应理解，这些详细说明只是对本申请的示例性实施方式的描述，而非以任何方式限制本申请的范围。在说明书全文中，相同的附图标号指代相同的元件。表述“和/或”包括相关联的所列项目中的一个或多个的任何和全部组合。
应注意，在本说明书中，第一、第二等的表述仅用于将一个特征与另一个特征区分开来，而不表示对特征的任何限制。因此，在不背离本申请的教导的情况下，下文中讨论的第一透镜也可被称作第二透镜，第二透镜也可被称作第一透镜。
在附图中，为了便于说明，已稍微夸大了透镜的厚度、尺寸和形状。具体来讲，附图中所示的球面或非球面的形状通过示例的方式示出。即，球面或非球面的形状不限于附图中示出的球面或非球面的形状。附图仅为示例而并非严格按比例绘制。
在本文中，近轴区域是指光轴附近的区域。若透镜表面为凸面且未界定该凸面位置时，则表示该透镜表面至少于近轴区域为凸面；若透镜表面为凹面且未界定该凹面位置时，则表示该透镜表面至少于近轴区域为凹面。每个透镜中最靠近像源侧的表面称为像源侧表面，每个透镜中最靠近成像侧的表面称为成像侧表面。
还应理解的是，用语“包括”、“包括有”、“具有”、“包含”和/或“包含有”，当在本说明书中使用时表示存在所陈述的特征、元件和/或部件，但不排除存在或附加有一个或多个其它特征、元件、部件和/或它们的组合。此外，当诸如“...中的至少一个”的表述出现在所列特征的列表之后时，修饰整个所列特征，而不是修饰列表中的单独元件。此 外，当描述本申请的实施方式时，使用“可”表示“本申请的一个或多个实施方式”。并且，用语“示例性的”旨在指代示例或举例说明。
除非另外限定，否则本文中使用的所有用语(包括技术用语和科学用语)均具有与本申请所属领域普通技术人员的通常理解相同的含义。还应理解的是，用语(例如在常用词典中定义的用语)应被解释为具有与它们在相关技术的上下文中的含义一致的含义，并且将不被以理想化或过度正式意义解释，除非本文中明确如此限定。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。下面将参考附图并结合实施例来详细说明本申请。
以下对本申请的特征、原理和其他方面进行详细描述。
根据本申请示例性实施方式的投影镜头可包括例如四片具有光焦度的透镜，即，第一透镜、第二透镜、第三透镜和第四透镜。这四片透镜沿着光轴由成像侧至像源侧依序排列。
在示例性实施方式中，第一透镜可具有正光焦度，其成像侧表面可为凸面；第二透镜具有正光焦度或负光焦度，其像源侧表面可为凸面；第三透镜可具有正光焦度；第四透镜具有正光焦度或负光焦度。
在示例性实施方式中，第二透镜可具有正光焦度，其成像侧表面可为凹面。
在示例性实施方式中，第四透镜的像源侧表面可为凹面。
在示例性实施方式中，本申请的投影镜头可满足条件式0＜(1+TAN(CRA))*TTL/IH＜2.5，其中，CRA为主光线的最大入射角度，TTL为投影镜头的光学总长度，IH为像源区域对角线长的一半。投影镜头的光学总长度是指从第一透镜的成像侧表面至像源面在光轴上的距离，例如，本申请中的光学总长度TTL可以是指从第一透镜的成像侧表面至像源面在光轴上的距离。更具体地，CRA、TTL和IH进一步可满足2.0＜(1+TAN(CRA))*TTL/IH＜2.5，例如，2.12≤(1+TAN(CRA))*TTL/IH≤2.31。满足条件式0＜(1+TAN(CRA))*TTL/IH＜2.5，可以获得较大的视场角和较短的光学总长度，以满足大深度识 别范围和投影模块小型化的需求。
在示例性实施方式中，本申请的投影镜头可满足条件式2.0＜|f1/f2|＜2.8，其中，f1为第一透镜的有效焦距，f2为第二透镜的有效焦距。更具体地，f1和f2进一步可满足2.29≤|f1/f2|≤2.63。满足条件式2＜|f1/f2|＜2.8，可以有效消除***象散误差，以保证子午和弧矢两个方向上的像质平衡。
在示例性实施方式中，本申请的投影镜头可满足条件式0.8＜R4/R5＜1.2，其中，R4为第二透镜的像源侧表面的曲率半径，R5为第三透镜的成像侧表面的曲率半径。更具体地，R4和R5进一步可满足0.83≤R4/R5≤1.07。满足条件式0.8＜R4/R5＜1.2，可以有效校正***的场曲像差，以保证中心区域和边缘区域成像质量的均衡。
在示例性实施方式中，本申请的投影镜头可满足条件式0.3＜SAG31/SAG32＜0.7，其中，SAG31为第三透镜的成像侧表面和光轴的交点至第三透镜的成像侧表面的有效半口径顶点在光轴上的距离，SAG32为第三透镜的像源侧表面和光轴的交点至第三透镜的像源侧表面的有效半口径顶点在光轴上的距离。更具体地，SAG31和SAG32进一步可满足0.40＜SAG31/SAG32＜0.60，例如，0.50≤SAG31/SAG32≤0.53。满足条件式0.3＜SAG31/SAG32＜0.7，可以有效消除***球差，以获得高清晰度的图像。
在示例性实施方式中，本申请的投影镜头可满足条件式0.7＜DT11/DT21＜1.0，其中，DT11为第一透镜的成像侧表面的有效半口径，DT21为第一透镜的像源侧表面的有效半口径。更具体地，DT11和DT21进一步可满足0.86≤DT11/DT21≤0.95。满足条件式0.7＜DT11/DT21＜1.0，有利于获得较短的镜头总长，以满足镜头小型化要求。
在示例性实施方式中，本申请的投影镜头可满足条件式1.5＜CT3/CT4＜2.5，其中，CT3为第三透镜于光轴上的中心厚度，CT4为第四透镜于光轴上的中心厚度。更具体地，CT3和CT4进一步可满足1.64≤CT3/CT4≤2.43。满足条件式1.5＜CT3/CT4＜2.5，有利于获得较大的视场角，并保证较高的成像质量。
在示例性实施方式中，本申请的投影镜头可满足条件式0.4＜T12/T23＜0.7，其中，T12为第一透镜和第二透镜在光轴上的间隔距离，T23为第二透镜和第三透镜在光轴上的间隔距离。更具体地，T12和T23进一步可满足0.56≤T12/T23≤0.62。满足条件式0.4＜T12/T23＜0.7，有利于降低镜头的公差敏感性，以满足镜头可加工性要求。
在示例性实施方式中，本申请的投影镜头在约800nm至约1000nm的光波波段中，光线透过率大于85％。这样的设置有利于获得高亮度的投影画面，并降低对投影镜头的光圈要求。
在示例性实施方式中，本申请的投影镜头可满足条件式0.9＜TAN(HFOV)＜1.2，其中，HFOV为投影镜头的最大半视场角。更具体地，HFOV进一步可满足0.95≤TAN(HFOV)≤1.04。满足条件式0.9＜TAN(HFOV)＜1.2，可以满足深度识别区域范围要求，并保持较高的识别精度。
在示例性实施方式中，上述投影镜头还可包括至少一个光阑，以提升镜头的成像质量。光阑可根据需要设置在任意位置处，例如，光阑可设置在成像侧与第一透镜之间。
可选地，上述投影镜头还可包括其他公知的光学投影元件，例如，棱镜、场镜等。
相比于普通镜头，投影镜头主要区别在于，一般摄像镜头的光线从物侧至成像侧形成一个像面；而一般投影镜头的光线从像源侧至成像侧，将像面放大投射直至投影面。一般投影镜头的进光量由物方数值孔径与镜头光阑控制。
根据本申请的上述实施方式的投影镜头可采用例如四片透镜，通过合理分配各透镜的光焦度、面型、各透镜的中心厚度以及各透镜之间的轴上间距等，使得投影镜头具有小型化、大视场、低敏感性、高成像品质、可满足深度识别要求等至少一个有益效果。
在本申请的实施方式中，各透镜的镜面中的至少一个为非球面镜面。非球面透镜的特点是：从透镜中心到透镜周边，曲率是连续变化的。与从透镜中心到透镜周边具有恒定曲率的球面透镜不同，非球面透镜具有更佳的曲率半径特性，具有改善歪曲像差及改善像散像差的 优点。采用非球面透镜后，能够尽可能地消除在成像的时候出现的像差，从而改善成像质量。
然而，本领域的技术人员应当理解，在未背离本申请要求保护的技术方案的情况下，可改变构成投影镜头的透镜数量，来获得本说明书中描述的各个结果和优点。例如，虽然在实施方式中以四片透镜为例进行了描述，但是该投影镜头不限于包括四片透镜。如果需要，该投影镜头还可包括其它数量的透镜。
下面参照附图进一步描述可适用于上述实施方式的投影镜头的具体实施例。
实施例1
以下参照图1至图2C描述根据本申请实施例1的投影镜头。图1示出了根据本申请实施例1的投影镜头的结构示意图。
如图1所示，根据本申请示例性实施方式的投影镜头沿光轴由成像侧至像源侧依序包括：光阑STO、第一透镜E1、第二透镜E2、第三透镜E3和第四透镜E4。
第一透镜E1具有正光焦度，其成像侧表面S1为凸面，像源侧表面S2为凹面；第二透镜E2具有正光焦度，其成像侧表面S3为凹面，像源侧表面S4为凸面；第三透镜E3具有正光焦度，其成像侧表面S5为凹面，像源侧表面S6为凸面；以及第四透镜E4具有负光焦度，其成像侧表面S7为凸面，像源侧表面S8为凹面。S9可以是像源面，来自投影镜头像源面的光依序穿过各表面S8至S1并最终成像在屏幕上(未示出)。
在约800nm至约1000nm光波波段中，该投影镜头的光线透过率大于85％。
表1示出了实施例1的投影镜头的各透镜的表面类型、曲率半径、厚度、材料及圆锥系数，其中，曲率半径和厚度的单位均为毫米(mm)。
Figure PCTCN2018086743-appb-000001
Figure PCTCN2018086743-appb-000002
表1
由表1可知，第一透镜E1至第四透镜E4中的任意一个透镜的成像侧表面和像源侧表面均为非球面。在本实施例中，各非球面透镜的面型x可利用但不限于以下非球面公式进行限定：
Figure PCTCN2018086743-appb-000003
其中，x为非球面沿光轴方向在高度为h的位置时，距非球面顶点的距离矢高；c为非球面的近轴曲率，c＝1/R(即，近轴曲率c为上表1中曲率半径R的倒数)；k为圆锥系数(在表1中已给出)；Ai是非球面第i-th阶的修正系数。下表2给出了可用于实施例1中各非球面镜面S1-S8的高次项系数A 4、A 6、A 8、A 10、A 12、A 14和A 16。
面号 A4 A6 A8 A10 A12 A14 A16
S1 1.5615E-01 -4.1916E+00 1.0055E+02 -1.0841E+03 5.7844E+03 -1.4246E+04 1.2976E+04
S2 4.9464E-01 6.9931E-01 1.4940E+01 -1.8713E+02 1.8504E+03 -8.8115E+03 1.9038E+04
S3 -4.1066E-01 -2.8918E+01 5.3999E+02 -5.5399E+03 2.9869E+04 -8.1639E+04 9.0669E+04
S4 -2.8917E-01 7.5873E+00 -9.6838E+01 6.3678E+02 -2.2453E+03 3.9455E+03 -2.6261E+03
S5 -3.7771E-01 -1.0334E+00 6.5029E+00 -1.0025E+01 7.1543E+00 -2.4772E+00 3.3604E-01
S6 -1.1253E+00 4.5667E+00 -1.0239E+01 1.3167E+01 -8.9996E+00 3.0492E+00 -4.0198E-01
S7 -1.5132E+00 1.9426E+00 -9.7812E-01 6.1994E-02 1.5356E-01 -6.4488E-02 8.2865E-03
S8 -4.8483E-01 3.1658E-02 3.9269E-01 -4.0333E-01 1.9364E-01 -4.5723E-02 4.1905E-03
表2
表3给出实施例1中投影镜头的光学总长度TTL(即，从第一透镜E1的成像侧表面S1至像源面S9在光轴上的距离)、最大半视场角HFOV、总有效焦距f以及各透镜的有效焦距f1至f4。
Figure PCTCN2018086743-appb-000004
表3
实施例1中的投影镜头满足：
(1+TAN(CRA))*TTL/IH＝2.12，其中，CRA为主光线的最大入射角度，TTL为投影镜头的光学总长度，IH为像源区域对角线长的一半；
|f1/f2|＝2.43，其中，f1为第一透镜E1的有效焦距，f2为第二透镜E2的有效焦距；
R4/R5＝0.98，其中，R4为第二透镜E2的像源侧表面S4的曲率半径，R5为第三透镜E3的成像侧表面S5的曲率半径；
SAG31/SAG32＝0.50，其中，SAG31为第三透镜E3的成像侧表面S5和光轴的交点至第三透镜E3的成像侧表面S5的有效半口径顶点在光轴上的距离，SAG32为第三透镜E3的像源侧表面S6和光轴的交点至第三透镜E3的像源侧表面S6的有效半口径顶点在光轴上的距离；
DT11/DT21＝0.89，其中，DT11为第一透镜E1的成像侧表面S1的有效半口径，DT21为第一透镜E1的像源侧表面S2的有效半口径；
CT3/CT4＝1.94，其中，CT3为第三透镜E3于光轴上的中心厚度，CT4为第四透镜E4于光轴上的中心厚度；
T12/T23＝0.56，其中，T12为第一透镜E1和第二透镜E2在光轴上的间隔距离，T23为第二透镜E2和第三透镜E3在光轴上的间隔距离；
TAN(HFOV)＝1.04，其中，HFOV为投影镜头的最大半视场角。
图2A示出了实施例1的投影镜头的轴上色差曲线，其表示不同波长的光线经由镜头后的会聚焦点偏离。图2B示出了实施例1的投影镜头的象散曲线，其表示子午像面弯曲和弧矢像面弯曲。图2C示出了实施例1的投影镜头的畸变曲线，其表示不同视角情况下的畸变大小值。根据图2A至图2C可知，实施例1所给出的投影镜头能够实现良好的成像品质。
实施例2
以下参照图3至图4C描述根据本申请实施例2的投影镜头。在本实施例及以下实施例中，为简洁起见，将省略部分与实施例1相似的描述。图3示出了根据本申请实施例2的投影镜头的结构示意图。
如图3所示，根据本申请示例性实施方式的投影镜头沿光轴由成像侧至像源侧依序包括：光阑STO、第一透镜E1、第二透镜E2、第三透镜E3和第四透镜E4。
第一透镜E1具有正光焦度，其成像侧表面S1为凸面，像源侧表面S2为凹面；第二透镜E2具有正光焦度，其成像侧表面S3为凹面，像源侧表面S4为凸面；第三透镜E3具有正光焦度，其成像侧表面S5为凹面，像源侧表面S6为凸面；以及第四透镜E4具有负光焦度，其成像侧表面S7为凸面，像源侧表面S8为凹面。S9可以是像源面，来自投影镜头像源面的光依序穿过各表面S8至S1并最终成像在屏幕上(未示出)。
在约800nm至约1000nm光波波段中，该投影镜头的光线透过率大于85％。
表4示出了实施例2的投影镜头的各透镜的表面类型、曲率半径、厚度、材料及圆锥系数，其中，曲率半径和厚度的单位均为毫米(mm)。
Figure PCTCN2018086743-appb-000005
表4
由表4可知，在实施例2中，第一透镜E1至第四透镜E4中的任 意一个透镜的成像侧表面和像源侧表面均为非球面。表5示出了可用于实施例2中各非球面镜面的高次项系数，其中，各非球面面型可由上述实施例1中给出的公式(1)限定。
面号 A4 A6 A8 A10 A12 A14 A16
S1 5.8004E-01 -8.6984E+00 1.7481E+02 -7.4245E+02 -1.3055E+04 1.5452E+05 -4.6982E+05
S2 1.1649E-01 5.0713E+00 -7.7669E+01 6.2275E+02 -1.5735E+03 -7.0330E+02 0.0000E+00
S3 -4.3396E-01 -2.8939E+01 5.4167E+02 -5.5339E+03 2.9901E+04 -8.1363E+04 9.2991E+04
S4 -2.6746E-01 7.6096E+00 -9.6765E+01 6.3707E+02 -2.2443E+03 3.9475E+03 -2.6135E+03
S5 -3.7659E-01 -1.0333E+00 6.5034E+00 -1.0024E+01 7.1554E+00 -2.4757E+00 3.3877E-01
S6 -1.1248E+00 4.5657E+00 -1.0239E+01 1.3167E+01 -8.9995E+00 3.0491E+00 -4.0221E-01
S7 -1.4989E+00 1.9491E+00 -9.8034E-01 6.4599E-02 1.5061E-01 -6.3319E-02 8.1308E-03
S8 -4.8857E-01 3.2148E-02 4.0434E-01 -4.0875E-01 1.9894E-01 -4.8208E-02 4.4787E-03
表5
表6给出实施例2中投影镜头的光学总长度TTL、最大半视场角HFOV、总有效焦距f以及各透镜的有效焦距f1至f4。
Figure PCTCN2018086743-appb-000006
表6
图4A示出了实施例2的投影镜头的轴上色差曲线，其表示不同波长的光线经由镜头后的会聚焦点偏离。图4B示出了实施例2的投影镜头的象散曲线，其表示子午像面弯曲和弧矢像面弯曲。图4C示出了实施例2的投影镜头的畸变曲线，其表示不同视角情况下的畸变大小值。根据图4A至图4C可知，实施例2所给出的投影镜头能够实现良好的成像品质。
实施例3
以下参照图5至图6C描述了根据本申请实施例3的投影镜头。图5示出了根据本申请实施例3的投影镜头的结构示意图。
如图5所示，根据本申请示例性实施方式的投影镜头沿光轴由成像侧至像源侧依序包括：光阑STO、第一透镜E1、第二透镜E2、第三透镜E3和第四透镜E4。
第一透镜E1具有正光焦度，其成像侧表面S1为凸面，像源侧表面S2为凹面；第二透镜E2具有正光焦度，其成像侧表面S3为凹面，像源侧表面S4为凸面；第三透镜E3具有正光焦度，其成像侧表面S5为凹面，像源侧表面S6为凸面；以及第四透镜E4具有负光焦度，其成像侧表面S7为凹面，像源侧表面S8为凹面。S9可以是像源面，来自投影镜头像源面的光依序穿过各表面S8至S1并最终成像在屏幕上(未示出)。
在约800nm至约1000nm光波波段中，该投影镜头的光线透过率大于85％。
表7示出了实施例3的投影镜头的各透镜的表面类型、曲率半径、厚度、材料及圆锥系数，其中，曲率半径和厚度的单位均为毫米(mm)。
Figure PCTCN2018086743-appb-000007
表7
由表7可知，在实施例3中，第一透镜E1至第四透镜E4中的任意一个透镜的成像侧表面和像源侧表面均为非球面。表5示出了可用于实施例2中各非球面镜面的高次项系数，其中，各非球面面型可由上述实施例1中给出的公式(1)限定。
面号 A4 A6 A8 A10 A12 A14 A16
S1 3.6418E-01 -4.2484E+00 1.7253E+02 -7.6872E+02 -1.3616E+04 1.5380E+05 -4.3657E+05
S2 2.7243E-01 3.4752E+00 -6.0200E+01 6.5103E+02 -1.5180E+03 -1.2495E+03 0.0000E+00
S3 -5.1748E-01 -2.9525E+01 5.3533E+02 -5.5151E+03 3.0152E+04 -7.9913E+04 9.7487E+04
S4 -2.1095E-01 7.5296E+00 -9.7206E+01 6.3590E+02 -2.2444E+03 3.9587E+03 -2.6054E+03
S5 -2.7582E-01 -1.0365E+00 6.4469E+00 -1.0020E+01 7.1576E+00 -2.4712E+00 3.4350E-01
S6 -1.0491E+00 4.4781E+00 -1.0164E+01 1.3186E+01 -9.0173E+00 3.0361E+00 -3.9036E-01
S7 -1.4776E+00 1.9597E+00 -9.8528E-01 6.4358E-02 1.5180E-01 -6.3891E-02 8.2018E-03
S8 -4.8982E-01 2.9768E-02 4.0658E-01 -4.0842E-01 1.9888E-01 -4.8349E-02 4.3821E-03
表8
表9给出实施例3中投影镜头的光学总长度TTL、最大半视场角HFOV、总有效焦距f以及各透镜的有效焦距f1至f4。
Figure PCTCN2018086743-appb-000008
表9
图6A示出了实施例3的投影镜头的轴上色差曲线，其表示不同波长的光线经由镜头后的会聚焦点偏离。图6B示出了实施例3的投影镜头的象散曲线，其表示子午像面弯曲和弧矢像面弯曲。图6C示出了实施例3的投影镜头的畸变曲线，其表示不同视角情况下的畸变大小值。根据图6A至图6C可知，实施例3所给出的投影镜头能够实现良好的成像品质。
实施例4
以下参照图7至图8C描述了根据本申请实施例4的投影镜头。图7示出了根据本申请实施例4的投影镜头的结构示意图。
如图7所示，根据本申请示例性实施方式的投影镜头沿光轴由成像侧至像源侧依序包括：光阑STO、第一透镜E1、第二透镜E2、第三透镜E3和第四透镜E4。
第一透镜E1具有正光焦度，其成像侧表面S1为凸面，像源侧表面S2为凹面；第二透镜E2具有正光焦度，其成像侧表面S3为凹面，像源侧表面S4为凸面；第三透镜E3具有正光焦度，其成像侧表面S5为凹面，像源侧表面S6为凸面；以及第四透镜E4具有负光焦度，其成像侧表面S7为凸面，像源侧表面S8为凹面。S9可以是像源面，来自投影镜头像源面的光依序穿过各表面S8至S1并最终成像在屏幕上(未示出)。
在约800nm至约1000nm光波波段中，该投影镜头的光线透过率大于85％。
表10示出了实施例4的投影镜头的各透镜的表面类型、曲率半径、厚度、材料及圆锥系数，其中，曲率半径和厚度的单位均为毫米(mm)。
Figure PCTCN2018086743-appb-000009
表10
由表10可知，在实施例4中，第一透镜E1至第四透镜E4中的任意一个透镜的成像侧表面和像源侧表面均为非球面。表11示出了可用于实施例4中各非球面镜面的高次项系数，其中，各非球面面型可由上述实施例1中给出的公式(1)限定。
面号 A4 A6 A8 A10 A12 A14 A16
S1 5.3149E-01 -8.3884E+00 1.7885E+02 -7.5712E+02 -1.3476E+04 1.5316E+05 -4.4688E+05
S2 3.6122E-02 5.7148E+00 -8.0089E+01 5.7882E+02 -1.6399E+03 3.7888E+02 0.0000E+00
S3 -3.1367E-01 -2.8910E+01 5.4553E+02 -5.5178E+03 2.9882E+04 -8.1978E+04 8.7675E+04
S4 -9.0248E-02 7.2188E+00 -9.6116E+01 6.3941E+02 -2.2421E+03 3.9436E+03 -2.6396E+03
S5 -3.7940E-01 -1.0355E+00 6.5031E+00 -1.0026E+01 7.1514E+00 -2.4784E+00 3.3924E-01
S6 -1.1388E+00 4.5679E+00 -1.0241E+01 1.3165E+01 -9.0009E+00 3.0484E+00 -4.0259E-01
S7 -1.5062E+00 1.9490E+00 -9.7977E-01 6.5003E-02 1.5082E-01 -6.3256E-02 8.1176E-03
S8 -4.9308E-01 2.9134E-02 4.0407E-01 -4.0863E-01 1.9907E-01 -4.8110E-02 4.5562E-03
表11
表12给出实施例4中投影镜头的光学总长度TTL、最大半视场角HFOV、总有效焦距f以及各透镜的有效焦距f1至f4。
Figure PCTCN2018086743-appb-000010
Figure PCTCN2018086743-appb-000011
表12
图8A示出了实施例4的投影镜头的轴上色差曲线，其表示不同波长的光线经由镜头后的会聚焦点偏离。图8B示出了实施例4的投影镜头的象散曲线，其表示子午像面弯曲和弧矢像面弯曲。图8C示出了实施例4的投影镜头的畸变曲线，其表示不同视角情况下的畸变大小值。根据图8A至图8C可知，实施例4所给出的投影镜头能够实现良好的成像品质。
实施例5
以下参照图9至图10C描述了根据本申请实施例5的投影镜头。图9示出了根据本申请实施例5的投影镜头的结构示意图。
如图9所示，根据本申请示例性实施方式的投影镜头沿光轴由成像侧至像源侧依序包括：光阑STO、第一透镜E1、第二透镜E2、第三透镜E3和第四透镜E4。
第一透镜E1具有正光焦度，其成像侧表面S1为凸面，像源侧表面S2为凹面；第二透镜E2具有正光焦度，其成像侧表面S3为凹面，像源侧表面S4为凸面；第三透镜E3具有正光焦度，其成像侧表面S5为凹面，像源侧表面S6为凸面；以及第四透镜E4具有正光焦度，其成像侧表面S7为凸面，像源侧表面S8为凹面。S9可以是像源面，来自投影镜头像源面的光依序穿过各表面S8至S1并最终成像在屏幕上(未示出)。
在约800nm至约1000nm光波波段中，该投影镜头的光线透过率大于85％。
表13示出了实施例5的投影镜头的各透镜的表面类型、曲率半径、厚度、材料及圆锥系数，其中，曲率半径和厚度的单位均为毫米(mm)。
Figure PCTCN2018086743-appb-000012
Figure PCTCN2018086743-appb-000013
表13
由表13可知，在实施例5中，第一透镜E1至第四透镜E4中的任意一个透镜的成像侧表面和像源侧表面均为非球面。表14示出了可用于实施例5中各非球面镜面的高次项系数，其中，各非球面面型可由上述实施例1中给出的公式(1)限定。
面号 A4 A6 A8 A10 A12 A14 A16
S1 5.0519E-01 -8.6079E+00 1.8062E+02 -7.2450E+02 -1.3482E+04 1.5082E+05 -4.3927E+05
S2 -9.8834E-03 5.8792E+00 -7.5804E+01 5.7759E+02 -1.9467E+03 2.1590E+03 0.0000E+00
S3 -3.1328E-01 -2.9784E+01 5.4264E+02 -5.5215E+03 2.9905E+04 -8.1677E+04 9.0278E+04
S4 -9.1581E-02 7.0852E+00 -9.6316E+01 6.3912E+02 -2.2428E+03 3.9412E+03 -2.6493E+03
S5 -3.7945E-01 -1.0358E+00 6.5023E+00 -1.0028E+01 7.1498E+00 -2.4795E+00 3.4191E-01
S6 -1.1307E+00 4.5723E+00 -1.0240E+01 1.3165E+01 -9.0007E+00 3.0486E+00 -4.0225E-01
S7 -1.5099E+00 1.9490E+00 -9.7984E-01 6.4954E-02 1.5081E-01 -6.3254E-02 8.1228E-03
S8 -4.8520E-01 2.9035E-02 4.0341E-01 -4.0887E-01 1.9901E-01 -4.8124E-02 4.5537E-03
表14
表15给出实施例5中投影镜头的光学总长度TTL、最大半视场角HFOV、总有效焦距f以及各透镜的有效焦距f1至f4。
Figure PCTCN2018086743-appb-000014
表15
图10A示出了实施例5的投影镜头的轴上色差曲线，其表示不同波长的光线经由镜头后的会聚焦点偏离。图10B示出了实施例5的投影镜头的象散曲线，其表示子午像面弯曲和弧矢像面弯曲。图10C示出了实施例5的投影镜头的畸变曲线，其表示不同视角情况下的畸变大小值。根据图10A至图10C可知，实施例5所给出的投影镜头能够 实现良好的成像品质。
综上，实施例1至实施例5分别满足表16中所示的关系。
条件式\实施例 1 2 3 4 5
(1+tan(CRA))*TTL/IH 2.12 2.25 2.31 2.23 2.27
|f1/f2| 2.43 2.44 2.29 2.47 2.63
R4/R5 0.98 0.97 0.83 1.07 1.05
SAG31/SAG32 0.50 0.50 0.50 0.53 0.53
DT11/DT21 0.89 0.86 0.95 0.86 0.87
CT3/CT4 1.94 1.83 2.43 1.67 1.64
T12/T23 0.56 0.62 0.59 0.58 0.61
TAN(HFOV) 1.04 0.95 0.95 1.00 1.02
表16
以上描述仅为本申请的较佳实施例以及对所运用技术原理的说明。本领域技术人员应当理解，本申请中所涉及的发明范围，并不限于上述技术特征的特定组合而成的技术方案，同时也应涵盖在不脱离所述发明构思的情况下，由上述技术特征或其等同特征进行任意组合而形成的其它技术方案。例如上述特征与本申请中公开的(但不限于)具有类似功能的技术特征进行互相替换而形成的技术方案。

Claims (19)

  1. 投影镜头，沿光轴由成像侧至像源侧依序包括：第一透镜、第二透镜、第三透镜和第四透镜，其特征在于，
    所述第一透镜具有正光焦度，其成像侧表面为凸面；
    所述第二透镜具有正光焦度或负光焦度，其像源侧表面为凸面；
    所述第三透镜具有正光焦度；以及
    所述第四透镜具有正光焦度或负光焦度。
  2. 根据权利要求1所述的投影镜头，其特征在于，满足0＜(1+TAN(CRA))*TTL/IH＜2.5，
    其中，CRA为主光线的最大入射角度，TTL为投影镜头的光学总长度，IH为像源区域对角线长的一半。
  3. 根据权利要求1所述的投影镜头，其特征在于，所述投影镜头的最大半视场角HFOV满足0.9＜TAN(HFOV)＜1.2。
  4. 根据权利要求1所述的投影镜头，其特征在于，在800nm至1000nm的光波波段中，所述投影镜头的光线透过率大于85％。
  5. 根据权利要求2至4中任一项所述的投影镜头，其特征在于，所述第一透镜的有效焦距f1与所述第二透镜的有效焦距f2满足2.0＜|f1/f2|＜2.8。
  6. 根据权利要求1至4中任一项所述的投影镜头，其特征在于，所述第二透镜的像源侧表面的曲率半径R4与所述第三透镜的成像侧表面的曲率半径R5满足0.8＜R4/R5＜1.2。
  7. 根据权利要求1至4中任一项所述的投影镜头，其特征在于，满足0.3＜SAG31/SAG32＜0.7，
    其中，SAG31为所述第三透镜的成像侧表面和所述光轴的交点至 所述第三透镜的成像侧表面的有效半口径顶点在所述光轴上的距离，SAG32为所述第三透镜的像源侧表面和所述光轴的交点至所述第三透镜的像源侧表面的有效半口径顶点在所述光轴上的距离。
  8. 根据权利要求1至4中任一项所述的投影镜头，其特征在于，所述第一透镜的成像侧表面的有效半口径DT11与所述第一透镜的像源侧表面的有效半口径DT21满足0.7＜DT11/DT21＜1.0。
  9. 根据权利要求1至4中任一项所述的投影镜头，其特征在于，所述第三透镜于所述光轴上的中心厚度CT3与所述第四透镜于所述光轴上的中心厚度CT4满足1.5＜CT3/CT4＜2.5。
  10. 根据权利要求1至4中任一项所述的投影镜头，其特征在于，所述第一透镜和所述第二透镜在所述光轴上的间隔距离T12与所述第二透镜和所述第三透镜在所述光轴上的间隔距离T23满足0.4＜T12/T23＜0.7。
  11. 投影镜头，沿光轴由成像侧至像源侧依序包括：第一透镜、第二透镜、第三透镜和第四透镜，其特征在于，
    所述第一透镜具有正光焦度，其成像侧表面为凸面；
    所述第二透镜具有正光焦度或负光焦度，其像源侧表面为凸面；
    所述第三透镜具有正光焦度；
    所述第四透镜具有正光焦度或负光焦度；以及
    其中，所述第一透镜的有效焦距f1与所述第二透镜的有效焦距f2满足2.0＜|f1/f2|＜2.8。
  12. 根据权利要求11所述的投影镜头，其特征在于，所述第二透镜的像源侧表面的曲率半径R4与所述第三透镜的成像侧表面的曲率半径R5满足0.8＜R4/R5＜1.2。
  13. 根据权利要求11所述的投影镜头，其特征在于，满足0.3＜SAG31/SAG32＜0.7，
    其中，SAG31为所述第三透镜的成像侧表面和所述光轴的交点至所述第三透镜的成像侧表面的有效半口径顶点在所述光轴上的距离，SAG32为所述第三透镜的像源侧表面和所述光轴的交点至所述第三透镜的像源侧表面的有效半口径顶点在所述光轴上的距离。
  14. 根据权利要求11所述的投影镜头，其特征在于，所述第一透镜的成像侧表面的有效半口径DT11与所述第一透镜的像源侧表面的有效半口径DT21满足0.7＜DT11/DT21＜1.0。
  15. 根据权利要求11所述的投影镜头，其特征在于，所述第三透镜于所述光轴上的中心厚度CT3与所述第四透镜于所述光轴上的中心厚度CT4满足1.5＜CT3/CT4＜2.5。
  16. 根据权利要求11所述的投影镜头，其特征在于，所述第一透镜和所述第二透镜在所述光轴上的间隔距离T12与所述第二透镜和所述第三透镜在所述光轴上的间隔距离T23满足0.4＜T12/T23＜0.7。
  17. 根据权利要求12至16中任一项所述的投影镜头，其特征在于，满足0＜(1+TAN(CRA))*TTL/IH＜2.5，
    其中，CRA为主光线的最大入射角度，TTL为投影镜头的光学总长度，IH为像源区域对角线长的一半。
  18. 根据权利要求12至16中任一项所述的投影镜头，其特征在于，所述投影镜头的最大半视场角HFOV满足0.9＜TAN(HFOV)＜1.2。
  19. 根据权利要求12至16中任一项所述的投影镜头，其特征在于，在800nm至1000nm的光波波段中，所述投影镜头的光线透过率大于85％。
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