CN117784361A - Projection lens, projection device and vehicle - Google Patents

Projection lens, projection device and vehicle Download PDF

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Publication number
CN117784361A
CN117784361A CN202211186811.6A CN202211186811A CN117784361A CN 117784361 A CN117784361 A CN 117784361A CN 202211186811 A CN202211186811 A CN 202211186811A CN 117784361 A CN117784361 A CN 117784361A
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China
Prior art keywords
lens
projection
focal length
projection lens
efl
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贺保丁
李睿
张德伦
罗宇哲
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Priority to CN202211186811.6A priority Critical patent/CN117784361A/en
Priority to PCT/CN2023/105347 priority patent/WO2024066634A1/en
Publication of CN117784361A publication Critical patent/CN117784361A/en
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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
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)

Abstract

The embodiment of the application provides a projection lens, projection arrangement and vehicle, projection lens include along the optical axis from projection side to pixel side first lens, second lens, third lens and fourth lens that arrange in proper order, and the focus f1 of first lens and the focus f2 of second lens satisfy: 2. not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group formed by the first lens and the second lens and the focal length EFL of the projection lens meet the following conditions: the f12/EFL is more than or equal to 5, and the focal length f3 of the third lens and the focal length f4 of the fourth lens meet the following conditions: 1.5 Not less than f3/EFL not less than 0.8,1.5 not less than f4/EFL not less than 0.8, and f3> f4. The projection lens of the first lens, the second lens, the third lens and the fourth lens structure realizes large aperture design, can be well matched with a miniature light-emitting diode display chip, is beneficial to improving the utilization rate and output power of luminous energy and improves the illumination brightness of a projection device.

Description

Projection lens, projection device and vehicle
Technical Field
The present disclosure relates to projection display technologies, and in particular, to a projection lens, a projection device, and a vehicle.
Background
With the development of display technology, projection display has been widely used in daily life, such as a common projector, a multimedia projection device, and the like. In addition, in transportation equipment such as vehicles, attention is paid to the application of projection display technology, for example, a head-up display projection device mounted in a vehicle, and an intelligent car lamp provided on the vehicle and having illumination, signal indication functions, multi-pixel and intelligent projection functions.
The Micro Light-Emitting Diode (Micro LED) projection display technology has the advantages of simple structure and low cost. The projection display device comprises a Micro LED display chip and a projection lens, wherein the Micro LED display chip is an integrated high-density Micro-sized LED array on one chip, and can independently switch and regulate current for each independent microstructure area on the chip, so that the collection of functions of a light source and the projection chip is realized, namely, the Micro LED display chip is used as a light source and an image generation module, the structure of a display system is obviously simplified, and the cost is reduced. The display image formed by the Micro LED display chip is projected onto the projection position through the projection lens, so that projection display is realized.
In order to meet the brightness requirement of the projection device, the utilization rate and output power of the luminous energy can be improved, so that a projection lens suitable for the micro light emitting diode display technology and having a large aperture design is needed to improve the luminous flux, so that more light can be projected to the projection position through the projection lens, and the brightness performance of the projection device is improved.
Disclosure of Invention
The utility model provides a projection lens, projection arrangement and vehicle, projection lens match miniature emitting diode display chip that can be fine, and have big light ring and high luminous flux, be favorable to promoting the utilization ratio and the output to the luminous energy, satisfy the requirement to projection arrangement high brightness.
A first aspect of the present application provides a projection lens, including a first lens group including a first lens and a second lens, the projection lens further including a third lens and a second lens group including one or more fourth lenses, the fourth lenses of the first lens, the second lens, the third lens and the second lens group being sequentially arranged from a projection side to a pixel side along a direction of an optical axis;
the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the conditional expression: 2. not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 5;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than 0.8, and the focal length f3 of the third lens and the focal length f4 of the second lens group satisfy the following conditional expression: f3> f4. The projection lens formed by the framework of enabling the first lens, the second lens, the third lens and the fourth lens to meet the above conditions has a small F#, can realize the design of a large aperture, increases the luminous flux of the projection lens, is suitable for a projection device, can improve the utilization rate and the output power of luminous energy, and improves the brightness of the projection device.
In addition, the projection lens only realizes the large aperture design through the first lens, the second lens, the third lens and the fourth lens, and the projection lens can be of a four-lens framework, so that the number of lenses is small, the structure is simple, the size is small and the cost is low. When the image display module of the projection device is a micro light emitting diode display chip, the number of the internal independent micro structure switches of the chip is relatively small, the display pixels are relatively low, and the pixels of the projection lens with a simple structure are relatively low, so that the micro light emitting diode display chip with relatively low pixel matching requirements can be well matched, the changing requirements of the projection image are met, and the projection lens has the design of a large aperture, a small volume, low cost and low pixel adaptation image display module.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.9 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 6;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.9: 1.4 Not less than f4/EFL not less than 0.8. The framework of the projection lens is optimized, the aperture is further increased, and the utilization rate and the output rate of luminous energy are improved.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.8 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 6;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 1.0: 1.3 Not less than f4/EFL not less than 0.8. The framework of the projection lens is optimized, the aperture is further increased, and the utilization rate and the output rate of luminous energy are improved.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.7 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 7.5;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 1.2: 1.2 Not less than f4/EFL not less than 0.8. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.6 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 8;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 1.1: 1.0 Not less than f4/EFL not less than 0.8. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.4 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 8.9;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 1.3: 1.5 Not less than f4/EFL not less than 1.0. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.5 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 10.6;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.4 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 0.9. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.9 Not less than |f1/f2| not less than 1.3, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 9;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.2 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.1. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.9 Not less than |f1/f2| not less than 1.4, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 11.1;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.3 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.0. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.9 Not less than |f1/f2| not less than 1.5, and the focal length f12 of the first lens group and the focal length EFL of the projection lens satisfy the following conditional expression: f12/EFL is more than or equal to 12;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.1 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.2. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.9 Not less than |f1/f2| not less than 1.6, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 14;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.0 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.3. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.8 Not less than |f1/f2| not less than 1.4, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 15;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.3 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.9: 1.3 Not less than f4/EFL not less than 0.8. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 1.7 Not less than |f1/f2| not less than 1.5, and the focal length f12 of the first lens group and the focal length EFL of the projection lens satisfy the following conditional expression: f12/EFL is more than or equal to 13.6;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.2 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 1.0: 1.4 Not less than f4/EFL not less than 1.1. The structure of the projection lens is optimized, which is further beneficial to increasing the aperture, so that the projection lens has higher light energy utilization rate and output rate.
In one possible implementation, the F-number #f of the projection lens satisfies the conditional expression: f# is more than or equal to 0.6 and less than or equal to 1.0, and F# is smaller, thereby meeting the design requirement of a large aperture of a projection lens.
In one possible implementation, the F-number #f of the projection lens satisfies the conditional expression: f# is more than or equal to 0.6 and less than or equal to 0.8. Further optimize the diaphragm number, better satisfy big diaphragm design demand.
In one possible implementation manner, the f# of the projection lens is 0.6-0.7, the ultra-large aperture design of the projection lens is realized, and the luminous flux of the projection lens is remarkably increased.
In one possible implementation, the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy the following conditional expression: 2.5 The total length of the projection lens is reduced, and the small-volume design of the projection lens is facilitated.
In one possible implementation, the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy the following conditional expression: 2.3 More than or equal to TTL/EFL more than or equal to 1.5. The length of the projection lens is further reduced, and the small-volume design of the projection lens is met.
In one possible implementation, the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy the following conditional expression: 2.0 More than or equal to TTL/EFL more than or equal to 1.5. Further reduce the length of the projection lens and meet the small-volume design of the projection lens
In one possible implementation, the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy the following conditional expression: 2.5 More than or equal to TTL/EFL more than or equal to 1.9. Further reduce the length of the projection lens and meet the small-volume design of the projection lens
In one possible implementation, the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy the following conditional expression: 2.5 More than or equal to TTL/EFL more than or equal to 2.1. Further reduce the length of the projection lens and meet the small-volume design of the projection lens
In one possible implementation, the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy the following conditional expression: 2.4 More than or equal to TTL/EFL more than or equal to 1.7. Further reduce the length of the projection lens and meet the small-volume design of the projection lens
In one possible implementation, the back focal length BFL of the projection lens and the half image height of the projection lens satisfy the following conditional expression: 1.4 The BFL/IH is more than or equal to 0.6, so that the projection lens has larger half image height on the premise of ensuring that the projection lens has smaller total length, the large target surface design of the projection lens is realized, the increase of the luminous area is facilitated, the luminous power of the projection device can be improved, and the brightness of the projection device is further improved.
In one possible implementation, the back focal length BFL of the projection lens and the half image height of the projection lens satisfy the following conditional expression: 1.4 More than or equal to BFL/IH more than or equal to 0.8. Further increases half image height, meets the design requirement of a large target surface of the projection lens, and more effectively improves the luminous power of the projection device.
In one possible implementation, the back focal length BFL of the projection lens and the half image height of the projection lens satisfy the following conditional expression: 1.4 More than or equal to BFL/IH more than or equal to 1.1. Further increases half image height, meets the design requirement of a large target surface of the projection lens, and more effectively improves the luminous power of the projection device.
In one possible implementation, the back focal length BFL of the projection lens and the half image height of the projection lens satisfy the following conditional expression: 1.2 More than or equal to BFL/IH more than or equal to 0.6. Further increases half image height, meets the design requirement of a large target surface of the projection lens, and more effectively improves the luminous power of the projection device.
In one possible implementation, the back focal length BFL of the projection lens and the half image height of the projection lens satisfy the following conditional expression: 1.3 More than or equal to BFL/IH more than or equal to 0.6. Further increases half image height, meets the design requirement of a large target surface of the projection lens, and more effectively improves the luminous power of the projection device.
In one possible implementation, the back focal length BFL of the projection lens and the half image height of the projection lens satisfy the following conditional expression: 1.2 More than or equal to BFL/IH more than or equal to 0.7. Further increases half image height, meets the design requirement of a large target surface of the projection lens, and more effectively improves the luminous power of the projection device.
In one possible implementation, the abbe number Vd1 of the first lens satisfies the condition: vd1 is more than or equal to 52, and Abbe number Vd2 of the second lens meets the condition formula: vd2 is less than or equal to 30, and the Abbe number Vd1 of the first lens and the Abbe number Vd2 of the second lens satisfy the following conditional expression: vd1/Vd2 is more than or equal to 1.8. That is, the abbe number of the first lens is larger than that of the second lens, the first lens is a lens with a high abbe number, the second lens is a lens with a low abbe number, the first lens and the second lens can be in complementary balance in terms of dispersion capability, imaging chromatic aberration is reduced or eliminated, and imaging quality of the projection lens is further improved.
In one possible implementation, the abbe number Vd1 of the first lens satisfies the condition: vd1 is more than or equal to 54, and Abbe number Vd2 of the second lens meets the condition formula: vd2 is less than or equal to 20, and the Abbe number Vd1 of the first lens and the Abbe number Vd2 of the second lens meet the conditional expression: vd1/Vd2 is more than or equal to 2.7. The first lens and the second lens are optimized, imaging chromatic aberration is further reduced or eliminated, and the projection lens has better imaging quality.
In one possible implementation, the abbe number Vd1 of the first lens satisfies the condition: vd1 is more than or equal to 56, and Abbe number Vd2 of the second lens meets the condition formula: vd2 is less than or equal to 24, and the Abbe number Vd1 of the first lens and the Abbe number Vd2 of the second lens meet the conditional expression: vd1/Vd2 is more than or equal to 2.3. The first lens and the second lens are optimized, imaging chromatic aberration is further reduced or eliminated, and the projection lens has better imaging quality.
In one possible implementation, the first lens and the second lens are plastic lenses and the third lens and the fourth lens are glass lenses. Under the condition of ensuring the optical performance of the projection lens, part of the lenses are plastic lenses, which is beneficial to further reducing the cost of the projection lens. In addition, the projection lens adopting the glass lens and plastic lens framework can realize mutual compensation by utilizing the matching of the refractive index temperature coefficient of the glass lens and the refractive index temperature coefficient of the plastic lens, is favorable for reducing the thermal difference of the projection lens, realizes the design of eliminating the thermal difference of the projection lens, ensures that the projection lens can be suitable for high and low temperature environments, and ensures the stability and reliability of the performance of the projection lens in different temperature environment scenes.
Moreover, the first lens and the second lens which are relatively far away from the image display module are plastic lenses, so that the influence of heat generated by the image display module during operation on the plastic lenses can be reduced, and the reliability of the projection lens can be further improved.
In one possible implementation, the first lens and the second lens are aspherical lenses, and the third lens and the fourth lens are spherical lenses, i.e. the glass lens is a spherical lens, with lower costs. The plastic lens is an aspheric lens, and can be matched with the spherical lens to ensure the design of a large aperture, and meanwhile, the spherical aberration introduced by the spherical lens can be reduced or eliminated, the imaging performance of the projection lens is ensured, and the design with high reliability and low cost is realized.
In one possible implementation, the first lens has positive focal power, the second lens has negative focal power, the third lens has positive focal power, and the fourth lens has positive focal power, so that the focal power is reasonably distributed, aberration is reduced, and imaging quality of the projection lens is improved.
In one possible implementation, at least a portion of a surface of the first lens facing the projection side corresponding to the optical axis is convex, and at least a portion of a surface of the first lens facing the pixel side corresponding to the optical axis is convex.
At least a portion of a surface of the second lens facing the projection side, which corresponds to the optical axis, is convex, and at least a portion of a surface of the second lens facing the pixel side, which corresponds to the optical axis, is concave.
At least a portion of a surface of the third lens facing the projection side, which corresponds to the optical axis, is concave, and at least a portion of a surface of the third lens facing the pixel side, which corresponds to the optical axis, is convex.
At least a portion of a surface of the fourth lens facing the projection side, which corresponds to the optical axis, is convex, and at least a portion of a surface of the fourth lens facing the pixel side, which corresponds to the optical axis, is concave. Therefore, the shape and the focal power of each lens in the projection lens can be reasonably distributed, the processing, the assembly and the realization are convenient, the aberration is reduced, and the imaging quality of the projection lens is improved.
In one possible implementation manner, the projection lens further comprises a diaphragm, the diaphragm is located between the second lens and the third lens, and the diaphragm can play a role in adjusting the intensity of light so as to realize further adjustment of luminous flux.
A second aspect of the present application provides a projection lens, including a first lens group and a third lens group, the first lens group including a first lens and a second lens, the third lens group including a plurality of third lenses, the projection lens further including a fourth lens, the first lens, the second lens, the third lens, and the fourth lens being sequentially arranged from a projection side to a pixel side along a direction of an optical axis;
The focal length f1 of the first lens and the focal length f2 of the second lens satisfy the conditional expression: 2. not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 5;
the focal length f3 of the third lens group and the focal length EFL of the projection lens satisfy the following conditional expression: 1.5 Not less than f3/EFL not less than 0.8, and the focal length f4 of the fourth lens and the focal length EFL of the projection lens satisfy the following conditional expression: 1.5 Not less than 0.8, and the focal length f3 of the third lens group and the focal length f4 of the fourth lens satisfy the following conditional expression: f3> f4. The projection lens has the advantages of large aperture, small volume, low cost and low cost, is suitable for the design of the image display module with lower pixels, and reduces the cost under the condition of improving the imaging quality.
A projection lens provided in a third aspect of the present application includes a first lens group including a first lens and a second lens, a third lens group including a plurality of third lenses, and a second lens group including a plurality of fourth lenses, the first lens, the second lens, the third lens, and the fourth lens being sequentially arranged from a projection side to a pixel side in a direction of an optical axis;
the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the conditional expression: 2. not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 5;
The focal length f3 of the third lens group and the focal length EFL of the projection lens satisfy the following conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than 0.8, and the focal length f3 of the third lens group and the focal length f4 of the second lens group satisfy the following conditional expression: f3> f4. The projection lens has the advantages of large aperture, small volume, low cost and low cost, is suitable for the design of the image display module with lower pixels, and reduces the cost under the condition of improving the imaging quality.
A fourth aspect of the present application provides a projection apparatus, which at least includes an image display module and the above projection lens.
The projection surface of the image display module is opposite to the fourth lens on the side, closest to the pixel, of the projection lens, and the image display module is configured to form a display image and transmit the display image to the projection lens through the projection surface. Through including the projection lens, the projection lens has big light ring, adaptation lower pixel image display module and low-cost characteristic concurrently, is favorable to promoting projection arrangement to the utilization ratio and the output of the luminous energy of image display module to promote projection arrangement's brightness. In addition, the projection lens and the image display module have good adaptation degree, and the cost of the projection device is reduced under the condition of ensuring the performance of the projection device.
In one possible implementation manner, the image display module comprises a chip and a plurality of micro light emitting diodes distributed on the chip in an array manner, so that the integration of the light source and the projection chip is realized, the structure of the projection device is simplified, and the image display module can be well matched with a projection lens.
A fifth aspect of the present application provides a vehicle, at least comprising a vehicle body and the above-mentioned projection device, the projection device being disposed on the vehicle body.
Drawings
Fig. 1 is a schematic structural diagram of a vehicle according to an embodiment of the present application;
fig. 2 is a schematic projection diagram of a projection device according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of an image display module in a projection apparatus according to an embodiment of the present application;
fig. 4 is a schematic structural diagram of a projection lens according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of another projection apparatus according to an embodiment of the present disclosure;
fig. 6 is a graph of a modulation transfer function of a projection lens at normal temperature according to an embodiment of the present application;
FIG. 7 is a graph of a modulation transfer function of a projection lens at-40deg.C according to an embodiment of the present application;
FIG. 8 is a graph of a modulation transfer function of a projection lens at 105℃according to an embodiment of the present application;
Fig. 9 is a field diagram of a projection lens according to an embodiment of the present application;
fig. 10 is a distortion chart of a projection lens according to an embodiment of the present disclosure;
FIG. 11 is a graph of relative illuminance of a projection lens according to an embodiment of the present disclosure;
FIG. 12 is a graph illustrating a modulation transfer function of another projection lens according to an embodiment of the present disclosure at room temperature;
FIG. 13 is a graph of a modulation transfer function of another projection lens according to an embodiment of the present disclosure at-30deg.C;
FIG. 14 is a graph of a modulation transfer function of another projection lens according to an embodiment of the present disclosure at 85deg.C;
FIG. 15 is a field curvature of another projection lens according to an embodiment of the present disclosure;
FIG. 16 is a graph illustrating distortion of another projection lens according to an embodiment of the present disclosure;
FIG. 17 is a graph showing the relative illuminance of another projection lens according to an embodiment of the present application;
FIG. 18 is a graph illustrating a modulation transfer function of a projection lens at room temperature according to an embodiment of the present disclosure;
FIG. 19 is a graph of a modulation transfer function of a projection lens at-30deg.C according to an embodiment of the present application;
FIG. 20 is a graph of a modulation transfer function of a projection lens at 105℃according to an embodiment of the present application;
FIG. 21 is a field curvature of a projection lens according to an embodiment of the present disclosure;
FIG. 22 is a graph illustrating distortion of a projection lens according to an embodiment of the present disclosure;
fig. 23 is a graph showing the relative illuminance of a projection lens according to another embodiment of the present application.
Reference numerals illustrate:
100-projection means;
10-an image display module; 11-chip; 12-micro light emitting diode;
20-a projection lens; 201-a first lens group; 21-a first lens; 22-a second lens; 23-a third lens; 24-fourth lens;
200-projection positions;
300-vehicle; 301-a vehicle body; 302-lamp shade.
Detailed Description
The terminology used in the description section of the present application is for the purpose of describing particular embodiments of the present application only and is not intended to be limiting of the present application.
The projection device is used for projecting the display image to a projection position through the projection lens so as to realize projection display of the display image. The conventional projection device generally includes a light source, an image generating module and a projection lens, wherein light generated by the light source forms a display image through the image generating module, and the display image is projected to a projection position after being amplified, focused and the like through the projection lens so as to realize the display of the image on the projection position. The image generation module forms higher image pixels, the requirement on the pixels of the projection lens matched with the image generation module is higher, the projection lens has higher resolution ratio, the volume of the projection lens is relatively larger, and the cost is higher.
With the continuous development of projection technology, in order to reduce the cost of the projection device, a Micro Light-Emitting Diode (Micro LED) projection display technology is gradually receiving attention and research. The projection device based on the Micro light emitting diode projection display technology comprises a Micro LED display chip and a projection lens, wherein the Micro LED display chip refers to an integrated high-density Micro-sized LED array on one chip, and can independently switch and regulate current for each independent microstructure area on the chip, so that the collection of functions of a light source and the projection chip is realized, namely, the Micro LED display chip is used as the light source and the image generation module, the structure of the projection device is remarkably simplified, and the cost is reduced. The number of independent microstructure switches in the display chip is small, the display pixels are relatively low, and the conventional projection lens is used to cause problems of high cost and large volume.
In addition, to meet the requirements of brightness of the projection image of the projection device, the improvement of the utilization rate of luminous energy and the output power of the projection device can be started. For example, the luminous flux of the projection lens can be increased, so that the light emitted by the image display module can be fully irradiated to the projection position through the projection lens, and the utilization rate and the output power of luminous energy are improved. The luminous flux of the projection lens is directly related to the aperture of the lens, so that the large aperture design of the projection lens is realized, and the brightness of the projection device is improved.
In addition, the luminous area can be increased to improve the luminous power of the image display module, so that the brightness is improved, namely the large target surface design of the projection lens is realized, the projection lens is matched with the image display module, and the brightness of the projection device is improved.
Based on this, the embodiment of the application provides a projection lens and projection device, and projection device can be the device based on miniature emitting diode projection technique, and the miniature emitting diode display chip in the projection device of projection lens matching that projection lens can be fine has less volume and lower cost, and projection lens has super large light ring and big target surface characteristic, can effectual promotion luminous flux, satisfies the high illumination brightness demand to projection device.
For ease of understanding, related art terms related to the embodiments of the present application are explained and explained first.
The image element side is the side facing the display image with the lens as the interface, and in the embodiment of the application, the side facing the image display module and facing away from the projection position with the projection lens as the interface is the image element side.
The projection side is the projection side with the lens as a boundary, and the side facing the projection position and facing away from the display image is the projection side.
The optical axis refers to a straight line passing through the center of each lens of a lens (e.g., a projection lens).
The focal length, also called focal length, is generally indicated by an effective focal length (Effective Focal Length, EFL for short) to be distinguished from parameters such as front focal length and back focal length. The focal length or effective focal length is a measure of the concentration or emission of light in an optical system, which refers to the perpendicular distance from the optical center of a lens or lens group to the focal plane when an infinitely distant scene is brought into clear images at the focal plane by a lens or lens group (e.g., a projection lens).
The back focal length (Back Focal Length, BFL for short) is the distance from the last optical surface vertex of the lens to the focal point behind the lens. In the embodiment of the application, the distance from the vertex of the surface facing the pixel side in the fourth lens adjacent to the pixel side in the projection lens to the rear focal point of the projection lens is referred to.
The aperture is used for controlling the quantity of light entering the device through the lens, and the size of the aperture is expressed by an F# value in the lens.
F# is a relative value (reciprocal of relative aperture) obtained by the focal length of the lens and the lens light passing diameter, and the smaller the f# value is, the more the amount of light is entered in the same unit time. The larger the f# value is, the smaller the depth of field is, and the photographed background content will be virtual, so that the effect similar to a tele lens is generated.
The total optical length (Total Track Length, abbreviated as TTL) refers to the distance from the vertex of the front surface of the first lens element to the image plane to the projection plane of the image display module. In this embodiment of the present application, the distance between the vertex of the surface of the projection lens, which is adjacent to the projection side and faces the projection side, and the projection surface of the image display module is referred to as the first lens.
Half height (IH) refers to the radius of the imaging circle, and in the embodiment of the present application, refers to half of the diagonal line of the projection surface of the Image display module.
The target surface refers to an imaging portion of the image sensor, and in this embodiment, refers to a light emitting surface (such as a projection surface of an image display module) of a display image, where the larger the target surface is, the larger the available light emitting area of the display image is, and the higher the brightness of the display image is.
The angle of View (FOV) is the angle formed by the two edges of the maximum range of the lens, which takes the lens as the vertex, and the image can pass through the lens, and is called the angle of View. The size of the angle of view determines the field of view of the lens, the larger the angle of view, the larger the field of view.
The optical power, which characterizes the refractive power of the lens to an incident parallel beam, is equal to the reciprocal of the focal length.
The Abbe number is used for measuring the light dispersion degree of the medium, the Abbe number is smaller when the light dispersion degree is larger, and conversely, the Abbe number is larger when the light dispersion degree is smaller.
Distortion refers to the difference in height between the off-axis point and the intersection of the chief ray on the image plane as the ideal (paraxial) image plane.
Relative illuminance refers to the ratio of the central illuminance to the peripheral illuminance. Too low contrast is manifested as a brighter center of the image and darker surroundings, a phenomenon known as vignetting. Too low a contrast may also result in color distortion.
The refractive index temperature coefficient refers to the relationship coefficient between the refractive index of the optical material and the temperature change.
Luminous flux refers to the light energy emitted by a light source per unit time.
Athermalization refers to reducing or eliminating the effect of temperature on lens performance (e.g., imaging performance, etc.).
The projection device provided in the embodiment of the application may be any device capable of realizing a projection function, such as a projector, a projection lamp, and the like. The projection device may be adapted for indoor projection, e.g. home projection, conference projection, theatre projection, indoor signage projection, etc. Alternatively, the projection device may be applied to projection of scenes such as outdoors, roads, etc., for example, advertisement projection, outdoor projection, road indication mark projection, etc.
The projection device may also be a projection lamp, a Head Up Display (HUD) device of a vehicle, or other devices suitable for the projection requirement of the vehicle.
Fig. 1 is a schematic structural diagram of a vehicle according to an embodiment of the present application.
The embodiment of the present application further provides a vehicle 300, as shown in fig. 1, taking an automobile as an example, the vehicle 300 may include a vehicle body 301 and a projection device 100, taking the projection device 100 as a projection vehicle lamp as an example, the projection device 100 is fixed on the vehicle body, specifically, the projection device may be located in the vehicle body 301, and illustratively, the vehicle body 301 may be further provided with a lampshade 302, and the projection device 100 may be opposite to the lampshade 302. The display image projected by the projection device 100 can be irradiated outside the vehicle body 301 through the lamp housing 302, and the illumination and other display requirements of the vehicle 300 are realized by the projection device 100.
It should be appreciated that the vehicle 300 may also include other structures to complete its function, for example, braking systems, drive systems, cameras, sensors, inductors, and the like.
Fig. 2 is a schematic projection diagram of a projection apparatus according to an embodiment of the present application.
Specifically, referring to fig. 2, the projection device 100 may include an image display module 10 and a projection lens 20, where the image display module 10 may form a light display image to be projected, the image display module 10 may include a projection surface 10a, the projection surface 10a may be opposite to a light incident surface of the projection lens 20, the display image formed by the image display module 10 may be transmitted to the projection lens 20 through irradiation of the projection surface 10a, the projection lens 20 may perform functions of amplifying, focusing, and the like on the display image, and the display image is irradiated to a preset projection position 200 after passing through the projection lens 20, so as to realize projection display of the display image.
In the projection device 100, a side of the projection lens 20 facing the projection surface 10a of the image display module 10 is a pixel side, a side of the projection lens 20 facing the projection position 200 and facing away from the image display module 10 is a projection side, the projection lens 20 forms an image at the projection position 200, and an imaging surface of the projection lens 20 may be a plane in which the projection position 200 is located.
It should be understood that, the projection position 200 is used to carry the display image projected by the projection device 100 to display the display image, the projection position 200 may be a projection curtain, or the projection position 200 may be a window, a glass, or the like, or the projection position 200 may be any structure capable of carrying the display image, such as a wall surface.
Fig. 3 is a schematic structural diagram of an image display module in a projection apparatus according to an embodiment of the present application.
The image display module 10 may be a Micro light emitting diode display chip (Micro LED display chip), specifically, referring to fig. 3, the image display module 10 may include a chip 11 and a plurality of Micro light emitting diodes 12, where the plurality of Micro light emitting diodes 12 are distributed on the chip 11 in an array manner, and the projection surface 10a may be a plane where the plurality of Micro light emitting diodes 12 are distributed in an array manner. The light emitting diode 12 is used as a light source, and simultaneously, the chip 11 can realize the functions of independent switch and current regulation of each independent microstructure on the chip 11, namely, the Micro LED display chip realizes the integration of the light source and the projection chip, and the structure of the projection device 100 is simplified.
Of course, in some other examples, the image display module 10 may be other devices capable of forming a projection image, for example, the image display module 10 may be formed of a separate light source and image forming module.
The following describes a projection lens in a projection device according to an embodiment of the present application with reference to the accompanying drawings.
Fig. 4 is a schematic structural diagram of a projection lens according to an embodiment of the present application, and fig. 5 is a schematic structural diagram of another projection apparatus according to an embodiment of the present application.
The projection lens 20 may include a plurality of lenses having optical power, and specifically, referring to fig. 4, with L as an optical axis of the projection lens 20, the projection lens 20 may include at least a first lens 21, a second lens 22, a third lens 23, and a fourth lens 24 sequentially arranged from a projection side to a pixel side along the optical axis direction.
Referring to fig. 5, when the projection lens 20 is applied to the projection apparatus 100, the fourth lens 24 closer to the pixel is disposed facing the projection surface 10a of the image display module 10, the fourth lens 24 may be a light incident surface of the projection lens 20, and the first lens 21 is disposed facing the projection position 200.
The first lens 21, the second lens 22, the third lens 23 and the fourth lens 24 may be single lens, that is, the projection lens 20 includes four lenses, which is a four-lens structure.
It should be noted that, the structure of the projection lens 20 may be changed by adjusting the focal lengths of the first lens 21, the second lens 22, the third lens 23 and the fourth lens 24 included in the projection lens 20, so as to change the performance of the projection lens 20, so that the projection lens 20 may implement a large aperture design.
Specifically, with the focal length of the projection lens 20 being EFL, the focal length of the first lens 21 being f1, the focal length of the second lens 22 being f2, the focal length f1 of the first lens 21 and the focal length f2 of the second lens 22 may satisfy the following conditional expression: 2. not less than |f1/f2| not less than 1.2. The first lens group 201 is composed of the first lens 21 and the second lens 22, the focal length of the first lens group 201 is f12, and the focal length f12 of the first lens group 201 and the focal length EFL of the projection lens 20 can satisfy the following conditional expression: the f12/EFL is more than or equal to 5.
The focal length f3 of the third lens element 23, and the focal length f3 of the third lens element 23 and the focal length EFL of the projection lens 20 can satisfy the following conditional expression: 1.5 Not less than f3/EFL not less than 0.8, the focal length of the fourth lens 24 is f4, and the focal length f4 of the fourth lens 24 and the focal length EFL of the projection lens 20 can satisfy the following conditional expression: 1.5 Not less than 0.8 in terms of F4/EFL, and the focal length f3 of the third lens 23 may be greater than the focal length f4 of the fourth lens 24. The projection lens 20 formed by the first lens 21, the second lens 22, the third lens 23 and the fourth lens 24 meeting the above conditional expression has a small f#, can realize a large aperture design, increases the luminous flux of the projection lens 20, and can improve the utilization ratio and output power of luminous energy of the image display module 10 and the illumination brightness of the projection device 100 when applied to the projection device 100.
In addition, the projection lens 20 realizes a large aperture design only through the first lens 21, the second lens 22, the third lens 23 and the fourth lens 24, and the projection lens 20 can be a four-lens structure with fewer lenses, simple structure, smaller volume and lower cost. The projection lens 20 with a simple structure has relatively low pixels, can be well matched with a miniature light-emitting diode display chip with low pixel requirement, and meets the changing requirement of projection images, so that the projection lens 20 has the design of a large aperture, a small volume, low cost and low pixel image display module 10.
It should be noted that, the number of lenses included in the projection lens 20 may be greater than 4, for example, in some other examples, from the projection side to the pixel side along the optical axis direction, the projection lens may include a first lens, a second lens, a third lens, and a second lens group, and the second lens group may include a plurality of fourth lenses.
That is, the lens close to the pixel side can be a lens group, which is convenient to realize and is helpful for improving imaging quality. In addition, the lens group can be a lens group formed by glass lenses, and the cost is reduced under the condition of improving the imaging quality.
Wherein the second lens group may include two fourth lenses, although in some other examples the number of fourth lenses may be three or more. The large aperture design of the projection lens is realized, the structure is simpler, the cost is lower, the formed projection lens framework pixels are relatively lower, and the micro light-emitting diode display chip can be well adapted.
When the second lens group includes a plurality of fourth lenses, the plurality of fourth lenses are sequentially disposed from the pixel side to the projection side along the optical axis direction, and a fourth lens closer to the pixel side among the plurality of fourth lenses is opposite to the projection plane of the image display module.
When the projection lens comprises a first lens group, a third lens and a second lens group, and the second lens group comprises a plurality of fourth lenses, referring to the framework of the four lenses, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the following conditional expression: 2. not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 5;
the focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the conditional expression: 1.5 The focal length f4 of the second lens group and the focal length EFL of the projection lens meet the condition that the ratio of F3/EFL is not less than 0.8: 1.5 Not less than 0.8, and the focal length f3 of the third lens and the focal length f4 of the second lens group satisfy the following conditional expression: f3> f4. It should be noted that, the focal length f4 of the second lens group refers to a focal length of a lens group formed by a plurality of fourth lenses.
Alternatively, in some other examples, the projection lens may include a first lens, a second lens, a third lens group including a plurality of third lenses, and a second lens group including a plurality of fourth lenses from the projection side to the pixel side in the optical axis direction. Correspondingly, the focal length f3 of the third lens group refers to the focal length of the lens group formed by a plurality of third lenses, which is convenient to realize and is beneficial to reducing the cost under the condition of improving the imaging quality.
The third lens group may include two third lenses, or the number of third lenses may be other. The formed projection lens has the advantages of large aperture, small volume, low cost and adaptation to the design of a lower pixel image display module.
Or, in some other examples, from the projection side to the pixel side along the optical axis direction, the projection lens includes a first lens, a second lens, a third lens group, and a fourth lens, and the third lens group includes a plurality of third lenses, which can also reduce costs under the condition of improving imaging quality. The formed projection lens has the advantages of large aperture, small volume, low cost and adaptation to the design of the image display module with lower pixels.
In this embodiment, the projection lens includes four lenses, i.e., a first lens, a second lens, a third lens and a fourth lens.
In order to further increase the aperture, so as to improve the utilization rate and output rate of the projection lens to the luminous energy, the projection device has better luminous flux, and the focal length f1 of the first lens and the focal length f2 of the second lens can satisfy the following conditional expression: 1.9 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 6. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.5 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 0.9: 1.4 Not less than f4/EFL not less than 0.8.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.8 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 6. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.5 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 1.0: 1.3 Not less than f4/EFL not less than 0.8.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.7 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 7.5. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.5 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 1.2: 1.2 Not less than f4/EFL not less than 0.8.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.6 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 8. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.5 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 1.1: 1.0 Not less than f4/EFL not less than 0.8.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.4 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 8.9. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.5 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 1.3: 1.5 Not less than f4/EFL not less than 1.0.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.5 Not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 10.6. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.4 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 0.9.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.9 Not less than |f1/f2| not less than 1.3, the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 9. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.2 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.1.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.9 Not less than |f1/f2| not less than 1.4, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 11.1.
The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.3 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.0.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.9 Not less than |f1/f2| not less than 1.5, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 12.
The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.1 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.2.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.9 Not less than |f1/f2| not less than 1.6, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 14.
The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.0 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 0.8: 1.5 Not less than f4/EFL not less than 1.3.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.8 Not less than |f1/f2| not less than 1.4, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 15.
The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.3 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 0.9: 1.3 Not less than f4/EFL not less than 0.8.
Alternatively, the focal length f1 of the first lens and the focal length f2 of the second lens may satisfy the conditional expression: 1.7 Not less than |f1/f2| not less than 1.5, and the focal length f12 of the first lens group and the focal length EFL of the projection lens can satisfy the following conditional expression: the f12/EFL is more than or equal to 13.6. The focal length f3 of the third lens and the focal length EFL of the projection lens may satisfy the conditional expression: 1.2 The focal length f4 of the fourth lens and the focal length EFL of the projection lens can meet the condition that the F3/EFL is not less than 1.0: 1.4 Not less than f4/EFL not less than 1.1.
Specifically, the f# of the projection lens 20 may range from: f# is more than or equal to 0.6 and less than or equal to 1.0, and F# is smaller, so that the design requirement of a large aperture of the projection lens 20 is met.
In order to further optimize the F-number of the projection lens 20 to better meet the requirement of large F-number design of the projection lens, the range of the F-number #f of the projection lens may be: f# is more than or equal to 0.6 and less than or equal to 0.8.
Further, the f# of the lens 20 may be smaller than 0.7, so as to realize an ultra-large aperture design of the lens 20, and further increase the luminous flux of the lens 20.
Taking the total optical length of the projection lens 20 as TTL, the total optical length of the projection lens 20 TTL and the focal length EFL of the projection lens 20 may satisfy the following conditional expression: 2.5 And the total length of the projection lens 20 is reduced, so that the small-volume design of the projection lens 20 can be realized.
In order to further reduce the optical total length of the projection lens, the length of the projection lens is compressed to better meet the small-volume design requirement of the projection lens, and the optical total length TTL of the projection lens and the focal length EFL of the projection lens can meet the conditional expression: 2.3 More than or equal to TTL/EFL more than or equal to 1.5.
Alternatively, the optical total length TTL of the projection lens and the focal length EFL of the projection lens may satisfy the conditional expression: 2.0 More than or equal to TTL/EFL more than or equal to 1.5.
Alternatively, the optical total length TTL of the projection lens and the focal length EFL of the projection lens may satisfy the conditional expression: 2.5 More than or equal to TTL/EFL more than or equal to 1.9.
Alternatively, the optical total length TTL of the projection lens and the focal length EFL of the projection lens may satisfy the conditional expression: 2.5 More than or equal to TTL/EFL more than or equal to 2.1. Further reduce the length of the projection lens and meet the small-volume design of the projection lens
Alternatively, the optical total length TTL of the projection lens and the focal length EFL of the projection lens may satisfy the conditional expression: 2.4 More than or equal to TTL/EFL more than or equal to 1.7.
In addition, with the back focal length of the projection lens 20 being BFL, the half image height of the projection lens 20 being IH, the back focal length of the projection lens 20 BFL and the half image height of the projection lens 20 may satisfy the conditional expression: 1.4 The BFL/IH is more than or equal to 0.6, so that the projection lens 20 has larger half image height on the premise of ensuring that the projection lens 20 has smaller total length, large target surface design of the projection lens 20 is realized, and the increase of the luminous area is facilitated, thereby improving the luminous power of the projection device 100 and further improving the brightness of the projection device 100.
Under the condition of ensuring the small total length of the projection lens, in order to further increase the half image height, the design requirement of a large target surface of the projection lens is better met, so that the luminous power of the projection device is more effectively improved, and the back focal length BFL of the projection lens and the half image height of the projection lens can meet the condition: 1.4 More than or equal to BFL/IH more than or equal to 0.8.
Alternatively, the back focal length BFL of the projection lens and the half image height of the projection lens may satisfy the conditional expression: 1.4 More than or equal to BFL/IH more than or equal to 1.1.
Alternatively, the back focal length BFL of the projection lens and the half image height of the projection lens may satisfy the conditional expression: 1.2 More than or equal to BFL/IH more than or equal to 0.6.
Alternatively, the back focal length BFL of the projection lens and the half image height of the projection lens may satisfy the conditional expression: 1.3 More than or equal to BFL/IH more than or equal to 0.6.
Alternatively, the back focal length BFL of the projection lens and the half image height of the projection lens may satisfy the conditional expression: 1.2 More than or equal to BFL/IH more than or equal to 0.7.
That is, the projection lens in the embodiment of the application, through the lens framework with simple structure, such as the four-lens framework, can realize that the projection lens 20 has the characteristics of large aperture, large target surface, small volume and low cost, and greatly reduces the volume and cost of the projection lens 20 on the premise of improving the luminous flux of the projection lens 20, thereby having good practicability.
Specifically, among the plurality of lenses of the projection lens 20, part of the lenses may be plastic lenses, and part of the lenses may be glass lenses, so that the cost of the plastic lenses is low, and the cost of the projection lens 20 is further reduced by making part of the lenses be plastic lenses under the condition of ensuring the optical performance of the projection lens 20.
In addition, the projection lens 20 using the glass lens and plastic lens structure can utilize the matching of the refractive index temperature coefficient of the glass lens and the refractive index temperature coefficient of the plastic lens, for example, the refractive index temperature coefficient of the glass lens is a negative number, the refractive index temperature coefficient of the plastic is a positive number, so as to realize mutual compensation, be favorable for reducing the thermal difference of the projection lens 20, that is, reducing the influence of temperature on the imaging performance of the projection lens 20, and the like, and be favorable for realizing the design of heat difference elimination of the projection lens 20, so that the projection lens 20 can be suitable for high and low temperature environments, and the stability and reliability of the performance of the projection lens 20 in different temperature environment scenes can be ensured.
Specifically, the third lens 23 and the fourth lens 24 are located at positions adjacent to the pixel side, and the first lens 21 and the second lens 22 are located at positions adjacent to the projection side, that is, the third lens 23 and the fourth lens 24 are disposed adjacent to the image display module 10 and the like, and the first lens 21 and the second lens 22 are located relatively far from the image display module 10 and the like. The first lens 21 and the second lens 22 can be made of plastic lenses, and the third lens 23 and the fourth lens 24 can be made of glass lenses, so that the influence of heat generated by the image display module 10 during operation on the plastic lenses can be reduced, and the reliability of the projection lens 20 can be improved.
In addition, the first lens 21 and the second lens 22 may be aspherical lenses, and the third lens 23 and the fourth lens 24 may be spherical lenses, that is, glass lenses are spherical lenses, with lower cost. The plastic lens is an aspheric lens, and can be matched with the spherical lens to ensure the design of a large aperture, and meanwhile, the spherical aberration introduced by the spherical lens can be reduced or eliminated, the imaging performance of the projection lens 20 is ensured, and the design with high reliability and low cost is considered.
The fourth lens 24 and the third lens 23 adjacent to the pixel side may have positive optical power, the second lens 22 may have negative optical power, and the first lens 21 may have positive optical power, which reasonably distributes optical power, thereby being beneficial to reducing aberration and improving imaging quality of the projection lens 20.
With the abbe number of the first lens 21 being Vd1, the abbe number Vd1 of the first lens 21 may satisfy the conditional expression: vd1 is more than or equal to 52. With the abbe number of the second lens 22 being Vd2, the abbe number Vd2 of the second lens 22 may satisfy the condition: vd2 is less than or equal to 30. And the abbe number Vd1 of the first lens 21 and the abbe number Vd2 of the second lens 22 may satisfy the conditional expression: vd1/Vd2 is more than or equal to 1.8.
That is, the abbe number of the first lens 21 is greater than the abbe number of the second lens 22, the first lens 21 is a lens with a high abbe number, the second lens 22 is a lens with a low abbe number, the first lens 21 and the second lens 22 can perform complementary balancing in terms of dispersion capability, which is beneficial to reducing or eliminating imaging chromatic aberration, and further improving the imaging quality of the projection lens 20.
In order to further reduce or eliminate chromatic aberration, the projection lens has better imaging quality, and the abbe numbers of the first lens and the second lens can be optimized, for example, the abbe number Vd1 of the first lens can satisfy the following conditional expression: vd1 is greater than or equal to 54, and Abbe number Vd2 of the second lens can meet the following conditional expression: vd2 is less than or equal to 20, and the Abbe number Vd1 of the first lens and the Abbe number Vd2 of the second lens can meet the conditional expression: vd1/Vd2 is more than or equal to 2.7.
Alternatively, the abbe number Vd1 of the first lens may satisfy the conditional expression: vd1 is greater than or equal to 56, and Abbe number Vd2 of the second lens can meet the following conditional expression: vd2 is less than or equal to 24, and the Abbe number Vd1 of the first lens and the Abbe number Vd2 of the second lens can meet the conditional expression: vd1/Vd2 is more than or equal to 2.3.
As shown in fig. 4, at least a portion of a surface of the first lens 21 facing the projection side corresponding to the optical axis may be convex, or at least a portion of a surface of the first lens 21 facing the pixel side corresponding to the optical axis may be convex, for example, the first lens 21 may be a lenticular lens.
At least a portion of a surface of the second lens 22 facing the projection side corresponding to the optical axis may be convex, and at least a portion of a surface of the second lens 22 facing the pixel side corresponding to the optical axis may be concave, for example, the second lens 22 may be a meniscus lens.
At least a portion of a surface of the third lens 23 facing the projection side corresponding to the optical axis may be concave, and at least a portion of a surface of the third lens 23 facing the pixel side corresponding to the optical axis may be convex, for example, the third lens 23 may be a meniscus lens.
At least a portion of a surface of the fourth lens 24 facing the projection side corresponding to the optical axis may be convex, and at least a portion of a surface of the fourth lens 24 facing the pixel side corresponding to the optical axis may be concave, for example, the fourth lens 24 may be a meniscus lens. Therefore, the shape and the focal power of each lens in the projection lens 20 can be reasonably distributed, the processing, the assembly and the realization are convenient, the aberration is reduced, and the imaging quality of the projection lens 20 is improved.
In addition, the projection lens 20 may further include a diaphragm, and the diaphragm may be located between the second lens 22 and the third lens 23, where the diaphragm may play a role in adjusting the intensity of light, so as to further adjust the luminous flux.
The architecture and performance of the projection lens provided in this application are described below in connection with specific examples.
Example 1
In this example, the projection lens 20 includes four lenses (see fig. 4) of a first lens 21, a second lens 22, a third lens 23, and a fourth lens 24, which are arranged in this order from the projection side to the pixel side along the optical axis, the first lens 21 and the second lens 22 being aspherical plastic lenses, and the third lens 23 and the fourth lens 24 being spherical glass lenses.
Wherein, the focal length f1=37 mm of the first lens 21, the focal length f2= -18mm of the second lens 22, the focal length f1 of the first lens 21 and the focal length f2 of the second lens 22 satisfy: the focal length f12= 266.2mm of the first lens group 201 composed of the first lens 21 and the second lens 22, the focal length efl=29.82 mm of the projection lens 20, and the focal length f12 of the first lens group 201 and the focal length EFL of the projection lens 20 satisfy: f12/efl=8.9.
The focal length f3=45 mm of the third lens 23, the focal length f4=33 of the fourth lens 24, and the focal length f3 of the third lens 23 is larger than the focal length f4 of the fourth lens 24. The focal length f3 of the third lens 23 and the focal length EFL of the projection lens 20 satisfy: f3/efl=1.5, the focal length f4 of the fourth lens 24 and the focal length EFL of the projection lens 20 satisfy: f4/efl=1.1.
The abbe number Vd1 of the first lens 21=55.98, the abbe number Vd2 of the second lens 22=23.53, and the abbe number Vd1 of the first lens 21 and the abbe number Vd2 of the second lens 22 satisfy: vd 1/vd2=2.4.
The first lens 21 has positive optical power, and the first lens 21 is a biconvex lens. The second lens 22 has negative power, the second lens 22 is a meniscus lens, and a surface of the second lens 22 facing the projection side is a convex surface. The third lens 23 has positive power, the third lens 23 is also a meniscus lens, and a surface of the third lens 23 facing the pixel side is a convex surface. The fourth lens 24 is a meniscus lens, and a surface of the fourth lens 24 facing the projection side is a convex surface.
F# =0.7 for the projection lens 20.
The optical total length ttl= 54.50mm of the projection lens 20, the maximum diameter of the projection lens 20 is 42mm, the optical total length TTL of the projection lens 20 and the focal length EFL of the projection lens 20 satisfy: TTL/efl=1.8.
The back focal length bfl=9.01 mm of the projection lens 20, the half image height IH of the projection lens 20=6.61 mm, and the back focal length BFL of the projection lens 20 and the half image height IH of the projection lens 20 satisfy: BFL/ih=1.4.
Table 1 below shows optical parameters of each lens in a projection lens according to an embodiment of the present application.
Wherein L1, L2, L3 and L4 respectively denote a first lens 21, a second lens 22, a third lens 23 and a fourth lens 24, S1 and S2 respectively denote a face of the first lens 21 facing the projection side and a face of the second lens 22 facing the pixel side, S3 and S4 respectively denote a face of the second lens 22 facing the projection side and a face of the third lens 23 facing the pixel side, S5 and S6 respectively denote a face of the third lens 23 facing the projection side and a face of the fourth lens 24 facing the pixel side, and S7 and S8 respectively denote a face of the fourth lens 24 facing the projection side and a face of the pixel side.
R represents the radius of curvature of the lens. Th denotes the center thickness of the lens or the air space thickness of two adjacent lenses at the position corresponding to the optical axis in the optical axis direction, for example, th corresponding to S1 row denotes the center thickness of the first lens 21, th corresponding to S2 row denotes the distance between the surface of the first lens 21 facing the pixel side and the surface of the second lens 22 facing the projection side in the optical axis direction at the position corresponding to the optical axis, and so on.
Nd represents the refractive index of the lens. Vd represents the abbe number of the lens and f represents the focal length of the lens.
Table 2 below shows the aspherical coefficients of each lens in a projection lens according to an embodiment of the present application.
Face number k A 2 A 4 A 6 A 8
S1 0 0 -6.11E-6 3.21E-8 -1.18E-10
S2 -10.57 0 1.70E-5 -4.37E-8 -4.74E-13
S3 -0.17 0 -9.22E-5 1.43E-7 -1.41E-10
S4 -2.02 0 -1.69E-5 4.63E-8 3.28E-11
The projection lens 20 includes four lenses, wherein the first lens 21 and the second lens 22 are aspherical lenses, and the aspherical lenses can satisfy:
wherein Z is the sagittal height of the aspheric surface, r is the radial coordinate of the aspheric surface, c is the curvature of the aspheric apex sphere, k is the quadric constant, and A2, A4, A6 and A8 are aspheric coefficients.
The optical parameters of the projection lens 20 composed of the above lenses can be seen in table 3 below.
Table 3 shows optical parameters of a projection lens according to an embodiment of the present application.
Focal length EFL 29.82mm
F# value of F # 0.7
FOV (field of view) 25.4°
Half height IH 6.61mm
Total optical length TTL 54.50mm
Back focal length BFL 9.01mm
As can be seen from table 3, the projection lens 20 provided in the embodiment of the present application has the characteristics of large aperture, large target surface and low total optical length, improves the luminous flux and imaging performance of the projection lens 20, and has a smaller volume.
Fig. 6 is a graph of a modulation transfer function of a projection lens at normal temperature according to an embodiment of the present application.
In the examples herein, the room temperature was 20 ℃. Referring to fig. 6, at a spatial frequency of 12.5LP/mm, the optical transfer function coefficient (Optical Transfer Function, abbreviated as OTF) corresponding to the central field of view of the projection lens 20 is above 0.8 (see TS in fig. 6 for a curve of 0.0000 nm), the OTF coefficient corresponding to the IH field of view of 0.7 times is above 0.5 (see TS in fig. 6 for a curve of 6.6000 nm), and the projection lens 20 has good resolution and contrast, ensuring high imaging quality.
Fig. 7 is a graph of a modulation transfer function of a projection lens at-40 ℃ according to an embodiment of the present application, and fig. 8 is a graph of a modulation transfer function of a projection lens at 105 ℃ according to an embodiment of the present application.
Referring to fig. 7 and 8, in a scene of-40 ℃ at low temperature and 105 ℃ at high temperature, the OTF coefficient corresponding to the central field of view of the projection lens 20 is above 0.35, the OTF coefficient corresponding to the 0.7 times of IH field of view is above 0.2, and the influence of the high temperature or low temperature environment on the imaging performance of the projection lens 20 is small, so that the athermal design of the projection lens 20 is realized. After focusing in normal temperature environment, the imaging can be clearly performed without focusing again by switching to the environment of-40 ℃ to 105 ℃, and the imaging stability and reliability are good.
Fig. 9 is a field diagram of a projection lens according to an embodiment of the present application, and fig. 10 is a distortion curve of a projection lens according to an embodiment of the present application.
Fig. 9 and 10 show the field curvature and distortion curve of light having wavelengths of 611 nm,525nm and 460nm, respectively, after passing through the projection lens 20, where S is the field curvature in the sagittal direction and T is the field curvature in the meridional direction, and as can be seen from fig. 9, the projection lens 20 has a smaller field curvature.
As can be seen from fig. 10, the distortion of the projection lens 20 is less than 3%, the distortion is small, the imaging quality is high, and the display image projected through the projection lens 20 is not distorted.
Fig. 11 is a graph of relative illuminance of a projection lens according to an embodiment of the present application.
Fig. 11 shows a graph of the relative illuminance of 460nm light passing through the projection lens 20, and as can be seen from fig. 11, the relative illuminance of the projection lens 20 is greater than 90%, the projection lens 20 has a large luminous flux, and the brightness of the display image projected through the projection lens 20 is uniform.
Example two
In this example, the focal length f1=24.9 mm of the first lens, the focal length f2= -16.4mm of the second lens, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: the first lens group formed by the first lens and the second lens has a focal length f12=312.5 mm, the projection lens has a focal length efl=29.58 mm, and the first lens group has a focal length and the projection lens has a focal length EFL satisfying: f12/efl=10.6.
The focal length f3=44.1 mm of the third lens, the focal length f4=36.3 of the fourth lens, and the focal length f3 of the third lens is greater than the focal length f4 of the fourth lens. The focal length f3 of the third lens and the focal length EFL of the projection lens satisfy: f3/efl=1.5, the focal length f4 of the fourth lens and the focal length EFL of the projection lens satisfy: f4/efl=1.2.
The abbe number Vd 1= 55.31 of the first lens, the abbe number Vd 2=23.53 of the second lens, and the abbe number Vd1 of the first lens and the abbe number Vd2 of the second lens satisfy: vd 1/vd2=2.4.
The first lens has positive optical power, and the first lens is a biconvex lens. The second lens has negative focal power, is a meniscus lens, and has a convex surface facing the projection side. The third lens has positive focal power, is also a meniscus lens, and has a convex surface facing the pixel side. The fourth lens is a meniscus lens, and one surface of the fourth lens facing the projection side is a convex surface.
F# = 0.7804 of the f# -F.
The total optical length of the projection lens ttl=55.00 mm, the maximum diameter of the projection lens is 42mm, and the total optical length of the projection lens TTL and the focal length of the projection lens EFL satisfy: TTL/efl=1.9.
The back focal length bfl=9.46 mm of the projection lens, the half image height IH of the projection lens=6.61 mm, and the back focal length BFL of the projection lens and the half image height IH of the projection lens satisfy: BFL/ih=1.4.
Table 4 below shows the optical parameters of each lens in another projection lens provided in the embodiments of the present application.
The description of each parameter in table 4 refers to embodiment one, and will not be repeated in this embodiment.
Table 5 below shows the aspherical coefficients of each lens in another projection lens provided in the embodiment of the present application.
Face number k A 2 A 4 A 6 A 8
S1 0 0 -4.95E-6 3.22E-8 -1.18E-10
S2 -8.95 0 1.83E-5 -4.40E-8 -1.32E-12
S3 -0.28 0 -9.57E-5 1.37E-7 -1.36E-10
S4 -2.03 0 -2.09E-5 4.14E-8 2.98E-11
The projection lens comprises four lenses, wherein the first lens and the second lens are aspheric lenses, and the aspheric lenses can meet the following conditions:
wherein Z is the sagittal height of the aspheric surface, r is the radial coordinate of the aspheric surface, c is the curvature of the aspheric apex sphere, k is the quadric constant, and A2, A4, A6 and A8 are aspheric coefficients.
The optical parameters of the projection lens composed of the above lenses can be seen in table 5 below.
Table 6 shows the optical parameters of another projection lens provided in an embodiment of the present application.
Focal length EFL 29.58mm
F# value of F # 0.804
FOV (field of view) 25.6°
Half height IH 6.61mm
Total optical length TTL 55.00mm
Back focal length BFL 9.46mm
As can be seen from table 6, the projection lens provided in the embodiment of the present application has the characteristics of large aperture, large target surface and low total optical length, improves the luminous flux and imaging performance of the projection lens, and has a smaller volume.
Fig. 12 is a graph of modulation transfer function of another projection lens at normal temperature according to an embodiment of the present application.
Referring to fig. 12, at a spatial frequency of 12.5LP/mm, the optical transfer function coefficient (Optical Transfer Function, abbreviated as OTF) corresponding to the central field of view of the projection lens is above 0.8 (see TS in fig. 12 for a curve of 0.0000 nm), the OTF coefficient corresponding to the IH field of view of 0.7 times is above 0.5 (see TS in fig. 12 for a curve of 6.6000 nm), and the projection lens has good resolution and contrast, and ensures high imaging quality.
Fig. 13 is a graph of a modulation transfer function of another projection lens at-30 ℃ according to an embodiment of the present application, and fig. 14 is a graph of a modulation transfer function of another projection lens at 85 ℃ according to an embodiment of the present application.
With reference to fig. 13 and 14, in a scene of-30 ℃ at low temperature and 85 ℃ at high temperature, under a spatial frequency of 12.5LP/mm, the OTF coefficient corresponding to the central view field of the projection lens is above 0.35, the OTF coefficient corresponding to the 0.7 times IH view field is above 0.2, and the influence of the high temperature or low temperature environment on the imaging performance of the projection lens is small, so that the athermal design of the projection lens is realized. After focusing in normal temperature environment, the imaging can be clearly performed without focusing again by switching to the environment of-30 ℃ to 85 ℃, and the imaging stability and reliability are good.
Fig. 15 is a field diagram of another projection lens according to an embodiment of the present application, and fig. 16 is a distortion curve of another projection lens according to an embodiment of the present application.
Fig. 15 and 16 show the field curvature and distortion curves of light having wavelengths of 611 nm,525nm and 460nm, respectively, after passing through the projection lens, where S is the field curvature in the sagittal direction and T is the field curvature in the meridional direction, and as can be seen from fig. 15, the projection lens has a smaller field curvature.
As can be seen from fig. 16, the distortion of the projection lens is less than 3%, the projection lens has small distortion, high imaging quality, and the display image projected by the projection lens is not distorted.
Fig. 17 is a graph of relative illuminance of another projection lens according to an embodiment of the present application.
Fig. 17 shows a graph of the relative illuminance of 460nm light passing through the projection lens, and as can be seen from fig. 17, the relative illuminance of the projection lens is greater than 90%, the projection lens has a large luminous flux, and the brightness of the display image projected through the projection lens is very uniform.
Example III
In this example, the focal length f1=28.2 mm of the first lens, the focal length f2= -18.1mm of the second lens, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: the first lens group formed by the first lens and the second lens has focal length f12=329.1 mm, the projection lens has focal length efl= 29.53mm, and the focal length f12 of the first lens group and the focal length EFL of the projection lens satisfy: f12/efl=11.1.
The focal length f3=43.3 mm of the third lens, the focal length f4=34.3 of the fourth lens, and the focal length f3 of the third lens is greater than the focal length f4 of the fourth lens. The focal length f3 of the third lens and the focal length EFL of the projection lens satisfy: f3/efl=1.5, the focal length f4 of the fourth lens and the focal length EFL of the projection lens satisfy: f4/efl=1.2.
The abbe number Vd 1= 55.31 of the first lens, the abbe number Vd 2=29.91 of the second lens, and the abbe number Vd1 of the first lens and the abbe number Vd2 of the second lens satisfy: vd 1/vd2=1.8.
The first lens has positive optical power, and the first lens is a biconvex lens. The second lens has negative focal power, is a meniscus lens, and has a convex surface facing the projection side. The third lens has positive focal power, is also a meniscus lens, and has a convex surface facing the pixel side. The fourth lens is a meniscus lens, and one surface of the fourth lens facing the projection side is a convex surface.
F# =0.807 for the projection lens.
The total optical length ttl= 55.84mm of the projection lens, the maximum diameter of the projection lens is 42mm, the total optical length TTL of the projection lens and the focal length EFL of the projection lens satisfy: TTL/efl=1.9.
The back focal length bfl=9.00 mm of the projection lens, the half image height IH of the projection lens=6.61 mm, and the back focal length BFL of the projection lens and the half image height IH of the projection lens satisfy: BFL/ih=1.4.
Table 7 below shows the optical parameters of each lens in yet another projection lens provided in an embodiment of the present application.
The description of each parameter in table 7 refers to embodiment one, and will not be repeated in this embodiment.
Table 8 below shows aspherical coefficients of each lens in still another projection lens provided in the embodiment of the present application.
Face number k A 2 A 4 A 6 A 8
S1 0 0 3.46E-6 2.87E-10 -6.85E-11
S2 -8.36 0 1.09E-5 -3.55E-8 4.18E-12
S3 -0.43 0 -1.74E-4 3.44E-7 -4.69E-10
S4 -1.81 0 -7.56E-5 2.83E-7 -4.05E-10
The projection lens comprises four lenses, wherein the first lens and the second lens are aspheric lenses, and the aspheric lenses can meet the following conditions:
wherein Z is the sagittal height of the aspheric surface, r is the radial coordinate of the aspheric surface, c is the curvature of the aspheric apex sphere, k is the quadric constant, and A2, A4, A6 and A8 are aspheric coefficients.
The optical parameters of the projection lens composed of the above lenses can be seen in table 9 below.
Table 9 shows the optical parameters of yet another projection lens provided in an embodiment of the present application.
Focal length EFL 29.53mm
F# value of F # 0.807
FOV (field of view) 25.6°
Half height IH 6.61mm
Total optical length TTL 55.84mm
Back focal length BFL 9.00mm
As can be seen from table 9, the projection lens provided in the embodiment of the present application has the characteristics of large aperture, large target surface and low total optical length, improves the luminous flux and imaging performance of the projection lens, and has a smaller volume.
Fig. 18 is a graph of a modulation transfer function of a projection lens at normal temperature according to another embodiment of the present application.
Referring to fig. 18, at a spatial frequency of 12.5LP/mm, the optical transfer function coefficient (Optical Transfer Function, abbreviated as OTF) corresponding to the central field of view of the projection lens is above 0.8 (see TS in fig. 18 for a curve of 0.0000 nm), the OTF coefficient corresponding to the IH field of view of 0.7 times is above 0.5 (see TS in fig. 18 for a curve of 6.6000 nm), and the projection lens has good resolution and contrast, and ensures high imaging quality.
Fig. 19 is a graph of a modulation transfer function of a projection lens at-30 ℃ according to an embodiment of the present application, and fig. 20 is a graph of a modulation transfer function of a projection lens at 105 ℃ according to an embodiment of the present application.
With reference to fig. 19 and 20, in a scene of-30 ℃ at low temperature and 105 ℃ at high temperature, under a spatial frequency of 12.5LP/mm, the OTF coefficient corresponding to the central view field of the projection lens is above 0.35, the OTF coefficient corresponding to the 0.7 times IH view field is above 0.2, and the influence of the high temperature or low temperature environment on the imaging performance of the projection lens is small, so that the athermal design of the projection lens is realized. After focusing in normal temperature environment, the imaging can be clearly performed without focusing again by switching to the environment of-30 ℃ to 105 ℃, and the imaging stability and reliability are good.
Fig. 21 is a field curvature diagram of a projection lens according to an embodiment of the present application, and fig. 22 is a distortion curve diagram of a projection lens according to an embodiment of the present application.
Fig. 21 and 22 show the field curvature and distortion curves of light having wavelengths of 611 nm,525nm and 460nm, respectively, after passing through the projection lens, where S is the field curvature in the sagittal direction and T is the field curvature in the meridional direction, and as can be seen from fig. 21, the projection lens has a smaller field curvature.
As can be seen from fig. 22, the distortion of the projection lens is less than 3%, the distortion is small, the imaging quality is high, and the displayed image projected by the projection lens is not distorted.
Fig. 23 is a graph showing the relative illuminance of a projection lens according to another embodiment of the present application.
Fig. 23 shows a graph of the relative illuminance of 460nm light passing through the projection lens, and as can be seen from fig. 23, the relative illuminance of the projection lens is greater than 90%, the projection lens has a large luminous flux, and the brightness of the display image projected through the projection lens is very uniform.
In the description of the embodiments of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, indirectly connected through an intermediary, or may be in communication with each other between two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances. The terms "first," "second," "third," "fourth," and the like, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the embodiments of the present application, and are not limited thereto; although embodiments of the present application have been described in detail with reference to the foregoing embodiments, it will be appreciated by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims (13)

1. A projection lens, characterized by comprising a first lens group, wherein the first lens group comprises a first lens and a second lens, the projection lens further comprises a third lens and a second lens group, the second lens group comprises one or more fourth lenses, and the first lens, the second lens, the third lens and the fourth lenses of the second lens group are sequentially arranged from a projection side to a pixel side along the direction of an optical axis;
the focal length f1 of the first lens and the focal length f2 of the second lens satisfy the conditional expression: 2. not less than |f1/f2| not less than 1.2, and the focal length f12 of the first lens group and the focal length EFL of the projection lens meet the following conditional expression: f12/EFL is more than or equal to 5;
The focal length f3 of the third lens and the focal length EFL of the projection lens satisfy the following conditional expression: 1.5 Not less than f3/EFL not less than 0.8, wherein the focal length f4 of the second lens group and the focal length EFL of the projection lens meet the following conditional expression: 1.5 Not less than f4/EFL not less than 0.8, and the focal length f3 of the third lens and the focal length f4 of the second lens group satisfy the following conditional expression: f3> f4.
2. The projection lens according to claim 1, wherein an f# of the projection lens satisfies a conditional expression: f# is more than or equal to 0.6 and less than or equal to 1.0.
3. The projection lens according to claim 1 or 2, wherein an optical total length TTL of the projection lens and a focal length EFL of the projection lens satisfy a conditional expression: 2.5 More than or equal to TTL/EFL more than or equal to 1.5.
4. A projection lens according to any one of claims 1-3, wherein the back focal length BFL of the projection lens and the half image height of the projection lens satisfy the following conditional expression: 1.4 More than or equal to BFL/IH more than or equal to 0.6.
5. The projection lens of any one of claims 1-4, wherein the abbe number Vd1 of the first lens satisfies the following conditional expression: vd1 is more than or equal to 52, and Abbe number Vd2 of the second lens meets the following conditional expression: vd2 is less than or equal to 30, and the Abbe number Vd1 of the first lens and the Abbe number Vd2 of the second lens meet the conditional expression: vd1/Vd2 is more than or equal to 1.8.
6. The projection lens of any of claims 1-5 wherein the first lens and the second lens are plastic lenses and the third lens and the fourth lens are glass lenses.
7. The projection lens of claim 6 wherein the first and second lenses are aspheric lenses and the third and fourth lenses are spherical lenses.
8. The projection lens of any of claims 1-7 wherein the first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has positive optical power.
9. The projection lens according to any one of claims 1 to 8, wherein a surface of the first lens facing the projection side is convex at least in a portion corresponding to the optical axis, and a surface of the first lens facing the pixel side is convex at least in a portion corresponding to the optical axis;
the surface of the second lens facing the projection side is at least a convex surface corresponding to the optical axis, and the surface of the second lens facing the pixel side is at least a concave surface corresponding to the optical axis;
the surface of the third lens facing the projection side is at least concave, and the surface of the third lens facing the pixel side is at least convex;
The surface of the fourth lens facing the projection side is at least a convex surface corresponding to the optical axis, and the surface of the fourth lens facing the pixel side is at least a concave surface corresponding to the optical axis.
10. The projection lens of any of claims 1-9 further comprising a diaphragm positioned between the second optic and the third optic.
11. A projection device comprising at least an image display module and a projection lens according to any one of claims 1-9;
the projection surface of the image display module is opposite to the fourth lens on the side, closest to the pixel, of the projection lens, and the image display module is configured to form a display image and transmit the display image to the projection lens through the projection surface.
12. The projection device of claim 11, wherein the image display module includes a chip and a plurality of micro light emitting diodes arrayed across the chip.
13. A vehicle comprising at least a vehicle body and a projection device according to claim 11 or 12, said projection device being arranged on said vehicle body.
CN202211186811.6A 2022-09-27 2022-09-27 Projection lens, projection device and vehicle Pending CN117784361A (en)

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Publication number Priority date Publication date Assignee Title
CN101387736B (en) * 2007-09-13 2012-05-23 鸿富锦精密工业（深圳）有限公司 Projecting lens
TW201137497A (en) * 2010-04-30 2011-11-01 E Pin Optical Industry Co Ltd Four-piece projection lens system and the projection apparatus using the same
JP2012027420A (en) * 2010-07-28 2012-02-09 Konica Minolta Opto Inc Projection optical system and projection device
JP2017161562A (en) * 2016-03-07 2017-09-14 コニカミノルタ株式会社 Optical element, illumination optical unit and illumination device
US10459194B2 (en) * 2018-03-26 2019-10-29 Newmax Technology Co., Ltd. Four-piece infrared single wavelength projection lens system
CN110727079B (en) * 2018-07-16 2021-10-19 宁波舜宇车载光学技术有限公司 Optical lens
CN112882211B (en) * 2021-01-18 2021-12-07 广东烨嘉光电科技股份有限公司 Large-aperture four-piece optical lens
CN114280758B (en) * 2021-02-07 2024-06-25 宁波舜宇车载光学技术有限公司 Optical lens and electronic device

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