CN218896250U - Projection lens - Google Patents
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- CN218896250U CN218896250U CN202223406294.7U CN202223406294U CN218896250U CN 218896250 U CN218896250 U CN 218896250U CN 202223406294 U CN202223406294 U CN 202223406294U CN 218896250 U CN218896250 U CN 218896250U
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
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Abstract
The utility model discloses a projection lens, which sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a color combining prism from an object side to an image side along an optical axis; the first lens has positive optical power, the second lens has negative optical power, the third lens has negative optical power, and the fourth lens has positive optical power; the color combining prism comprises four right-angle prisms which are perpendicular to each other, and the midpoints formed by converging the four right-angle prisms are positioned on the optical axis;the effective focal length of the projection lens is EFL, and the distance from the projection lens along the diaphragm surface to the optical axis of the image source surface of the projection lens is TTL, so that the following conditions are satisfied:
the four lenses are sequentially arranged and matched with the arrangement mode that the color combining prism consists of four right-angle prisms, so that the large view field and the large clear aperture of the color lens under the condition of small volume are realized, and the near-eye display effect of the projection equipment is further improved.
Description
Technical Field
The present disclosure relates to optical lenses, and particularly to a projection lens.
Background
At present, with the continuous progress of technology, interactive devices such as augmented reality (Augmented Reality) are gradually developed, and the application range of projection lenses is also wider and wider. The AR equipment projects a virtual display image to human eyes through a near-eye display device, so that a user can receive information of a real world and information of a virtual world at the same time, and ultra-sensory visual experience is obtained; conventional projection schemes based on active luminous display sources of liquid crystal display (Liquid CrystalDisplay, LCD) screens and Organic Light-Emitting Diode (OLED) screens, and projection schemes based on passive luminous display sources of liquid crystal on silicon (LiquidCrystal On Silicon, LCOS) screens and digital Light processing (Digital LightProcessing, DLP) screens are generally large in size, heavy in weight and poor in comfort for users to wear for a long time. So Micro LED screen is as a novel high-brightness miniaturized luminous display source equipment, uses Micro LED screen as the projection scheme of luminous display source to realize light-weighted, portable comfortable wearing experience more easily, more receives user's favor.
However, the existing projection lens on the market still cannot meet the requirements of large Field of View and light weight, the micro led micro display screen mainly comprises single red (R), single green (G) and single blue (B), the adaptive monochromatic projection lens is provided for users to be more close to the real world color augmented reality display effect to be enhanced, the existing micro led color scheme is large in size and low in light efficiency, and the large FOV (Field of View) is provided under the acceptable comfortable wearing volume of the users to be improved, so that the near-eye display effect is still required to be improved.
Accordingly, the prior art is still in need of improvement and development.
Disclosure of Invention
The utility model aims to solve the technical problems of the prior art, provides a projection lens, and aims to solve the problems that the near-to-eye display effect of AR projection equipment is to be improved in the prior art.
The technical scheme adopted for solving the technical problems is as follows:
a projection lens, wherein the projection lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a color combining prism from an object side to an image side along an optical axis;
the first lens has positive optical power, the second lens has negative optical power, the third lens has negative optical power, and the fourth lens has positive optical power;
the color combining prism comprises four right-angle prisms which are perpendicular to each other, and the midpoints formed by converging the four right-angle prisms are positioned on the optical axis;
the projection lens satisfies the following inequality:
wherein EFL is the effective focal length of the projection lens, and TTL is the distance from the projection lens along the aperture surface to the optical axis of the image source surface of the projection lens.
In one implementation, the method further comprises:
a diaphragm which is positioned at one side of the first lens, which is away from the second lens, and is provided with a diaphragm surface arranged on an optical axis;
the projection lens satisfies the following conditions:
wherein EPD is the diameter of the light passing hole of the diaphragm.
In one implementation, the projection lens further includes:
the first display screen is arranged on the optical axis and is positioned at one side of the color combining prism, which is away from the fourth lens, and the first display screen comprises an image source surface;
the second display screen is positioned at one side of the color combining prism;
the third display screen is positioned at the other side of the color combining prism;
the second display screen and the third display screen are oppositely arranged, and the first display screen is close to one end of the second display screen, which is away from the fourth lens, and the third display screen is close to one end of the second display screen, which is away from the fourth lens.
In one implementation, the projection lens satisfies:
wherein BACK is the distance between the surface of the fourth lens facing the image side and the optical axis of the image source surface, and CT5 is the center thickness of the color combining prism; the following is also satisfied:
wherein, CT1 is the center thickness of the first lens, CT2 is the center thickness of the second lens, CT3 is the center thickness of the third lens, and CT4 is the center thickness of the fourth lens.
In one implementation, the projection lens satisfies:
1.74≤n 1 ≤1.96，30≤VD 1 ≤50；
1.5≤n 2 ≤1.6，50≤VD 2 ≤60；
1.61≤n 3 ≤1.68，19≤VD 3 ≤26；
1.5≤n 4 ≤1.6，50≤VD 4 ≤60；
wherein n is 1 To be the instituteRefractive index, VD of the first lens 1 Is the Abbe number of the first lens, wherein n 2 For the refractive index of the second lens, VD 2 Is the Abbe number of the second lens, wherein n 3 For the refractive index of the third lens, VD 3 Is the Abbe number of the third lens, wherein n 4 For the refractive index of the fourth lens, VD 4 Is the abbe number of the fourth lens.
In one implementation, the projection lens satisfies:
c 11 less than or equal to 0; and/or the number of the groups of groups,
c 12 less than or equal to 0; and/or the number of the groups of groups,
c 21 not less than 0; and/or the number of the groups of groups,
c 22 ≥0；
wherein c 11 C is the curvature of the surface center point of the first lens towards the object side 12 A curvature of a surface center point of the first lens toward the image side, wherein c 21 C is the curvature of the surface center point of the second lens towards the object side 22 Is the curvature of the surface center point of the second lens toward the image side.
In one implementation, the projection lens satisfies:
f1/EFL is more than or equal to 0.8 and less than or equal to 1.3; and/or the number of the groups of groups,
-12 < f2/EFL < 6; and/or the number of the groups of groups,
-2 < f3/EFL < 0.5; and/or the number of the groups of groups,
0.4≤f4/EFL≤2；
wherein f1 is an effective focal length of the first lens, f2 is an effective focal length of the second lens, f3 is an effective focal length of the third lens, and f4 is an effective focal length of the fourth lens.
In one implementation, the projection lens satisfies:
3.6≤TTL/(I mgh * 2) Less than or equal to 4.5; and/or the number of the groups of groups,
24°≤D FOV not more than 34 degrees; and/or the number of the groups of groups,
0.15≤(CT 23 +CT 34 )/TOTL≤0.25；
wherein I is mgh Is one half of the diagonal length in the effective projection area of the image source surface, D FOV CT for the angle of view of the projection lens along the diagonal direction 23 CT is the distance between the center point of the surface of the second lens facing the image side and the center point of the surface of the third lens facing the object side 34 The TOTL is the distance between the center point of the surface of the first lens facing the object side and the center point of the surface of the fourth lens facing the image side, which is the distance between the center point of the surface of the third lens facing the image side and the center point of the surface of the fourth lens facing the object side.
In one implementation, the projection lens satisfies:
wherein, wherein c 31 C is the curvature of the surface center point of the third lens towards the object side 32 Is the curvature of the surface center point of the third lens toward the image side.
In one implementation, the first lens, the second lens, the third lens, and the fourth lens are all aspheric lenses;
a first optical film is arranged on a first diagonal surface formed by the four right-angle prisms and used for transmitting blue light and green light and reflecting red light;
and a second optical film is arranged on a second diagonal surface formed by the four right-angle prisms and used for transmitting blue light and green light and reflecting red light.
The beneficial effects are that: the utility model provides a projection lens, which sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a color combining prism from an object side to an image side along an optical axis; the first lens has positive optical power, the second lens has negative optical power, the third lens has negative optical power, andthe fourth lens has positive focal power; the color combining prism comprises four right-angle prisms which are perpendicular to each other, and the midpoints formed by converging the four right-angle prisms are positioned on the optical axis; the effective focal length of the projection lens is EFL, and the distance from the projection lens to the optical axis in the image side direction along the object is TTL, which satisfies the following conditions:
the four lenses are sequentially arranged and matched with the arrangement mode that the color combining prism consists of four right-angle prisms, so that the large view field and the large clear aperture of the color lens under the condition of small volume are realized, and the near-eye display effect of the projection equipment is further improved. />
Drawings
FIG. 1 is a schematic view of a projection lens according to the present utility model;
FIG. 2 is a schematic diagram of a color combining prism and a red, green and blue micro display screen according to the present utility model;
FIG. 3 is a schematic view of a light path of a color combination of a projection lens according to the present utility model;
FIG. 4 is a graph showing the modulation transfer function of a projection lens according to the present utility model;
FIG. 5 is a diagram of field curvature and distortion of a projection lens of the present utility model;
FIG. 6 is an axial chromatic aberration diagram of a projection lens according to the present utility model;
FIG. 7 is a vertical axis color difference chart of the projection lens of the present utility model;
FIG. 8 is a graph of relative illuminance of a projection lens according to the present utility model;
FIG. 9 is a spectral distribution of a light source of a red, green and blue micro display according to the present utility model;
FIG. 10 is a graph showing the transmittance of a first diagonal plane of the blue-green light-transmissive red light-reflective film layer according to the present utility model;
FIG. 11 is a graph showing the transmittance of a second diagonal plane red-green-transmitted reflective blue-light film according to the present utility model.
Reference numerals illustrate:
10-a first lens; 20-a second lens; 30-a third lens; 40-a fourth lens; 50-a color combining prism; 51-a first diagonal; 52-a second diagonal; 60-diaphragm; 71-a first display screen; 72-a second display screen; 73-third display screen.
Detailed Description
The present utility model provides a projection lens, and the present utility model will be further described in detail below in order to make the objects, technical solutions and effects of the present utility model more clear and definite. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.
It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It should also be noted that in the drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that, if there is an azimuth or positional relationship indicated by terms such as "upper", "lower", "left", "right", etc., based on the azimuth or positional relationship shown in the drawings, it is only for convenience of describing the present utility model and simplifying the description, but it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and thus, terms describing the positional relationship in the drawings are merely for exemplary illustration and are not to be construed as limitations of the present patent, and specific meanings of the terms described above may be understood by those skilled in the art according to specific circumstances.
At present, the schemes of the augmented reality near-to-eye display device are various, and the traditional projection schemes based on active luminous display sources of an LCD screen and an OLED screen and the traditional projection schemes based on passive luminous display sources of an LCOS screen and a DLP screen are large in size and heavy in weight, so that the augmented reality near-to-eye display device is unfavorable for users to wear for a long time in a comfortable mode. At the same time, users prefer to display virtual pictures with wider fields of View, and it is difficult for the AR projection scheme on the market to balance between large FOV (Field of View) and high image quality, small volume, low cost, and high brightness. As a novel high-brightness miniaturized light-emitting display source device, a micro led screen needs to be matched with a projection lens with a large view field, light weight and reasonable cost, and realizes light weight and portable comfortable wearing experience while providing a high-quality and high-brightness virtual image for a user. At present, micro led micro display screens on the market are single red (R), single green (G) and single blue (B), and an adaptive monochromatic projection lens cannot provide a color augmented reality display effect which is closer to the real world for users, and the existing micro led color schemes have large volume and low light efficiency, and cannot provide a large FOV (Field of View) under the acceptable comfortable wearing volume of users, so that the color augmented reality display effect with high image quality and high brightness is achieved.
In order to solve the problems, the utility model provides a projection lens, which can realize the color projection display of a single red (R), single green (G) and single blue (B) micro LED screen, can provide large-view-field, large-clear-aperture and high-image-quality color augmented reality projection under a small volume, and is beneficial to further improving the experience of the near-eye display effect of the current user augmented reality equipment; as shown in fig. 1 or 2, the optical lens assembly includes, in order from an object side to an image side along an optical axis, a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and a color combining prism 50 for projection imaging;
the first lens 10 has positive optical power, the second lens 20 has negative optical power, the third lens 30 has negative optical power, and the fourth lens 40 has positive optical power;
the color combining prism 50 comprises four right-angle prisms which are perpendicular to each other, and the midpoints formed by the convergence of the four right-angle prisms are positioned on the optical axis;
the effective focal length of the projection lens is EFL, and the distance from the projection lens along the object to the optical axis in the image side direction is TTL (i.e. the distance from the aperture surface of the projection lens to the image source surface of the projection lens on the optical axis), which satisfies the following conditions:
it is worth to describe that the path of the projection light from the center point of the image source to the center point of the diaphragm is called as the optical axis, and the optical path in the projection lens is shown in fig. 2, and five lenses are sequentially arranged on the optical axis, so that the near-to-eye display effect of the current user augmented reality equipment is improved based on the large field of view, large clear aperture and high-image-quality color augmented reality projection of a single red (R), single green (G) and single blue (B) micro LED screen under a small volume.
Specifically, the outgoing side of the diaphragm 60 is the object side (e.g., left side in fig. 1) of the projection lens, the image source side of the projection lens is the image side (e.g., right side in fig. 1), the vertical line of the diaphragm 60 in fig. 1 is the diaphragm plane, the horizontal line of the vertical line is used to limit light transmission, and the vertical plane of the first display screen 71 in the right side in fig. 1 is the image source plane.
In the preferred embodiment of the projection lens, by adopting the technical scheme, the four lenses are sequentially arranged and matched with the arrangement mode of the color combining prism formed by the four right-angle prisms, the large view field and the large clear aperture of the color lens under the condition of small volume are realized, and the near-to-eye display effect of the projection device is further improved.
In a preferred embodiment of the present utility model, as shown in fig. 1, the projection lens further includes:
a diaphragm 60 located on a side of the first lens 10 facing away from the second lens 20, the diaphragm 60 having a diaphragm surface disposed on an optical axis;
the diameter of the light passing hole of the diaphragm 60 is EPD, and the projection lens satisfies:
in a preferred embodiment of the present utility model, the projection lens is configured to receive a projection light emitted by the display unit, and the projection light is directed to the diaphragm through the projection lens; as shown in fig. 1 or 2, the display unit includes:
the first display screen 71 is disposed on the optical axis and is located at a side of the color combining prism 50 away from the fourth lens 40, and the first display screen 71 includes an image source surface;
a second display screen 72 located at one side of the color combining prism 50;
a third display screen 73 located at the other side of the color combining prism 50;
the second display screen 72 is disposed opposite to the third display screen 73, and the first display screen is close to the second display screen 72 and the third display screen 73 and is away from one end of the fourth lens 40.
Specifically, a first optical film is disposed on a first diagonal surface 51 formed by the four right-angle prisms, and is used for transmitting blue light and green light and reflecting red light;
a second optical film is disposed on a second diagonal surface 52 formed by the four right angle prisms, and is used for transmitting blue light and green light and reflecting red light.
It should be noted that, the color projection lens uses three micro-display screens of red (R), green (G) and blue (B) as light sources (i.e. display units), and the color is projected by the subsequent optical lens after being combined by the color combining prism 50 to achieve the color display effect. The relative positions of the micro led red (R) (i.e., the second display screen 72), green (G) (i.e., the first display screen 71), and blue (B) micro display screen (i.e., the third display screen 73) are shown in fig. 2, and the spectral distribution is shown in fig. 9.
The color combining prism is formed by gluing four right-angle prisms plated with specific optical films, the four right-angle prisms are glued to form two mutually perpendicular diagonal surfaces, one diagonal surface (namely a first diagonal surface 51) is plated with an optical film which transmits blue light and green light and reflects red light, and the transmittance curve of the diagonal surface 1 film (namely the first optical film) is shown in fig. 10; the other diagonal surface 2 (i.e., second diagonal surface 52) is coated with an optical film that transmits red light and green light and reflects blue light, and the transmittance curve of the diagonal surface 2 film (i.e., second optical film) is shown in fig. 11. The monochromatic images of the red (R) 72, the green (G) 71 and the blue (B) 73 micro display screen are overlapped and combined after passing through the film plating diagonal surface 1 (namely the first optical film) and the film plating diagonal surface 2 (namely the second optical film), and then are projected through the rear optical lens to realize the color display effect.
The diaphragm 60 of the optical system is positioned in front of the first lens 10, and sequentially comprises a diaphragm, a first lens, a second lens, a third lens, a fourth lens, a color combining prism and an image source surface.
In this embodiment, the first lens, the second lens, the third lens, and the fourth lens are all aspherical lenses.
In this embodiment, the surface of the first lens element 10 facing the object side is concave, and the surface facing the image side is convex; the surface of the second lens 20 facing the object side is convex, and the surface facing the image side is concave; the surface of the third lens 30 facing the object side is convex, and the surface facing the image side is concave; the surface of the fourth lens 40 facing the object side is convex, and the surface facing the image side is convex. The first lens 10 to the fourth lens 40 and the color combining prism 50 are arranged, and the interval between the first lens and the fourth lens is adjusted, so that the focal length of the projection lens can be adjusted, the total length of light transmission in the projection lens is reduced while clear projection is met, and the purposes of light weight and large view field are achieved; meanwhile, the cost and the space are saved.
In a preferred embodiment of the present utility model, the projection lens satisfies:
wherein BACK is the distance between the surface of the fourth lens 40 facing the image side (i.e. the center point of the lens surface) and the optical axis of the image source surface, and CT5 is the center thickness of the color combining prism; the following is also satisfied:
wherein CT1 is the center thickness of the first lens 10, CT2 is the center thickness of the second lens 20, CT3 is the center thickness of the third lens 30, and CT4 is the center thickness of the fourth lens 40.
In a preferred embodiment of the present utility model, the projection lens satisfies:
1.74≤n 1 ≤1.96，30≤VD 1 ≤50；
1.5≤n 2 ≤1.6，50≤VD 2 ≤60；
1.61≤n 3 ≤1.68，19≤VD 3 ≤26；
1.5≤n 4 ≤1.6，50≤VD 4 ≤60；
wherein n is 1 For the refractive index of the first lens 10, VD 1 Is the Abbe number of the first lens 10, where n 2 VD is the refractive index of the second lens 20 2 Is the Abbe number of the second lens 20, where n 3 For the refractive index of the third lens 30, VD 3 Is the Abbe number of the third lens 30, where n 4 VD is the refractive index of the fourth lens 40 4 An abbe number of the fourth lens 40.
In a preferred embodiment of the present utility model, the projection lens satisfies:
c 11 less than or equal to 0; and/or the number of the groups of groups,
c 12 less than or equal to 0; and/or the number of the groups of groups,
c 21 not less than 0; and/or the number of the groups of groups,
c 22 ≥0；
wherein c 11 C, which is the curvature of the surface center point of the first lens 10 toward the object side 12 A curvature of a surface center point of the first lens 10 toward the image side, where c 21 C, which is the curvature of the surface center point of the second lens 20 toward the object side 22 Is the curvature of the surface center point of the second lens 20 toward the image side.
In a preferred embodiment of the present utility model, the projection lens satisfies:
f1/EFL is more than or equal to 0.8 and less than or equal to 1.3; and/or the number of the groups of groups,
-12 < f2/EFL < 6; and/or the number of the groups of groups,
-2 < f3/EFL < 0.5; and/or the number of the groups of groups,
0.4≤f4/EFL≤2；
wherein f1 is the effective focal length of the first lens 10, f2 is the effective focal length of the second lens 20, f3 is the effective focal length of the third lens 30, and f4 is the effective focal length of the fourth lens 40.
In a preferred embodiment of the present utility model, the projection lens satisfies:
3.6≤TTL/(I mgh * 2) Less than or equal to 4.5; and/or the number of the groups of groups,
24°≤D FOV not more than 34 degrees; and/or the number of the groups of groups,
0.15≤(CT 23 +CT 34 )/TOTL≤0.25；
wherein I is mgh Is one half of the diagonal length in the effective projection area of the image source surface, D FOV CT for the angle of view of the projection lens along the diagonal direction 23 CT is the distance between the center point of the surface of the second lens 20 facing the image side and the center point of the surface of the third lens 30 facing the object side 34 The TOTL is the distance between the center point of the surface of the third lens element 30 facing the image side and the center point of the surface of the fourth lens element 40 facing the object side, and the center point of the surface of the first lens element 10 facing the object side and the center point of the surface of the fourth lens element 40 facing the image side.
In a preferred embodiment of the present utility model, the projection lens satisfies:
wherein, wherein c 31 C, which is the curvature of the surface center point of the third lens 30 toward the object side 32 Is the curvature of the surface center point of the third lens 30 toward the image side.
Specifically, the detailed parameters of the optical performance of each lens surface in the projection lens are shown in table 1;
table 1:
table 2 shows the system parameters of the projection lens in summary in this embodiment.
Table 2:
| TTL | 13.56mm |
| I mgh | 1.655 |
| D | |
| FOV | 30° |
as shown in fig. 4, the abscissa is the spatial frequency (period/mm) and the ordinate is the mode of OTF, and it can be seen from fig. 4 that the projection lens of the present embodiment has a modulation transfer function value between 0.6 and 1.0 for light rays with wavelengths ranging from 0.4360 micrometers to 0.6560 micrometers, and the spatial frequency is between 0lp/mm and 125 lp/mm.
As can be seen from the left side of fig. 5, the projection lens of the present embodiment has a curvature of field between-0.028 mm and 0.039 mm for light rays having wavelengths of 0.6560 microns, 0.5876 microns, 0.5460 microns, 0.4850 microns and 0.4360 microns, and in the meridian (tangnosial) direction and the Sagittal (Sagittal) direction. As can be seen from the right side of fig. 5, the distortion of the projection lens of this embodiment is between-0.95% and 0% for light having wavelengths of 0.6560 microns, 0.5876 microns, 0.5460 microns, 0.4850 microns and 0.4360 microns.
As can be seen from fig. 6, the projection lens of the present embodiment has axial chromatic aberration values between-10 microns and 30 microns for light rays with wavelengths of 0.656 microns, 0.588 microns, 0.546 microns, 0.485 microns and 0.436 microns.
As can be seen from fig. 7, the projection lens of the present embodiment has a paraxial color difference value between-1 micron and 3 microns for light rays with wavelengths of 0.6560 microns, 0.5876 microns, 0.5460 microns, 0.4850 microns and 0.4360 microns at different field heights.
As can be seen from fig. 8, the projection lens of the present embodiment has a Y field of 0 mm to 1.65 mm for light with a wavelength of 0.546 μm, and the relative illumination value of the projection lens is between 0.9 and 1.0.
Obviously, the curvature of field, distortion, axial chromatic aberration and vertical chromatic aberration of the projection lens of the embodiment can be effectively corrected, and the resolution and focal depth of the lens can meet the use requirements, so that better optical performance can be obtained. The projection lens disclosed by the embodiment can achieve the effects of large field of view, large clear aperture, small volume and high image quality.
In summary, the present utility model provides a projection lens including, in order from an object side to an image side along an optical axis, a first lens element, a second lens element, a third lens element, a fourth lens element and a color combining prism; the first lens has positive optical power, the second lens has negative optical power, the third lens has negative optical power, and the fourth lens has positive optical power; the color combining prism comprises four right-angle prisms which are perpendicular to each other, and the midpoints formed by converging the four right-angle prisms are positioned on the optical axis; the effective focal length of the projection lens is EFL, and the distance from the projection lens along the diaphragm surface to the optical axis of the image source surface of the projection lens is TTL, so that the following conditions are satisfied:
the utility model realizes large view field and large clear aperture of the color lens under small volume by arranging the four lenses in sequence and matching with the arrangement mode formed by the color combining prism and the four right angle prisms, thereby improving the near-eye display effect of the projection equipment
It is to be understood that the utility model is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.
Claims (10)
1. The projection lens is characterized by sequentially comprising a first lens, a second lens, a third lens, a fourth lens and a color combining prism from an object side to an image side along an optical axis;
the first lens has positive optical power, the second lens has negative optical power, the third lens has negative optical power, and the fourth lens has positive optical power;
the color combining prism comprises four right-angle prisms which are perpendicular to each other, and the midpoints formed by converging the four right-angle prisms are positioned on the optical axis;
the projection lens satisfies the following inequality:
wherein EFL is the effective focal length of the projection lens, and TTL is the distance from the projection lens along the aperture surface to the optical axis of the image source surface of the projection lens.
2. The projection lens of claim 1 further comprising:
a diaphragm which is positioned at one side of the first lens, which is away from the second lens, and is provided with a diaphragm surface arranged on an optical axis;
the projection lens satisfies:
wherein EPD is the diameter of the light passing hole of the diaphragm.
3. The projection lens of claim 2 wherein the projection lens further comprises:
the first display screen is arranged on the optical axis and is positioned at one side of the color combining prism, which is away from the fourth lens, and the first display screen comprises an image source surface;
the second display screen is positioned at one side of the color combining prism;
the third display screen is positioned at the other side of the color combining prism;
the second display screen and the third display screen are oppositely arranged, and the first display screen is close to the second display screen and the third display screen and is away from one end of the fourth lens.
4. A projection lens according to claim 3, wherein the projection lens satisfies:
wherein BACK is the distance between the surface of the fourth lens facing the image side and the optical axis of the image source surface, and CT5 is the center thickness of the color combining prism; the following is also satisfied:
wherein, CT1 is the center thickness of the first lens, CT2 is the center thickness of the second lens, CT3 is the center thickness of the third lens, and CT4 is the center thickness of the fourth lens.
5. The projection lens of claim 1 wherein the projection lens satisfies:
1.74≤n 1 ≤1.96，30≤VD 1 ≤50；
1.5≤n 2 ≤1.6，50≤VD 2 ≤60；
1.61≤n 3 ≤1.68，19≤VD 3 ≤26；
1.5≤n 4 ≤1.6，50≤VD 4 ≤60；
wherein n is 1 For the refractive index of the first lens, VD 1 Is the Abbe number of the first lens, wherein n 2 For the refractive index of the second lens, VD 2 Is the Abbe number of the second lens, wherein n 3 For the refractive index of the third lens, VD 3 Is the Abbe number of the third lens, wherein n 4 For the refractive index of the fourth lens, VD 4 Is the abbe number of the fourth lens.
6. The projection lens of claim 1 wherein the projection lens satisfies:
c 11 less than or equal to 0; and/or the number of the groups of groups,
c 12 less than or equal to 0; and/or the number of the groups of groups,
c 21 not less than 0; and/or the number of the groups of groups,
c 22 ≥0；
wherein c 11 C is the curvature of the surface center point of the first lens towards the object side 12 A curvature of a surface center point of the first lens toward the image side, wherein c 21 C is the curvature of the surface center point of the second lens towards the object side 22 Is the curvature of the surface center point of the second lens toward the image side.
7. The projection lens of claim 1 wherein the projection lens satisfies:
f1/EFL is more than or equal to 0.8 and less than or equal to 1.3; and/or the number of the groups of groups,
-12 < f2/EFL < 6; and/or the number of the groups of groups,
-2 < f3/EFL < 0.5; and/or the number of the groups of groups,
0.4≤f4/EFL≤2；
wherein f1 is an effective focal length of the first lens, f2 is an effective focal length of the second lens, f3 is an effective focal length of the third lens, and f4 is an effective focal length of the fourth lens.
8. A projection lens according to claim 3, wherein the projection lens satisfies:
3.6≤TTL/(I mgh * 2) Less than or equal to 4.5; and/or the number of the groups of groups,
24°≤D FOV not more than 34 degrees; and/or the number of the groups of groups,
0.15≤(CT 23 +CT 34 )/TOTL≤0.25；
wherein I is mgh Is one half of the diagonal length in the effective projection area of the image source surface, D FOV CT for the angle of view of the projection lens in the diagonal direction 23 CT is the distance between the center point of the surface of the second lens facing the image side and the center point of the surface of the third lens facing the object side 34 The TOTL is the distance between the center point of the surface of the first lens facing the object side and the center point of the surface of the fourth lens facing the image side, which is the distance between the center point of the surface of the third lens facing the image side and the center point of the surface of the fourth lens facing the object side.
9. The projection lens of claim 6 wherein the projection lens satisfies:
wherein, wherein c 31 In a surface of the third lens facing the object sideCurvature of heart point c 32 Is the curvature of the surface center point of the third lens toward the image side.
10. The projection lens of claim 3 wherein the first lens, the second lens, the third lens and the fourth lens are all aspheric lenses;
a first optical film is arranged on a first diagonal surface formed by the four right-angle prisms and used for transmitting blue light and green light and reflecting red light;
and a second optical film is arranged on a second diagonal surface formed by the four right-angle prisms and used for transmitting blue light and green light and reflecting red light.
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| CN202223406294.7U CN218896250U (en) | 2022-12-15 | 2022-12-15 | Projection lens |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202223406294.7U CN218896250U (en) | 2022-12-15 | 2022-12-15 | Projection lens |
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| CN218896250U true CN218896250U (en) | 2023-04-21 |
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